Gametogenesis

Question 1

Give the steps in female gamete formation

Answer 1

1. Primordial germ cells (PGCs) differentiate to oogonia
2. By mth 3, oogonia in fetal ovaries generate primary oocytes
3. Primary oocytes enter meiosis I but arrest at prophase
4. Resume prophase during menstrual cycle
5. Meiosis II completed only when oocyte fertilized

Question 2

Outline oocyte formation

Answer 2

1. 5th mth of prenatal development, no. germ cells in ovary approx 7mil
2. Primary oocytes remain in prophase and dont finish meiotic division before puberty
3. At puberty a pool of growing follicles established
4. Every mth 15-20 recruited to pass through maturation
5. Follicle stages:
   Primary (prenatal)
   Secondary (antral)
   Pre-ovulatory

Question 3

Outline ovarian cycle

Answer 3

1. 1 follicle reaches full maturity
2. LH surge causes pre-ovulatory growth
3. Meiosis I occurs
4. Secondary oocyte receives most of cytoplasm (resulting in polar bodies)
5. Meisis II occurs

Question 4

Outline spermatogenesis

Answer 4

1. Induced at puberty in response to LH surge
2. LH promortes testoterone secretion by leydig cell
3. Testosterone binds to sertoli cells to promote spermatogenesis
4. FSH binds to sertoli
5. Spermatocyte develops into spermatid
6. Process of transforming spermatid into mature spermatozoa called spermiogenesis, and takes approx 64days.

Question 5

What is the function of sertoli cells?

Answer 5

1. Support germ cells
2. Provide nutrition
3. Assist spermatozoa release