Two rams were injected intratesticularly with [1-14C]-palmitic acid, and the amounts and distributions of radiolabel in the sperm and seminal plasma lipids of ejaculates were monitored for 63 days. The residual label remaining in the epididymal spermatozoa and fluid and the testicular tissue of one animal was also examined.
After Day 17, two broad areas of high specific activity were observed in sperm lipids, with maxima occurring on Days 28 and 42. The pattern of labelling of seminal plasma lipids was similar, but the major peaks of activity occurred on Days 31 and 45. By Day 63, both sperm and plasma activities were low.
In spermatozoa, the radioactivity was largely confined to phospholipid fractions, with phosphatidylinositol showing high specific activity relative to other lipids in each ejaculate. The only neutral lipids to have measurable activity were 1,2-diglycerides, but the distribution of label among the various lipid classes altered considerably with time.
A detailed analysis of the distributions of label in ejaculates on Days 28 and 42 revealed that 10 to 12% of the 14C in sperm lipids on each day was present in mono-unsaturated components. The labelling of plasmalogenic aldehydes accounted for 19·3% and 25·8% of the radioactivity in sperm phospholipids on Day 28, but only 9·9% and 9·8% on Day 42 in ejaculates from the two rams.
Testicular tissue differed markedly from epididymal and ejaculated spermatozoa on Day 63, in that triglycerides and 1,3-diglycerides showed high specific activity.
These findings have been discussed in relation to the processes of spermatogenesis in the ram.