Blood-testis barrier: evidence for intact inter-Sertoli cell junctions after hypophysectomy in the adult rat.

To study the hormonal dependence of the blood-testis barrier, adult rats were hypophysectomized and the ultrastructural integrity of the inter-Sertoli cell junctional complex was examined at various times with a lanthanum tracer technique. It was found that the structural integrity of the inter-Sertoli cell junctions and their capacity to exclude lanthanum from the adluminal compartment were preserved up to 35 days after hypophysectomy. Furthermore, transport of newly formed spermatocytes through the inter-Sertoli cell junctions still occurred 20 days after hypophysectomy. It is therefore concluded that the function of the inter-Sertoli cell junctional complex is not directly dependent on gonadotrophic or androgenic hormones, but is regulated by other mechanisms.

Age-dependent response of the rat testes to di(2-ethylhexyl) phthalate.

Spermatogenesis starts soon after birth in the Sprague-Dawley rat but is not fully established until about 56 days of age. When high oral doses of the plasticizer di(2-ethylhexyl) phthalate (DEHP) were given to rats of different ages, testicular damage was observed in immature but not in mature animals. Plasma concentration and urinary excretion data suggested that the gastrointestinal absorption of the DEHP-derived metabolite mono(2-ethylhexyl) phthalate was higher in young animals. Young rats were not more susceptible than older for repeated intravenous infusions of DEHP. It is suggested that the age-related difference observed in testicular response after oral administration of DEHP may be due to pharmacokinetic rather than tissue sensitivity differences. It is concluded that in assessing risks of testicular injuries in children exposed to DEHP, additional studies are required using species in which testicular development is more similar to that of humans.

In vitro synthesis of rat testicular androgen-binding protein (ABP).

Testicular tissue from immature and adult rats shows in vitro synthesis of androgen-binding protein (ABP). The ABP synthesis is dependent on a complete tissue culture medium, the incubation temperature and the age of the rats. ABP synthesis is inhibited at 0 degrees C or in the presence of cycloheximide, puromycin or sodium fluoride. Immature (17-25-day-old rat) testes showed a higher rate of ABP synthesis per 100 mg tissue than adult rat testes during 'baseline' conditions (no additions to the medium). Addition of NIH-FSH-S10 or testosterone to the medium increases the production of ABP by the testicular minces. The in vitro techniques have proved to be useful for studies of direct hormonal influence on the Sertoli cell protein synthesis.

Comparison of nuclear hydration in boar spermatozoa before and after freeze-thawing: contrast analysis of cells embedded in bromide-labeled medium.

Epon labeled with bromide was used to embed ejaculated and freeze-thawed spermatozoa, with the hypothesis that it replaces most of cell water. Image analysis of relative contrasts between sperm nuclei and the surrounding medium revealed that when used in low concentrations, bromide is mostly adsorbed to the nuclear structures. For higher concentrations, the chromatin is saturated, and the increase in contrast can be used to calculate relative differences in the hydration of nuclei. Boar sperm nuclei are more hydrated after freeze-thawing than before.

Steroid metabolism and morphologic features of the human testis.

Serum FSH, LH, and testosterone were studied in 114 infertile men with poor sperm production. Testicular biopsies were taken and classified morphologically. In 90 specimens, the pattern of conversion of progesterone was determined in vitro and expressed as the ratio of 20 alpha-hydroxy-4-pregnene-3-one to 17 alpha-hydroxyprogesterone. An excess of the former metabolite indicates a prepubertal type of steroid metabolism. The normal limit of this ratio is given. The collected data indicate that the prepubertal type of steroid metabolic pattern is related to the thickness of the lamina propria of the seminiferous tubules only, and not to peripheral hormone levels. In particular, the presence of hyaline deposits in the lamina propria seems to determine the metabolic pattern. It is suggested that the character of the lamina propria separating the tubular and interstitial compartments of the testis is of crucial importance for the functional interrelationship between these compartments. This supports the concept of an intratesticular regulatory mechanism of both steroid metabolism and spermatogenesis.

Testicular lesions of coprine and benzcoprine.

The effect on the testis of the disulfiram-like compounds benzcoprine (N-[1-ethoxycyclopropyl] benzamide) and coprine (N5-[1-hydroxycyclopropyl]-L-glutamine) was studied in rats and dogs. Severe degeneration of the seminiferous epithelium was induced in rats by subacute oral administration of each compound. 60 days after termination of treatment with benzcoprine most seminiferous tubules contained only occasional spermatogonia and the testicular weight was markedly decreased. The blood-testis barrier was unaffected in the benzcoprine-treated rats as judged by a lanthanum tracer technique. In dogs, oral administration of benzcoprine for 1 month caused impaired spermatogenesis, degeneration of germ cells and a decrease in the testicular weight. The results indicate that both compounds act directly on the germ cells. The effect is similar to that of alkylating compounds. Other effects of benzcoprine and coprine (bone marrow depression, lymphocytopenia, positive Ames test in organisms sensitive to base-pair substitution) are well-known properties of alkylating agents. In conclusion benzcoprine and coprine were found to cause severe changes in the testis in rats and dogs, probably due to a direct effect on the germ cells.

Synaptonemal Complex Analysis of Spermatocytes in Hybrids of Silver Fox and Blue Fox.

Investigations of male meiosis in silver fox x blue fox hybrids have revealed meiotic arrest at the first prophase stage. Synaptonemal complex analysis using light and electron microscopy demonstrated the occurrence of multivalents, bivalentlike structures, and unpaired axes. We conclude that the sterility of male hybrid foxes probably is due to pairing problems of chromosomes caused by extensive karyotypical differences of the two species, resulting in unpaired chromosomes, chromosome segments, and broken chromosomes.

Tissue distribution of bovine cystatin C analysed by in situ hybridisation.

Cysteine proteinase inhibitors of the cystatin superfamily have been identified in many living organisms. However, knowledge of the tissue distribution of such inhibitors is limited. To elucidate this distribution in mammals, we have investigated the expression of the gene for cystatin C, belonging to cystatin family II, in several bovine tissues. In situ hybridisation with a digoxigenin-labelled cRNA probe demonstrated a high concentration of bovine cystatin C mRNA in the secretory epithelial cells of the choroid plexus, and also intense staining in cells of lymphoid tissue and in Sertoli cells. Cystatin C mRNA was also present in scattered neurons and glial cells throughout the cerebrum and the cerebellum. In the submandibular gland, specific mRNA was found mainly in striated intralobular ducts and interlobular ducts. The expression of cystatin C in brain tissue is of particular interest, as the inhibitor appears to be involved in certain neurological diseases. The main production of cystatin C within the brain is believed to be by astrocytes. However, this work shows that also neurons from young, normal individuals express cystatin C.

Does HCG treatment induce inflammation-like changes in undescended testes in boys?

Twenty-two cryptorchid boys previously unsuccessfully treated with human chorionic gonadotropin (hCG) were operated. Testicular biopsies were taken and a routine orchidopexy was performed in each case. As controls eight cryptorchid boys without prior hormonal treatment were operated in the same way. A mild inflammation-like reaction was found in the cryptorchid testes in the period immediately following the last hCG injection. However, in testes studied 6 to 12 months after the last hCG injection there were no apparent signs of hCG-induced tubular damage.

Electron microscopic observations on the epithelium of ram seminal vesicles.

The ultrastructure of the secretory cells of the ram seminal vesicle was studied on material fixed by immersion or by vascular perfusion. The signs of apocrine secretion seen after immersion fixation did not appear after perfusion fixation and are therefore interpreted as artefacts. Instead, vacuoles with a granule in them were seen. Such vacuoles were observed in the Golgi apparatus and in the apical cytoplasm. Further indications of merocrine secretion were also found. It therefore appears that protein secretion in the ram seminal vesicle follows the typical pattern of serous glands. The possibility that fructose is extruded with the protein as the vacuoles open at the luminal cell surface is discussed.

The morphology of the human undescended testis with special reference to the Sertoli cell and puberty.

The morphology of the undescended testis was studied in 50 boys aged 1-15 years. A low mean number of spermatogonia was found, but there were marked differences between the boys, some having high numbers whereas others were devoid of spermatogonia. Most Sertoli cells did not undergo normal maturation during puberty, but instead seemed to proliferate at a slow rate. It is concluded that treatment of undescended testes should be performed during the prepubertal period. It is also suggested that some undescended testes have a primary defect whereas others are damaged during the onset of puberty.

The influence of human chorionic gonadotrophin (hCG) on the morphology of the prepubertal human undescended testis.

The effect of hCG-treatment on the morphology of the undescended testis was studied in testicular biopsies from 36 prepubertal boys operated on at intervals of 1 day to 2 years after discontinuation of hormonal treatment. Immediately after treatment, mature Leydig cells were observed, and the Sertoli cells were increased in size; serum testosterone had increased to adult levels. All these changes were reversible as judged from the material taken one month or more after the last hCG injection. Based on the observations and the results of a previous study it is suggested that hCG treatment does not induce any premature onset of Sertoli cell or germ cell maturation either in the undescended or in the contralateral testis.

Restricted lesions after testicular biopsies in young and adult rats.

In order to evaluate the possible harmful effects of surgical removal of a testicular biopsy, adult and immature rats were subjected to unilateral testicular biopsy and were studied 2-4 months later. One group of adult rats were sham-operated. Perfusion-fixed, plastic-embedded specimens of the testes were examined by light microscopy. No morphological differences were found between rats that were immature and those that were adult at the time of biopsy. The lesions observed were focal and occurred only in the vicinity of the site of biopsy. Only about 0.5% (range 0.01-4.5) of the testis was affected. No morphological signs of any immune reaction were observed. It is suggested that the lesions are caused mainly by interference with local blood flow, and to a minor extent by disruption of the flow of seminiferous tubule fluid.

Comparative aspects of mammalian spermiogenesis.

The testes of some different orders of eutherian mammals were examined by conventional electron microscopy with respect to their pattern of spermiogenesis. In addition, some of the testes were studied by cytochemical methods for demonstration of certain nuclear proteins and of glycoproteins in the acrosome and the plasma membrane of spermatids. It was found that although the basic pattern of spermiogenesis was similar in all species studied, there were pronounced dissimilarities in the final shape of the spermatids. Differences were also observed in the timing of the differentiation of several organelles. The head of late spermatids and spermatozoa of Primates, Carnivora and Perissodactyla was cone-shaped, whereas in Artiodactyla and Lagomorpha it was flattened or paddle-shaped, and in Rodentia hook-shaped. The size and shape of the acrosome varied considerably between the orders, as did the length of the middle piece.

The nature of the 1;29 translocation in cattle as revealed by synaptonemal complex analysis using electron microscopy.

Synaptonemal complex analyses were carried out by electron microscopy on surface-spread spermatocytes of one normal bull and two bulls that were heterozygous for the so-called 1;29 translocation. The autosomal bivalents of the normal karyotype, which could be arranged by size in a series, demonstrated kinetochores at the terminally located attachment plaques. One autosomal bivalent was clearly larger than the rest and apparently consisted of the long arm of the 1;29 translocation. The 1;29 translocation was the longest autosome in the set and had a kinetochore in a subtelocentric position. Some of the autosome pairs had nucleolus organizer regions in telomeric regions. The X and Y chromosomes, which were not paired at zygotene, demonstrated association in a very short segment at early pachytene; in no cells could a synaptonemal complex be seen between the X and Y. Very often the sex chromosomes were dissociated. At zygotene, a few, usually large, bivalents were unpaired proximally. This always also involved the proximal parts of the arms of the 1;29 translocation and their normal homologs. At early pachytene, the 1;29 trivalent, although to a less extensive degree, was also unpaired in the pericentric region. Configurations in which one chromosome, either 1 or 29, was completely paired with its corresponding arm in the 1;29 translocation chromosome also occurred. When unpaired proximally, the size of chromosome 1 agreed fairly well with the size of its corresponding arm, but the size of chromosome 29 was considerably larger than the corresponding arm of the 1;29 translocation chromosome. During late zygotene and early pachytene, the percent difference between chromosome 29 and its corresponding arm decreased, and at mid and late pachytene there had been a complete synaptic adjustment. The size difference and pairing behavior indicated that a deletion of the kinetochore and the most proximal segment of chromosome 29 had preceded the fusion with chromosome 1 into the 1;29 translocation. The unique structural appearance of the 1;29 translocation chromosome compared to that of other centric fusion translocations in cattle lends support to the theory of a monophyletic origin of the 1;29 translocation. The importance of the pairing behavior observed in governing recombination and chromosome disjunction is briefly discussed.

The mammalian tubuli recti: ultrastructural study.

The ultrastructure of the tubuli recti was studied in the testes of sexually mature bulls, boars, rams, goats, rabbits and rats fixed by vascular perfusion. The tubuli recti are lined with a simple epithelium that varies in height, from squamous to tall columnar according to the species and the region. The cells are characterized by extensive lateral and tortuous basal plasma membranes and a luminal border with microvilli. Tight junctions and desmosomes are found in the upper half of the lateral borders. The Golgi apparatus is sizable and associated with it are coated vesicles and many smooth vesicles concentrated towards the luminal border. A distal segment of the tubuli recti is found in bulls only and is characterized by a high epithelium which is thrown into folds giving the lumen a festooned appearance. It is suggested that the epithelial cells of the tubuli recti are involved in fluid exchange and in the removal of unwanted spermatozoa.