DevelopmentDevelopment

A. Development during pregnancyA. Development during pregnancy

1. Fertilization1. Fertilization

2. Formation of the morula2. Formation of the morula

3. Development of the 3. Development of the blastocystblastocyst

4. Implantation4. Implantation

B. Embryonic developmentB. Embryonic development

1. Beginnings of organ 1. Beginnings of organ systemssystems

2. Embryonic membranes2. Embryonic membranes

3. Placenta and umbilical cord3. Placenta and umbilical cord

C. Fetal growthC. Fetal growth

D. Hormones of pregnancyD. Hormones of pregnancy

E. Partuition and laborE. Partuition and labor

F. Adjustments of the infant at F. Adjustments of the infant at birthbirth

1. Respiratory system1. Respiratory system

2. Cardiovascular system2. Cardiovascular system

G. Physiology of lactationG. Physiology of lactation

What is pregnancy (gestation)?What is pregnancy (gestation)?– 266 days (lasts from conception to childbirth)266 days (lasts from conception to childbirth)

– (gestation calendar 280 days (40 weeks) from 1(gestation calendar 280 days (40 weeks) from 1stst day of LMP) day of LMP)

What is fertilization?What is fertilization?– Union of sperm and eggUnion of sperm and egg

How many sperm reach the ovum?How many sperm reach the ovum?– (2,000 – 3,000) out of 300 million in ejaculate reach the ovum vicinity

Where and when does fertilization occur?Where and when does fertilization occur?– Arrive within 5 – 10 minutes of ejaculation?

– fertilization occurs in ampulla of oviduct

Factors that affect sperm Factors that affect sperm movement towards the ovummovement towards the ovum

1. lashing of tails (flagellum)1. lashing of tails (flagellum)

2. guided by strands of cervical mucus2. guided by strands of cervical mucus

3. prostaglandins in semen3. prostaglandins in semen

4. uterine tenting and contractions4. uterine tenting and contractions

5. chemical attractant from the ovum?5. chemical attractant from the ovum?

What is capacitation?What is capacitation?

requires ~10 hoursfemale fluids remove cholesterol from sperm membranessperm membrane becomes more fragile

Viability of sperm-- 6 days in female reproductive tract“window of opportunity” = a few days before ovulation to 14 hr after (causes it takes another

10 hours for capacitation) (Margin of error does exist)

FertilizationFertilization1. acrosome reaction1. acrosome reaction

hyaluronidase and acrosinhyaluronidase and acrosin2. barriers2. barriers a. corona radiataa. corona radiata b. zona pellucidab. zona pellucida c. egg cell membranec. egg cell membrane3. genetic events3. genetic events4. zygote4. zygote5. blocks to polyspermy5. blocks to polyspermy (fast vs. slow)(fast vs. slow)

CleavageCleavage

1. blastomeres1. blastomeres

- Zygote to 16 cells- Zygote to 16 cells

2. morula2. morula

-free in uterus 4-5 days-free in uterus 4-5 days

- 100 cells- 100 cells

3. blastocyst3. blastocyst

a. trophoblasta. trophoblast

b. inner cell massb. inner cell mass

c. blastocoelc. blastocoel

Lots of mitosis

ImplantationImplantation1. occurs 6 days after ovulation 1. occurs 6 days after ovulation

in fundus of posterior wall of uterusin fundus of posterior wall of uterus

2. trophoblast2. trophoblast --invasion of stratum functionalis

3. accomplishments3. accomplishments - formation of the chorion (fetal placenta)

- human chorionic gonadotropin (hCG) secretion

Summary of Fertilization and ImplantationSummary of Fertilization and Implantation

Stages of DevelopmentStages of Development

Prembryonic Stage (0- 16 days)Prembryonic Stage (0- 16 days)

Embryonic Stage (16 days to 8 weeks)Embryonic Stage (16 days to 8 weeks)

Fetal Stage ( 8- 40 weeks)Fetal Stage ( 8- 40 weeks)

Embryonic PeriodEmbryonic Period

1. weeks 3 – 8 ( 16 days to 8 weeks)1. weeks 3 – 8 ( 16 days to 8 weeks)

2. gastrulation2. gastrulation

3. primary germ layers3. primary germ layers

a. ectoderma. ectoderm

b. endodermb. endoderm

c. mesodermc. mesoderm

The Developing HumanThe Developing Human

Extraembryonic membranesExtraembryonic membranes

1. yolk sac1. yolk sac

2. amnion2. amnion

3. chorion3. chorion

4. allantois4. allantois

4 weeks

12 weeks

Extraembryonic MembranesExtraembryonic Membranes

Placenta and Umbilical CordPlacenta and Umbilical Cord

PlacentaPlacenta

1. fetal vs maternal1. fetal vs maternal2. functions2. functions

Umbilical cordUmbilical cord

1. 2 umbilical arteries1. 2 umbilical arteries2. 1 umbilical vein2. 1 umbilical vein3. Wharton's jelly3. Wharton's jelly4. umbilicus4. umbilicus

Fetal period (weeks 9 - 38)Fetal period (weeks 9 - 38)

Fetal Development and RiskFetal Development and Risk

Hormones of PregnancyHormones of Pregnancy1. human chorionic gonadotropin1. human chorionic gonadotropin

2. estrogen2. estrogen

3. progesterone3. progesterone

4. human chorionic somatomammotropin4. human chorionic somatomammotropin

5. relaxin5. relaxin

Parturition and laborParturition and labor

Uterine ContractilityUterine Contractilityfalse labor (Braxton Hicks contractions)true labor = parturition

Positive Feedback of Laborbegin ~30 minutes apart progress to every 1 – 3 minutescervical stretch neuroendocrine reflex oxytocin secretion uterine contraction more stretch repeat

1. stage of dilation1. stage of dilation2. stage of expulsion2. stage of expulsion3. placental stage3. placental stage

Respiratory system adjustments Respiratory system adjustments at birthat birth

COCO2 2 accumulates in baby’s blood and accumulates in baby’s blood and

strongly stimulates the respiratory strongly stimulates the respiratory chemoreceptorschemoreceptors

First two weeks 45 bpm, then 12 bpmFirst two weeks 45 bpm, then 12 bpm

Cardiovascular System Changes Cardiovascular System Changes at Birthat Birth

1. foramen ovale -->fossa ovalis1. foramen ovale -->fossa ovalis2. ductus arteriosus -->ligamentum arteriosum2. ductus arteriosus -->ligamentum arteriosum3. ductus venosum -->ligamentum venosum3. ductus venosum -->ligamentum venosum4. umbilical vein -->ligamentum teres4. umbilical vein -->ligamentum teres5. umbilical arteries -->median umbilical ligaments5. umbilical arteries -->median umbilical ligaments

Physiology of LactationPhysiology of Lactation

1. What is lactation?1. What is lactation?2. How are the breasts prepared?2. How are the breasts prepared?estrogens and other hormones causes duct growth and branchingprogesterone causes development of secretory acinisteroids prevent milk synthesis

3. Why do the breasts NOT need to produce 3. Why do the breasts NOT need to produce milk until a couple of days after birth?milk until a couple of days after birth?Infants are born with excess body water and fatInfants are born with excess body water and fatColostrum(1/3 less fat, and lots of immunoglobulins) secreted for the first 3 daysplacental delivery = no estrogens and progesterone secretionmilk synthesis now begins

Physiology of LactationPhysiology of Lactation

4. What is the neuroendocrine reflex that lactation?4. What is the neuroendocrine reflex that lactation? a. Tactile stimulation of areola and nipple causesa. Tactile stimulation of areola and nipple causes b. Sensory input to hypothalamus, leading tob. Sensory input to hypothalamus, leading to c. Secretion of oxytocin and prolactin from c. Secretion of oxytocin and prolactin from

pituitary gland pituitary gland (1) Oxytocin stimulates contraction of (1) Oxytocin stimulates contraction of

myoepithelial cells of mammary glands, myoepithelial cells of mammary glands, leading to milk letdown leading to milk letdown

(2) Prolactin stimulates renewed milk (2) Prolactin stimulates renewed milk synthesis synthesis by mammary gland cellsby mammary gland cells