Leucocytes containing ingested spermatozoa have been found in the female genital tract in small laboratory animals (McDonald, Black, McNutt & Casida, 1952; Austin, 1957; Yanagimachi & Chang, 1963), in pigs (Pitkjanen, 1960) and in ruminants (Howe & Black, 1963; Mattner, 1968). Using electron microscopy, Bedford (1965) found that the cell membranes and acrosomal cap remained intact in many of the spermatozoa present within leucocytes obtained from the uteri of oestrous rabbits inseminated 12 hr previously. The latter finding indicates that leucocytes may ingest undamaged, living spermatozoa as well as dead or damaged spermatozoa in the female genital tract. The present communication reports visual observations on the ingestion of motile spermatozoa in bovine cervical mucus and the failure of leucocytes to attack dead spermatozoa in the same medium.
Cervical mucus containing numerous polymorphonuclear leucocytes was obtained from cows in late oestrus. Threads of mucus and bovine semen were placed in