Ovarian Cycle: Follicular phase – Ovulation – Luteal phase
Uterine Cycle: Menstruation – Proliferation – Secretory
1. Follicle Stimulation Hormone (FSH)
- Produced by anterior pituitary gland
- Stimulates primary follicles to develop
2. Estrogen
- Produced by primary follicles
- Endometrium to proliferate
- Stop production of FSH so that other primary follicle don’t develop
- Stimulate production of LH (Luteinizing Hormone)
3. Luteinizing Hormone (LH)
- Produced by anterior pituitary gland
- Stimulates ovulation
- Rest of Graffian follicle forms corpus luteum – produces progesterone
4. Progesterone
- Maintain thick endometrium (secretory phase of endometrium)
NB:
- If fertilized, corpus luteum will form corpus luteum of pregnancy – produces progesterone and is maintained by gonadotropic hormones produced by the embryo until placenta takes over to produce progesterone
- If not fertilized, corpus luteum will form corpus albicans which will then degenerate
- Reduction in production of progesterone leads to menstruation
- Reduction in production of estrogen leads to FSH production
- Proteolytic enzymes prevent coagulation of blood during menstruation
- Germinal period – 2 weeks; formation of 3 germ layers
- Embryonic period – 3rd week to 3rd month; differentiation of the 3 germ layers into organs and systems
- Fetal period – growth of various organs and systems
1st week after fertilization
Zygote →Cleavage division → Morula → Blastocyst → Hatching (degeneration of zona pellucida) → Late blastocyst
Inner cell mass forms embryoblast
Outer cell mass forms trophoblast; which has 2 poles:
- Embryonic pole – faces site of implantation
- Abembryonic pole – opposite pole
Process of Implantation:
- Trophoblast erodes endometrium
- Penetration defect in endometrium
- Blastocyst embedded in endometrium of uterus
- Penetration defect closed by fibrin clot
Clinicals:
- Ectopic Pregnancy – implantation can occur in the abdomen, ovarian and fallopian tube
- Blighted ovum – dead embryoblast
- Downs syndrome – Trisomy of chromosome 21
- Turners syndrome – monosomy of x chromosome
- Triple x syndrome