Lecture 36: Reproductive System Microanatomy

Question 1

what structures make up the female reproductive system

Answer 1

• ovaries
• Fallopian tubes
• uterus
• cervix
• vagina
• (placenta during pregnancy)

Question 2

describe the histological structure of the ovary

Answer 2

• single outer layer of germinal epi
• DIRCT capsule tunica albuginea
• cortex –> oocyte and follicular development
• medulla –> loose CT w/ bv from hilum

Question 3

what 4 hormones drive the histological changes of the female reproductive organs

Answer 3

• follicle stimulating
• leutinising
• oestrogen
• progesterone

Question 4

where in the ovary are most of the ovarian follicles found

Answer 4

in the cortex

Question 5

what cells in the CT stroma of the ovary will respond to the hormones e.g. oestrogen

Answer 5

fibroblasts

Question 6

what are the 4 types of follicles that can be distinguished in ovary

Answer 6

• primordial
• primary
• secondary
• vesicular

Question 7

what does an empty follicle become once the oocyte has been ovulated

Answer 7

corpus luteum

Question 8

what is the major endocrine organ during the first few months of pregnancy and why

Answer 8

• corpus luteum

- b/c no placenta

Question 9

what happens to corpus lute if there is no pregnancy

Answer 9

undergoes atrophy and becomes fibrotic to form corpus albicans

Question 10

what happens to most follicles between utero and puberty

Answer 10

• lost through atresia

- ~4mil –> ~200K

Question 11

describe primordial follicles

Answer 11

oocyte covered by single layer of flattened granulosa (follicle) cells which provide nutritional network and endocrine signalling

Question 12

describe primary follicle

Answer 12

• growth stimulated by follicle stimulating hormone
• granulosa cells now cuboidal (will secrete progesterone and help convert precursor oestrogen into full oestrogen)
• layer of glycoproteins called Zona Pellucida separates oocyte from granulosa cells

Question 13

describe secondary follicle

Answer 13

• ^ in cell layers
• zona granulosa
• theca cells which surround stroma and produce androgens (go on to form corpus luteum post ovulation)
• basement membrane separates theca cells from zona granulosa

Question 14

what develops in a late secondary follicle

Answer 14

an antrum –> fluid filled cavity

Question 15

describe a Graafian follicle

Answer 15

• presence of antrum
• pressure of antrum pushes some granulosa cells to periphery and others surrounding oocyte known now as cumulus cells (cumulus radiata)
• oocyte surrounded by cumulus cells = cumulus oocyte complex

Question 16

what are theca cells derived from

Answer 16

fibroblasts

Question 17

what is the effect of ^ oestrogen production by Graafian follicle

Answer 17

• causes LH surge

- which stimulates ovulation and development of corpus luteum

Question 18

what happens as a result of LH surge

Answer 18

• collagenase activity ^
• continued ^ in follicular fluids and pressure
• thinning of ovarian cortex surrounding follicle
• stigma (bulge adjacent to follicle forms)
• follicle ruptures releasing COC to be taken up by fallopian tube

Question 19

describe the structure and histology of fallopian tube

Answer 19

• 10cm long
• lined by simple columnar epi (secretory and ciliated)
• smooth muscle layer

fimbriae:
- finger like extensions
- create current over ovary to waft oocyte into fallopian tube

infundibulum:
- highly folded mucosa
- thin Muscularis

ampulla:
- highly folded mucosa
- thick Muscularis
- fertilisation takes place here

isthmus:
- mucosa has fewer folds
- thickest Muscularis

Question 20

describe the three layers of the uterus

Answer 20

endometrium:

• simple columnar epi
• functional zone (glands)
• basilar zone (closest to myometrium not sloughed during menses)

myometrium:
- smooth muscle and vasculature

perimetrium:
- CT

Question 21

outline what structures the male reproductive system consists of

Answer 21

• testes
• epididymis
• ductal system
• accessory glands
• penis

Question 22

describe the histological structure of the testes

Answer 22

• enclosed in thick CT –> Tunica Albuginea
• septa from Tunica Albuginea divides organ into appx 250 pyramidal lobules
• each lobule contains 1-4 seminiferous tubules
• tubules connect via rete testis prior to efferent ducts that lead to epididymis

Question 23

describe the seminiferous tubules histologically

Answer 23

• site of spermatogenesis
• lined by Sertoli cells (simple columnar) which support and nourish developing germ cells
  tight junctions between Sertoli cells
• germ cells sit in invaginations of Sertoli cell cytoplasm
• Leydig cells occur in CT around tubules, secrete testosterone

Question 24

what 4 populations of germ cells are in the seminiferous tubules

Answer 24

• spermatogonia
• spermatocytes (1st and 2nd)
• spermatids
• spermatozoa

Question 25

what is spermiogenesis

Answer 25

late spermatid --> spermatozoan

Question 26

describe the epididymis

Answer 26

- site of maturation and storage of spermatozoa | - highly convoluted duct w/ pseudo stratified columnar epi and stereocilia (microvilli)

Question 27

describe the Vas Deferens

Answer 27

- encapsulated w/ DIRCT - columnar epi - thick wall w/ 3 smooth muscle layers - -> inner and outer longitudinal - -> middle circular - contraction of muscle moves spermatozoa from epididymis to urethra during ejaculation

Question 28

give the 3 accessory glands and their function

Answer 28

seminal vesicles: - prod viscous secretion containing sperm activating substances (60% of ejaculate) prostate: - produces thin milky fluid containing several enzymes (30% of ejaculate) - alkaline pH to counter vaginal acidity bulbourethral (Cowper's) - produce clear fluid prior to ejaculation to lubricate distal urethra and neutralise it

Question 29

describe the penis histologically

Answer 29

- erectile tissues composed of DIRCT and smooth muscle - comprised of 3 vascular cylinders - -> 2x corpus cavernosa - -> 1x corpus spongiosum - corpus cavernosa sit dorsally separated by median septum, surrounded by Tunica Albuginea - corpus spongiosum ventral and contains urethra