The Genital Organs Differentiation

7/29/2019 The Genital Organs Differentiation

1/31

The Genital Organs

DifferentiationBy: E. Suryadi

Faculty of Medicine GMU


2/31

Introduction

At fertilization the genetic sex of an embryo isdetermined, there is no morphological indicationof sex until the 7th week, when the gonads beginacquire sexual characteristics.

This period of early genital development isreferred to as indifferent stage organs.

How the genital organs differentiation process?And what are the influence factors?


3/31

Differentiation of early embryonic

tissuesBlastomere

Endoderm Mesoderm

Ectoderm

ParaxialisIntermediate

Lateralis

Splachnicus SomaticusCrista urogenitalis

Crista gonadalisMesothelium

mesenchym

Embryoblast

Trophoblast Allantois

Primordial

GerminalCells

Migration

Spermatogonium

Sertoli Cell

Leydig CellTDFIndifferent

Gonad


4/31


5/31


6/31

Embryonic structure

??-Male genital organs

-Female genital organs


7/31

Ovarium

Tuba uteri

Uterus

Vagina Clitoris

Labium minor

Labium major

Testis Epididymis

Ductus deferens

Seminal gland

Prostate gland

urethra

penis

scrotum

Embryonic structure

(Indifferent gonad) Mesonephric tubulus

Mesonephric duct

Paramesonephricduct

Urogenital sinus

Phallus

Urogenital folds

Labioscrotal swelling

Femalegenital

organ

Male

genitalorgan


8/31

Development of The Gonads

The gonad Cells are derived from three

sources of cells:

1. mesothelium lining of the abdominal

wall and

2. underlying mesenchyme

3. primordial germ cells


9/31

The Indifferent Gonads

Gonadal development is the first indicated during

the fifth week when a thickened area of coelomic

epithelium.

It develops on the medial aspect of urogenitalridge and then becomes gonadal ridge

Soon finger-like epithelium cords is formed, called

primary sex cords, grow into the underlying

mesenchyme.

The indifferent gonad now consists of an outer as

a cortex and an inner as a medulla


10/31

Origin of The Germ Cell

Primordial germ cell (PGC) during third weekcan be found on the posterior wall of the Yolksac near the origin of the allantois

They are large size and clear cytoplasm PGC reach the gonads by migration

(amoeboid movement) around the wall of theposterior gut and then through the dorsal

mesentery to the gonadal ridge. During migration is guided by laminin and

fibronectin (Extra- Cellular Matrix)

A chemotactic influence from the gonads

guides the final stage of the migration


11/31


12/31

The Multiplication of The

Germ Cell by Mitosis The number of primary germ cell (PGC)

increases during their migration from a fewhundred to a few thousand

- after they have settled down in the gonad,

from a few thousand to about 7 million

Mitotically active germ cell:

- in female are called oogonia- in male are called spermatogonia

The pattern of mitotic activity of oogonia andspermatogonia is different


13/31

Sex Determination Genetic sex is established at fertilization

Gonadal sex is determined by the sexchromosome ( X or Y )

At the short arm Y chromosome has SRY genefor TDF as a strong testis determining effect onthe medulla of indifferent gonad.

TDF induces the gonadal cords to condense andextend into medulla of indifferent gonad, wheresex cord branch and anastomose to form therete testis and gonadal cord become seminiferuscord.

The gonads then determine the type of sexualdifferentiation that occurs in the genital ductsand external genitalia.


14/31


15/31

Development of testes

In embryos with a Y chromosome theprimary sex cords condense and extendinto medulla of gonad.

Here they branch and their endsanastomose to form the rete testis.

The prominent sex cords, calledseminiferus cord

Soon lose their connections with thegerminal epithelium because of thedevelopment of a thick fibrous capsule

called tunica albuginea


16/31


17/31

Chromosome Y

In Chromosome Y laid the SRY gene ( for a testisdetermining factor (TDF)), which is located in the shortarm region of the Y chromosome.

At sixth week SRY protein is produced so that :

1. sertoli precursor (mesothelium cells) aggregate intocords become tubulus seminiferus sertoli cellproduce Mullerian inhibitory factor(MIF) and

2. mesenchymal cells of the gonadal ridge begin todifferentiate into Leydig cell Leydig cells producetestosteron

Mullerian inhibitory factor and testosteron influence thedevelopment of the genital duct and the genital externalto differentiate in the male direction.


18/31

Molecular regulation of genital

duct development SRY ---> master gene for testes development.

SRY also upregulates SF1 ---> acts through another

transcription factor (SOX9) to induce defferentiation of

sertoli and leydig cells.

Sertoli cells produce MIS/AMH that cause regression

which enters cells of target tissues where it may

remain or be converted to dihydrotestoterone by a 5

reductase enzyme.

Testosteron + dihydrotestoterone bind to a spesific

high-affinity intraceluller receptor protein, and

ultimately binds to DNA to regulate trancription of

tissue-spesific genes and their protein product.

Penis


19/31

Indifferent

gonadTestis

Y chromosome

Testis

Determining

factor Leydig cells

Sertoli cells

Testosterone

Androgen

Binding

Factor

Mullerian

Inhibiting Factor

Mullerian

Duct Degenerates

Germ cells Spermatozoa

Wolffian

Duct

Epididymis

Vas deferens

Seminal vesicle

5-alfa

reductase

Dihydro-testosterone

Urethral endothelium Prostate

Genital swelling Scrotum

Tuberculum genitale Penis

The developing process of the male genital organs

SOX9


20/31

Development of Gonads


21/31


22/31

Development of Genital Ducts

Mesonephric duct epididymis , defferen

duct & ejaculatory duct, seminal gland

The Paramesonephric duct develop

lateral to the gonads and mesonephric

ducts, pass caudally, parallel to the

mesonephric ducts, until they reach the

future pelvic region of the embryo, and todevelop to the tuba uterina, and uterus.


23/31

Development of Genital Duct

Testis fetal menghasilkan hormon untuk maskulinisasi yitestosteron, dan substansi inhibiting mullerian (MIS). Sel

sertoli mulai menghasilkan MIS pd minggu ke-6 s/d -7.

Sel leydig mulai menghasilkan testosteron mulai minggu

ke-8.


24/31

Development of Male Genital Ducts

and Glands

1. Prostate

The glandular epithelium of

the prostate

differentiates from theendodermal cells, and

the associated

mesenchyme

differentiates into thedense stroma and

smooth muscle of the

prostate.


25/31


26/31

Development of Male External Genitalia

Inducedby testosterone which produced by the

interstitial cells of the fetal testes.


27/31

Cont male external genital

The phallusdevelop penis The urogenital folds forms the lateral wall of the urethral

groove lined by a proliferation of endodermal cells,

the urethral plate,

The urogenital folds fuse each other and forms spongy

urethra

The surface ectoderm forms the penile raphe and

enclosing the spongy urethra within the penis

During the 12th week a circular ingrowth of ectoderm

occurs at the periphery of the glans penis, and when itsbreakdown it forms the prepuce (foreskin), which

covering fold of skin.


28/31

Development of Inguinal Canals

The inguinal canals form pathways for the testes todescend from theirintra-abdominal position through the

anterior abdominal wall into the scrotum


29/31

Descent of the Testes

This is association with

- Enlargement of testes and

- atrophy of mesonepros,

- atrophy of paramesonepridicus duct,

- enlargement of processus vaginalis,

- enlargement of pelvis foetal,

- increase in abdominal pressure resultingfrom the growth of abdominal viscera


30/31

Cont.

By 26 weeks, the testes have descendedretroperitoneally (external to the peritoneum)

from the posterior abdominal wall to the deep

inguinal rings

.This change in position occurs as the fetalpelvis enlarges and the trunk of the embryo

elongates.

Little is known about the cause of testicular

descent through the inguinal canals into thescrotum, but the process is controlled by

androgens (e.g., testosterone) produced by the

fetal testes.


31/31

Male derivative Indifferent structure Female derivative

testis gonad ovary

Spermatozoa Primordial germ cells Ova

Seminiferus tubulus(sertoli cells)

Sex cords Follicular cells

Efferent ductules Mesonephric tubules Epoophoron

Epididymal duct,

ductus defferens

Mesonephric (Wolffian)

duct

Degenerates (ovarian,

round ligament )

Degenerates Paramesonephric

(Mullerian) duct

Uterine tubes, uterus,

part of vagina

Bladder, protaste

urethra

Early urogenital sinus Bladder, paraurethral

gland, urethra, vagina

Lower urethra, bulbo

urethral gland

Definitive urogenital sinus Vestibule, Major

vestibular gland

Penis Genital tubercle = phallus clitoris

Floor of penile urethra Urogenital fold Labia minora

The Genital Organs Differentiation

Documents

Transcript of The Genital Organs Differentiation