spermatogenesis

Question 1

role of testes

Answer 1

houses seminiferous tubules, site of spermatogenesis

Question 2

epididymis

Answer 2

sperm storage and maturation

Question 3

vas deferens

Answer 3

transport of sperm from epididymis to urethra during ejaculation

Question 4

seminal vesicle

Answer 4

produces mucus secretion which aids the mobility of the sperm

Question 5

prostate gland

Answer 5

produces an alkaline secretion that neutralises acidity of urine in urethra and aids mobility of the sperm

Question 6

2 functions of testes

Answer 6

• produce sex androgens and other hormones for sexual differentiation and secondary sexual characteristics
• produce spermatozoa for sexual reproduction, occurs in seminiferous tubules

Question 7

what does the stroma consist of?

Answer 7

blood vessels, lymph and leydig cells

Question 8

what happens to PGCs around 6 weeks gestation?

Answer 8

PGC population expands by mitosis and migrates to the genital ridge primordium

Question 9

what can happen if something disrupts mitosises of sertoli cells?

Answer 9

can get low sperm count

Question 10

when does spermatogenesis begin?

Answer 10

puberty- about 10 million sperm produced per day

Question 11

how are spermatogonial stem cells self-regenerating?

Answer 11

undergo rounds of mitosis

Question 12

what morphologically distinct cells emerge at intervals?

Answer 12

type A spermatogonia

Question 13

how are type B spermatogonia formed?

Answer 13

the type A produce a clone of 16 cells which enter further rounds of mitosis with some differentiation inbetween them

Question 14

what dictates whether they divide or differentiate?

Answer 14

growth factors

Question 15

what direction does development occur?

Answer 15

in a centripetal direction- from basement membrane towards lumen

Question 16

what is spermiation

Answer 16

when fully differentiated sperm are released into lumen

Question 17

how is the acrosome cap formed in spermiogenesis

Answer 17

formed from golgi

Question 18

what else happens in spermiogenesis

Answer 18

the nucleus changes shape to fit in the head, one of the centrioles of the spematid becomes a tail, remaining excess cytoplasm and organelles are removed by sertoli cells via phagocytosis

Question 19

when does X and Y chromosmomes transcription stop?

Answer 19

before meiotic divisions

Question 20

when does autosomal transcription cease?

Answer 20

during spermiogenesis

Question 21

what are histones replaced with in sperm?

Answer 21

protamines and the chromatin becomes condensed

Question 22

what do sertoli cells form?

Answer 22

gap junctional complexes

Question 23

what separates the basal and adluminal compartments

Answer 23

blood testis barrier formed by gap junctional complexes

Question 24

which compartment is immune privaleged?

Answer 24

the adluminal one, so haploid cells not immune rejected

Question 25

when do spermatogonia become spermatocytes?

Answer 25

once they enter meiosis and move away from the basement membrane and into the adluminal compartment

Question 26

round and elongating spermatids are located where?

Answer 26

in adluminal compartment

Question 27

how often does a section of seminiferous tubule produce a sperm? why

Answer 27

every 16 days. since it takes 64 days to complete spermatogenesis but there are 4 sperm developing at staggered points in the cycle

Question 28

why are there populations at 4 different stages of development?

Answer 28

set lag time between development of SSC families

Question 29

what provides a means for communication

Answer 29

gap junctions between adjacent sertoli cells provides a means for communication

Question 30

3 main functions of testosterone in sertoli cells

Answer 30

- maintains blood-testis barrier integrity - required for sertoli-spermatid cohesion - essential for spermiation

Question 31

what does testosterone bind to?

Answer 31

androgen binding proteins and then travels to and stimulates ducts

Question 32

what is testosterone converted to in sertoli cells?

Answer 32

dihydrotestosterone and oestrogen

Question 33

how long does passage through epididymis take?

Answer 33

5-11 days.

Question 34

what happens to sperm in epididymis to mature them?

Answer 34

sperm acquired the potential to swim and fertilise oocytes- dependent on androgens.

Question 35

where are mature sperm stored?

Answer 35

tail end of epidiymis