On the Ultrastructure of Seven Day Old Normal (Blastocysts) and Abnormal Bovine Embryos

Twenty‐four 7 day old bovine embryos were collected from spontaneously ovulating heifers. The embryos were classified into three groups; normal, morphologically deviating or degenerated. Electron microscopy was used to ascertain the ultrastructural correlates to the phase contrast microscope classification. This study sustains the conclusion that only those embryos classified as normal blastocysts are likely to undergo further development.