A series of recent studies has been devoted to the systematic examination of characteristics of the semen of subhuman primates, with particular reference to the successful freeze-preservation of these specimens. Roussel & Austin (1967a) showed that trypsin will liquefy the coagulum which appears in these ejaculates without harm to the motility of the sperm cells and the survival rates of cells from five species after 3 days' storage in liquid nitrogen have also been reported (Roussel & Austin, 1967b). The initial content of fructose, lactic acid and citric acid in the frozen semen of animals from eleven species was studied (Ackerman & Roussel, 1968) in order to establish the extent of variability among
D. R. ACKERMAN and J. D. ROUSSEL
D. R. ACKERMAN and J. D. ROUSSEL
Comparative studies of semen characteristics in subhuman primate species should be of value in the selection of appropriate species for experiments in reproduction. In addition, basic information obtained in such studies may be helpful for the successful preservation of frozen semen and insemination. These techniques will probably be essential in the maintenance of large primate colonies. Finally, comparative information of this kind should be of interest to students of primate classification. Animals providing specimens for this study were selected from over 800, representing a dozen or more species, located at the Delta Regional Primate Research Center, Covington, Louisiana. The classification employed is that outlined in the Progress Report of the Primate Centers' Committee
J. D. ROUSSEL and C. R. AUSTIN
As early as 1897, Davenport found that human spermatozoa would survive freezing to − 17° C, but little progress in the freeze-preservation of spermatozoa was made until 1949 when Polge, Smith & Parkes reported that the use of glycerol made possible the revival of motility in fowl spermatozoa kept at − 79° C for long periods of time. Later, freeze-preservation of the semen of several animals became a routine procedure (see Sherman, 1964). Success, however, appeared to depend upon closely controlled rates of freezing and thawing, which de-manded the use of specialized equipment. It was first shown by Sherman (1963) with human semen, and by Roussel, Kellgren & Patrick (1964) with bovine semen, that successful freezing and storage of spermatozoa in liquid nitrogen vapour for indefinite periods of time could be achieved without instrumentation. The present report describes the employment of this procedure for primate semen.
J. D. ROUSSEL and O. T. STALLCUP
Alkaline and acid phosphatase levels, and various other semen characteristics, have been examined in 149 semen samples from twelve Holstein-Friesian bulls. Alkaline phosphatase and acid phosphatase mean values were 26·1 ± 18·0 and 7·4±7·8 Sigma units/ml for spermatozoa free of seminal plasma and 105·7±42·5 and 24·7±11·8 Sigma units/ml for seminal plasma. Alkaline phosphatase activity of spermatozoa was significantly correlated with the percentage of motile spermatozoa, and percentage of live spermatozoa. When acid phosphatase values were adjusted for concentration of spermatozoa per sample, highly significant negative correlations were obtained with the percentage of motile spermatozoa and the percentage of live spermatozoa, and a positive correlation with the percentage of abnormal spermatozoa. When alkaline phosphatase of seminal plasma and the alkaline phosphatase/acid phosphatase ratio in seminal plasma were adjusted for concentration of spermatozoa per sample, highly significant negative correlations were obtained with the percentage of motile spermatozoa and the percentage of live spermatozoa, and a positive correlation with the percentage of abnormal spermatozoa. The percentage of motile spermatozoa was significantly correlated with alkaline phosphatase and acid phosphatase in seminal plasma, whereas the percentage of abnormal spermatozoa was negatively correlated with alkaline phosphatase and acid phosphatase.
W. E. GREER, J. D. ROUSSEL and C. R. AUSTIN
Monkey semen characteristically coagulates during ejaculation, and samples obtained by electrical stimulation consist wholly or largely of a rubbery mass. Some spontaneous dissolution occurs when the ejaculate is held in vitro at room or body temperature, but more than half the mass, usually about 75%, remains unchanged. Use of monkey semen for laboratory studies or for artificial insemination is hampered by this feature. To some extent, the trouble can be remedied by the use of proteolytic enzymes, of which trypsin seems to be the least deleterious to sperm viability (Roussel & Austin, 1967), but the presence of trypsin raises problems for many biochemical studies. Accordingly, the possibility was investigated that surgical removal of the coagulum-producing gland from the male tract might result in the ejaculation of coagulum-free semen, without seriously interfering with the volume and other semen charac