Reproduction

Question 1

describe gametogenesis

Answer 1

production of gametes from meiosis

production of 4 haploid (n) gametes from each diploid oogonium (2n) or spermatogonium (2n)

Question 2

describe spermatogenesis

Answer 2

Spermatogonia
primary spermatocyte
secondary spermatocyte
spermatids
spermatozoa

Question 3

describe spermatozoa anatomy

Answer 3

head contains acrosome, nucleus and plasma membrane
mid piece contains centriole at base of head, mitochondria providing energy and a terminal disc
tail contains axial filament and end piece

Question 4

describe oogenesis

the 3 stages

Answer 4

1. oocytogenesis
   formation of oogonia
   results in formation of primary oocytes
2. ootidogenesis
   formation of secondary oocytes
3. formation of ovum if fertilised

Question 5

run through the production of oocytes and their release from the ovary

Answer 5

primary oocyte is produced in a primordial follicle
the follicle develops and grows from a primary follicle to an antral one
then becomes a ruptured follicle as the now secondary oocyte is expelled from the ovary

Question 6

define the SRY gene

what does it do?

Answer 6

Sex determining R of Y gene

it codes for the Testis Determining Factor (TDF)

Question 7

how do males and females vary in respect to Y chromosome primordial gonad breakdown and development?

Answer 7

in males, at week 7, the outer layers of the gonads will degenerate and the inner part will form testis ONLY IF TDF IS PRESENT

in females, around week 11, the inner layers of the gonads will degenerate and the outer layer will form the ovaries

Question 8

What is required for the ovaries to be fully functional?

Answer 8

two DSS (Double dose genes) genes

Question 9

Walk through the male and female development in the context of SRY presence

Answer 9

males: SRY dictates development of testis
testis develop anti-mullerian hormone that breaks down the mullerian ducts (These would become the fallopian tubes)
testosterone then triggers the conversion of wolffian ducts into seminal vesicle, vas deferens and epididymis

females: the absence of SRY means no testi development
the absence of testosterone causes wolffian duct to degenerate
the absene of antimullerian hormone means the mullerian ducts can develop into the fallopian tube, uterus and upper part of the vagina

Question 10

what do sertoli cells secrete?

what does it do?

Answer 10

Anti mullerian hormone

triggers the breakdown of the mullerian duct

Question 11

what produces testosterone and dihydrotestosterone (androgens) ?
what do the two products do?

Answer 11

leydig cells
testosterone stimulates development of the wolffian duct, leading to development of the seminal vesicle and vas deferens
DHT stimulates fusion of labial-scrotal fold (scrotum)
growth of phallus and prostate

Question 12

Describe the HPG axis in males and females

Answer 12

Hypothalamus Pituitary Gonad Axis

The hypothalamus releases GnRH, this stimulates the release of LH and FSH from the anterior pituitary gland
these hormones then trigger the production of testosterone in males and estrogen and progesterone in females
these product hormones act as negative feedback loops via the anterior pituitary (and positive feedback in females)

Question 13

functions of leydig cells?

Answer 13

produce androgens (test, DHT and DHAS)
influence secondary sexual characteristics
increase spermatogenesis

stimulated by LH to produce these hormones

FSH increases how the leydig cells respond to LH

Question 14

why does seminal fluid contain buffers?

Answer 14

to neutralise the acidic nature of the vagina

Question 15

what are the types of hermaphroditism?

Answer 15

true hermaphrodite, has both ovarian and testicular tissue

male pseudohermaphrodite: has testes but female phenotype

female pseudohermaphrodite: has ovaries but male phenotype