WEEK 4: EMBRYOLOGY OF THE MALE REPRODUCTIVE SYSTEM Flashcards
What forms the GONADAL or urogenital ridges?
They are formed by proliferation of the epithelium and a condensation of the mesenchyme of the intermediate mesoderm
Pirmodial germ cells appear at the GONADAL ridge at Week 7 of development.
Where do they originate from?
*In the epiblast
Describe the pathway of pirmodial germ cells from the epiblast to the GONADAL ridge
Week3 : from the epiblast they migrate through the primitive streak and reside among endoderm cells in the wall of the yolk sac close to the allantois
Week 4: they migrate by the ameboid movement along the dorsal mesentery of the hindgut
Week 5: Arrive at the primitive gonads
Week 6 : invade GONADAL ridges
Which embryological layer is the male reproductive system formed from?
- Intermediate mesoderm
Name the gene on the Y chromosome which encodes the testis determing factor TDF
SRY gene (sex determining region on Y gene)
Name the structure formed when the epithelial cells penetrate the underlying mesenchyme after the proliferation of the epithelial of the GONADAL ridge
Indifferent GONAD/ primitive GONAD/ Primitive sex cords
What is the function of the Testis determing factor TDF?
Encode the primitive sex cords to continue to proliferate and penetrate deep into the medulla to form the TESTIS or MEDULLARY CORDS
Where are the Sertoli cells derived from?
From the surface epithelium of the gland
They are derived fromthe epithelial sex cords of the developing gonads
Where are the interstitial cells of Leydig derived from?
From the original mesenchyme of the GONADAL ridge
They lie between the testis cords
At what time does the Leylig cells produce testosterone?
Week 8 of gestation
The testis cords remain solid until puberty when they acquire a lumen.
What structure do they form afterwards?
Seminiferous tubules
What is the other name for the mesonephric duct?
What structure does it form?
*wolffian duct
*ductus deferens and the male duct system
What are the two pairs of genital ducts found in both male and female initially before diferentiation ?
Mesonephric duct (Wolffian duct)
Paramesonephric duct ( Mullerian ducts)
Name the master gene for testes development
SRY
Name the other gene that the SRY appears in conjunction with to induce testis differentiation
SOX9
What is produced by the SRY in conjunction with the SOX9 that acts as a chemotactic factor that causes tubules from the mesonephric duct to penetrate the GONADAL ridge?
FGF9
Name the hormone that results in the regression of the parametanephric ducts
AMH ( antimullerian hormone)/ Mullerian inhibiting hormone
What structure forms the duct system of the male reproductive system?
( Epididymis,vas deferens, urethra,seminal vesicles,
Wolffian duct ( mesonephric duct)
What hormone stimulates the differentiation of the Sertoli and Leydig cells?
SF1
What two hormones join that results in the increase in AMH?
SF1
SOX9
What enzyme convert testosterone to dihydrotestosterone in the target cell tissue?
5 alpha reductase
State the 2 functions of the dihydrotestosterone
*Results in virilization of the mesonephric duct to form vas deferens, seminal vesicles, efferent ductules and epididymis.
*Regulates transcription of tissue-specific genes and their protein products
*results in the formation of the male external genitalia
Name the 5 parts of the primitive reproductive system
*mesonephric duct
*paramesonephric duct
*Gubernaculum
*urogenital sinus
*gonads
Where does the urogenital sinus form form?
anterior part of the cloaca
What cells produce mullerian inhibiting hormone?
sertoli cells in the testis
What is the function of the gubernaculum?
*guides the testis down into the scrotum
*A gelatinous tissue, the gubernaculum, pulls the testes through the abdomen, through the inguinal canal in the groin, and down into the scrotum
What structures does the urogenital sinus form?
bladder and a part of the urethra
List the structures that form the primitive external genitalia
*Genital tubercle
*Labio-scrotal swellings
*urogenital sinus
*Urethral folds
What do the following parts of the primitive external genitalia give rise to;
*Genital tubercle
*Labio-scrotal swellings
*urogenital sinus
*Urethral folds
*Genital tubercle: Glans penis, corpus spongiosum, corpus cavernosum
*Labio-scrotal swellings: scrotum
*urogenital sinus: Prostatic urethra, membronous urethra, postate gland, cowper’s gland
*Urethral folds: shaft of the penis, penile urethra
Which part of the primitive gonad does the testis dive from?
cortex o medulla?
Medulla
Anomalies
*cryprorchidism: Undescended testis
*congenital inguinal hernia
*hypostadiasis : failure of the to open from its usual location o the head of the penis
What is genetic sex?
The sex which depends on the combination of sex chromosomes at the time of conception
What is GONADAL sex?
Whether testis develop or ovaries develop
What is the relationship between genetic and GONADAL sex?
Genetic sex determines GONADAL sex
What is phenotypic sex?
It is apparent anatomic sex of an individual, is hormonally mediated and depends on the genetically determined sex.
What is sexual differentiation?
The embryonic development of the external genitalia and reproductive tract along either male or female lines
What does genetic sex depends on?
Combination of sex chromosomes
What does GONADAL sex depends on?
Presence or absence of SRY gene
Name the hormone released by the placenta that is responsible for the early stimulation of testicular secretion
Human Chorionic Gonadotropin
What form the inguinal canal?
Processus vaginalis
