Fatty acid incorporations and lipid compositions of mature and immature bovine testes

1. 1. The incorporation of [I- 14C]myristic, -palmitic, -stearic, -oleic and -linoleic acids in vitro into the lipids of bovine testicular tissues was measured after incubation for 2 hours. Tissue slices from the testes of adult, 4-month and 2-week-old animals were used. 2. 2. The mature testis incorporated less of each substrate than immature testes, but each tissue incorporated linoleic acid to the greatest extent. 3. 3. Phosphatidylinositol and diglycerides were metabolically more active than other major phospholipid and neutral lipid fractions in the mature testis, and the metabolism of cholesteryl esters was also significant at this stage. 4. 4. With the immature testes a more general metabolism was apparent, reflecting the lack of functional specialization in these tissues. 5. 5. Incorporated linoleic acid was readily desaturated, with maximal desaturase activity occurring in the testis tissue from the 4-month-old calf. Fatty acid incorporations were not related to the endogenous fatty acid concentrations of testis lipids. 6. 6. The lipid fractions of all tissues contained very little docosapentaenoic acid, but considerable amounts of docosahexaenoic acid, particularly in the ethanolamine phosphoglycerides. Within the phospholipids, docosahexaenoic acid content increased with maturation, whereas arachidonic acid content decreased. PIasmalogenic aldehydes were more saturated in character in the mature testis.