95. 96. spermatogenesis/ oogenesis

Question 1

oogenesis where do primordial cells go in a genetic female

Answer 1

cortex of gonad

divides by mitosis + increasex in number

Question 2

after oogonia undergo mitosis, some degenerate.
what happens to the remining cells

Answer 2

primary oocytes undergo meiosis 1

primary oocytes/primordial follicle get arrested at prophase in meiosis 1

this is called DIPLOTENE STAGE

first meiotic division is not reached until puberty

Question 3

how does a primordial follicle turn into a primary follicle

Answer 3

flat follicular cells become cuboidal then produces a stratified epithelium of granuosa cells.

granulosa cells and oocyte secrete glycoproteins = forms zona pellicuda

Question 4

what is theca externa and interna

Answer 4

layers of follicles that secrete hormones important for yellow body development (corpus luteium)

Question 5

in the secondary follicle what is the fluid filled cavity called

Answer 5

Antrum: it enlarges as it develops

Question 6

what surrounds the secondary follicle

Answer 6

Granulosa cells where the oocyte is on form the cumulus oophorus
surrounding the oocyte = corona radiata

Question 7

what happens to the follicles as tey develop

Answer 7

only 1 fully matures, the others degenerate and become atretic

Question 8

what is the largest ovarian follicale and its size

Answer 8

25mm - mature (grafian) follicle

Question 9

Just before ovulation, what happens to the primary oocyte in the graafian follicle

Answer 9

surge in Luteinizing hormone causes the oocyte to complete meiosis 1 and enter meiosis II
secondary oocyte forms and first polar body (meiosis I): oocyte gets all cytoplasm polar body none

secondary oocyte gets arrested at metaphase meiosis II
stays there until it is fertilized

if fertilization occurs, secondary oocyte completes meiosis II and becomes mature oocyte (gamete) and secondary polar body formed

Question 10

what is controls the growth of the ovarian follicles

Answer 10

FSH

Question 11

steps of spermatogenesis

Answer 11

spermatogonia, primary spermatocytes, secondary spermatocytes, spermatids, spermatozoa

Question 12

what is the process called when spermatids turn into spermatozoa

Answer 12

spermiogenesis

Question 13

where does spermatogenesis occur

Answer 13

seminiferous tubules of the testis

PGCs give rise to spermatagonial stem cells

Question 14

what is the process duration from a spermatagonia to mature spermatazoon

Answer 14

74 days

Question 15

what are the peculiarities of spermatogenesis

Answer 15

maturation begins at puberty
2 meiotic divisions without interphase stage
4 mature spermatozoa formed from 1 spermatogonia

Question 16

What are Sertoli cells

Answer 16

derived from surface epithelium of testes
has occluding junctions- creates blood testis barrier
support and protection of developing spermatazoa
phagocytosis of resisdual bodies

Question 17

What are Leydig cells

Answer 17

found in between seminiferous tubules
polygonal cells with lipid droplets
steroid secreting cells eg testosterone

Question 18

spermatogenesis is regulated by what hormone
what does it cause

Answer 18

LH-luteinizing hormone from pituitary gland

it binds to receptors on Leydig cells which produce testosterone

testosterone binds to Sertoli cells to promote spermatogenesis

FSH also binds to Sertoli cells and produces testicular fluid

Question 19

what does spermatogonial stem cells turn into and how

Answer 19

Type A spermatigonia which divides by MITOSIS to form clones
Then Type B wich dvdes to form primary spermatocytes

Question 20

how does primary spermatocytes turn to secondary spermatocytes

Answer 20

prolonged prophase (dont hv interphase) then completes MEIOSIS l.

Question 21

how does it become spermatids after secondary spermatocytes

Answer 21

undergoes meiosis ll
haploid 23 chromasomes

Question 22

what occurs in spermiogenesis

Answer 22

1. Golgi Phase: proacrosomal phase
2. acrosomal phase: formation of acrosome which contain enzymes to penetrate the egg + condensed nucleus.
3. maturation phase: formation of neck, middle piece , tail.+ shedding of cytoplasm into residual bodies

Spermiation: mature spermatozoa released form Sertoli cells to seminiferous tubules. in epididymis they gain full motility

Question 23

how is spermiogenesis regulated

Answer 23

GRH - hypothslmus
FSH
LH
regulating factors: temperature, alcohol malnutrition, x rays

Question 24

Abnormal gametes

Answer 24

more commmon in spermatozoa (10%) - giants, dwarfs, abnormal heads/tails. lacks motility