LORI.bovine

Partially persistent hymen 

Keywords: hymen, bovine, partial, persistent, heritability

A persistent hymen in any mammal represents incomplete breakdown of the conjoined embryonic margins of ectoderm and endoderm. Apoptosis of that structure is a normal phenomenon in the formation of a patent anus and vagina. The junction of ectoderm and endoderm in the vagina occur just cranial to the urethral orifice, dividing the vagina into the vestibule and cranial vagina. The reason for incomplete breakdown is unknown. Interestingly, atresia ani, an allied phenomenon, is well known to have a heritable basis in pigs and may also be heritable in calves and some breeds of dogs. Yet, persistent hymen, is not known to be heritable in any domestic animal.

In this case, there was a partial breakdown of the hymen in a beef heifer, seen during a postmortem examination for other reasons. As expected, this animal had shown none of the typical signs of a persistent hymen seen in a heifer i.e. a distended cranial vagina with occasional signs of tenesmus as described elsewhere in LORI.

Figure 1. A partially persistent hymen in a beef heifer. In this case, the hymen (black arrow) seen on the left is merely a thin dorso-ventral band, just cranial to the external urethral orifice (green arrow). On the right, the vagina has been opened and the hymen remnant, transected. The pair of forceps indicates its earlier location. Image size: 3000 x 2165px

Note: In this image the terms “cranial vagina” and “vestibule of the vagina” are used. Some prefer to simplify these terms to “vestibule” and “vagina”; an argument that remains contentious.

Selected references:

Kılıç, N. and Sarıerler, M. (2004). Congenital ıntestinal atresia in calves: 61 Cases (1999–2003). Revue Méd Vét, 155:381-384

Vianna, M.L. et al 2005 Atresia Ani in the Dog: A Retrospective Study. JAAHA 41:317-322