Agonadal presumptive XX/XY leukochimeric pig

Background: XX/XY chimeric pigs are uncommon and their reproductive anatomy is variable and unpredictable. Method: A piglet was identified by its enlarged vulva as a possible intersex. Venous blood was collected at 1.5 and 9 months for karyotyping and determination of testosterone and estrone sulphate concentrations. At 1 year euthanasia was performed. The reproductive tract was carefully dissected and examined histologically. Results: As the animal matured the vulva did not develop relative to the size of the animal. Lymphocyte cultures indicated a 70% XX/30% XY chimera. The reproductive tract consisted of a strand of tissue enveloped by fascia. Histological study revealed presumptive Wolffian derivatives, coiled bilateral ducts along the tract, and a Müllerian derivative, a medially located duct in the caudal third of the tract. No gonads were found. Plasma levels of estrone sulfate and testosterone were negligible. Conclusions: In utero exposure to exogenous androgens from a male cotwin or weak endogenous adrenal androgens may account for the enlarged vulva at birth and retention of the androgen dependent Wolffian duct primordia. An atesticular state is supported by retention of the Müllerian duct primordia and the negligible peripheral sex steroids. © 1995 Wiley‐Liss, Inc.