EMBRYOLOGY Flashcards
wHAT is Gastrulation?
- you get the 3 layers in (ecto-, meso- and endoderm) from the epiblast layer …replacing the hypoblast layer
What are the 3 groups of the mesoderm?
Paraxial
Intermediate
Lateral Plate
What is characterisitic of the cranial folding ?
- bring heart field down to chest
Where does the UROGENITAL system develop from?
-intermediate mesoderm
What is the metanephric system?
- kidneys
What do these primordial germ cells form?
the gonads
Name the 2 genital ducts.
- MESONEPHRIC DUCT (Wolfian)
- PARAMESONEPRHIC DUCT (Mullerian)
What ducts connect caudally?
- paramesonephric ducts
The presence of what transcription factor determines the Male sexual development of the fetus?
SRY-tf
sex determining region of Y
What does the SRY- protein help do?
- form sertoli cells
-How? the somatic supprt cells hug PGC; exposure to SRY makes them into SERTOLI CELL
responsible for testosterone
> stimulate the formation of leydig cells
What does the anti-mullerian hormone do?
- degenerates the Paramesonephric duct in men
Where do the female reproductive organs arise from?
- paramesonephric duct
Where do the testes arise from?
- from 10th thoracic
- pulled CAUDALLY by gubernaculum
When does sexual differentiation occur?
- from week 7
Where do both the genital ducts connect to?
- the posterior wall of the urogenital sinus
What gives rise to the primitive sex cords?
- coelomic epithelium proliferate => GENITAL RIDGES
- this proliferating epithelium will form SOMATIC support cells
(envelops the PGC’s)
===>primitive sex cords
What do the primitive sex cords consequently give rise to?
- testis and medullary cords
What is the other name of the paramesonephric duct ?
Mullerian duct
Where do germ cells arise from and what do they form?
- germ cells derive from the EPIBLAST cells
- devlops into SPERMS and EGGS
What is KEY for gonadal development?
- failure of germ cells to reach the gonadal ridges.
What does the SRY gene code for?
- testis determining factor
- —helps form Sertoli and Leydig cells
What does the Leydig cells responsible for?
- release of testosterone > Male development
- medullary cords also form
As a result of no SRY gene present, what occurs to the female reproductive system?
- medullary cords “regress”
- cortical cords develop and form CLUSTERS and SURROUND to form the germ cells
What are do the genital ducts develop in to?
- In Males, the Mesonephric (WOLFFIAN) ducts form the epididymis, vas deferens, seminal vesicle and ejacutlatory ducts
- In Females, the Mullerian ducts (Paramesonephric ducts) form the fallopian tubes, uterus and upper vagina
How to stop the development of the female reproductive system?
- Sertoli cells release MIF (suppresses the develop. of the paramesonephric ducts)
- —-in males, the remnant is the Appendix Testis
What is released by a particular cell to drive the development of the mesonephric ducts?
- Androgens by the Leydig cells
What are the seminal vesicles?
- glands behind the bladder
- secretes 75% of fluid into semen
- connects with the ejaculatory ducts
What are the ejaculatory ducts?
- collect sperm and fluid from the vas deferens and the seminal vesicle
> pass through the PROSTATE
>urethra
What is a Wolffian remanant in Females?
Gartner’s duct
- found on vaginal walls (may form cysts)
Some of the internal genitalia come from the genital ducts. What is another derivative of internal genitalia?
- Urogenital Sinus…comes from the CLOACA
What does the UROGENITAL sinus give rise to in males ?
Bladder, Prostate, prostatic urethra and penile urethra
And does the urogential sinus give rise to females?
- bladder, inferior 1/3rd of the vagina, connects with the paramesonephric ducts
How does the uterus form?
- by fusion of the left and the right Mullerian ducts
What is the most COMMON type of uterine anomaly?
LATERAL fusion defects and septat uterus
What do uterine anomalies result in?
-n pregnancy LOSS and infertility
What is septate uterus?
What is the RX?
- an anomaly where a septum divides the uterus in to 2 uterine cavities (should have been resorbed after Mullerrian duct fusion.
- Septoplasty
