Gender Preselection in Domestic Animals Using Flow Cytometrically Sorted Sperm1

Preselecting the gender of offspring in both humans and animals has been of keen interest since the beginning of recorded history. Numerous attempts have been made to accomplish gender preselection in both humans and animals. However, virtually all attempts have ended in failure, primarily because they lacked a scientific basis upon which to determine a measurable difference. Some methods have been derived from folklore, in which case there was virtually no possibility for success. This paper deals briefly with the numerous “physical separation” methods that have been proposed and(or) used to separate X- and Y-chromosome-bearing sperm, but the main emphasis is given to the technique of flow cytometry for sperm validation and X- and Y-bearing sperm separation. Flow cytometric analysis of sperm DNA is very useful for evaluating the proportions of X- and Y-bearing sperm in a sample of semen. Similarly, flow cytometric sorting of X-and Y-bearing sperm has also proven itself to be the only laboratory method that skews the sex ratio of semen. This flow cytometric sorting method has been used successfully to produce progeny from rabbits and swine surgically inseminated from separate populations of X- and Y-bearing sperm.