Influence of ejaculation frequency on semen characteristics in chimpanzees (Pan troglodytes)

in Reproduction

Summary. Semen samples were obtained by masturbation from 6 chimpanzees and the spontaneously liquefied fraction and the remaining coagulum were studied separately. When semen was collected once or twice a week, large intra-individual variations were observed for all measures. The liquefied fraction represented 26·5 ± 3·2% (weighted mean ± s.d.) of the total ejaculate but contained 51·3 ± 3·8% of all emitted spermatozoa. Fructose concentration was higher in the coagulum than in the liquefied fraction (29·3 ± 3·0 μmol/ml vs 12·0 ± 2·7 μmol/ml, P < 0·001) whereas acid phosphatase was less concentrated in the coagulum than in the liquefied fraction (3·5 ± 0·3 × 103 IU/ml vs 13·0 ± 0·9 × 103 IU/ml, P < 0·001). l-Carnitine and citrate concentrations did not differ between the two fractions of the ejaculate.

When semen collection was repeated every hour for 5 h, the ejaculate volume increased from 2·6 ± 0·7 to 4·7 ± 0·6 ml (P < 0·001), whereas total sperm count decreased from 1278 ± 872 × 106 to 587 ± 329 × 106 (P < 0·05) between the 1st and the 6th ejaculate. In the spontaneously liquefied fraction, the sperm count decreased from 984 to 369 × 106. The 6 successive ejaculates gave a total of 20·2 ± 7·6 ml and 4278 ± 2884 × 106 spermatozoa. The increase of the ejaculate volume was essentially due to an increase of the volume of the coagulum which closely correlated with total amount of fructose (from seminal vesicles) (r = 0·913, P < 0·001). The volume of the liquefied fraction and total amounts of l-carnitine (from epididymis), citrate and acid phosphatase (both from prostate) did not show any significant variations.

These results suggest (1) a high reserve capacity of the male genital tract in chimpanzees and (2) an increase in seminal vesicle secretion resulting from sexual stimulation induced by high masturbation frequency.

Keywords: semen; chimpanzee; ejaculation frequency; masturbation; fructose

 

An official journal of

Society for Reproduction and Fertility

Information

Cited By

PubMed

Google Scholar

Related Articles

Altmetrics

Metrics

All Time Past Year Past 30 Days
Abstract Views 0 0 0
Full Text Views 55 55 55
PDF Downloads 48 48 48