Vet. Res. 38 (2007) 399-408
DOI: 10.1051/vetres:2007004

Tritrichomonas foetus damages bovine oocytes in vitro

Marlene Benchimol^a, Reginaldo da Silva Fontes^b and Ângelo José Burla Dias<sup>b

a</sup>  Laboratório de Ultraestrutura Celular-Universidade Santa Ursula, Rua Jornalista Orlando Dantas 59, Botafogo, Rio de Janeiro, CEP 22231010, Brazil
^b  Setor de Fisiologia e Biotecnologia da Reprodução de Ruminantes/Laboratório de Reprodução e Melhoramento Genético Animal/ Centro de Ciências e Tecnologias Agropecuárias-Universidade Estadual do Norte Fluminense, Campos dos Goytacazes, Rio de Janeiro, Brazil

(Received 27 February 2006; accepted 1 December 2006; published online 13 March 2007)

Abstract - Tritrichomonas foetus is an extracellular parasite of the urogenital tract in cattle. It causes infertility and abortion, but there is no documented information on the susceptibility of bovine oocytes to the parasite, except by one article that claimed no effects of T. foetus on oocytes or embryos. The aim of the present study was to study the effects provoked by T. foetus when in interaction with bovine oocytes. Oocytes were obtained from cow ovaries and divided into two groups: (1) one group contained cumulus cells, whereas (2) a second group was denuded from these cells. Light microscopy, video microscopy and scanning electron microscopy (SEM) revealed that exposure of oocytes to T. foetus caused rapid adhesion of the trichomonads to cumulus cells and to the zona pellucida (ZP). Motile parasites were observed for 12 h. The ZP was completely damaged, and the parasites were able to infiltrate beneath the ZP and reached the oocytes directly when the oocytes were denuded of the cumulus cells. Both the oocytes and the cumulus cells exhibited morphological characteristics compatible with apoptosis after interaction with T. foetus, such as chromatin condensation, the presence of several cytoplasmic vacuoles, with intact cellular membranes and organelles. The results from this study demonstrate that when a large number of T. foetus interacts with oocytes in vitro damage and apoptosis are provoked in the cow's reproductive cells. The behavior of this parasite as one of the causes of cattle infertility is discussed.

Key words: Tritrichomonas foetus / oocytes / cow / ultrastructure / infertility

Corresponding author: marleneben@uol.com.br

© INRA, EDP Sciences 2007