AbstractEjaculated spermatozoa of boars, bulls, rabbits, and rams were fixed with glutaraldehyde and embedded in glycolmethacrylate. Thin sections were treated with phosphotungstic acid at low pH in order to localize cellular glycoproteins stained by the PAS technique at the light microscope level. At the ultrastructural level the glycoproteins were segregated in the anterior segment of mature spermatozoa. The distribution of these glycoproteins in the anterior segment was not homogeneous; it appeared species‐specific in detail, but as a rule, the maximum concentration was observed in a superficial layer, especially in the marginal thickening. The localization of other acrosomal components (eg, crystalline and basic proteins) is also reviewed. The origin and significance of the segregation of proteins and glycoproteins in the acrosome are discussed in relation to the fact that the acrosomal enzymes analyzed so far are glycoprotein