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W. D. Ratnasooriya and R. M. Wadsworth

Summary. Silastic rods containing 25% or 50% prazosin HCl were inserted adjacent to the epididymis of rats. Silastic collars containing 25% prazosin HCl were placed around the vas deferens of rats. Treated males were infertile or subfertile for 6–9 weeks after insertion of these rods or collars. The number of spermatozoa observed in the vaginal smears was reduced. It is concluded that the antifertility effect of prazosin results mainly from inhibition of ejaculation.

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In nine out of eleven operations, fistulae were established in the vas deferens of rams. This was accomplished by incising the vas deferens and suturing the orifice to a small surgical opening in the dorsal surface of the scrotum, close to the incision through which the vas deferens had been exposed.

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Experiments designed to determine the effects of shortterm unilateral cryptorchidism on testicular lipids have been carried out using twenty-four mature male rabbits. Testes from unoperated control rabbits and rabbits rendered unilaterally cryptorchid for 2, 4 and 6 days were analysed for wet and dry weight, total lipid, total, free and esterified cholesterol, total carboxyl ester, lipid phosphorus and triglyceride.

The translocated testes decreased in wet and dry weight (P<0·001) and total lipid content (P<0·001) 6 days after surgery. Lipid concentration increased (P<0·01) in translocated testes, as did concentrations of total cholesterol (P<0·005) and esterified cholesterol (P<0·005). Total carboxyl ester (P<0·001) and triglyceride (P<0·01) concentrations also increased in translocated testes, but lipid phosphorus concentration was unchanged.

The contralateral scrotal testes increased in total lipid concentration (P<0·01), esterified cholesterol concentration (P<0·05), total carboxyl ester (P<0·001) and triglyceride (P<0·01) concentrations.

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T. Jahnsen, J. O. Gordeladze, E. Haug and V. Hansson

Summary. Unilaterally cryptorchid rats were examined at 3, 8, 15, 22 and 28 days after operation. There was a selective decrease in the adenylate cyclase (ATP pyrophosphate–lyase (cyclizing), EC responses to gonadotrophin stimulation in the abdominal testis. This was associated with a parallel decrease in specific FSH and LH binding. There was no reduction in the response of testicular adenylate cyclases to prostaglandin (PG) E-1 or fluoride stimulation, indicating that both the GTP binding protein (N-component) and the catalytic subunit of the adenylate cyclase complexes were intact.

The reduction in FSH-responsive adenylate cyclase activity in the abdominal testis was not due to a change in the K m for adenylate cyclase activation, but was due to a reduction in maximal velocities.

Unilateral cryptorchidism was also associated with a rapid decline in soluble Mn2+-dependent adenylate cyclase activity in germ cells (spermatids). By 3 days after operation there was an 82% decrease in germ cell adenylate cyclase activity. The loss of soluble Mn2+-dependent adenylate cyclase activity was associated with a parallel decrease in Sertoli cell secretion of androgen binding protein, indicating that Sertoli cell factors may be important for the maintenance of germ cell adenylate cyclase activity. The desensitization of the gonadotrophin–responsive adenylate cyclases and the loss of gonadotrophin receptors in Leydig and Sertoli cells were not due to changes in plasma gonadotrophin values because LH concentrations were within normal limits and plasma FSH was only marginally elevated in the cryptorchid rats.

No significant alterations of any of these parameters were seen in the scrotal testis of unilaterally cryptorchid rats when compared to values for intact controls.

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C. L. Au, D. M. Robertson and D. M. de Kretser

Summary. The concentrations of inhibin in samples of rat testicular venous and arterial blood and interstitial fluid were measured by an in-vitro bioassay using pituitary cells in culture in which the standard was an ovine testicular lymph preparation (assigned potency 1 unit/mg). Inhibin levels were undetectable ( < 2 U/ml) in both blood samples but reached a mean concentration of 120 ± 7 U/ml in testicular interstitial fluid. After unilateral efferent duct ligation the rate of inhibin accumulation in seminiferous tubules was determined by the difference in the inhibin content of the ligated and unligated testes. Additionally, the rate of seminiferous tubule fluid production was obtained from the difference in weight between the ligated and non-ligated testes. In the 24 h after efferent duct ligation there were linear increases in inhibin (18·5 ± 1·0 U/h) and in seminiferous tubule fluid production (26 ± 1 μl/h), but there were no changes in serum FSH and LH levels.

Experimental induction of bilateral cryptorchidism led to a decrease in the inhibin content of the testis after 10 days. The rate of inhibin accumulation after efferent duct ligation declined more rapidly than the inhibin content, being significantly depressed in cryptorchid testes after 3 days, suggesting that this measurement is a more sensitive index of inhibin production than the determination of testicular inhibin content.

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Unilateral cryptorchidism has been induced in adult rats by transferring the testis from the scrotal sac into the abdominal cavity. The cell types found in the abdominal testis 30 days after the surgical procedure were `crust' spermatogonia, pachytene primary spermatocytes and Sertoli cells, accounting for 31%, 3% and 66%, respectively, of the total cells remaining in the germinal epithelium.

The incorporation of l-lysine-3H into protein of these cells has been studied in vitro. It was found that cryptorchidism resulted in a forty-fold increase in the incorporation of tritiated lysine into protein of the Sertoli cells as compared to the protein labelling of the Sertoli cells found in the corresponding scrotal testis of the same animal. In addition, a four-fold increase in protein labelling of both `crust' spermatogonia and pachytene primary spermatocytes was also observed in the abdominal testis. These data indicate that the greatest enhancement due to an increased abdominal temperature of protein labelling in the remaining cells of the germinal epithelium of the cryptorchid rat testis occurs in the Sertoli cells.

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The testis and body temperature of mature male rats and domestic fowl following cadmium (Cd) and/or zinc (Zn) injections, or cryptorchidism, were studied. In the rat, Cd initially caused an increased testicular temperature with the degree of increase dependent upon amount and route of the Cd injection. After the initial increase, which lasted for 50 to 120 min, there was a depression of temperature to below pre-injection levels, again dependent upon Cd level. Body temperature was unchanged with subcutaneous injections of Cd and dropped with intraperitoneal injections. Zinc caused body and testis temperatures to decline and pre-treatment with Zn prevented the increase in testicular temperature following injections of Cd. In the cryptorchid rat and in the fowl, testicular and body temperatures did not differ either before or after treatment. In the cryptorchid and castrated rat, body temperature appeared to decline more than in the rat with scrotal testes after Cd treatment, while in the chicken there was no change in either testis or body temperature.

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The lysosomal enzymes, dipeptidyl Aminopeptidase I and II, were found in rat testicular tissue. Enzyme I hydrolysed seryltyrosyl-β-naphthylamide (Ser-Tyr-β-NA) optimally at pH 4·5 and was activated by thiol-groups and chloride ions. Enzyme II had a model substrate of Lys-Ala-β-NA, which was optimally hydrolysed at pH 5·5. These enzymes were partially separated by DEAE-cellulose chromatography.

The major activity of Enzyme I appeared to be in the interstitial tissue, since isolated seminiferous tubules contained only trace amounts of this activity. By contrast, Enzyme II appeared to be present in both the interstitial and tubular tissues.

During the pubertal maturation of the testis, a gradual increase in Enzyme I activity was observed. Cryptorchidism caused an initial suppression in 5 days, followed by a rapid increase. These findings indicate a functional correlation of Enzyme I activity with the Leydig cells.

Enzyme II activity showed only a slight decrease during puberty. After cryptorchidism, an initial increase was encountered at 5 to 8 days, followed by a rapid decline. These observations further indicate the presence of this enzyme in both the interstitial and tubular tissues.

Cadmium chloride treatment caused an initial increase of Enzyme I activity which was coincidental with the rapid destruction of the seminiferous epithelium. Subsequently, a decline followed which was concurrent with the destruction of the interstitial cells. Enzyme II showed a more rapid suppression soon after cadmium chloride treatment.

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P. Dierickx and G. Verhoeven

Summary. Germinal cell aplasia was induced in rats by heat sterilization, fetal irradiation or bilateral cryptorchidism. The influence of these treatments on the plasma concentration of LH and FSH, on the levels of sorbitol dehydrogenase and gamma-glutamyl transpeptidase (GTP) in the testis and on the weight of androgen target tissues was compared. All these methods damaged the germinal cells but also affected the other tubular cells and the interstitial compartment to a variable degree. Local heating affected plasma LH levels and GTP activity only minimally. Studies of GTP in cell-enriched fractions from the testes of rats with germinal cell aplasia indicated that this enzyme is not a Sertoli cell specific marker.

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CM Rodriguez, Day JR and GJ Killian

The aim of this study was to localize expression of the prostaglandin D synthase gene in the reproductive tracts of Holstein bulls using northern blotting and in situ hybridization. For northern blotting, a digoxigenin-labelled prostaglandin D synthase cDNA probe was used to probe blots containing RNA isolated from the testes, epididymides, vas deferens, ampullae, seminal vesicles, prostate and bulbourethral glands of bulls. The digoxigenin-labelled cDNA for the bovine homologue of prostaglandin D synthase hybridized to a single band (approximately 0.9 kb) to RNA samples from the caput, corpus and cauda epididymides, as well as RNA samples from the vas deferens and the ampulla. The probe also detected a single band in testis samples, although the transcript size was slightly larger (approximately 1.0 kb) than the transcript found in the other tissues. The highest expression of prostaglandin D synthase was observed in the testes and caput epididymides. Prostaglandin D synthase transcripts were not found in the seminal vesicles or the prostate or bulbourethral glands using northern blotting. For in situ hybridization, antisense and sense riboprobes were synthesized and used to hybridize to cryosections obtained from the reproductive tissues of bulls. In situ hybridization of bull testes showed that prostaglandin D synthase transcripts were present within the germ cells in the adluminal compartment of the seminiferous tubules containing round and elongated spermatids, indicating that expression varied with stage of development of the seminiferous tubules. Prostaglandin D synthase expression was observed in the epithelial cells of the epididymides with greatest expression occurring in the caput epididymidis. Some expression was also observed in the epithelial cells of the vas deferens and a few cells of some lobules in the prostate and bulbourethral glands. Expression of the prostaglandin D synthase gene was not detected in ampullae or seminal vesicles by in situ hybridization.