Segmental aplasia of the paramesonephric duct in a New Zealand white rabbit and a review of the literature.

In females, the paramesonephric (syn: Müllerian) duct gives rise to the uterine tubes, uterus, cervix, and part of the vagina. Segmental uterine aplasia resulting from a paramesonephric duct abnormality has been reported in a range of species including bovids, canids, felids, equids, camelids, and lagomorphs. Here we document segmental aplasia of the left paramesonephric duct in a New Zealand white rabbit. The proximal 70 mm of the left uterine tube was present and terminated in adipose tissue. A 10 × 2 × 1-mm tag of cream tissue was present and was composed of sheets of adipose tissue and streams of smooth muscle, but otherwise, there was no evidence of the left uterine horn, supporting a diagnosis of unilateral uterine aplasia (uterus unicornis) analogous to a human class II (unicornuate uterus) lesion of the "no horn" subtype. In addition, our case had a concurrent uterine tube fimbrial cyst, minor cysts in the left kidney, and mammary gland hyperplasia with secretory activity. We suggest the adoption of a uniform classification system specifically for lagomorph uterine anomalies. Large-scale multi-center studies documenting prevalence of such lesions would facilitate identification of trends in laterality and other factors.