Lionel Edward Aston Rowson, O.B.E. 28 May 1914 −− 26...

July 1989: Elected F.R.S. 1973 26−−Lionel Edward Aston Rowson, O.B.E. 28 May 1914

Christopher Polge

, 483-497, published 1 November 2000462000 Biogr. Mems Fell. R. Soc.

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LIONEL EDWARD ASTON ROWSON, O.B.E.

28 May 1914 — 26 July 1989

Biog. Mems Fell. R. Soc. Lond. 46, 483–497 (2000)

on May 5, 2018http://rsbm.royalsocietypublishing.org/Downloaded from


LIONEL EDWARD ASTON ROWSON, O.B.E.

28 May 1914 — 26 July 1989

Elected F.R.S. 1973

B C P, C.B.E., F.R.S.

The Willows, 137 Waterbeach Road, Landbeach, Cambridge CB4 8EA, UK

L.E.A. Rowson was always known as Tim to his family, friends and colleagues alike. He was aveterinary surgeon who made important contributions to research in reproductive physiologyin farm animals and its application to animal breeding. In particular, he was a pioneer ofartificial insemination (AI) and embryo transfer, which have become two of the mostimportant technologies for livestock improvement in modern times.

He was appointed Director of the first AI centre for cattle breeding in Britain, establishedat Cambridge in 1942, and played a leading role in the application and rapid growth of thistechnology. In 1952 he contributed to the development of successful methods for the freezingand long-term storage of bull semen at very low temperatures. This had far-reachingconsequences for the future of AI and cattle breeding worldwide.

For thirty years he also worked at the Animal Research Station in Cambridge on methodsfor embryo transfer in sheep and cattle and their use in research and breeding. Thisculminated in the 1970s with the development of effective methods for collection and transferof cattle embryos by non-surgical means. The birth of the first calf after transfer of a deep-frozen embryo in 1973 was another landmark, and these advances led quite quickly to thecommercial application of embryo transfer in cattle breeding.

Tim Rowson is generally regarded as the founder of embryo transfer in farm animals, butimportant contributions were made by many collaborators. He always considered that he wasprivileged during his early years to have worked with Dr John (later Sir John) Hammond,F.R.S., who maintained that the function of applied science was to synthesize the detailedknowledge gained from fundamental research into a constructive whole so that it could beused for a specific purpose. Tim was a true disciple of this philosophy and always tried torelate a fundamental approach to a practical outcome.

485 © 2000 The Royal Society



486 Biographical Memoirs

B

Tim was born at Docksey in Stafford on 28 May 1914; he had two sisters, both older thanhimself. His father, Lionel Frederick Rowson, L.D.S., was a dental surgeon in private practice,who also had a keen interest in anaesthetics for use in dental surgery. He developed a newanaesthetic and for this was awarded the Charles Green Memorial Medal. Tim’s mother,Maude Aston, was a member of the well-known Aston family of that region. She was born atAshley in Staffordshire, but earlier generations of the family had lived at Tixall HallGatehouse, which has historical associations with Mary Queen of Scots.

Tim never knew his father, who died from an infection after a golfing accident when Timwas only six weeks old. This left the family with very little money. Tim recalled that his earlylife was ‘a bit of a struggle’, but this is probably an understatement because he also said heremembered sometimes walking to school with holes in his shoes and with just a bun in hispocket for lunch. His mother was a very determined character and kept the family going byschool-teaching. She encouraged Tim in his education and he attended King Edward VIthSchool in Stafford from the age of eight until he was nineteen. He worked hard and must havebeen proficient academically, but he also excelled in football and cricket. He was even offereda trial for Aston Villa Football Club, which he declined because he wanted to study veterinaryscience. His wish to become a vet probably stemmed from working on an uncle’s farm duringthe summer holidays. Several of his relatives had farms around Stafford and thus hedeveloped his interest in animals. However, entrance to a veterinary school in those days was aproblem because the family could not afford the fees. His mother, with her indomitablecharacter, therefore went to London to the Royal Veterinary College, where she persuadedthem to accept him on a scholarship. He obtained a County Major Scholarship to the RoyalVeterinary College in 1933 and so was able to pursue his chosen career. Tim was the firstperson to enter the Veterinary College in this way.

After qualifying M.R.C.V.S. in 1938, he joined Mr A.B. Forsyth’s practice in Cannock,Staffordshire, where he enjoyed two or three years in private practice. The pace of life wasmore leisurely in those days and, because he loved horse riding, he would often attend nearbycases on horseback. It was here that he met his future wife, Audrey Kathleen Foster, seconddaughter of Mr and Mrs H. Foster of Melbourne House, Cannock. Henry Foster was aMaster Baker and ran a successful business. Audrey had seen this good-looking young vetriding past the house and asked to be introduced. They were married on 8 January 1942. Bythis time Tim was working in Cambridge and they moved to the village of Histon, nearCambridge, in 1946. They had four children.

Tim came to Cambridge in 1940 because, soon after the outbreak of World War II, he wasappointed as a Sterility Investigation Officer for the Ministry of Agriculture and worked fromthe Pathology Laboratories on the Downing site. When the AI Centre was established in 1942he became Veterinary Officer in Charge and this marked the beginning of Tim’s career inanimal reproduction and research.

T C AI C

Much experimental work on AI and storage of semen in laboratory and farm animals hadbeen performed at Cambridge during the 1930s by Dr Arthur Walton in Hammond’s



Lionel Edward Aston Rowson 487

laboratory. Hammond had long been an ardent proponent of AI as a means for livestockimprovement and, in the years before the outbreak of World War II, he, Walton and JosephEdwards campaigned hard for official sanction and financial assistance to start an AI servicefor cattle breeding in Britain. This was not approved and it was not until two years into thewar, and in response to an urgent need to increase home food production, that the Minister ofAgriculture finally agreed to support a scheme to develop AI. Two experimental stations wereto be set up, one at Cambridge and one at Reading, ‘to promote the study of the fieldapplication of artificial insemination in Great Britain’. These were to be under the auspices ofthe Agricultural Improvement Committee, an advisory body to the Ministry of Agriculture.The first centre to start was at Cambridge in November 1942, when the Cambridge andDistrict Cattle Breeders Society, a farmers’ cooperative, was founded. Edwards and Waltonwere members of the management committee, and Tim, already working in Cambridge forthe Ministry of Agriculture, was well placed to become the Veterinary Officer in Charge.

The early years of AI

The centre started in a very small way with just two bulls and a staff comprising Tim, astockman and an office girl. An important addition in 1943 was Pilot Officer J.A. (Jim)Henderson, a Canadian who had come to Britain with the Royal Canadian Air Force but incivilian life was one of the few veterinary surgeons with practical experience in AI. He learntthe techniques in Denmark and later ran the first AI centre started in the USA in New Jerseyin 1938. It was fortunate that he was allowed to be released to help start the work atCambridge and he stayed until the end of the war, providing invaluable assistance and advice.

A service was provided for farmers within a twenty-mile radius of Cambridge and there isno doubt that the most arduous part of the job in those first years was the large distances thathad to be covered by the veterinary staff. Tim wrote after the first year, ‘seldom will aveterinary surgeon be content to spend his life doing routine inseminations and unlessfacilities are provided for research or some other outlet few centres will keep a veterinarysurgeon for any length of time’. In fact, lay people were later licensed to performinseminations under veterinary supervision, but this gives a clue to Tim’s desire andmotivation to get into research even at that early time.

There was a lot to do at the start because it was mostly breaking new ground, the onlyprevious experience being in the early experiments of Walton’s. Two important technicalinnovations were introduced quite soon. The first was the use of a semen diluent containingegg yolk, recently shown by workers in the USA to protect sperm from damage bytemperature shock, which allowed the semen to be cooled rapidly to 5 °C and stored for threeor four days of use. The second was the development of a simple and effective method forinsemination in which the cervix was located per rectum instead of by means of a speculum.These methods became universally adopted in the further development of AI. By the end ofthe first year, 1552 cows had been inseminated and the conception rate was slightly betterthan that of normal mating. This was a great achievement and did much to bring credit to thenew technology.

Interest in AI was growing rapidly throughout Britain and other centres were soon started,either privately or on a cooperative basis. Veterinary surgeons involved in developing thesenew centres came to seek advice from Tim and he travelled widely to provide practicalassistance. He even spent one year in 1946–47 supervising the work of the Mid-Worcester AICentre (now known as Avoncroft) when it had been experiencing poor results, while




continuing to run his own centre in Cambridge. The Centre was an offshoot of AvoncroftCollege, which catered for the rehabilitation of ex-servicemen and, in addition to his job at theCentre, he lectured in veterinary science at the College. Nevertheless, after a year he was keento get back to Cambridge, where he could engage in research. In the field of AI Tim’s skills,enthusiasm and good humour earned him the recognition, respect and friendship of farmers,veterinary colleagues and scientists alike.

By 1945 eight independent centres had been established in various parts of Britain. [O.K.?]

To provide a service for the whole of England and for Wales, a national network of centreswas set up by the Milk Marketing Board and this was completed in 1951. AI flourished, andten years after it had started in Cambridge 1.25 million cows were being bred by AI each year,representing over 60% of the dairy cattle population.

Testing of progeny

Reviewing the state of AI in 1952, Tim concluded that enormous technical progress had beenmade. From the point of view of providing the farmer with an efficient, economical andeffective service for getting cows in calf without having to keep a bull, there was no doubt thatit had been an unqualified success. It had also led to the reduction of a number of diseases.By contrast, it had become evident that very little progress had been made in geneticimprovement, which was one of the main reasons for promoting AI. This had been brought tolight by Alan Robertson of Edinburgh, who compared the milk production records of 1500daughters of AI bulls with those of other heifers from non-AI bulls in the same herds in thesame year. The average production of the AI heifers was only about one gallon per lactationbetter than that of non-AI heifers. Nevertheless, there were some bulls that did increase theyields of their daughters above those of their contemporaries. To identify such bulls withconfidence, Robertson and J.M. Rendel proposed a progeny-testing scheme for use in the AIservice based on the principle of contemporary comparison. The Agricultural ResearchCouncil (ARC) helped to finance a pilot scheme, which was introduced by Tim at Cambridgein 1952. Similar progeny-testing schemes were later adopted on a much larger scale by theMilk Marketing Board. Thus, AI provided the means whereby an individual bull couldproduce a sufficiently large number of daughters for an accurate assessment of his breedingmerit in comparison with other bulls. It also provided the means for extensive use of the bestbulls once they had been identified.

Frozen semen

Survival of bull sperm after freezing in media containing glycerol and storage in solid CO2 at−79 °C had been achieved by Dr Audrey Smith and myself in 1950 when working withDr Alan (later Sir Alan) Parkes, F.R.S., at the National Institute for Medical Research inLondon. Long-term storage of semen at very low temperatures would obviously be ofenormous potential benefit to the AI industry and Parkes obtained the collaboration of D.L.Stewart at the Reading Cattle Breeding Centre and Tim at Cambridge to test the fertilizingcapacity of frozen semen. Little progress was made during the first year. One calf was born atReading but at Cambridge no pregnancies had been obtained with frozen semen. In 1951,therefore, Parkes sent me to work at Cambridge equipped with a caravan converted to amobile laboratory. Tim continued to provide enthusiastic support and during the next fewmonths modifications were made to the methods and media for treatment of semen thatresulted in much improved sperm motility after freezing and thawing. Frozen semen was then




used to inseminate thirty-eight cows and it was exciting when most of these were diagnosedpregnant and a conception rate equivalent to that from fresh semen was obtained. Furtherexperiments demonstrated that there was no reduction in the fertilizing capacity of spermduring storage for at least a year at −79 °C. These results were reported at the SecondInternational Congress on Animal Reproduction in Copenhagen in 1952. They created hugeinterest, and marked changes in the organization and application of AI were to follow. Withinten years there were few centres around the world that had not converted to frozen semen; thelater introduction of liquid nitrogen as a refrigerant led to even greater efficiency. Many yearslater, surrounded by gleaming equipment and sleek storage vessels, Tim and I gained muchamusement from thinking of the early times when ampoules of semen were frozen in flasks ofalcohol cooled slowly by adding powdered solid CO2 with a wooden spoon.

Tim was involved in many of the changes that occurred within the AI service in theensuing years, but he was also becoming progressively more interested in research and fromthe late 1940s he started to spend more and more of his time at the Animal Research Station.

TA R S

The Animal Research Station was set up in the early 1930s as a Field Station for the School ofAgriculture’s Institute of Animal Nutrition. This was where Hammond, Walton and othershad done much of their work before World War II and it was where all the early work on AIhad been performed. When the new AI centre was established, therefore, it was built less thana mile away from the Research Station. The Animal Research Station was taken over in 1946by the ARC to create a Unit of Animal Reproduction within the university under thedirection of Hammond. One of Hammond’s visions, and an important objective of the unit,was to develop embryo transfer in cattle so as to increase the reproductive potential of femaleanimals, as AI had done for males. This is what inspired Tim and set him off on the line ofresearch that he was to follow for the rest of his career. He was appointed a part-time memberof Hammond’s unit in 1950 and a few years later was awarded an O.B.E. for services toagriculture, which included arduous overseas assignments for the British government.

Hammond retired in 1954 and there was concern, expressed mainly by elements of thefarming community, that there should not be a decline in the type of work that Hammondhad been promoting. Thus, when T.R.R. Mann, F.R.S., whose research interests were mainlyin the biochemistry of semen, was appointed Director, a balance was provided on thephysiological side by the appointment of Tim and Arthur Walton as Deputy Directors. Theunit was renamed the Unit of Reproductive Physiology and Biochemistry. Walton died withina few years and Tim remained as the Deputy Director until Mann retired in 1976. It was thenmerged administratively with the Institute of Animal Physiology at Babraham, and Timbecame the Officer in Charge until he retired in 1979. During the 1960s and 1970s the Unitgrew considerably, both in number of staff and in facilities, and became the largest ARC Unitin the UK. It grew also in research output and reputation and became recognized as one ofthe leading centres in the world for research on reproduction in farm animals. This was due, inno small measure, to the influence of Tim.

Early work on embryo transfer in cattle

Around 1948, Tim became involved in some preliminary experiments in cattle withD.F. Dowling, a research student in Hammond’s laboratory, who was working also on embryo




transfer in rabbits. Together they designed a piece of apparatus for the extraction of fertilizedeggs from the living cow; it was a catheter with an inflatable cuff that could be passed throughthe cervix to flush the uterine horns. This apparatus was very much at the experimental stage,however, and work on it was dropped in favour of what seemed then to be the more pressingneeds to develop effective methods for superovulation and embryo transfer.

During the next two years, therefore, Tim worked to develop optimal methods for inducingfollicle stimulation and egg production by using pregnant mares’ serum gonadotrophin(PMSG); later he and his colleagues extended this work to superovulation in calves in an ef-fort to shorten the generation interval and to maximize the number of embryos from valuablelivestock. However, in the early 1950s little work on embryo transfer in cattle had been doneelsewhere and there was just one report of a calf born in the USA after transfer of an embryoby surgical procedures. At Cambridge, however, the objective was to develop methods forembryo transfer in cows that might be applied very simply in a commercial system akin to AI.The surgical approach was considered unsuitable for practical application and the first pur-pose was to explore possibilities of transferring embryos to the uterine horns via the cervix.

Multiple ovulations were induced in cattle with PMSG and embryos were recovered fromthe Fallopian tubes after slaughter. Not a single pregnancy was obtained, however, in cows towhich embryos had been transferred via the cervix, but it was noticed that the uterusfrequently became infected. Because embryo transfer was being performed during the earlyluteal phase of the cycle, it seemed that the uterus became extremely sensitive to infectionwhen under the influence of progesterone. This was confirmed in experiments with G.E.Lamming and it was considered that risk of infection was the main barrier to successfulembryo transfer via the cervix. A few years later, a more important reason for lack of successwas discovered. With J.P. Bennett, radioactive gold resin spheres, similar in size and density toeggs, were used to study movement within the reproductive tract. When the spheres weretransferred via the cervix to the uterus of cows three days after oestrus it was found that theywere all expelled within one or two hours. Thus the expulsion of embryos and the risk ofinfection seemed to militate against successful non-surgical embryo transfer in cattle and littleprogress was made on this problem for several years.

Embryo transfer in sheep

Tim started some other work on embryo transfer in sheep during the early 1950s. At that timeresearch budgets were quite small and facilities not well developed; it was certainly moreeconomical and convenient to work with sheep than with cattle. There had also been someearlier reports from the USA on embryo transfer in sheep, although the results had not beenparticularly good. From the start, surgical methods were used for the collection and transferof embryos because it was difficult to imagine a non-surgical approach in this species.However, Tim was a very gifted surgeon and he loved the challenge of developing new piecesof equipment and technology. The first experiment on transfer of embryos between twobreeds of sheep was with C.E. Adams, a member of staff with experience of embryo transferin rabbits, and G.L. Hunter, a research student. It was very successful. The methods that Timdeveloped for flushing embryos from the Fallopian tubes or uterine horns worked very welland the pregnancy rates achieved after embryo transfer were equivalent to those of normalmating. One factor considered important was to transfer embryos to animals that were at asimilar stage of the reproductive cycle to that of the donors, but in later experiments, designedspecifically to study the importance of synchrony, it was found that a difference of two days




either way could be tolerated without significantly reducing conception rates. The results insheep were sufficiently good to render further experiments simply on techniques unnecessary;embryo transfer could therefore be used in studies on various aspects of reproductivephysiology. Most of these studies were in collaboration with research students from Australia,New Zealand or South Africa. In the past, many students from the Commonwealth had beenattracted to Hammond’s laboratory, and Tim maintained this tradition. Through the use ofembryo transfer it was possible to study the effect of maternal size on foetal growth (withHunter and Adams) the extent of embryonic mortality at different stages of pregnancy (withN.W. Moore) and the capacity of the uterus to carry multiple foetuses (with R.A.S. Lawson).Embryo transfer was also used very effectively (with R.M. Moor (F.R.S. 1994)) in studies onfactors affecting the lifespan of the corpus luteum in sheep. Clear evidence was obtained thatthe uterus affected the lifespan of the corpus luteum in a local manner. A strong luteolyticeffect of non-pregnant endometrium on the corpus luteum could be overcome by the presenceof a developing embryo within the uterus. This work preceded by several years the discoverythat prostaglandin F2α was the uterine luteolytic factor and that the anti-luteolytic effect ofthe embryo was due to a protein identified as interferon. Some years later, Tim and hiscolleagues were among the first to use prostaglandin F2α, or its synthetic analogues, to controlreproductive cycles in cattle and horses; the ability to induce oestrous synchronization was animportant advance in the development of embryo transfer.

Some early attempts were made with R.L.W. Averill to store sheep embryos under variousconditions in vitro and a few lambs were born after the transfer of embryos stored for up toseventy-two hours, but the success rate was low. In the absence of any satisfactory culturemethod, investigations were made, with Averill and Adams, into the survival of sheepembryos in the reproductive tract of a rabbit. It was found that the embryos continued normaldevelopment for at least five or six days in the rabbit’s oviduct; this observation permitted thefirst successful export of sheep embryos, sent in rabbits from England to South Africa, in1961.

Return to work on cattle

The excellent results in sheep were in marked contrast with those in cattle, in which repeatedefforts to establish pregnancies by non-surgical embryo transfer were completely unsuccessful.In 1965, however, interest in cattle was rekindled by a published report of some work in Japanin which two pregnancies had been obtained in cows to which embryos had been transferredby a method involving minimal surgery. The anterior wall of the vagina was pierced andembryos transferred through the uterine wall to the lumen, which had been inflated with CO2.Success was attributed to the fact that the cervix had been by-passed; inflation of the uteruswith CO2 had been done merely to ensure that embryos were deposited within the lumen. Thisreport led Tim and R.M. Moor, who by then had joined the staff of the Unit after completinghis PhD, to investigate a modification of the Japanese method. Embryos were transferred viathe cervix to the uterus, which was then inflated with CO2. Three out of fourteen recipientsbecame pregnant and, although this was a low pregnancy rate, the result was significantbecause it was the first time that pregnancies had been established in cattle where embryoshad been transferred via the cervix by a completely non-surgical method. The beneficial effectof CO2 was attributed to a decrease in myometrial activity and the prevention of embryoexpulsion.

This success led to a resurgence of work on cattle; Tim’s next critical experiment, withR.M. Moor and R.A.S. Lawson, was to compare results from a non-surgical transfer of




embryos with those that could be achieved by a surgical method. Two different media werealso used for collection of embryos. This was the first time that surgical techniques had beenused for embryo transfer in cattle at Cambridge, but Tim’s extensive experience with sheepand his natural skills in surgery soon enabled him to develop effective methods. The mediaused for the collection and transfer of embryos were either homologous serum or tissueculture medium 199 (TCM 199). Homologous serum had been used in all previousexperiments on embryo transfer in cattle and was used routinely in sheep, with good success.TCM 199 was chosen as an alternative medium simply because it was readily available in thelaboratory at that time. The results were clear-cut and dramatic. No pregnancies at all wereobtained after the surgical or non-surgical transfer of embryos in serum. By contrast, withTCM 199 a few successful transfers were obtained non-surgically, but with surgical methodsfor the collection and transfer of embryos the pregnancy rate was 91%.

The use of surgical methods and appropriate media for handling the embryos proved to bea watershed in the history of embryo transfer in cattle and enabled a number of fundamentalexperiments to be performed. Tim was particularly interested in the potential of embryotransfer for the induction of twinning, to increase productivity. It was found that twinningrate was very high when one embryo was transferred to the tip of each uterine horn and wasgreater than that after the transfer of two embryos to one horn. Surgical methods were alsoused to determine the importance of the degree of synchronization of oestrus between donorand recipient animals: the requirements in cattle were found to be somewhat more acute thanthose in sheep. The high pregnancy rates achieved in these experiments were mostencouraging and paved the way towards opportunities for practical application.

Early work on the practical application of embryo transfer in cattle

In the early 1950s, the idea of using surgical techniques for embryo transfer in cattle breedinghad been largely ruled out by Tim and others on the grounds that they would be too compli-cated and expensive for large-scale application. Twenty years later, however, economic circum-stances had changed and opportunities were emerging in which surgical methods for embryotransfer on a limited scale might be contemplated. At that time cattle breeders in severalcountries were importing new breeds to improve productivity but, owing to disease regu-lations, only small numbers of animals were permitted and they were therefore very valuable.Superovulation and embryo transfer were seen as methods for rapid multiplication of theseanimals and growing interest was being expressed in the results that Tim and his colleagueswere obtaining at Cambridge. In 1972, therefore, Tim organized a course at the AnimalResearch Station to provide training in the basic techniques of embryo transfer in cattle. Itwas characteristic of him that he was happy to provide free access to all the information andexperience that had been gained in the work at Cambridge, because his primary objective wasto promote the practical application of the technology. Thirteen veterinary surgeons from dif-ferent countries attended the course. When they returned home they became the nucleus of anew industry and, during the next few years, several commercial embryo transfer units wereestablished, principally in North America. All procedures were surgical and, although resultswere quite variable, they were sufficiently good to sustain commercial growth for several years.However, some units did not survive after the boom in ‘exotic’ breeds declined and long-termviability clearly required simpler and less expensive technology.

Nevertheless, in anticipation of the development of such technology, Tim embarked a fewyears later on a project to demonstrate the potential usefulness of embryo transfer in another




practical farming situation. This was intended to show how embryo transfer might be used toconvert a herd of cattle from one breed to another (Jersey to Friesian) in one generation. Theproject was undertaken on the Jersey herd at Sacrawell Farm, which belonged to the RoyalAgricultural Society of England. Embryo donors were provided by Friesian breeders. Surgicalprocedures were used for collection and transfer of embryos and technically it was successful,in that pregnancy rates achieved were equivalent to those of AI. However, from the practicalpoint of view, it was found that Jersey cows were not suitable recipients for Friesian embryos.It had been expected that prenatal growth of Friesian calves would be restricted by thesmaller uterus of Jersey cows. By contrast, they were born at their normal birthweight andunacceptable levels of dystochia were caused, particularly with male calves. However,experience gained in this experiment and in the commercial field was now providing a basisfor further practical application once technology had become sufficiently advanced.

Embryo freezing

Among techniques required for further advances in the practical application of embryotransfer was an effective method for the storage of embryos. Some progress had been made,with H.R. Tervit, on methods for the culture of sheep and cow embryos in a synthetic oviductfluid. It had also been shown that cow embryos, like those of the sheep, continued normaldevelopment for several days when transferred to the oviduct of a rabbit, but the real goal wasto be able to freeze cow embryos for long-term storage.

Several attempts to freeze mammalian embryos had been made in the past, but these hadbeen almost totally unsuccessful. In the early 1970s, therefore, I. Wilmut was appointed on apostdoctoral fellowship at the Animal Research Station to work specifically on the problem oflow-temperature preservation of embryos. A breakthrough was made in 1972 duringexperiments on mouse embryos, when it was discovered that the survival of embryos frozen ina cryoprotective medium containing dimethyl sulphoxide was dependent not only on a veryslow cooling rate but also on slow warming. High levels of survival of mouse embryos wereachieved and Wilmut then collaborated with Tim to work on cow embryos. It was found thatcow embryos frozen at the eight-cell stage did not survive, but experiments were alsoperformed with blastocysts recovered on days ten to thirteen of pregnancy. Some of theseblastocysts survived freezing and thawing and were transferred to recipients. One animalbecame pregnant and there was international acclaim at the birth of the first calf resultingfrom transfer of a frozen–thawed embryo in 1973. However, this advance was not followedimmediately by practical application because further work confirmed that younger embryos,recovered on day three or four of pregnancy, did not survive freezing. This was the age ofembryo most commonly used for transfer at that time. In later work, with A.O. Trounson andS.M. Willadsen, it was found that cow embryos younger than very late morulae or earlyblastocysts were highly sensitive to cooling and were therefore not suitable for freezing. Bycontrast, expanding blastocysts, recovered on day six or seven of pregnancy, were tolerant tocooling, and high survival rates were obtained after freezing and thawing, especially whenimproved methods were developed by Willadsen. By the late 1970s pregnancy rates achievedwith frozen–thawed embryos were only slightly below those with fresh embryos and thepotential value of this technology for international exchange of valuable genetic material wasdemonstrated when frozen cow embryos were exported from England to New Zealand in1976.




Development of non-surgical techniques for embryo transfer in cattle

The work on embryo transfer by Tim and his colleagues, and particularly the training coursein 1972, stimulated a marked growth of interest in this field, not only in the commercialsphere but also in a number of academic centres around the world. Thus, research outputgained momentum. The group working with Tim at Cambridge was also enlarged during the1970s. R. Newcomb, a veterinary surgeon who had attended the training course, joined theUnit in 1972; another veterinary surgeon, W.B. Christie, came in 1976. In addition, there weretwo research students, R.A.S. Lawson from Australia and H.R. Tervit from New Zealand, aswell as other visiting workers, A. Brand from The Netherlands and A.O. Trounson fromAustralia. S.M. Willadsen from Denmark joined the Unit in 1974 to work initially on embryofreezing. Thus, opportunities were provided to study in greater depth a number of factorsaffecting success in embryo transfer in cattle. However, the main aim was to develop effectivemethods for the collection and transfer of embryos by non-surgical means.

Risk of infection and expulsion of embryos had been identified as the main barriers tosuccess in non-surgical transfer. Infection could probably be avoided by use of aseptic tech-niques, but expulsion of embryos remained the greatest problem. In all previous work, trans-fer of embryos via the cervix had been made during the early luteal phase of the cycle, butthere was a growing body of evidence that non-surgical transfer should best be attempted inthe mid-luteal phase. In the first instance, it was found that radioactive resin spheres trans-ferred to the uterus via the cervix were better retained in the mid-luteal phase of the cyclethan at earlier stages; secondly, Tim and Newcomb noted that early-stage embryos recoveredthree or four days after oestrus did not survive well when transferred to the uterus, even bysurgical means. Thus, in the first experiments in which later-stage embryos were transferrednon-surgically on days six to nine after oestrus, it was encouraging that the pregnancy ratewas as high as 40%. Clearly, embryos were being retained within the uterus at this time, and itwas therefore of considerable interest when research elsewhere showed that the mid-lutealphase of the cycle coincided with the time that myometrial activity disappeared in cows inwhich the cervix had been stimulated. Thus the main problem in non-surgical transfer ofcattle embryos had been overcome and, as work progressed, pregnancy rates approachingthose achieved by surgical means were obtained. Tim was determined that non-surgicalembryo transfer should be successful. He and his colleagues performed many transfers; thesuccess rate improved with growing experience and expertise. The apparatus used for trans-ferring embryos was an elongated version of the insemination ‘gun’ developed for AI.

For non-surgical collection of embryos, a number of people in different countries wereexperimenting with catheters that could be introduced via the cervix to flush the uterinehorns. All the different designs of catheters were essentially variations of the apparatusdevised by Tim and Dowling in 1949. A. Brand in Utrecht was using a soft, flexible cuffcatheter that was introduced with a stilette through the cervix. This was modified atCambridge and the apparatus finally preferred was a three-way catheter with a cuff that couldbe inflated to occlude an area at the tip of the uterine horn; embryos were recovered by acirculation system of flushing. Non-surgical recovery could be attempted only when embryoshad entered the uterus at six or seven days after oestrus. It was appropriate that this coincidedquite closely with the optimum time for non-surgical transfer and when embryos were at theexpanding blastocyst stage of development, which was the optimum time for freezing.

During the late 1970s, Tim, with Newcomb and Christie, performed numerous experimentsto refine technologies and to study factors affecting success in surgical and non-surgical




embryo transfer in cattle. Essentially, however, conditions had been defined for the basis oflarge-scale application and the dream that Tim had had in 1950 had been fulfilled.

The Equine Fertility Unit

Tim had an important role in establishing the Equine Fertility Unit at the Animal ResearchStation. In 1970, through his interests in horse racing, Tim had got to know Peter Burrell,who was then Director of the National Stud and Chairman of the Thoroughbred BreedersAssociation (TBA). Burrell was keen to support work on freezing stallion semen and couldprovide a small amount of money through a trust administered by the TBA. Tim suggestedthat this work might be undertaken by W.R. Allen, who had recently completed a PhD at theVeterinary School, and laboratory accommodation could be provided at the Animal ResearchStation. This was the start of the Equine Reproduction Project, but the work on freezingsemen was soon to be suspended and research concentrated on reproduction in mares. In1972, more generous funding was obtained, the project was extended and the Equine FertilityUnit was established.

Tim was always very supportive of the work on horses. He and Allen performed the firstexperiments on embryo transfer in mares and he was associated with the early work oninterspecies embryo transfer between horses and donkeys.

Manipulation of eggs and embryos

Tim contributed to many experiments other than those directly related to embryo transfer,and he was particularly interested in wider aspects of developmental biology that could bestbe studied by the manipulation of early embryos.

In the 1960s, with N.W. Moore, some experiments were performed in rabbits and pigs onthe developmental potential of single blastomeres from early cleavage-stage embryos with theobjective of producing genetically identical animals. Some evidence was obtained that singleblastomeres from embryos up to the eight-cell stage could produce young, but a majorproblem was that embryos in which the zona pellucida had been severely damaged bymicromanipulation did not survive and this problem was not pursued further at that time.

The possibility of selecting the sex of offspring was always seen as an important objectivein animal breeding. At the AI centre, Tim had been involved in work on bull semen in whichattempts had been made to separate sperm with an X or Y chromosome by a sedimentationtechnique. This was unsuccessful in that there was no change in the sex ratio of calves born.By contrast, Tim and his colleagues were the first to determine successfully the sex of sheepembryos by karyotyping cells removed from the trophectoderm.

Chimaeras were produced in sheep by the injection of blastomeres into embryos of differ-ent parental origin; these were the first chimaeric animals in a species other than the mouse.Some experiments were also undertaken in the early 1970s on the fertilization of follicularoocytes in cattle, but few embryos developed. It was not until some years later that conditionswere laid down for the successful maturation and fertilization of farm animal oocytes in vitro.

Many of these experiments were of a preliminary nature and, referring to them in thesecond Hammond Memorial Lecture, which he gave in 1970, Tim admitted that they mightseem rather theoretical and unlikely to succeed. However, they had the potential forimportant developments in animal breeding and, looking to the future, Tim concluded:

One should not dismiss completely the possibility of what is sometimes termed ‘genetic engineering’being used as a method of increasing animal production. Fifty years ago even AI was looked upon by




many with repugnance, yet today it is accepted as routine practice. In another fifty years, it is quitepossible that the introduction of chromosomes into the egg may be received with equal equanimity.

Tim retired before genetic engineering became a reality, but what is certain is that his workon embryo transfer in farm animals provided the route whereby future advances in cellularand genetic manipulation of eggs and embryos could be applied.

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Tim never became tied down by administration, despite the fact that he was Director of theAI centre for more than forty years and Deputy Director of the ARC Unit for twenty-fiveyears. He made sure that he could spend as much time as possible in the laboratory or,preferably, in the surgery, where he could be involved in the actual practice of research. Evenup to the time that he retired, his colleagues knew that he would be in the surgery by 9 a.m.with his gown on and ready to go. He was generous in helping others and, to all who workedwith him, he was a friend and collaborator rather than a director. In the same way, he neverreally supervised his research students but gave them a free hand and was always willing todiscuss problems, give advice and share his skills.

Tim had a zest for life and a great enthusiasm for his work, but basically he was a shy,unassuming person who really disliked public speaking. In fact, the stress of having to give animportant lecture would sometimes make him physically ill. He preferred the seclusion of thelaboratory to the limelight of publicity and for this reason he never did much travellingabroad. For example, the only time that he went to North America was to Canada in 1985 toreceive the Pioneer Award from the International Embryo Transfer Society. However, he didattend most of the International Congresses on Animal Reproduction and at one of these, inItaly in 1964, he gave a demonstration of embryo transfer in sheep and pigs on closed-circuittelevision. In addition to his contacts and influence within the scientific community, heestablished long-lasting relationships with farmers and cattle breeders throughout the country.

Tim had a great sense of humour, always loved a joke and enjoyed playing harmlesspractical jokes on others. This was especially true when he and some colleagues used to go toWales in the late 1940s to bleed ponies for the production of PMSG. There were stories ofmany practical jokes during the ‘rodeo’ of those visits. Tim’s sense of fun went back to thedays when he was a boy and acquired his nickname from Tiger Tim, the prankster in thecomic of that title.

He retained his love of games throughout his life. He liked tennis, but he especially enjoyedplaying cricket and was a good batsman. He was a founder member of the Avoncroft cricketteam, which was the beginning of what became a thriving village club. At home he had acertificate from his school for throwing a cricket ball the longest distance, a record that wasnever beaten in his lifetime. He also enjoyed country sports such as shooting, but his greatloves were horses and National Hunt racing. He once owned a very good horse that won anumber of races, and his colleagues at the laboratory would celebrate these successes withhim. He also kept some thoroughbred breeding mares but was never lucky enough to breed areally good foal.

Tim died in July 1989 from cancer of the kidneys, two years after the death of his wife. Heleft two sons and two daughters.




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1955 O.B.E.1956 Thomas Baxter Prize1970 Sir John Hammond Memorial Lecture and Prize, Society for the Study of Fertility1972 Fellow of the Royal College of Veterinary Surgeons1973 Fellow of Wolfson College, Cambridge

Fellow of The Royal Society1974 Lifetime Honorary President, International Embryo Transfer Society

Wooldridge Memorial Lecture and Medal1975 Dalrymple-Champneys Cup and Medal1976 Bledisloe Veterinary Silver Medal1977 Membre Honoraire Étranger de l’Academie Royale de Médecine de Belgique1985 Pioneer Award, International Embryo Transfer Society1986 MA, ScD, University of Cambridge

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I wish to thank Mrs Mary Hart, daughter of Tim Rowson, for information relating to his family background.My thanks are also due to R.M. Moor, F.R.S., R. Newcomb, A.O. Trounson, J.A. Moss and W.R. Allen fordiscussion and comments on the manuscript.

The photograph was taken at the Animal Research Station, Cambridge, in about 1970.

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A full bibliography appears on the accompanying microfiche, a photocopy of which isavailable from The Royal Society’s Library at cost.



Lionel Edward Aston Rowson, O.B.E. 28 May 1914 −− 26...

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