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XY female marmoset (Callithrix jacchus).
Jose M Sanchez-Morgado1, Richard Haworth, Timothy H Morris
1Laboratory Animal Science, GlaxoSmithkline, The Frythe, Welwyn, Herts, AL6 9AR, United Kingdom.
Comparative Medicine
|December 6, 2003
Summary
This study details a marmoset with atypical genitalia, revealing it to be genetically male (XY) but with female internal organs. This case highlights the complex interplay of genetics and development in sex determination.
Area of Science:
- Primate genetics and reproductive biology.
- Comparative endocrinology and sex determination.
Background:
- Common marmosets (Callithrix jacchus) typically exhibit XX/XY chimerism and high steroid hormone levels.
- Phenotypic and genetic characterization is crucial for understanding variations in sexual development.
Observation:
- A marmoset presented with atypical external genitalia, including a single urethral opening.
- Internal examination revealed ovaries with developing follicles and a uterus, characteristic of female anatomy.
- Microscopic analysis confirmed a normal vaginal structure.
Findings:
- Genetic analysis identified Y-linked chromosome sequences, including the ZFY gene and SRY exon, confirming a male (XY) karyotype.
- Testosterone concentrations were comparable to those observed in female marmosets.
- Despite the presence of male sex-determining genes (SRY), the individual possessed female internal sexual organs.
Implications:
- This case represents a potential "XY female" in non-human primates, challenging established models of sex determination.
- The findings suggest that normal SRY gene expression can be associated with female internal sexual organ development in marmosets.
- Further research is needed to elucidate the mechanisms underlying this phenomenon and its broader implications for mammalian sex differentiation.