A method for the cytogenetic detection of early embryos in heifers

The objective of the study was to work out a simple and reliable method of the cytogenetic examination of bovine embryos. Whole embryos free of the zona pellucida, or parts of these embryos, were cultivated for five hours in a medium with 0.05 microgram colcemide per 1 millilitre. The embryos were hypotonized for 10 to 15 minutes in a mixture of medium and distilled water (1:2 ratio) at the temperature of 37 degrees C. Stepwise fixation was used: first in a mixture of acetic acid, methyl alcohol and water (1:4:5), followed by dropping a mixture of acetic acid and methyl alcohol (1:1) onto the embryo already on the microscope slide during microscopic control. The chromosomes were stained with a 3% solution of Giemsa dye for 10 minutes.