Localisation of specific glycoproteins secreted by the rabbit and hamster epididy¬ mis

To investigate the origin and fate of a number of specific epididymal proteins, the luminal con-tents from the cauda epididymides of sexually mature New Zealand White rabbits and Syrian ham-sters were collected by retrograde perfusion. Epididymal fluid, separated from spermatozoa by centrifugation over a 10 % Ficolh solution, was then subjected to isoelectric focussing on pohyacrylamide flat bed gels. Three epididymal-specific proteins from the rabbit, p1 3.45, 4.1 5 and 4.65 and two from the hamster, ph 3.40 and 4.1 5 were identified as glycoproteins by their how isoehectric point and their affinity for con-canavalin A. These fractions were isolated and implanted s.c. in guinea pigs and rabbits, respec tively, to produce monospecific antisera as verified by immunodiffusion and immunoehectropho resis. Localization of glycoprotein antigen within the epididymis was performed on longitudinal sections of snap-frozen epididymis using the unlabeled antibody enzyme method. Both rabbit and hamster glycoproteins were secreted mainly by epididymal epithehial cells in the caput and proxi-mal corpus region. However, the initial segments and testis were devoid of antigen. Differences were also apparent in the staining pattern of individual glycoproteins. In the rabbit, glycoproteins were first associated with spermatozoa in the distal caput and proximal corpus epididymidis while glycoproteins in the hamster epididymis were first associated with spermatozoa in the proximal caput region. Reaction product to glycoproteins in the cauda epididymidis of both species was present on spermatozoa and at the adhuminal border of epithehial cells. The significance of these re-suhts with regard to changes in the surface composition of the sperm plasmalemma during matura-tion is discussed