Changes in lipid composition of the maturing rat testis.

1. The lipids and fatty acids of the lipids of testes of rats aged 4 weeks to 6 months were separated and analysed. 2. A decrease in concentration of triglyceride was noted, but there was no significant change in the concentration of phospholipids, plasmalogen or cholesterol during this time. 3. There were no significant differences in the total lipid concentration of palmitic acid, stearic acid, linoleic acid, arachidonic acid and docosatetraenoic acid between the various age groups. 4. A decrease in the concentration of oleic acid in the phosphatide and triglyceride fractions and an increase in the concentration of docosapentaenoic acid (characterized as the Delta4,7,10,13,16-isomer) in phosphatides but not in triglyceride were observed during the maturation period. 5. Histological studies indicated that the lipid changes occurred at the same time as the appearance and maturation of the spermatids.