Characterization of fibronectin on human spermatozoa

Ejaculated human spermatozoa were shown to have fibronectin polypeptides on their surface. Immunofluorescence studies revealed fibronectin as a belt-like fluorescent band on the post-acrosomal area of sperm heads, whereas none was found in sperm tails. The location of the fluorescent band corresponded to the equatorial segment of the spermatozoon. Fibronectin polypeptides were heterogeneous with Mr ranging from 35000 to 210000, as revealed by immunoblotting and by immunoprecipitation of detergent extracts from surface-radioiodinated spermatozoa.