Morphological study of the bovine blastocyst with phase contrast microscopy.

The morpholoqical appearance of 40 bovine blastocysts. collected from single ovulating heifers 7 days after oestrus was evaluated with the aid of a phase contrast inverted microscope. Out of 40 blastocysts, 17 were classified normal (N), 14 in the process of degeneration (IPD) and 9 degenerated (D). There was no difference in the mean diameters of the three groups of blastocysts, whereas the mean diameters of cell mass was bigger in N than IPD and D blastocysts. This difference was highly significant (P<.005). The mean number of cells was greater in normal than in abnormal (99 vs 58). This difference was highly significant (P<.005). The results reported here indicate that the criteria used for classification of the morphological appearance of the 7 day old bovine blastocyst reflected the degree of cellular organization and the number of cells.