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\m=.\5 \ m=+-\ 3\m=.\2% (weighted mean \m=+-\ s.d.) of the total ejaculate but contained 51\m=.\3\m=+-\ 3\m=.\8%of all emitted spermatozoa. Fructose concentration was higher in the coagulum than in the liquefied fraction (29\m=.\3\ m=+-\ 3\m=.\0\g=m\mol/mlvs 12\m=.\0\ m=+-\ 2\m=.\7\g=m\mol/ml,P < 0\m=.\001) whereas acid phosphatase was less concentrated in the coagulum than in the liquefied fraction (3\m=.\5\ m=+-\ 0\m=.\3\m=x\103 IU/ml vs 13\m=.\0\ m=+-\ 0\m=.\9\m=x\103 IU/ml, P < 0\m=.\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\m=.\6\ m=+-\ 0\m=.\7to 4\m=.\7\ m=+-\ 0\m=.\6ml (P < 0\m=.\001), whereas total sperm count decreased from 1278 \ m=+-\ 872 \ m=x\106 to 587 \ m=+-\ 329 \ m=x\106 (P < 0\m=.\05) between the 1st and the 6th ejaculate. In the spontaneously liquefied fraction, the sperm count decreased from 984 to 369 \m=x\106. The 6 successive ejaculates gave a total of 20\m=.\2 \ m=+-\ 7\m=.\6ml and 4278 \ m=+-\ 2884 \ m=x\ 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\m=.\913,P < 0\m=.\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.

Abstract. Six men requesting male contraception received a daily oral dose of 20 mg medroxyprogesterone acetate (MPA) in combination with 50 or 100 mg percutaneous testosterone for 1 year. From the third month the sperm concentration was < 106/ml for all the men at one time or another during treatment, and usually < 5 × 106/ml, with an average reduction of 95% with respect to pre-treatment values. The sperm count returned to previous values 3–6 months after cessation of the treatment. While FSH and LH secretion was inhibited throughout the treatment period, plasma testosterone levels were not reduced. Oestradiol levels were unaffected while dihydrotestosterone was elevated. The secretory activity of the prostate and seminal vesicles was not appreciably affected; seminal carnitine concentration was reduced during the treatment with a subsequent return to pretreatment values. No pregnancies occurred during treatment. There was no impairment of libido in the subjects, nor any incidence of gynaecomastia, or increase in average body weight. The only observed metabolic side-effect was a moderate increase in glycaemia. A synergistic action of MPA and testosterone is proposed to explain the inhibition of gonadotrophin secretion.

Cellular and biochemical characteristics of semen obtained by masturbation were studied in 5 pubertal chimpanzees during 1.5 yr. The dental age corresponding to the beginning of the pubertal testicular growth (Po) ranged from 5.0 to 8.3 years (mean = 6.7 +/- 1.2 yr). Time-related variations of all studied parameters were analyzed according to Po and, therefore, independently of the dental age. The emission of first ejaculates, and therefore the onset of activity of the accessory sex gland, was estimated to occur 4 mo after Po. The ejaculate volume (n = 132, r = 0.704, p less than 0.001), as well as the total amounts of l-carnitine (n = 65, r = 0.649, p less than 0.001), fructose (r = 0.522, p less than 0.001), citrate (r = 0.748, p less than 0.001), and acid phosphatase (r = 0.756, p less than 0.001) increased with time. First-obtained ejaculates contained no spermatozoa. Spermarche was estimated to occur 9.4 mo after Po. Total sperm count increased with time (r = 0.595, p less than 0.001). The motility and viability of spermatozoa increased with time (r = 0.474, p less than 0.01 and r = 0.632, p less than 0.001, respectively) while their morphology did not vary. The volume of the liquefied fraction and its content in free spermatozoa considered as available for fecundation remained low until the end of the study, most likely because of a delayed maturation of the prostate. This study shows that the maturation of the male genital tract is a progressive process. (ABSTRACT TRUNCATED AT 250 WORDS)

Summary. In the epididymal fluid of boars, the concentration of carnitine (nmol/mg protein) began to increase from 20 in the distal caput, then rose progressively to 700 in the distal cauda. By contrast, the carnitine content of spermatozoa only started to increase in the proximal cauda where the concentration of carnitine in the fluid was 200\p=n-\300 nmol/mg protein then gradually increased in spermatozoa from more distal sites. The increase in the acetylcarnitine content of spermatozoa paralleled that of the carnitine amount and represented 50% of the total carnitine (carnitine + acetylcarnitine). We conclude that the acetylcarnitine content of epididymal spermatozoa may be used as a marker of maturation.

It has often been suggested that determination of free L(-)-carnitine in seminal plasma may provide a good indication of epididymal function. However, there has been disagreement regarding the origin of L(-)-carnitine (epididymis and seminal vesicles) and its concentration in human seminal plasma. In this study, free L(-)-carnitine was determined after deproteinization with an enzymatic spectrophotometric method. In 29 semen samples from fathers and with normal spermiograms (semen volume between 2 and 6 ml, sperm count over 20.10(6)/ml, more than 50% motile spermatozoa), the total free L(-)-carnitine in the seminal plasma was 1010 nmoles (SD: +/- 480), in 16 samples from vasectomized men it was 131 nmoles (SD: +/- 77), and in 5 from men with agenesis of the vas deferens and seminal vesicles it was 21 nmoles (SD: +/- 25). These results suggest that free L(-)-carnitine in the seminal fluid is predominantly of epididymal origin. The results of free L(-)-carnitine determinations in split ejaculates and the absence of a correlation between L(-)-carnitine and fructose concentrations in semen from normal subjects indicate that the seminal vesicles make only on minor contribution to L(-)-carnitine in the seminal plasma.