The surface membrane protein of boar sperm and the proteins in the fluid surrounding the gametes were analyzed during epididymal transit. The present study demonstrated that sequential dramatic changes occur in protein composition of the sperm membrane and epididymal fluid during epididymal transit. The maturation process of the boar sperm surface was characterized by a complex sequential evolution of the composition and orientation of macromolecules in the sperm membrane. Epididymal maturation resulted in the progressive disappearance of most of the surface testicular compounds, which were either renewed or masked by new permanent or transient low molecular weight polypeptides on the boar sperm surface membrane. In the fluid surrounding the spermatozoa, composition of the luminal proteins was altered throughout the epididymal transit and several new compounds were characterized. Very few proteins were correlated either with blood plasma or sperm surface compounds.

Internal pH and motility of testicular, epididymal and ejaculated ram and boar spermatozoa were studied as a function of external ionic composition. Internal pH was estimated by the amine distribution method and motility was characterized by percentage of cells that were motile and flagellar beat frequency. Upon dilution in media at different external pH values, internal pH of boar and ram spermatozoa changed rapidly towards the external pH. High external concentrations of Na+ or K+ had no effect on the rate of equilibration and only a slight effect on the final internal pH value, ruling out a role of Na(+)-H+ or K(+)-H+ exchange mechanisms in this process. In both species, a linear relationship was observed between internal and external pH but equilibration was incomplete suggesting that there is a complex regulatory mechanism. This result was unaffected by epididymal maturation and ejaculation. Ram and boar testicular spermatozoa showed no increase in movement after dilution, suggesting that simple changes in internal pH are not a sufficient trigger for motility. At high external pH, internal pH increased and motility of epididymal boar spermatozoa was initiated. Motility of ejaculated boar spermatozoa, and epididymal and ejaculated ram spermatozoa was less dependent upon external pH and affected only very slightly by the internal pH changes. K+ or Na+ had almost no effect on motility just after dilution. After 1 h of incubation, movement decreased. Maintenance of motility in sodium or potassium showed a sharp external pH optimum. Media without Na+ and K+ allowed a better conservation of motility at external pH > 8 for ram epididymal and ejaculated spermatozoa and at external pH > 6 for boar ejaculated spermatozoa.

Summary. This paper compares the principal modifications taking place in spermatozoa during epididymal transit in several species. The relations between changes in the epididymal medium and modifications in the metabolism, motility and/or fertility of spermatozoa are reviewed with particular reference to spermatozoon forward motility. The fertilizing ability of motile testicular and epididymal spermatozoa has been described.It is suggested that the maturation process may induce a series of spermatozoal changes in cyclic AMP content, external membrane composition and nuclear structure throughout the genital tract ; these changes would be under the control of the epididymal epithelium. The origins of these phenomena are practically unknown.Introduction.

Summary― Freezing-thawing effects on the nuclei of porcine and human spermatozoa were studied by determining native DNA percentage from fluorescence after acridine orange (AO)

Spermatozoa from the corpus epididymidis of boars and rams showed head\x=req-\ to-head agglutination when diluted. The occurrence of agglutination coincided with the appearance of motility but preceded the ability to bind to zona-free hamster eggs. Head-to-head agglutination was inhibited by the addition of caudal epididymal plasma. A protein acting as an antagglutinin on spermatozoa from the corpus epididymidis was extracted from cauda epididymal plasma and partly purified.