Spermatozoa from the corpus epididymidis of boars and rams showed head\x=req-\ to-head agglutination when diluted. The occurrence of agglutination coincided with the appearance of motility but preceded the ability to bind to zona-free hamster eggs. Head-to-head agglutination was inhibited by the addition of caudal epididymal plasma. A protein acting as an antagglutinin on spermatozoa from the corpus epididymidis was extracted from cauda epididymal plasma and partly purified.

Spermatozoa were collected from the rete testis and vas deferens of conscious rams. The endogenous oxygen uptake of the spermatozoa was unaffected by alpha-chlorohydrin added in vitro, although this compound abolished the stimulation of oxygen uptake caused by the addition of glycerol. The metabolism of [14C]glycerol by testicular and epididymal spermatozoa was markedly reduced by alpha-chlorohydrin, CO2 production and lactate accumulation being almost totally inhibited. These effects were dependent upon a period of preincubation of the spermatozoa with alpha-chlorohydrin alone, since the presence of glycerol protected the spermatozoa from its action. Longer exposure and a higher concentration of alpha-chlorohydrin were needed with testicular than with epididymal spermatozoa to achieve a maximal effect. The metabolism of [14C]glucose by both sperm types was also inhibited by alpha-chlorohyrin. Spermatozoa of the ram are therefore susceptible to the action of alpha-chlorohydrin throughout the epididymis, although more mature spermatozoa are more affected. It is suggested that alpha-chlorohydrin is converted to an intermediate which is the agent responsible for the inhibition of glycolysis in spermatozoa.

Summary. Lizard spermatozoa, which are non-motile in the testis, develop the ability to swim as they pass along the excurrent duct. The addition of caffeine, a phosphodiesterase inhibitor, induced forward motility in spermatozoa from the caput epididymidis and increased the velocity of spermatozoa from the distal part of the epididymis. Caffeine had no effect on the motility of testicular spermatozoa. This suggests that sperm motility in this species is cyclic AMP-dependent but this factor alone is not sufficient to induce testicular sperm motility. In samples from the distal region of the epididymis, sperm motility was maximal in April just after the breeding season and then decreased significantly during the following months. A parallel can be drawn between these data and the levels of testosterone in the plasma. In the lizard, as in mammals, the epididymis may play an important role in the maturation of spermatozoa.

In the male reproductive tract, very high concentrations (mmol l-1) of free L-carnitine and acetyl-L-carnitine are found in the epididymides, seminal plasma and spermatozoa. It has been reported that the uptake of free L-carnitine by spermatozoa might be related to the epididymal maturation of the sperm membrane, since a greater uptake was found by caput than by cauda spermatozoa in vitro. However, the free L-carnitine concentrations estimated inside the gametes were never greater than those of the surrounding medium. In this study, we investigated the mechanism of transport of free L-carnitine and its ester acetyl-L-carnitine, through the plasma membrane of mature and immature epididymal boar spermatozoa. In vitro, we found a passive diffusion of both compounds to the spermatozoa, whatever the maturation stage. The spermatozoa might progress in the epididymal lumen and accumulate high amounts of free L-carnitine. The active uptake of free L-carnitine occurs only across epididymal mucosa. These results are in agreement with those reported on cells of other organs that exchange pharmacological free L-carnitine concentrations (mmol l-1) by a passive mechanism through the plasma membrane. The acetylation of high amounts of free L-carnitine inside the spermatozoa was found only in caudal spermatozoa. This result suggests that oxidative metabolism (producing acetyl CoA) might be more active in mature cells. The acetyl-L-carnitine added to the incubation medium of boar spermatozoa was hydrolysed. Enzymatic activity of the sperm membrane is low and this may partially explain the low concentrations of acetyl-L-carnitine found in the caudal epididymal plasma.

Production of spermatozoa and secretion of rete testis fluid (RTF) in rams was assessed by a rete testis cannulating technique. Four breeds (Ile-de-France, Romanov, Préalpes du Sud and cross-breed Romanov) were studied throughout the year. Inhibitory effects of the cannulation process on spermatogenesis were observed for some animals. Between-breed differences were found in sperm concentration and flow rate of the RTF. The seasonal variations in the daily sperm production of the testis were more pronounced for Ile-de-France rams than for the other breeds. There was a seasonal variation in the flow rate of RTF in Ile-de-France rams, the minimum flow being in February (winter) and the maximum in August-September (autumn).

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.

No abstract

Northern blot analysis suggested that the boar epididymis produces closely related counterparts to human epididymal proteins HE1, HE3, HE4, HE5 and HE12. 'Full-length' cloning by nucleic acid and amino acid sequence similarity was achieved by RT-PCR methods in the case of the porcine counterparts of HE3 and HE4, while the homologues of HE5 and HE12, despite their cross-hybridization during Northern blot analysis, have not yet been cloned. The two novel porcine cDNAs were derived from moderately abundant epididymal mRNAs that were 75 and 83% identical to HE3 and HE4 cDNAs, respectively. To emphasize their relationship to the corresponding HEs, they were named Se3 and Se4 cDNAs. Their open reading frames predicted small secretory proteins with 55% (Se3) and 76% (Se4) conserved amino acids. Monospecific antipeptide antibodies to HE secretory proteins identified He3- and HE12-related proteins on Western blots of porcine epididymal fluid and semen. Both Northern and Western analyses indicated that the Se proteins were produced in a regionalized pattern and accumulated in the cauda fluid.