A method has been developed for the simultaneous isolation of spermatozoa and cytoplasmic droplets from bull, boar and ram semen. The glycolytic enzymes, hexokinase (HK), glucose phosphate isomerase (GPI) and lactate dehydrogenase (LDH) were demonstrated in both types of particle: on a per particle basis compared with spermatozoa, droplets contained similar quantities of GPI, less HK and only one-tenth the amount of LDH. The HK was partly bound while the GPI was entirely soluble in both. The LDH was partly bound in spermatozoa but soluble in droplets.
Suspensions of spermatozoa and cytoplasmic droplets were subjected to sudden cooling, freezing or hypo-osmotic shock, and leakage of GPI, HK and LDH into the extracellular medium was measured. Both spermatozoa and droplets released glycolytic enzymes during the treatments, but the droplets were more fragile than the spermatozoa. The proportion of loss varied between enzymes, as well as between droplet and spermatozoon; considerable GPI and little HK was released from both, whereas much LDH was lost from droplets but hardly any from spermatozoa.
The activities of these three glycolytic enzymes were also measured in seminal plasma from bull, boar and ram. The ratios of the activities found were compared with those in droplets or spermatozoa from the same species. It is suggested that much of the glycolytic enzyme activity in seminal plasma arises from disintegrated cytoplasmic droplets rather than from spermatozoa.
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