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B. P. SETCHELL

Summary.

Fluid secretion by the seminiferous tubules of the testes of rats, rams and goats has been calculated from measurements of weight and water content of the testes after ligation of the efferent ducts. Measurement of fluid secretion made in this way gave similar results to other studies where the volume of fluid flowing from a catheter in the rete testis was measured. Fluid secretion was absent in the testes of very young animals but had reached adult proportions before the first spermatozoa were shed. Surgically-induced cryptorchidism and hypophysectomy in rats had no immediate effect on fluid secretion. Hypophysectomy in rats 1 to 4 weeks before efferent duct ligation caused a reduction in fluid secretion, but this fluid secretion was the same as that by control testes of the same weight. Cryptorchidism of 2 to 7 days' duration led to a decrease in fluid secretion. The ionic composition of fluid secreted by the testis was calculated and found to be similar to that of fluid collected from a catheter.

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MATTI HÄRKÖNEN and MARTTI KORMANO

Summary.

The concentrations of glycogen, glucose, ATP, glucose-6-phosphate and lactate were studied in normal and cryptorchid rat testes using enzymatic pyridine nucleotide methods. With the exception of ATP, all the substrates were significantly higher in the cryptorchid testes. The decrease of the energy metabolites and the accumulation of lactate were also studied in testes incubated in the absence of O2 at the temperatures of 33·6° C and 36·6° C. The metabolic rate of the incubated organs was estimated in terms of the rate of use of high energy phosphate ( ~ P) calculated from changes in ATP, glucose and glycogen. A good parallelism between hexose utilization and lactate production was observed in both normal and cryptorchid testes. A rapid mobilization of glycogen, suggesting activation of phosphorylase, was observed in incubated cryptorchid testes. The calculated oxygen consumption of cryptorchid testes was about 100% higher than that of the normal testes at the same temperature. It is suggested that the basic metabolic rate of the interstitial tissue is higher than that of the seminiferous tubules.

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MANNFRED A. HOLLINGER and JOSEPH R. DAVIS

Summary.

The in vitro incorporation of [2-14C]thymidine and [2-14C]uridine into DNA and RNA respectively, has been studied in slices of immature, mature, cryptorchid, and contralateral-scrotal testes of the rat. The results demonstrate that DNA and RNA labelling are both enhanced in the cryptorchid testis following 30 days in the abdominal cavity. Of the four tissues studied, the immature testis possessed the highest in vitro rate of DNA and RNA labelling. In addition, uptake of [2-14C]uridine into RNA of the contralateral-scrotal testis of cryptorchid rats is elevated.

It is suggested that the enhanced nucleic acid labelling observed in the cryptorchid testis may be related to the predominance of those cells which normally synthesize nucleic acids during the cycle of the seminiferous epithelium, in association with compensatory gonadotrophin stimulation. Similarly, the increase in RNA labelling present in the contralateral scrotal testis may represent a compensatory `feed-back' mechanism from the pituitary by virtue of decreased testosterone production in the cryptorchid testis. Increased gonadotrophin output in cases of cryptorchidism may be a complicating factor in the increased tendency of abdominal testes to undergo neoplastic change.

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MN Ghabriel, JJ Lu, G Hermanis, C Zhu and BP Setchell

The endothelial barrier antigen (EBA) is a protein expressed specifically by the endothelial cells of the rat brain barrier vessels. This antigen has been described as a 'barrier protein' and is used as a marker for the competent blood-brain barrier. A blood-testis barrier has also been described. However, unlike the blood-brain barrier, which is formed by endothelial cells, the blood-testis barrier is formed mainly by the Sertoli cells, which provide an isolated environment for spermatogenic cells within the seminiferous tubules. Testicular blood vessels express the erythroid glucose transporter protein and other markers, which are strongly expressed in brain blood vessels, and may contribute to the blood-testis barrier. This study was carried out to determine whether Sertoli cells or testicular blood vessels express EBA. Tissues of other organs were used as controls for EBA expression. EBA was expressed by the endothelial cells in most microvessels of the testis, and in a few vessels of the epididymis, seminal vesicle, prostate gland, vas deferens and bladder-neck region. Furthermore, EBA was strongly and consistently detected in epithelial cells of the rete testis and dorsolateral prostate gland, and in a few epithelial cells of the ventral prostate gland, the seminal vesicle and the coagulating gland. However, Sertoli cells, which are the main site of the blood-testis barrier, were negative for EBA. In conclusion, EBA may have a wider role in rat tissues than has been previously appreciated.

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L. STUART SCOTT

Summary.

Seminal studies carried out in thirty-four cases of untreated, post-pubertal, unilateral cryptorchidism have revealed a high incidence of sterility and severely impaired fertility, while the seminal findings of six cases of retractile testis showed no diminution of fertility.

Testicular biopsies, carried out in two retractile testes, confirmed their normality, while similar studies of seven pubertal retained testes and nine pubertal ectopic testes showed that spermatogenesis is more severely damaged in the former than it is in the latter. Further biopsy studies of eight contralateral gonads in unilateral cryptorchids have disclosed an unexpectedly high incidence of spermatogenic arrest in the so-called normally descended opposite testis.

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M. Antich, E. Fabian, J. Sarquella and L. Bassas

The distribution and density of functional insulin-like growth factor I (IGF-I) receptors in cryptorchid and scrotal rat testes and epididymides during gonadal development were studied. Cryptorchidism was induced by unilateral gubernaculectomy in 4-day-old animals, and organs were studied at 15, 30, 60 and 90 days of age. Tissue membranes were assayed for125I-labelled IGF-I binding. Characterization and specificity of binding sites showed that both normal and contralateral undescended testes and epididymides exhibited typical type 1 IGF receptors. In normal testes, IGF-I receptor density was 20.6 nmol g−1 wet mass at day 15, and decreased to 12.8 nmol g−1 wet mass at adult age (day 90). Cryptorchid testes showed IGF-I receptor concentrations similar to normal testes at day 15 and day 30, but in postpubertal stages displayed a divergent pattern, with a continuous increase at day 60 and day 90, reaching a higher density than those found for immature ages (62 nmol g−1 wet mass). Both normal and cryptorchid epididymides had a similar concentration and a comparable decrease in IGF-I receptors throughout development. In studies with immunohistochemical techniques (αIR-3 antibody), IGF-I receptors were found in primary spermatocytes, Sertoli cells and Leydig cells. Cryptorchid tubules showed a lack of germinal epithelium and a marked increase of immunoreactive IGF-I receptors in Sertoli cells, compared with normal tubules from scrotal testes. Intense immunoreactivity for IGF-I receptors was present in the principal cells of epididymal tubules in both normal and cryptorchid organs. These results suggest that tubular damage induced by cryptorchidism in rats is associated with changes in the local regulation of IGF-I receptors.

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K. Sawada, K. Sakamaki and Y. Nishimune

Summary. The effect of the mutation for white belly spot controlled by the dominant gene W on spermatogenesis in mice was examined by experimental cryptorchidism and its surgical reversal. The course of spermatogenesis from spermatogonia to spermatid was normal in intact testes of W/+ mice. In cryptorchid testes, there was no difference in the number and activity of Type A spermatogonia between the testes of W/+ and +/+ mice, in mitotic and labelling indices. Although surgical reversal of the cryptorchid testis resulted in regenerative differentiation of germ cells in both genotypes, the recovery of cell differentiation in the W/+ testis was slower than in the +/+ testis. There were fewer germ cells, such as intermediate–Type B spermatogonia or more advanced ones, in W/+ testes. On Day 17 after surgical reversal, cell associations in W/+ testes were abnormal and the numbers of intermediate–Type B spermatogonia, spermatocytes and spermatids were approximately ∼70, 50 and 15%, respectively, of those in +/+ testes. These results indicate that the W gene affects spermatogenic cell differentiation in adult mice.

Keywords: W mutation; spermatogenesis; cryptorchidism; orchidopexy; mouse

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Gail S. Prins and L. J. D. Zaneveld

Summary. The movement of radio-opaque medium in the vas deferens of rabbits during sexual rest, after sexual stimulation, and after ejaculation, was followed. Bilateral injections of 20 μl Ethiodol were given at the vas–epididymal junction in the urethral direction. Serial radiographs revealed proximal transport of the dye (towards the testis) within 24 h and total containment in the cauda epididymidis within 1–4 days. Subsequently, small amounts of dye moved from the epididymis through the vas and out of the urethra during sexual rest until no dye remained (11 days–8 weeks). Animals with a ligated vas deferens showed no decrease in dye density. Sexual stimulation moved the dye from the epididymis into the vas. The dye was then either rapidly transported proximally during subsequent rest or removed distally if ejaculation followed stimulation. Ejaculation removed some vasal and epididymal dye via the urethra; however, dye left in the vas after ejaculation was rapidly (< 30 min) transported to the proximal duct and then into the epididymis by 24 h. It is concluded that vasal contents are transported in both urethral and testicular directions during sexual rest and that, after stimulation and ejaculation, the rate of proximal transport is increased. This may be indicative of a sperm removal mechanism by the vas deferens which involves the maintenance of an optimal sperm number in the cauda epididymidis at all times.

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Anna-Maria Hoffmann, A. Bergh and T. Olivecrona

Summary. A simple and reliable method was developed to determine the neutral cholesteryl ester hydrolase (CEH) activity in rat testes, using cholestery1-[1-14C]-oleate as substrate. The activity was due to a soluble enzyme present in the cytoplasm of predominantly Sertoli cells, which could be shown after depleting the testes of Leydig cells with ethane dimethyl sulphonate. This treatment also revealed that the loss of CEH activity in abdominal testes of experimentally cryptorchid rats takes place in the Sertoli cells. In prepubertal rats made unilaterally cryptorchid at birth, the CEH activity was significantly higher in the abdominal than in the scrotal testes at 16 days of age. This is earlier than any previously described biochemical change and coincides with, or may even precede, the earliest morphological changes which are accumulation of lipid droplets in the Sertoli cells. The testicular CEH activity then decreased to 30 days of age in the abdominal testes, whereas the activity increased in the contralateral, scrotal testes. When adult rats were made unilaterally cryptorchid for 24 h, the CEH activity decreased rapidly in the abdominal testes. These results suggest that a derangement in cholesteryl ester metabolism is an early event in the pathogenesis of testicular degeneration in cryptorchidism.

Keywords: testis; Sertoli cell; cryptorchidism; enzyme activity; assay; ethane dimethyl sulphonate

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B. D. Schanbacher

Summary. Response of the cryptorchid testis to gonadotrophic stimulation was assessed by comparison of the androgen production capability in vivo and in vitro with that of the normal scrotal testis. Serum androgen concentrations in cryptorchid rats were similar to those in normal rats, and the incremental increase 60 min after 50 i.u. hCG (i.v.) was about 7-fold for both groups. Basal and hCG-stimulated androgen production in vitro was higher for abdominal testes (557 and 3286 ng/pair) than for scrotal tests (157 and 504 ng/pair). Specific binding of hCG by testicular homogenates was slightly higher (P < 0·05) for cryptorchid testes when expressed per unit weight, but Scatchard analysis indicated that although hCG binding affinities did not differ (K a = 2 × 1010 m −1), hCG binding capacity of cryptorchid testes was only 75 ng, compared to 219 ng for scrotal testes. These data indicate that a discrepancy exists between androgen production in vivo and in vitro by cryptorchid testes and that normal serum androgen concentrations are maintained in the presence of decreased numbers of testicular LH/hCG receptors.