pelvic embryology Flashcards
What is the name given to the gonads when they first start development
genital ridges
what cell layer are the genital ridges (gonad) delivered from ?
a - intramediate mesoderm
b - lateral mesoderm
c - paraxial mesoderm
d- endoderm
Intermediate mesoderm
where do the germ cells move from to reach the genital ridges
germ cells move from the endoderm of the yolk sac to the genital ridges - this process starts at week 4 and finishes by week 6
What week in embryological development do the germ cells begin to migrate to the genital ridges?
week 2
week 3
week 4
week 5
week 4 the process starts
at what week in embryological development can we say that migration of germ cells to the genital ridges has completed
A WEEK 4
B WEEK 5
C WEEK 6
D WEEK 7
week 6
what is the karyotype of the male gonad
XY
what is the karyotype of the female gonad
XX
what gene contained in the male Y chromosome is responsible for the development of the male gonad?
SRY gene
Under the influence of the SRY gene the sex cords differentiate into what structure?
Testis cords
where is sperm produced in the male sex cords
seminiferous tubules
Leydig cells develop from what embryological cell layer
Intermediate mesoderm
what hormone do Leydig cells produce
Testosterone
during which week do leydig cells start to produce testosterone
A WEEK 4
B WEEK 6
C WEEK 8
D WEEK 10
WEEK 8 - production of testosterone drives the differentiation of the internal and external genitalia
what type of cords develop in the ovaries due to the absence of the SRY gene on the Y chromosome?
cortical cords
What are the two types of ducts that all embryos contain in the first weeks of urogenital development in the indifferent stage.
Mesonephros (wollfian) duct
Paramesonephros (mullerian) duct
which ducts remain in men (XY)
mesonephros (wolffian) ducts remain whilst the paramesonephros (mullerian) ducts regress
which ducts remain in females (XX)
Paramesonephros (mullerian) ducts remain and the mesonephros (wolffian) ducts regress
what hormone do leydig cells produce
testosterone
what hormone do sertoli cells produce
AMH (anti-mullerian hormone)
under the presence of testosterone what do the mesonephric ducts develop into?
testosterone cause mesonephric ducts to differentiate and develop into efferent ductules, epididymis, vas deferent and the seminal vesicles
Sertoli cells secrete AMH. What is the purpose of this in male gonads?
AMH causes regression of the paramesonephric (mullerian) ducts
in men what is the name of the embryological remnant of the paramesonephric duct
Appendix testis
in females what is the name of embryological remnant of the mesonephros (wolffian duct)
Vestigial remnant - Gartner’s duct
in females the absence of AMH allows for the development of what ducts
Paramesonephric ducts
What are the three parts of the paramesonephric duct in females and what do they form
cranial –> fallopian tubes
horizontal –> fallopian tubes
caudal –> uterus, cervix and upper 1/3 of the vagina
Fusion of the caudal paramesonephric ducts leads to formation of what structures in females
uterus, cervix and upper 1/3 of the vagina
Failure of the paramesonephric ducts to fuse in female embryological development can lead to what anatomical variant
bicorne uterus
the lower 1/3 of the vagina is formed from what structure
sinovaginal bulbs
H
H
what type of cells migrate from the primitive streak to the cloacal membrane to form a pair of cloacal folds?
mesenchymal cells
fusion cranially of the cloacal folds forms what structure
genital tubercule
fusion caudally of the cloacal folds form what two structures
anteriorly -urethral folds
posteriorly - anal folds
what androgen drives differentiation of the male external genitalia
DHT (dihydrotestosterone)
in men the genital tubercle becomes what structure?
phallus (penis)
the urethral folds in men develop to become what structure
urethral groove, this closes by the fourth month forming the penile urethra
what do the genital swellings in men become
scrotal swellings
failure of the urethral folds to completely close can cause what genital abnormality
hypospadias
what hormone drives female external genitalia to develop
oestrogen
what is the embryological origin of the clitoris
genital tubercle
what is the embryological origin of the labia minora
urethral folds
what is the embryological origin of the labia major
genital swellings
what structure attaches the gonads to the scrotum or labia in embryological development?
gubernaculum (a ligamentous structure derived from mesenchyme)
the scrotal ligament in men is the embryological remnant of what strucutre
the gubernaculum
what does the gubernaculum become in females following embryological development
ovarian ligament and round ligament of the uterus
what is the purpose of 5 alpha reductase
converts testosterone into DHT
by what week are gonadal ridges formed
week 6
By what week in embryological development are ovaries visible
week 9
until what week do mullerian and wolffian ducts remain undifferentiated
week 8
until what week does the urogenital sinus remain undifferentiated until
week 9
what week in development is external genitalia development completed
week 12
what embryological cell layer does the urogenital system develop from?
A- paraxial mesoderm
B- intermediate mesoderm
C- lateral mesoderm
D- inferior mesoderm
B - intermediate mesoderm
a patient is diagnosed with a gartner’s cyst. What is the cause of this pathology
A) failure of paramesonephric duct to degenerate
B) failure of the mesonephic duct to generate
C) failure of the paramesonephric and mesonephric duct to generate
D) failure of the pronephros to degenerate
B - failure of the mesonephric duct (also called wolfian duct) to degenerate fully
what hormone can be responsible in males for failure of the urethral folds to fuse and lead to hypospadias
A) oestrogen
B) testosterone
C) LH
D) FSH
B - testosterone
in females what does the lower 2/3rds of the vagina develop from
sinovaginal bulb
what does the upper 1/3rd of the vagina develop from
paramesonephric (mullerian ducts)
a patient is diagnosed with vaginal atresia by detection of a transverse septum. What embryological explanation would have caused this clinical finding?
A- failure of the sinovaginal bulb to develop and form the vaginal plate
B- failure of fusion of the paramesonephric ducts
C - failure of cannulisation of the vaginal plate
c
what is an absent vagina usual
