SIZING OF AGING BULL SPERMATOZOA WITH AN ELECTRONIC COUNTER

Cell size was evaluated as a criterion of the functional state of spermatozoa. Packed cell volume of 13 samples of bull semen stored at room temperature for 1, 3, 5, 7, 9 and 11.5 hours averaged 8.7, 10.6, 11.2, 12.0, 12.1, and 12.2%. Corresponding mean window values obtained with a Coulter Counter were 12.3, 14.3, 15.6, 16.0, 16.1, and 15.9. Correlations between these two types of measurements ranged from 0.87 to 0.99 (P < 0.01) for 11 of the 13 bulls. Spermatozoa killed by freezing and thawing did not swell. Mixtures of live and dead spermatozoa stored at 7 C show a bimodal distribution formed by the two types of cells. Following death of all cells, a single distribution remained. In a study of size changes during storage of 87 ejaculates from six bulls, bulls were found to differ (P < 0.05). Samples high in sperm concentration swelled less and for a shorter period; motility declined more rapidly during storage. Size changes measured in living cells with this technique offer an approach to studying maintenance of integrity of the cell in a variety of environments. © 1969, American Dairy Science Association. All rights reserved.