The recovery of ureaplasmas from bovine embryos following in vitro exposure and ten washes

Twenty-six unhatched embryos and ova were exposed to Ureaplasma diversum strain 2312 in vitro for 16 h and subsequently washed ten times. Fifteen of the embryos and their wash fluids were cultured for ureaplasmas. Of the remaining 11 embryos, six were incubated with rabbit anti-Ureaplasma immunoglobulin (RAI) and five were incubated with serum from naive rabbits(NRS), after which all were incubated with protein A gold and prepared for electron microscopy. On ultrastructural examination, ureaplasmas were observed on the outer surface of the zona pellucida of all 11 embryos. The ureaplasmas on the six embryos incubated with RAI were labeled with gold particles, while those on the five embryos incubated with NRS were not labeled. Ureaplasmas were recovered from all 15 of the cultured embryos and all of the first and second wash fluids as well as intermittently from the third, fourth, sixth, seventh, eighth and ninth wash but not fom the fifth or tenth wash. It was concluded that viable ureaplasmas adhered to the zona pellucida during in vitro exposure of bovine embryos and were not removed by ten washes.