Intersex

Introduction

• Developmental abnormalities resulting in discordance between genetic, gonadal or phenotypic sex.
• Includes true hermaphrodites, pseudohermaphrodites and other forms of sex reversal.

Hermaphroditism

• Individual possessing gonads of both sexes.
• Rare

Aetiology

• Failure of embryological differentiation of gonads during foetal life leads to the presence of both ovarian and testicular tissue (ovotestis or one of each type).

Consequence

• The tract is predominantly female, although there is often an enlarged clitoris and reduced vulval lips.
• Usually XX with H-Y antigen (protein normally coded for by Y chromosome).

Pseudohermaphroditism

• Gonads are of one sex and the ducts and external genitalia are modified towards, or are of, the opposite sex.
  • Male pseudohermaphrodite: Testis-like gonads and predominantly female genitalia.
    • Commonly found amongst pigs (and goats).
    • Affected animals behave like males and may mount.
    • There is a sub-anal genital opening with a prominent clitoris.
    • Testes may be in a scrotal structure or intra abdominal.
    • Poorly developed uterine horns which may contain mucus-like secretion.
  • Female pseudohermaphrodite: Ovary-like gonads and male-like genitalia,rare.

Aetiology

• Genetic
  • In goats the characteristic is linked to a gene for polledness (dominant).
  • Chromosomal studies in pigs, goats and dogs (Cocker Spaniels) have shown that most pseudohermaphrodites are basically genetic female (XX sex reversal) despite the testis-like nature of their gonads.

• XY gonadal dysgenesis (testicular feminisation syndrome)
  • Recognised in cattle and horses
  • Individuals are male pseudohermaphrodites with elevated testosterone levels.