Lecture 8 - Embryology Reproductive System 2 Flashcards
what occurs at 6 weeks
indifferent genital ducts form
what is the difference in genital ducts in male and female
Female - develop paramesonephric ducts (Mullerian) whereas in males they depress
Male - mesonephric ducts (Wolffian) - develop and in females they regress
What drives the development of the genital ducts
SRY gene
What does the SRY gene do?
encodes for testis determining factor (TDF)
somatic cells invest PGC’s (Proliferating Germ Cells) with SRY gene and differentiate into sertoli cells
What do sertoli cells do?
secrete anti-mullerian hormone
which causes degeration of the paramesonephric ducts
what are the derivatives of the mesonephric duct
vas deferens
epididymis
seminal vesicle
What are the remnants of the paramesonephric duct?
Appendix testis
Utriculus prostaticus
How do genital ducts form?
in the absence of SRY
no anti- mullerian hormone - paramesonephric ducts remain
No testosterone - mesonephric ducts degenerate
What are the 3 parts of the paramesonephric duct
cranial and horizontal - become uterine tubes
caudal - fuse to form uterine canal
Remnants of the mesophrenic duct
epophoron
paraoophoron
gartners cyst
how does the uterus and the vagina form?
cloaca divides into urogenital sinus and anus
urogenital sinus develops into sinovaginal bulbs that fuse with caudal tips of paramesonephric ducts to form vagina
abnormalities of the uterus
Failure of paramesonephric tubes to fuse
failure of uterine septum to degenerate
failure of one paramesonephric duct to elongate
affect 1% of non-fertile women - higher rates of miscarriage, premature delivery or dystocia
Persistent mullerian duct syndrome
affect genetic males
mutation in AMH gene
No AMH production - paramesonephric ducts persist
both mesonephric and paramesonephric duct derivatives develop
normal external genitalia but associated with crytorchidism
Indifferent stage of development of external genitalia
mesoderm cells migrate to surround cloacal membrane and form elevated cloacal folds
cloacal folds unite anteriorly to form genital tubercle - future penis or clitoris
fold - divide into anal and urethral divisions
genital swellings - appear next to folds - future scrotum or labia majora
what does development of male external genitalia depend on?
androgens
genital tubercle elongates to form phallus
genital swellings enlarge and move caudally
When does formation of the penile urethra occur?
9-10 weeks
formation of the penile urethra
urethral folds pull forward and form lateral walls of the urethral groove
urethral groove is lined by epithelium and form urethral plate
end of 3rd month - urethral folds close over urethral plate to form penile urethra
scrotal swellings fuse in midline
What is hypospadias
incomplete fusion of urethral folds - urethra opens on ventral surface of penis
occurs in 3-5/1000 births
difficulty urinating
can be repaired surgically using foreskin
Epispadias
opening in dorsal surface of penis
often associated with exstrophy of the bladder
incidence - 1 in 30,000
results from improper location of the genital tubercle posterior to urogenital sinus - urethral groove on dorsal surface
What is development of female genitalia dependent on
oestrogens
genital tubercle elongates slightly to form clitoris
urethral folds do not fuse - form labia minora
genital swellings - labia majora
urogenital groove - remains open
When can you tell the difference between males and females
13 weeks
size of phallus and clitoris are similar until 12 weeks
