The document discusses the development of the male genital system from the early indifferent stage through differentiation and formation of the testes, internal genital ducts, and external genitalia. It describes the roles of genes and hormones like testosterone and dihydrotestosterone in directing the development. Potential anomalies are also outlined, including undescended testes.

1. Development of male genital
system
Dr. Naema Yousri Elnehrawy

2. 2
Early genital systems in two sexes are similar; this initial
period is called indifferent state of sexual development
 The gonads begin to attain sexual
characteristics from the 7th week.
Male sex determination
Genetic..XY
Gonades…testes
Phenotype… male genital organs
Development of genital systemDevelopment of genital system

3.  Gonads (primitive sex glands)
 Genital ducts
 External genitalia
MaleMale
Genital SystemGenital System

4. Genetic determination of male sexGenetic determination of male sex
1-SRY…the main regulator for testicular differentiation
2-DSS…dosage sensitive sex reversal gene
3-MIS gene

5.  It's the 1st stage in male sex organs development.
 It includes development of 3 main components:
1-development & migration of primitive germ cells
2-Sertoli cells
3-Leydig cells
with the formation & canalization of the Seminiferous
tubules.
Development of gonads/testisDevelopment of gonads/testis

6.  5th week>>> proliferation of the cells of the coloemic
epith.& mesoderm to from 2 gonadal ridges (sex cords)
along the dorsal body wall medial to the mesonephros.
They are solid cords of cells then canalize to form the
ST that will anastomose to form rete testis.
 6th week>>>migration of the primitive germ cells from
the Yolk sac to the gonadal ridges by amoeboid
movement to form spermatogonia later on.
Development of gonads/testis (con't)Development of gonads/testis (con't)

8.  7th week>>> Formation of sertoli cell (inside ST) from
the coloemic epith. part of the gonadal ridge.
 8th week>>> Formation of ledyig cell (outside ST) from
the mesodermal cells part of the gonadal ridge.
 Failure of migration of the germ cells >>> Sertoli cell
only syndrome.
Development of gonads/testis (con't)Development of gonads/testis (con't)

9. A) Pre-differentiation stage:(untill
8th week)
1. Gonadal ridge
2. Mesonephric duct (Wolffian duct)
3. Paramesonephric duct (Mullerian
duct)
4. Urogenital sinus (US)
B) Post-differentiation stage:
1-Regression of PMD
sertoli cells secrete MIS >>>
Regression of PMD except for 2
rudimentary portions
*Appendix testis
*Prostatic utricle
Development of internal genital ductsDevelopment of internal genital ducts

10.  B) Post-differentiation
stage:
2- Progression of MD
 XY>>genes>>testicular
differentiation>>formation
of Leydig&sertoli cells
 Leydig cells
>>Testosterone>>
Proliferation of MD
 MD>>> Epididymis, vas, SV
& Ejaculatory d. (12w)
 Appendix
epididymis>>>Remenants of
MD.
Development of internal genital ductsDevelopment of internal genital ducts

11.  It's dependant on dihydrotestosterone that's
derived from testosterone by the action of 5-alfa-
reductase enz.
 Under its effect:
-Genital tubercle>>>elongates to form the Penis
-Genital swelling>>>scrotum
-urogenital folds>>>Penile urethra&urethral
meatus
Development of external genitaliaDevelopment of external genitalia

12. Accessory glands
 Seminal vesicles:
secrete alkaline fluid(neutralizes the acid in the
vaginal tract) that contains fructose as energy
source, enzymes (essential for clotting) &
prostaglandins (for motility & viability).
 Prostate glands:
secrete citrate (energy source for sperm motility)
& enzymes to break down the semen clot once
inside female reproductive tract.

13.  Periurethral glands:
1-Bulbourethral (Cowper's) glands:
two, round pea sized tubular glands embeded in the
urethral sphincter on each side of the prostate. They
secrete visid fluid that forms part of the seminal fluid
/ corresponds to bartholin glands in the female.
2-Littre's glands (Urethral glands):
Many glands arise along the urethra from the
bladder neck to the glans penis. They secrete
mucous /colloid secretion/ glycosaminoglycans/
protects the urethral epith. from the urine.
Accessory glands

14. Ureter
Deferent duct
Ampulla of the deferent duct
Seminal vesicle
Ejaculatory duct
Prostatic utricle
Prostate
Prostatic part of the urethra
Diaphragmatic part of the urethra
Ureter opening in the urinary
bladder
Urinary bladder
Deferent duct
Ampulla of the deferent duct
Seminal vesicle
Ejaculatory duct
Prostate
Outflow canals of the prostate
Bulbourethral gland (Cowper's)
Urethral gland (Littre's)
Prostatic part of the urethra
Membranous part of the urethra
Spongy part of the urethra

15.  Anomalies of the development:
True hermaphrodite..both ovarian & testicular tissues.
Male pseudoherm…..xy + testes + female phenotypic sex
Female pseudoherm…xx + ovaries + malephenotypic sex
 Anomalies of the meatus:
1)-Abnormal size
pinhole meatus>>>Cong.
>>>Acquired>>infl. dt. adhesions
>>cutt. of frenular a./devasc.
2)-Abnormal position
Hypospadius>> undersurface/ improper fusion of urogenital
folds/ +/- incomplete ventral surface or bifid scrotum/ infert.
Epispadius>>dorsal surface/infertility
Anomalies of male genital systemAnomalies of male genital system

16.  Anomalies of the penis:
1)-Abnormal size (micropenis):
< 2.5 cm SD below the mean size (13 cm +/- 1.6)
< 2 cm at birth
2)-Abnormal shape:
 Concealed penis: buried, normally developed/ covered by suprabubic fat
on the dorsal surface.
Cong.>>dt.inelastic dartos fascia
Acq.>>circumcision/ Excessive suprapubic fat
 Webbed penis:normally developed, covered by scrotal skin on the ventral
surface.
Cong>>abnormal attachment
Acq.>>after circumcision.
Anomalies of male genital systemAnomalies of male genital system

17. Rudementary portions
 Of PMD
1. Prostatic utricle
2. Appendix testis
 Prostatic utricle is the remaining blind pouch
that opens into the post.urethra at colliculus
seminalis.
 In abnormal cases,
cong.cysts..obstruction..infert.
 Prostatic carcinoma /endonetrial type dt
Presence of some uterine tissue.

18. Rudementary portions
Of MD
Appendix epididymis (para-epididymis)
Remenants of wolffian duct related to the head of
the epididymis.
Cong.bilateral absence of the vas has also absent
seminal vesicles and so characteristic semen
analysis.

19. Testicular desent
Testicles are formed as a retroperitoneal organ in
the post. Abd. Wall.
3rd
trimester, slip down accompanied by its
neurovascular supply.
7th
m, internal ing ring…ing canal…..scrotum.
Resposible factors:
hormonal
mechanical
neurological

20. 1) Hormonal factors:
 Non androgenic control (MIS):
The descent till the internal ing. ring (IIR) by the
effect of MIS secreted by sertoli cells.
 Androgenic control (DHT):
The extrabdominal descent below the IIR depends
on DHT from testosterone by ledig cells.
 Hypothalamus>GnRH>pitutary>gonadotrophin
s((FSH&LH); LH>Leydig cells>Ts/5alfa
reductase>DHT>Testicular descent.
Testicular desent

21. Testicular descent
2)Mechanical factors:
Traction theory: (gubernaculum testis)
*Disappearance of cranial gonadal lig.
*Growth of caudal gonadal lig. toward scrotum.
*During descent, it is accompanied by peritoneal
pouch(processus vaginalis) /oblitration…Tunica
vaginalis
Pressure theory:
Increased downward p by the growing abd viscera.

22. Testicular descent
3) Neurological theory: (Genitofemoral nerve; gfn)
Androgens effect on the nuclei of gfn stimulate
release of some factors as calcitonin gene related
peptide by the nerve terminals to modulate the str.&
function of the gubernaculum.
Incidence of undescended testis:
30%...among preterm
3%...full term
1%....1y old child

23. Undescended testis
 Coincidence of undescended
testis& hyposp…raise suspision
of intersex.
 It may be associated with
endocrinal disorders of hypoth,
pit.or testis as Kallman
syn.pit.aplasia& androgen
defecit syn.
 Failure of obliteration of
processus vaginalis may leads to
formation of hernia or hydrocele.