Case 2 ovarian cycle - histology

Question 1

what surrounds primordial follicles?

Answer 1

enclosed by single layer squamous pre-granulosa cells and basal lamina

Question 2

what triggers the development of primordial follicles?

Answer 2

FSH = menstrual phase

Question 3

what is the difference between an early and late primary follicle?

Answer 3

early - single layer - cuboidal granulosa cells with developing zona pellucida
late - multi layer - stratified granulosa cells and enlarged zona pellucida/ stromal cells in concentric layers surrounding granulosa = theca interna

Question 4

what happens in the proliferative phase?

Answer 4

FSH stimulates production of oestrogen by granulosa cells which cause further production of oestrogen themselves and primary follicles develop into secondary folliclesq

Question 5

what is the defining feature of a secondary follicle?

Answer 5

antrum - containing follicular fluid

Question 6

what is the effect of oestrogen on uterus?

Answer 6

endometrial proliferation - development of stratum functionalis from stratum basalis
- endometrial glands and spiral arteries proliferate
in uterine tubes:
- cilia elongate and beat rate increases
- increased secretion from peg cells

Question 7

what is the name of the matured follicle? when does this occur?

Answer 7

graafian follicle - tertiary

after first meiotic division - pre-ovulation

Question 8

describe the features of a graafian follicle

Answer 8

oocyte eccentrically located it has distinctive zona pellucida enclosed by corona radiata (cumulus oophorus attaches it to wall) and large antrum

Question 9

what happens in ovulation

Answer 9

graafian follicle protudes onto surface of ovary = stigma
LH surge -stimulates proteolytic activity in the theca externa and tunica albuginea then the ovum is expelled into the entrance of the uterine tube

Question 10

what occurs in the luteal phase?

Answer 10

LH stimulates luteinisation - transformation of corpus luteum from granulosa cells (blood clot surrounded by collapsed layers of granulosa in thecal capsule and lipid inclusions)

Question 11

what do the granulosa and theca interna cells secrete in the luteal phase?

Answer 11

granulosa secrete progesterone - thcikens endometrium for implantation/ stimulate glands/ develop stroma
theca interna secrete oestrogen

Question 12

what happens if fertilisation does not occur?

Answer 12

decrease in LH - involution of corpus luteum into corpus albicans (cells replaced by collagen) - decrease in progesterone secretion and oestrogen

Question 13

what precipitates the next menstrual cycle?

Answer 13

decreased progesterone lvels leads to contraction of spiral arteries -ischaemia/ degeneration of stratum functionalis and shed as menses