Phospholipid and Cholesterol Content of Epididymal and Jaculated Ram Spermatozoa and Seminal Plasma in Elation to Cold Shock

Abstract

The concentration of total phospholipid, phosphatidyl-choline, phosphatidylethanolamine, and choline plasmalogen in spermatozoa from the caput epididymis of the ram was higher than in spermatozoa from the cauda. The phospholipid composition of spermatozoa from the latter region of the epididymis more closely resembled ejaculated spermatozoa. In general, the plasma of caput and cauda semen was similar in total phospholipid content and composition. The total phospholipid concentration of ejaculated seminal plasma was only about one-fifth that of the caput and cauda fluid and all phospholipid fractions were greatly reduced. The glycerylphosphorylcholine content of caput spermatozoa and seminal plasma was less than that of the corresponding semen fractions obtained from the cauda epididymis, and after ejaculation. The concentration of non-esterified cholesterol in both the spermatozoa and plasma decreased on passing from the caput to the cauda epididymis and was even less in the corresponding fractions of ejaculated semen. Spermatozoa taken from the testis and caput epididymis were little affected by cold shock whereas spermatozoa from the cauda epididymis and ampulla were much more susceptible, as judged by increased permeability to stain. It is suggested that a decrease in the phospholipid and cholesterol content of spermatozoa may be associated with an increase in the susceptibility of ram spermatozoa to cold shock as they pass through the male reproductive tract.