Spermatogenesis

Question 1

where spermatogenesis occurs

Answer 1

seminiferous tubules of testis

Question 2

1st phase spermatogenesis

Answer 2

spermacytogenesis

1. primodial germ cells from wall of yolk sac arrive at testes at week 4 and remain dormant (inactive)
2. At puberty, the prrimodial germ cells undergo differentiate into Type A spermatogonia.
3. Type A undergo mitosis to form Type B spermatogonia.

Question 3

2nd phase of spermatogenesis

Answer 3

Meiosis

1. type B enter meiosis I to form primary spermatocyte
2. primary spermatocyte completes meiosis I to form secondary spermatocyte.
3. secondary spermatocytes completes meiosis II with 4 spermatids.

Question 4

3rd phase of spermatogenesis

Answer 4

Spermiogenesis (spermatids to sperm)

1. the spermatids undergo series of morphological changes to form sperm
2. formation of acrosome, shedding of most of cytoplasm, condensation of nucleus, formation of head, neck and tail.

Question 5

total time of sperm formation

Answer 5

64 days

Question 6

what is oligospermia

Answer 6

less than 10 million of sperm/ml of semen

normal - 100 mil/ml of semen

Question 7

why newly ejeculated sperms incapable of fertilization

Answer 7

because they are not undergo capacitation in female reproductive tract yet to unmask its glycosyl transferase and remove its protein coating.

Question 8

capacitation

Answer 8

1. important for fertilization to occur
2. occur in female reproductive tract
3. unmasking of glycosyl transferase
4. remove protein coating of sperm surface

*25% or more abnormal sperms may cause infertility

Question 9

Oogenesis

Answer 9

1. primordial germ cells from wall of yolk sac arrive at ovary and become oogonia. (4th week)
2. oogonia enters meiosis I to form primary oocytes (remain until puberty) - ovary has primary oocyte since birth
3. at puberty, primary oocytes complete meiosis I to form secondary oocyte and 1st polar body during ovarian cycle.
4. secondary oocytes remain in meiosis II until fertilization occurs.

Question 10

what fertilization does to secondary oocytes

Answer 10

1. at fertilization, secondary oocyte completes meiosis II to form mature oocyte (ovum) and 2nd polar body.
   * primary oocyte gives rise to one ovum and 3 polar bodies.

Question 11

Primordial follicle

Answer 11

primary oocyte surrounded with a layer of follicular cells.

Question 12

Primary follicle

Answer 12

primary oocyte is surrounded by zona pelucida and layers of granula cells

Question 13

secondary follicle

Answer 13

1. fluid filled space become follicular antrum (cavity)
2. follicullar cells differentiate into theca interna and externa
3. primary oocyte located at middle down

Question 14

follicle stage

Answer 14

1. AKA Graffian follicle
2. size increased
3. primary oocyte surrounded by cumulus oophurus cells.

Question 15

Ovulation process

Answer 15

1. LH secretion from pituitary gland trigger primary oocyte to complete meiosis I to form secondary oocyte and 1st polar body before ovulation.
2. At ovulation, secondary oocyte and its corona radiata cells leave ruptured graffian follicle.
3. Secondary oocyte ONLY complete meiosis II if fertilization occur to form ovum and 2nd polar body.

*if no fertilization, secondary oocyte degenerates and become atretic (disappear).

Question 16

What is corpus luteum and its function?

Answer 16

• formed from ruptured graffian follicle
• form corpus albicans if no fertilization (degenerated corpus luteum)
• if fertilization occurs, lives for 3 months to produce progesterone before placenta takes over the role
• synthesize progesterone to stimulate secretion of endometrial gland