S2 The female reproductive system and Development of the reproductive tracts

Question 1

what is the ovary

Answer 1

ovum producing reproductive organ

Question 2

what is the arterial supply of the ovary

Answer 2

comes from ovarian arteries which are direct branches off the abdominal aorta

Question 3

what is the venous drainage of the ovary

Answer 3

comes from the pampiniform plexus that converges to form the right ovarian vein which enters the IVC and the left ovarian vein which enters the left renal vein. Ovary lymphatics drain to the para-aortic nodes

Question 4

what are ovarian cysts ?

Answer 4

fluid filled lesions which can be benign or malignant, patient shall present with pain or bloated

Question 5

is the ovary covered fully by peritoneum ?

Answer 5

no, the ovary is suspended but not covered fully by peritoneum allowing its oocytes to be released into the peritoneal cavity that can subsequently be trapped by the fimbriae of the uterine tubes

Question 6

what is the uterus ?

Answer 6

thick walled organ where the embryo can implant and develop

anterior to uterus is the bladder, posterior is rectum

Question 7

what happens to the uterus during pregnancy ?

Answer 7

pushes organs such as the stomach and intestines so women can get acid reflux or constipation. pushing on bladder can increase urinary frequency

Question 8

where is the site of fertilisation ?

Answer 8

uterine tubes are the site of fertilisation, in the ampulla. During ovulation, the egg ruptures through the wall of the ovary and enters the peritoneal cavity

Question 9

what is the cervix made up of

Answer 9

the internal os, which opens onto the uterine cavity
endocervical canal
the external os, which opens into the vagina
before pregnancy, the external os of the cervix is round shaped after it is slit-shaped

Question 10

what are peritoneal ligaments of the uterus ?

Answer 10

broad ligament - peritoneal fold
round ligament and ligament of the ovary - remnants of the gubernaculum- pulls the gonads down to the pelvis
suspensory ligament of the ovary - neurovascular pathway bulging into the peritoneum

Question 11

what is the broad ligament ?

Answer 11

double layer of peritoneum that extends from the side of the uterus to walls and floor of the pelvis
contains :
the suspensory ligament surrounds the ovarian vessels
the mesovarium suspends ovary
the mesosalpinx attaches the ovary to fallopian tube
the mesometrium is the mesentery for the uterus itself

Question 12

what is the ligament of the ovary

Answer 12

remnant of the gubernaculum, attaching the ovary to uterus

Question 13

what is the round ligament

Answer 13

also a remnant of the gubernaculum and attaches the ovary to the labium majus

Question 14

what is the blood supply of the uterus

Answer 14

derived from uterine artery (from the internal iliac artery) with some anastomosing with the ovarian artery
venous drainage is via uterine veins
the ureters run under the uterine artery “water under the bridge’. In males, ureters pass under Vas Deferens

Question 15

describe the angles of the uterus

Answer 15

the uterus is anterverted(tipped anterosuperiorly relative to the axis of the vagina) and anteflexed ( flexed anteriorly relative to the cervix, creating the angle of flexion). Angles must be <180, thus when the bladder is empty, the uterus lies in the transverse plane. this position is maintained by the broad ligament

Question 16

describe the microanatomy of the vagina

Answer 16

stratified squamous epithelium lines the vagina. it contains glycogen as they are the food of lactobacilli - the bacteria in the uterus, which turn it into lactic acid, creating the low pH

Question 17

during early embryonic development what 3 germ layers arise ?

Answer 17

ectoderm, mesoderm and endoderm

the intermediate mesoderm is where the kidneys, gonads and genitalia develop

Question 18

when does the embryo fold and how does this relate to development of the reproductive tracts ?

Answer 18

in the 4th of development creating a cavity inside the embryo with a gut tube suspended within it
as the embryo folds , it pinches off the yolk sac forming a gut tube, the hindgut is the region where repro and urinary tract development occurs

Question 19

which tracts share a common caudal opening

Answer 19

GI, REPRO and URINARY

Question 20

describe the nature of the hindgut

Answer 20

the hindgut ends in a dilated structure - the cloaca which is closed to the outside by the cloacal membrane so there is no mesoderm. Mesoderm gives rise to the CVS system and therefore blood vessels so as this membrane is avascular it shall die and rupture giving us an opening

Question 21

where is the gonad derived from

Answer 21

intermediate mesoderm and Primordial germ cells , when PGC migrates to the gonad, they direct the development of the repro tract . they undergo gametogenesis giving sperm or oocytes
mesonephric duct contributes to the differentiation of the internal genitalia

Question 22

what are primordial germ cells

Answer 22

arise in the wall of the yolk sac - migrate into the retroperitoneum, along the dorsal mesentery

Question 23

how does the gonad develop

Answer 23

PGC migrate to the gonadal ridge where they shall eventually give us gametes
the ridge has mesothelial cells, which gives structures that help develop PGC (males - seminiferous tubules, females - ovarian follicles)
mesenchymal cells in the ridge shall produce supprting cells (males - sertoli cells, females - ovarian support stroma)
y chromosome in men has sex determining region - SRY, producing the gamete testis, absent in females so produces ovaries

Question 24

what are the hormones produced by the internal genitalia during development ?

Answer 24

testis produce androgen class hormones which influence the development of the internal genitalia
androgens maintain the mesonehpric duct - mesonephric/wolffian will give us the epididymis, vas deferens and seminal vesicle 
the ovary doesnt produce many androgens
paramesonephric duct shall dominate as a result 
paramesonephric/mullerian will give us the uterus, cervix and 1/3 vagina

Question 25

describe the nature of the genital ducts

Answer 25

two ducts develop in males and females both end at the urogenital sinus (bladder) part of the cloaca
in a normal male, testis produce a mullerian inhibiting hormone (MIH), preventing production of the mullerian tube
testis also produce androgens and testosterone (via Leydig cells ) supporting the Wolffian duct
in a female with no functional testes, there is no MIH so mullerian duct can develop and no androgen production so wolffian duct shall degenerate

Question 26

how does the mesonephric duct develop ?

Answer 26

duct drains into the urogenital sinus which become the bladder and prostate. the duct becomes the Vas deferens, the seminal vesicles and epididymis , then the gubernaculum migrates these and the testis as they descend

Question 27

how does the paramesonephric duct develop ?

Answer 27

mullerian duct moves closer forming the structures (1/3 vagina etc). the gubernaculum attaches to the ovary during descent. the urogenital sinus gives us the bladder and lower vagina `
caudally : duct makes contact with the cloaca (urogenital sinus)
cranially : open into the abdominal cavity

Question 28

what happens exogenous androgen sources are introduced in females

Answer 28

shall support Wolffian duct but as there are no testis , there shall be no MIH, so mullerian duct shall not be suppressed and both ducts shall develop

Question 29

what happens in androgen insensitivity syndrome in males

Answer 29

testosterone receptors dont work so the Wolffian duct dies yet the testis still produce MIH so there is no Mullerian duct either

Question 30

what are the basic components of the external genitalia and what do they develop to in males ?

Answer 30

genital tubercle (GT) - elongates into the glans penis
genital folds - fuse to form the spongy urethra, influenced by dihydrotestosterone (DHT)
genital swellings fuse forming the scrotum
urogenital sinus fuses forming urogenital groove

Question 31

what do the basic components of the external genitalia develop to

Answer 31

no fusion occurs in the female due to no DHT
GT develops into clitoris
genital folds become labia minora
genital swellings become labia majora
urethra opens into the vestibule

Question 32

describe the descent of the testis

Answer 32

testis are behind the peritoneum
testes are attached by the gubernaculum to the scrotal folds
proc vag leads the way for the testes to follow
testes reaches scrotum
proc vag closes up, scrotal ligament is the remnant of the male gubernaculum

Question 33

describe the descent of the ovary

Answer 33

gubernaculum attaches ovary inferiorly to labio-scrotal folds
ovary descends to the pelvis
uterus has developed which prevents further descent
the gubernaculum becomes ovarian and round ligament