Indifferent stage

This development occurs between gestational weeks 8 and 12.

• 2 mesenchymal cloacal folds form on either side of cloacal membrane
• The 2 cloacal folds fuse infront of the cloacal membrane to form cloacal eminence

1. Cloacal eminence enlarges – forms genital tubercle
2. Cloacal membrane divides into urogenital membrane and anal membrane
3. Cloacal fold divides into genital fold and anal fold

• Another pair of elevation forms on either side of genital fold – genital swelling

In females:

• Genital tubercle – clitoris
• Genital fold – labia minora
• Genital swelling – 2 labia majoras

In males:

• Genital tubercle – elongates to form phallus
• Genital fold – elongates to form urethral groove which forms urethral plate and then urethral canal
• Genital swelling – 2 scrotal swellings, fuse – scrotum

Congenital anomalies:

1. Absence of penis/clitoris – no genital tubercle develops
2. Small penis – underdeveloped genital tubercle
3. large clitoris – overdeveloped genital tubercle
4. Divided scrotum – failure of genital swelling to fuse
5. False hermaphrodite – gonads are of one sex, external genitalia are of opposite sex