RAM DAYAL

Embryologist

What is Infertility? Inability to conceive a baby after one year of

unprotected intercourse.

Affects the reproductive organs of both men and women.

Infertility affects about 15% of couples in the United States.

InfertilityRequirements for a successful conception:

A healthy sperm and a healthy egg unite to form a zygote

Place for fertilization to occur (a fallopian tube)

Place for the fetus to grow (a uterus)

Causes of Infertility in Males Low sperm count

Low sperm motility

Impotence including erectile dysfunction

Aspermia

Other Causes of Infertility in Females

Secondary amenorrhea

Fallopian tube blockage

Other Factors Influence Fertility Personal habits

Environmental factors

Age associated with decreased fertility and increased risk of chromosomal abnormality

Sexually transmitted diseases

Social factors

Age and Infertility

Causes of Infertility in Women

Most Common Choices of Treatment In Vitro Fertilization

Artificial Insemination

Frozen Embryos

Gamete Intra Fallopian Transfer

Zygote Intra Fallopian Transfer

Methods of Assisted Reproduction In vitro fertilization (IVF) Gametes are collected and fertilized in a dish The resulting zygote is implanted in the uterus

Gamete intrafallopian transfer (GIFT) Gametes are collected and placed into a womans

oviduct

Intracytoplasmic sperm injection (ICSI) An egg is fertilized by microinjection of a single sperm

(for defects in sperm count or motility)

IVF (in vitro fertilization) is a method in

which egg cells are fertilized by sperm

cells outside the mothers womb (in vitro). The resulting embryos are then

transferred back into the uterus.

Oocyte at Ovulation 2 oocyte arrested in Metaphase II

Completion of Meiosis only if fertilization occurs

Follicular cells of corona radiata protect ovum as it breaks through ovary wall

Hormonaltreatment

Female

Harvest the ovum

Mix in a test tube

Natural ejaculation

Collect semen

Mature Ova

Motile sperms

Keep to develop embryo

Transfer to mother

Male

Basic Principle of IVF

Oocytes with granulosa cells

"Naked" Oocyte

Fertilization:the fusion of the sperm cell nucleus with the egg cell nucleus to produce a zygote (fertilized egg)

FertilizationTaking place in ??

Viability of gametes: Oocyte 12-24 h

Sperm 12-48 h

Acrosome contains hyaluronidase acrosomal reaction breaks down intercellular cement between adjacent follicle cells

Single sperm fuses with oocyte

amphimixis - fusion of sperm and oocyte pronuclei

Sperm parts

Acrosome

tail

Egg parts

Corona radiata

zona pellucida

Plasma membrane

Polyspermy prevented by a

change in the zone pellucida

membrane charge as one

sperm enters

The male and female pronuclei are indistinguishable from one another.

The second polar body can be seen (arrow).

The plasma membranes of the two pronuclei are dissolving and one diploid

nucleus will remain.

Fusion of the pronuclei:(in vitro)

Advanced Fertility Center of Chicago

http://www.advancedfertility.com/

Stage of fertilization: Membranes of the pronuclei break down,

chromosomes condense and arrange themselves for mitotic cell division

On membrane dissolution, there is 1 cell with 46 chromosomes = diploid (2N)

The first cleavage follows shortly, leaving 2 cells, each with 46 chromosomes.

Mitosis in the new zygote uses centrioles derived from the sperm. The oocyte has no centrioles.

Fertilization facts: Completed within 24 hours of ovulation

Approximately 400 to 600 MILLION sperms are deposited at cervical opening during ejaculation.

Some sperm are held up by the folds of the cervix and are gradually released into the cervical canal; this gradual release increases the chances of fertilization.

Most human sperms do not survive longer than 48 hours in the female genital tract.

Only about 200 sperms reach the fertilization site; most degenerate and are absorbed by the female genital tract.

The results of fertilization: Stimulates the secondary oocyte to complete meiosis.

Restores the normal diploid number of chromosomes (46).

Results in variation of human species as maternal and paternal chromosomes intermingle.

The embryo contains only maternal mitochondria because the sperm mitochondria are dispersed into the egg cytoplasm and discarded.

Determines the sex of the embryo. The sex chromosome (Y or X) carried by the successful

sperm determines embryonic sex.

Twins: still 1 sperm per egg Monozygotic (monoovular): A fertilized, single egg splits into two developing zygotes at

a very early stage.

Identical twins; same sex.

Dizygotic (polyovular): Result from the fertilization by two sperm of two separate

ova that have reached maturation at the same time.

Not identical twins; can be different sexes

Incidence increases with age of the mother

HIGH QUALITY THREE DAY OLD EMBRYO

Intrauterine Insemination (IUI)

In intrauterine insemination (IUI), donor sperm is placed into the uterus of an ovulating woman. The sperm swim up the oviduct and fertilize the egg.

Fertilization to implantation:

Know where this happens.

Gamete Intrafallopian Transfer (GIFT)

Fig. 16-9a, p. 360

Zygote Intrafallopian Transfer (ZIFT)

Fig. 16-9, p. 360

Implantation:

After 6 days the blastocyst

imbeds into the

endometrium. Usually on

the high back wall of the

uterus

How can fertilization go awry? Too many sperm = dispermy or triploidy

Leads to spontaneous abortion in most cases.

Infertility

Bad timing:

The sperm can only survive 48 hours within the female genital tract.

In vitro studies show the ovulated egg cannot be fertilized after 24 hours.

Triploidy (in vitro)

Advanced Fertility Center of Chicago

http://www.advancedfertility.com/

There are 3 pronuclei within this one zygote. In the laboratory, such embryos are discarded. In vivo, such embryos almost always abort spontaneously.

Use of ART Carries Risks to Parents and Children

Risks of ART

Threefold increase in ectopic pregnancies

Multiple births (35% in IVF)

Increased risk of low birth weight

Increased risk of transmitting genetic defects to male children (in ICSI)

Surrogacy is another form of ART

Fig. 16-10, p. 361

IVF has Resulted in the Birth of Millions of Children

Fig. 16-7, p. 359

Thank you