ILA 147 immunoreactivity of the bull spermatozoa membrane during epididymal maturation

A cytochemical quantitative study was carried out to detect immunostaining of bull spermatozoa during epididymal maturation using an ILA 147 monoclonal antibody and a standard immunoperoxidase method. This antibody recognizes a bovine panleukocyte determinant. Microdensitometric measurements were made on spermatozoa collected from different sites of the male genital tract (caput, corpus and cauda epididymidis and ductus deferens). On the basis of ILA 147 staining, at least 5 subpopulations of sperm cells from each site of the genital tract were found. These subpopulations showed: 1) immunostaining in the acrosome domain and in the cytoplasmic droplet in a proximal position; 2) immunostaining in the acrosome domain and in the distal cytoplasmic droplet; 3) immunostaining in the acrosomal region and lack of a cytoplasmic droplet; 4) immunostaining only in the cytoplasmic droplet; 5) lack of a cytoplasmic droplet and absence of staining of the head. The possible relationship between the presence of ILA 147 on the sperm head and the maturation process was evaluated, and we suggest that the most significant changes in ILA 147 expression occur in the corpus epididymidis. The absence of immunocytochemical staining in some spermatozoa may be related to plasma membrane damage due to spontaneous peroxidative damage of lipids.