Observations on the early development of embryos from repeat breeder heifers.

The early development of embryos collected from repeat breeder heifers after slaughter was studied using different methods; morphological appearance, number of cells and features in semithin sections of Epon embedded material. Embryos collected from virgin heifers were used as controls. The incidence of abnormal embryos was higher in the repeat breeder than in the virgin heifers. The abnormalities were mainly confined to cell organization. They could be seen already during the oviductal transit of the ova.