Embryology

Question 1

what occurs in gastrulation

Answer 1

formation of the trilaminar disc - invagination of the epiblast cells through the primitive streak to form the definitive endoderm and mesoderm

Question 2

what are the 3 parts of the mesoderm

Answer 2

paraxial mesoderm
intermediate mesoderm
lateral plate

Question 3

the urogenital system arises from _____

Answer 3

intermediate mesoderm

Question 4

what is the name of the common cavity that the excretory ducts of the urogenital system enter

Answer 4

cloaca

Question 5

when do primordial germ cells within the yolk sac migrate to the intermediate mesoderm

Answer 5

weeks 4-6

Question 6

how are the genital ridges formed

Answer 6

coelomic epithelium proliferates and thickens to form genital ridges

Question 7

proliferating epithelium will form somatic support cells which ________ forming the _____

Answer 7

envelope the PGCs forming primitive sex cords

Question 8

what are the names of the 2 genital ducts

Answer 8

mesonephric (wolffian) duct

paramesonephric (mullerian) duct

Question 9

what makes up the bipotential/ambisexual phase

Answer 9

development of the genital ducts and the indifferent gonads

Question 10

when does sexual differentiation occur

Answer 10

from week 7 onwards

Question 11

what triggers male development

Answer 11

presence of SRY transcription factor

Question 12

in males what do somatic support cells develop into

Answer 12

sertoli cells

Question 13

in males what do the primary sex cords form

Answer 13

testis/medullary cords which engulf the PGCs

Question 14

what do the rete testis connect

Answer 14

the mesonephric tubules to the testis cords

Question 15

what is the name of the thickened layer of connective tissue between the coelomic epithelium and testis cords

Answer 15

tunica albuginea

Question 16

what stimulates the formation of sertoli cells

Answer 16

SRY

Question 17

what do sertoli cells secrete

Answer 17

AMH (anti-mullerian hormone)

Question 18

what does the AMH secreted by the sertoli cells do

Answer 18

causes the degenerative of the paramesonephric (mullerian) duct

Question 19

sertoli cells stimulate gonadal ridge cells to form what

Answer 19

leydig cells

Question 20

what do leydig cells secrete

Answer 20

testosterone

Question 21

what does the testosterone secreted by the leydig cells do

Answer 21

induces formation of epididymis, vas deferens and seminal vesicles

Question 22

what induces male specific external genitalia and prostate development

Answer 22

dihydrotestosterone (DHT)

Question 23

what is persistent mullerian duct syndrome

Answer 23

mullerian (paramesonephric) duct fails to regress in males

Question 24

how does persistent mullerian duct syndrome present

Answer 24

uterus, vagina and uterine tubes with male external genitalia
testes in ovarian location

Question 25

how is persistent mullerian duct syndrome caused

Answer 25

mutations of AMH or AMH receptor genes

Question 26

where do the testes originate

Answer 26

10th thoracic level

Question 27

what pulls the testes caudally

Answer 27

gabernaculum

Question 28

what is failure of one or both testes to descend called

Answer 28

crytorchidism

Question 29

what is the tunica vaginalis made from

Answer 29

descended peritoneum

Question 30

what are the 3 accessory glands in males

Answer 30

prostate bulbourethral seminal

Question 31

when do the 3 accessory glands in males develop

Answer 31

week 10

Question 32

from what does the seminal gland develop

Answer 32

mesonephric duct

Question 33

how are the prostate and bulbourethral glands formed

Answer 33

endodermal invaginations from the urethra

Question 34

the prostate is above/below the bulbourethral glands

Answer 34

above

Question 35

from what does the vas deferens form

Answer 35

mesonephric duct

Question 36

female development occurs in the absence of ___

Answer 36

SRY transcription factor

Question 37

in females germ cells develop into ____ and then into ____

Answer 37

oogonia and then into primary oocytes

Question 38

in females what differentiates into granulosa cells and surrounds the primary oocytes

Answer 38

somatic support cells

Question 39

what duct degenerates in females

Answer 39

mesonephric (wolffian) - wolff is a boys name

Question 40

what stimulates the formation of the female external genitalia and development of the paramesonephric ducts

Answer 40

ovarian oestrogens and from maternal sources

Question 41

what do the paramesonephric (mullerian) ducts give rise to

Answer 41

uterine tubes uterus superior vagina

Question 42

what is a Gartner's cyst

Answer 42

remnant of mesonephric duct

Question 43

what are the 3 parts of the paramesonephric duct

Answer 43

cranial portion horizontal portion caudal portion

Question 44

what gives rise to the uterus and superior vagina

Answer 44

the fused caudal portion of the paramesonephric duct

Question 45

what does the caudal portion of the paramesonephric duct fuse with

Answer 45

the paramesonephric duct on the opposite side

Question 46

vacuolisation of the paramesonephric portion of the vagina and the sinuvaginal bulbs gives rise to what

Answer 46

vaginal lumen and the fornices

Question 47

how is the spongy urethra formed in males

Answer 47

proximal to distal zipping of the urethral groove | then ectodermal ingrowth at the tip of the glans penis meets the spongy urethra

Question 48

how is the foreskin (prepuce) formed

Answer 48

circular ingrowth of ectoderm around periphery of the glans

Question 49

when is the foreskin formed

Answer 49

week 12

Question 50

what is hypospadias

Answer 50

external urethral opening doesnt lie at the tip of the penis - lies in an abnormal position along the ventral aspect of the penis (varying degrees of severity)

Question 51

when does the first trimester complete

Answer 51

12 weeks

Question 52

when does the second trimester complete

Answer 52

28 weeks

Question 53

when does the 3rd trimester complete

Answer 53

40 weeks

Question 54

how long after fertilisation can pregnancy be detected by urine test

Answer 54

10 days

Question 55

the Y chromosome has the sex determining region and causes the development of testes from the ______

Answer 55

bipotential gonad

Question 56

fetal testes secrete _____

Answer 56

testosterone and mullerian inhibiting factors (AMH)

Question 57

what causes the development of the male internal genital tract

Answer 57

testosterone and MIF (AMH)

Question 58

in males the _____ ducts form the reproductive tract

Answer 58

wolffian (mesonephric)

Question 59

in males the ____ ducts degenerate

Answer 59

mullerian (paramesonephric)

Question 60

what is the bipotential gonad ridge

Answer 60

area of the embryo with potential to develop into male or female gonads

Question 61

in the absence of testicular hormones a fetus will develop _____

Answer 61

female internal genital tract

Question 62

when can you tell sex of fetus on scan

Answer 62

16 weeks