TOB CL4 Gametogenesis till Implantation

Question 1

Terminology
What is gametes in male and female ?

Answer 1

Gametes - reproductive cell
M - Spermatozoon
F - Ovum

Question 2

Terminology
What is gametogenesis in male and female ?

Answer 2

Gametogenesis - process of reproductive cell formation / development
M - spermatogenesis
F - oogenesis

Question 3

Terminology
What is gonads in male and female ?

Answer 3

Gonad - organ
M - testes
F - ovaries

Question 4

Terminology
What is PGCs in gonads in male and female ?

Answer 4

M - spermatogonia
F - oogonia

Question 5

State the process of spermatogenesis ( 4+1)

Answer 5

1. Primordial germ cells (PGCs)
   - 2nd week : away to the wall of yolk sac
   - 4th week : back to the gonads by amoeboid movement > spermatogonia
   - mitosis
2. Spermatogonia
   - A type - dark ( maintain spermatogonia population ) , pale ( precursor for B type )
   - B type - differentiate to form primary spermatocyte
3. Meiosis
   - primary > secondary > spermatids
4. spermatozoa from spermatids via spermatogenesis

4 steps spermatogenesis ( spermatids to spermatozoa )

1. Formation of acrosome
2. Condensation of chromosome
3. Formation of neck, mid-piece and tail
4. Shedding of cytoplasm

Question 6

What is the fxn of sertoli cells ?

Answer 6

supporting cells that is held together by tight junction to form blood-testes barrier

Question 7

Where spermatogenesis occurs and when it begins ?

Answer 7

seminiferous tubule
begins at puberty

Question 8

Where oogenesis occurs and when it begins ?

Answer 8

ovary
before birth

Question 9

Oogenesis
the process of b4 birth (4)

Answer 9

1. PGCs in ovary > oogonia > primary oocyte by mitosis
2. Most PGCs lost through atresia ( apoptosis)
3. arrest in prophase I inhibited by oocyte maturation inhibitor> diplotene stage
4. primary oocyte is surrounded by flat follicular cells > primordial follicle

Question 10

Oogenesis
After puberty (3)

Answer 10

1. flat follicular cell increase in size > stratified cuboidal granulosa cell
2. accumulation of antrum > secondary follicle > tertiary follicle - Graafican follicle
3. Theca folliculi > Theca interna ( highly vascular and glandular - outside ) and Theca externa ( fibrous - inside )

Question 11

Oogenesis
Prior to ovulation (2)

Answer 11

1. Surge in LH > Primary oocyte completes meiosis I but arrest in metaphase II
2. If no fertilization, degrade within 24 hours
   if got, cont. complete meiosis II

Question 12

Oogenesis
Ovulation (8)

Answer 12

1. Surge in LH
2. Increase prostaglandin
3. Ovarian muscle contraction
4. Extrusion of secondary oocyte and cumulus oophorus
5. cumulus oophorus after ovulation > cumulus radiata
6. remaining ( Theca folliculi + granulosa cell ) > corpus luteum
7. Corpus luteum , lutean cells secrete oestrogen and progesterone
   8 if no fertilization, degradation of lutean cells
   if got, cont to grow > corpus lutean graviditatis

Question 13

Oogenesis
Egg transport (2)

Answer 13

1. ovulated egg > uterine tubule
   - Frimbae sweeps over the surface of the ovary
   - peristaltic contraction of the tube
2. uterine tube > uterine cavity
   - peristaltic contraction
   - cilia in tubal mucossa

Question 14

1st week of development
Fertilization
1. where it occurs ?
2. Prior to fertilization, what are the 2 processes that spermatozoa must undergo?
3. capacitation (5)
4. Explain the 3 phases of fertilization
5. Results of fertilization (3)

Answer 14

1. ampulla
2. capacitation, acrosome reaction
3. • cond : spermatozoa in female reproductive tract
   • interaction of spermatozoa and mucosal surface of the uterine tube
   • removal of cholesterol
   • removal of glycoprotein coat overlaying the acrosome
   • only capacitated sperm can penetrate the corona radiata and undergoes acrosome reaction
4. • Penetration of corona radiata
   • Penetration of Zona Pellucida - acrosome reaction occurs - release acrosome enzyme induced by ZP3, Zona protein - degrade Zona Pellucida
   • Fusion of spermatozoa and oocyte - cortisol reaction - cortisol granules releases proteolytic enzyme - hydrolyzed ZP3 - no acrosome reaction - Zona reaction - change in Zona Pellucida ‘s permeability - prevent polyspermy - resume meiosis II > ovum
5. • restoration of diploid chromosome
   • determination of sex
   • initiation of cleavage

Question 15

1st week of development
cleavage (4)

Answer 15

1. zygote > blastomere
2. cell become smaller - not cell growth
3. 8-/16 cell - compaction held tgt by tight and gap junction
4. Blastocyst hatching
   - rupture of zona pellucida

Question 16

1st week of development
Implantation

Answer 16

1. blastocyst to uterine wall
2. mucosa of uterus in secretory phase
   - uterine gland and arteries are coiled