Embryology of the Genital Embryology of the Genital OrgansOrgans

Per BrodalPer BrodalInstitutt for medisinske basalfagInstitutt for medisinske basalfag

Universitetet i OsloUniversitetet i Oslo

9th Semester 20089th Semester 2008

The Mesonephric Duct

Cloaca

Mesonephros

Metanephros

Mesonephric duct

Ureter bud

34 days (~ 5 weeks) 6 mm CR-length

Mesonephric excretory tubules

2P. Brodal

Early Gonadal Development

Primordial germ cells

Yolk sac

Gonadal ridge

Coelomic cavity

Mesonephric duct

Mesonephric ridge

3P. Brodal

Early Development of The Internal Genitals

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Neural tube

Dorsal aorta

Notochord

Dorsal mesentery

Coelomic cavity

Mesonephric duct

Mesonephric tubules

Gonadal (genital) ridge

The Gonadal Ridge

4 week embryo

Langman

Gonadal ridge Primitive sex cordsProliferating

coelomic epithelium

Mesonephric duct

6 week embryo

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Further Development - Male

Tunica Albuginea

Testis cords

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Undifferentiated stage (6 w)Mesonephric tubules

Gonadal anlage

Mesonephric duct(Wolff’s duct) ♂

Paramesonephric duct (Müller’s duct) ♀

Urogenital sinus (from the cloaca)

Primordia of accessory glands7P. Brodal Netter

Male and Female Gonadal Development

The mesonephric duct

The paramesonephric duct

Medullary sex cords

8P. Brodal

Male Female

The Female Genital Tract – Further Development

9P. Brodal

Malformations of the Uterus

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Development of the Urogenital Sinus

Allantois Cloaca

Rectum

Future bladder

Definitive urogenital sinus

Defective partitioning of the cloaca results in anomalies of anorectal, urinary or genital structures; e.g rectourethral fistula or rectovaginal fistula 11P. Brodal

Further development

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Netter

External Genitals

4 weeks 6 weeks

Genital tubercleCloacal fold

Cloacal membrane Urogenital membrane

Urogenital fold

5 months Newborn

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Hypospadia

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Descent of the Testes

Scrotum

Peritoneum

Retentio testis (kryptorchismus):

When the testes do not reach the scrotum

Inguinal hernia

when tunica vaginalis still communicates with the peritoneal cavity (processus vaginalis persists)

15P. Brodal