Gametogenesis

Question 1

follicle (3)

Answer 1

• born with certain amount
• package that contains oocyte
• enables ovary to fulfill dual function

Question 2

folliculogenesis (2)

Answer 2

• formation of Graafian follicle
• primary follicle development to mature follicle

Question 3

follicle turnover

Answer 3

• frequent emergence of new follicles, following by follicle atresia

Question 4

ovulation

Answer 4

• release of oocyte from Graafian follicle

Question 5

follicles development and ovulation (2)

Answer 5

• always start with cohort of follicles, with one follicle fully developing and going into ovulation
• 90-95% of follicles are turned over every cycle

Question 6

events during follicle growth (7)

Answer 6

1. recruitment of follicles
2. selection of dominant follicle and atresia of remaining
3. nuclear maturation of oocyte
4. cytoplasmic maturation of oocyte
5. steroid synthesis
6. stigma formation
7. release of egg

Question 7

1. recruitment of follicles (4))

Answer 7

• beginning of estrous cycle
• preantral follicles are not hormonal dependent
• cohort of follicles selected in both ovaries
• theca interna and granulosa cells develop FSH receptors and become FSH dependent

Question 8

2. selection of dominant follicle (3)

Answer 8

• development of LH receptors in granulosa cells
• atresia of remaining follicles
• steroidogenesis; production of estradiol

Question 9

3. nuclear maturation of oocyte (2)

Answer 9

• meiotic arrent in prophase I until LH surge (ovulation)
• meiotic resumption after ovulation through metaphase I and arrent at metaphase II

Question 10

4. cytoplasmic maturation of oocyte

Answer 10

• accumulation of mRNA, proteins, substrates, and nutrients required to achieve oocyte and embryonic development

Question 11

polar bodies (2)

Answer 11

• primary oocyte splits into 2 cell to form one secondary oocyte and one polar body
• secondary oocyte splits into two cells to form one mature ovum and one polar body

Question 12

polar body purpose

Answer 12

• done to conserve cytoplasm into 1 cell

Question 13

5. steroid synthesis (3)

Answer 13

• cholesterol transport to the ovarian follicle
• testosterone synthesis by theca interna (androstenedione to testosterone) controlled by LH
• estradiol synthesis by granulosa cells (testosterone to estradiol) by aromatase

Question 14

6. stigma formation (3)

Answer 14

• apical wall becomes thin
• avascular
• rupture of follicle at ovulation

Question 15

7. release of egg or ovum (3)

Answer 15

• loosening of cumulus-oophorus complex
• prostaglandin role of contracting theca externa
• expulsion and pick up by oviduct

Question 16

follicular fluid

Answer 16

• peripheral plasma by transudation across the follicle membrane from mother

Question 17

follicular fluid: general biochemical composition (2)

Answer 17

• steroids and glycoproteins secreted by cells of follicle wall and serum exudate
• enzymes, prostaglandins, and gonadotropins

Question 18

follicular fluid: specific components (4)

Answer 18

• estradiol
• progesterone
• androstenedione
• oocyte maturation inhibitor and inhibin that keep oocyte in desirable state for certain processes

Question 19

follicular fluid functions (6)

Answer 19

• regulation of granulosa cells functions
• initiation of follicular growth, oocyte maturation, ovulation, and egg transport to oviduct
• steroidogenesis
• preparation of corpus luteum
• regulation of follicular cycle
• sperm metabolism, capacitation, and early embryonic development

Question 20

what major changes does the pre-ovulatory follicle undergo (3)

Answer 20

• cytoplasmic and nuclear maturation of the oocyte; resumption of meiosis and accumulation of things important to early embryonic development
• disruption of cumulus cell cohesiveness among cells of granulosa layer
• thinning and rupture of external follicular wall

Question 21

site of ovulation

Answer 21

• anywhere in the ovary except the hilus (medulla portion)

Question 22

neuroendocrine and biochemical mechanism of ovulation (4)

Answer 22

• GnRH and LH surge
• transient progesterone increase
• collagenase loosens cells and thins wall while aromatase inhibition causes estradiol levels to decrease
• synthesis of prostaglandin

Question 23

neuroendocrine and biochemical mechanism of ovulation: PG synthesis (2)

Answer 23

• stimulates neuromuscular thecal system
• stimulates remodeling of follicle layers

Question 24

spermatogenesis structures (4)

Answer 24

• seminiferous tubules; major structural unit
• sertoli cell; major support cell
• spermatogonium; primary diploid cell (2n)
• leydig cell; steroidogenesis, testosterone production

Question 25

spermatogenesis result

Answer 25

- continuous release of haploid (n) cells; spermatozoa

Question 26

semen (2)

Answer 26

- liquid cellular suspension - spermatozoa + accessory glands fluid

Question 27

regulation of seminiferous tubules (3)

Answer 27

- leydig cells produce testosterone - testosterone travels to blood vessels and into seminiferous tubule - sertoli cells in seminifeorus tubule are affected by testosterone

Question 28

spermatozoa mitotic and meiotic divisions (6)

Answer 28

1. spermatogonium (2n) undergo mitosis 2. spermatogonia (2n) undergo cell growth 3. primary spermatocyte (2n) undergo meiosis 1 4. two secondary spermatocytes (n) undergo meiosis 2 5. four spermatids (n) undergo cell differentiation 6. spermatozoa (n)

Question 29

spermatozoa (3)

Answer 29

- final male gamete - haploid (n) cells - free to go into lumen of seminiferous tubule and go along male pathway

Question 30

spermatozoa components (2)

Answer 30

- head - tail

Question 31

spermatozoa head (4)

Answer 31

- protamines condense DNA in similar way to histones so transcription cannot occur - contains nucleus - contains acrosome (transformed Golgi apparatus) - hydrolytic enzymes to penetrate zona pellucida

Question 32

spermatozoa tail - function (1) - components (5)

Answer 32

- motility using 9 + 2 double tubules arrangement - neck, middle, annulus, principal, end piece

Question 33

organized migration to form spermatozoa (5)

Answer 33

- centrioles reconstruct cytoskeleton to make tail - sucking of cytoplasm into tail - mitochondria go into neck portion for energy generation - excess cytoplasm is removed with help from sertoli cells - nucleus becomes whole head

Question 34

spermatozoa head layers (6)

Answer 34

- plasma membrane - outer acrosomal membrane - acrosomal contents - inner acrosomal membrane - nuclear membrane - nucleus

Question 35

hormonal control of spermatogenesis

Answer 35

- FSH, LH and testosterone have direct control

Question 36

hormonal control of spermatogenesis: sertoli cells (4)

Answer 36

- FSH receptors for FSH from anterior pituitary - testosterone receptors for T from Leydig cells - secretion of ABP, inhibin, and activin - aromatase and 5alpha reductase which are needed for spermatogenesis to occur

Question 37

sertoli cells: inhibin function

Answer 37

- important for negative feedback with pituitary

Question 38

sertoli cells: aromatase

Answer 38

- turns testosterone into estradiol

Question 39

sertoli cells: 5alpha reductase

Answer 39

- turns testosterone into dehydrotestosterone (DHT)

Question 40

hormonal control of spermatogenesis: leydig cells (2)

Answer 40

- LH receptors - testosterone synthesis