The labelling of ram semen in vivo with radioactive phosphate and [carboxy-14C]stearic acid

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Abstract
Rams were injected with P32-phosphate and carboxy-C14-stearic acid, and a study was made of the appearance rate of labeled P compounds and fatty acids in the seminal plasma and sperm of serially collected samples of semen. The maximum p32-labeling of seminal glycerylphosphorylcholine occurred some 15-18 days after injection, and next appeared the sperm phospholipids, acid-soluble phosphorus and a fraction designated as residual phosphorus, all having maxima at about 21-26 days. The labeled sperm deoxyribonucleic acid appeared much later, reaching a maximum at 50-52 days. In one animal ejaculating non-motile sperm, the appearance of labeled glycerlphosphorylcholine in the semen was considerably delayed compared with the normal rams. In a ram in which the connections between the epididymides and testes were severed surgically, the seminal-plasma glycerylphosphorylcholine and sperm acid-soluble P became labeled with P32, but no appreciable activity appeared in the phospholipids, residual P and deoxyribonucleic acids of the ejaculated sperm. Simultaneous injection of a ram with p32-phosphate and Cl4-stearic acid did not indicate any transfer of labeled fatty acids to the sperm at the time of formation of glycerylphosphorylcholine. From these results, the minimum time taken for the sperm to pass through the epididymides and also the time taken for the spermatocytes to be converted into the spermatozoa was determined.