Intersex

Introduction

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

INTERSEX

(Information by permission of Professor RW Else)

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

HERMAPHRODITISM

• True hermaphrodite is an individual possessing gonads of both sexes. This is rare.
• 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). 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).

• Pseudohermaphrodite 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 + predominantly female genitalia. More common.

Female pseudohermaphrodite = ovary-like gonads + male-like genitalia. Rare.

• Male pseudohermaphrodites are 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.
• Tnere may be a poorly developed uterine horns which may contain mucus-like secretion.

Aetiology:

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

Equine conditions:

1. XY Sex-reversal:
   • Inherited trait with XY Karyotypes but variably female phenotype of external genitalia.
   • Wide range of morphology from near-normal tract with inactive ovaries, to hypoplastic ovaries or ovotestes with aplastic genital tract.
   • Thought to involve Y chromosome mutation.
2. Testicular feminisation:
   • XY genotype with testosterone producing but sterile gonads internally and female external genitalia.
   • The vagina is blind-ending with absence of internal genital tract.
   • These male pseudohermaphrodites exhibit male behaviour and have significant testosterone levels.

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.