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B P Setchell

Publications and source records attributed to B P Setchell.

At least 37 records · Page 2Linked to original sources
PubMed1990

Recent evidence for immune privilege in the testis.

In the last 20 years, it has been shown that while first-set intra-testicular grafts rarely induce systemic immunity, second-set intra-testicular grafts are usually rejected, if a pre-existing immunity has been generated by first-set skin grafts. These observations suggest that while the efferent limb of the pre-sensitized immune response is operative in the testis, the immune system can not be activated against antigens present only in this site. Various theories have been advanced to explain this phenomenon. The most likely explanation at present seems to be that the testis contains specific immunosuppressive factors that inhibit lymphocyte activation in this site.

Animals↗
PubMed1990

Testis physiology relevant to immunoregulation.

Intra-testicular transplants are placed in rodents into the large lymphatic sinusoids of the interstitial tissue of the testis. These sinusoids are filled with a protein-rich extracellular fluid that supplies all the requirements of the grafts until vascularization takes place. The testicular microvascular endothelium regulates transport of T lymphocytes and immunoglobulin G to the testis and may thus contribute to regulation of the immune system in this organ. Differences in the organization of the lymphatic drainage exist between species, but in every studied species lymphatic drainage from the testis leads to lymph nodes.

Animals↗
PubMed1990

Feeding lupin grain for six days prior to a cloprostenol-induced luteolysis can increase ovulation rate in sheep irrespective of when in the oestrous cycle supplementation commences.

Three groups of 40 parous Merino ewes were supplemented with 500 g of lupin grain/ewe/day for 7 days starting on either Day 3, 7 or 11 of the oestrous cycle and induced to ovulate by injecting cloprostenol on the sixth day of feeding. Supplementation with lupin grain significantly increased ovulation rate in all groups compared with corresponding controls by increasing the proportion of ewes with twin ovulations. Increases in ovulation rate did not depend on the stage of the cycle at which supplementation began or when during the luteal phase luteolysis was induced. It is concluded that the ovulatory response to lupin grain is initiated near the time of luteolysis.

Animal Feed↗
PubMed1990

Stimulation of protein secretion in the initial segment of the rat epididymis by fluid from the ram rete testis.

Zone 1A of the ductus epididymidis was perfused with ovine rete testis fluid (nRTF) and modifications of it, and a synthetic medium (sRTF) based on the inorganic composition of nRTF. There was little fluid transport by the duct mucosa and nRTF stimulated protein secretion. The secretagogue activity was not extracted by charcoal, was sensitive to protease digestion and was present in a portion of nRTF with a molecular weight of greater than 10,000. The addition of bovine serum albumin to the sRTF stimulated protein secretion, but not to the same extent as equal amounts of protein in nRTF. Polyacrylamide gel electrophoresis of the perfusates showed that proteins with molecular weights of 19,000 (all rats studied), and 22,000, 30,000 and 60,000 (at least half the rats studied) were secreted into the perfusion fluids as well as some blood proteins, but the pattern of secretion was not affected by the composition of the perfusion fluid.

Animals↗
PubMed1989

Microvascular permeability to IgG in the rat testis at puberty.

Immunoglobulin G (IgG) spaces and permeability surface area products (PS) were calculated separately in the testis parenchyma, capsule and interstitial tissue in four age groups of rats to see if there were regional differences in microvascular permeability in the rat testis and if there were changes in PS with age. The results demonstrated a marked increase in PS to IgG at 27 days of age in the testicular interstitial tissue, whereas PS in the capsule did not show such consistent changes. Blood volumes per gram, as indicated by the 3 min IgG spaces, were considerably greater in the testicular capsule than in the interstitial tissue, although the weight of the capsule was only about one-third of the interstitial tissue weight. Maximal IgG spaces were reached at 5 h in the testicular parenchyma, but in most groups only at 20 h in the capsule. IgG was demonstrated immunohistochemically in the testicular interstitial tissue from 33 days of age onwards.

Animals↗
PubMed1989

Growth factor activity in luminal fluids from the male reproductive tract of the ram, rat, tammar wallaby (Macropus eugenii) and Japanese quail (Coturnix coturnix japonica).

Growth factor activity in luminal fluids from the male reproductive tract was assayed by measuring the stimulation of [3H]thymidine incorporation into BALB/c 3T3 fibroblasts. The potency of fluids from the rete testis of the rat, ram, tammar wallaby and Japanese quail was much the same. However, about 90% of the activity in fluid from the rete testis of the rat and tammar was lost during its passage through the epididymis.

Animals↗
PubMed1989

Testosterone concentrations in testicular interstitial fluid collected with a push-pull cannula or by drip-collection from adult rats given testosterone or aminoglutethimide.

This study was designed to investigate the differences in testosterone concentrations measured in testicular extracellular interstitial fluid obtained with a push-pull cannula or by post-mortem drip-collection. In the first experiment, testosterone-filled silicone elastomer capsules (2-16 cm lengths) or empty 2 cm capsules were implanted s.c. in adult male rats for 1 week. Animals were then anaesthetized and interstitial fluid was collected with a push-pull cannula for 1 h from one testis in each animal. Testicular and peripheral venous blood were then sampled and supernatant fluid was collected from the dispersed cells of the same testis. The contralateral testis in each animal was removed, and postmortem interstitial fluid obtained by drip-collection for 20 h at 4 degrees C. In animals given empty capsules, testosterone concentrations in drip-collected interstitial fluid were significantly (P less than 0.01) greater than testicular and peripheral venous blood levels, testicular fluid levels, and levels in interstitial fluid calculated from push-pull cannula samples. The concentrations of testosterone calculated in interstitial fluid collected with a push-pull cannula were never significantly greater than testicular venous blood levels. In animals with testosterone-filled capsules, testosterone concentrations measured in drip-collected interstitial fluid were similar to those calculated from push pull cannulae samples, and to testicular venous blood levels. In a second experiment, a group of adult male rats was pretreated with amino-glutethimide to block steroidogenesis. Two hours later, interstitial fluid was drip-collected from the testes of these animals and from a group of vehicle-treated controls.(ABSTRACT TRUNCATED AT 250 WORDS)

Aminoglutethimide↗
PubMed1989

Effect of a single injection of human chorionic gonadotrophin on testosterone levels in testicular interstitial fluid, and in testicular and peripheral venous blood in adult rats.

We have used a push pull cannula to collect interstitial fluid from the testes of anaesthetized rats at various times after a single injection of human chorionic gonadotrophin (hCG; 50 IU), and compared the levels of testosterone in this fluid with the levels in testicular and peripheral venous blood collected at the same times. Following hCG injection, significant increases in testosterone concentrations were observed in all fluids with notable peaks occurring in interstitial fluid at 2, 8 and 24 h, in testicular venous blood at 2, 8 and 30 h, and in peripheral venous blood at 2, 8, 24 and 72 h. The results demonstrate for the first time that changes in testosterone concentrations in interstitial fluid can be different from those in testicular venous blood. In addition, when testosterone levels in interstitial fluid were compared with levels in testicular venous blood at each time-point, the results suggested that the partitioning of testosterone between these two compartments can be regulated. Furthermore, the changes in both interstitial fluid and testicular venous blood levels of testosterone do not always parallel those in peripheral venous blood, suggesting that changes in testicular blood flow and peripheral clearance rates of testosterone may also be important in the control of circulating testosterone concentrations.

Animals↗
PubMed1988

The rejection of thyroid allografts in the ovine testis.

The survival of thyroid autografts and allografts in the ovine testis has been investigated. Thyroid autografts survived and concentrated iodine 4 weeks after transplantation. Healthy colloid-containing follicles were found in the graft at this time, although no response of the grafts to a thyrotropin releasing hormone (TRH) challenge could be detected and there was no detectable basal thyroxine secretion into testicular venous blood or lymph. Thyroid allografts, however, were effectively rejected within 4 weeks of transplantation and did not concentrate iodine. No healthy tissue in the allografts could be found at 4 weeks after transplantation. Thus, in contrast to rodents and related species, the ovine testis does not appear to be an immunologically privileged site. This suggests that the immune privileged status of the rodent testis is not necessarily a general mammalian characteristic.

Animals↗
PubMed1988

Development of the blood-testis barrier and changes in vascular permeability at puberty in rats.

The effectiveness of the blood-testis barrier to water-soluble substances was assessed in rats of various ages by measuring the volumes of distribution of Cr-EDTA and albumin, and estimating the proportion of the testis made up by interstitial tissue and tubular lumen by morphometric techniques on cryostat sections of frozen tissue. The interstitial tissue volume fell from 15 days to reach adult values at about 30 days of age. A lumen was present in some animals at 15 days, and it enlarged progressively to reach adult levels at about 45 days of age. The 1-h Cr-EDTA space began to fall after 25 days, and reached adult values by 33 days; in rats aged 25 and 30 days, the Cr-EDTA space was almost twice the measured interstitial tissue volume, but even in the older rats, the Cr-EDTA space remained appreciably greater than the interstitial tissue volume. The 20-h albumin space did not begin to fall until after 33 days, and had still not reached adult values in rats aged 44 days. Thus, the functional barrier to water-soluble markers develops later and more gradually than the barrier to electron-opaque markers as used by previous authors, and its appearance correlates more closely with enlargement of the tubular lumen than with formation of the inter-Sertoli cell junctions. The rate at which the albumin space approached its final value was used to calculate the vascular permeability to albumin. This rose to a maximum between 25 days and 33 days of age, and then fell again, although adult values had still not been reached by 44 days of age.

Animals↗
PubMed1988

Effects of local heating of the testes on the concentration of testosterone in jugular and testicular venous blood of rats and on testosterone production in vitro.

Heating both testes of rats to between 39 degrees C and 41 degrees C for 30 min was apparently without effect 21 days later, but heating to between 41.5 degrees C and 43 degrees C for 30 min resulted in a significant drop in testis weight accompanied by significant rises in the serum levels of LH and FSH. There were no changes in serum testosterone concentration in the peripheral circulation although there were increases in the concentration in testicular venous blood. The ability of the heated testis to secrete testosterone in vivo in response to maximal stimulation by hCG was reduced, as judged by testosterone levels in peripheral blood, while there was a supranormal increase in testosterone levels in testicular venous blood. Maximally stimulated testosterone production in vitro by the heated testis was supranormal whereas the basal production of testosterone per testis was not different from control values. Therefore, it appears that the testosterone produced by Leydig cells from heated testes may not be secreted as effectively as in normal testes.

Animals↗
PubMed1988

Effects of local heating of the testis on testicular blood flow and testosterone secretion in the rat.

Exposure of one or both testes of rats to heating at 43 degrees C for 30 min resulted in a significant reduction in blood flow per testis, as measured using microspheres. The effects on the testes of unilateral and bilateral heating were similar, although the changes in FSH levels in peripheral blood were in general less marked after unilateral heating. Testicular blood flow fell, along with testicular weight, beginning at 2-4 days and reaching minimum values 14-21 days after heating. Both blood flow per testis and testicular weight were beginning to recover 35 days post-heating and blood flow per testis was normal by 56 days following heat treatment, although testicular weight was still slightly reduced at that time. Heating one or both testes to 42 degrees C produced similar but smaller responses 21 days later, whereas temperatures of 41 degrees C or lower were without effect on the parameters measured, except for some rises in serum LH and FSH. With slight reductions in blood flow, there were corresponding increases in testicular venous testosterone concentration so that testosterone secretion was unaffected. Further reductions in blood flow at 14 and 21 days after heating to 43 degrees C were not fully compensated by an increase in the concentration of testosterone in testicular venous blood, with the result that testosterone secretion fell.

Animals↗
PubMed1988

The composition of extracellular interstitial fluid collected with a push-pull cannula from the testes of adult rats.

1. A push-pull cannula has been used to obtain extracellular interstitial fluid from the testes of anaesthetized adult rats. 2. Assuming or having demonstrated that appropriate radioactive markers had equilibrated between the vascular and extracellular fluid compartment of the testis, the dilution of the cannula infusate by extracellular interstitial fluid of the testis has been determined. These dilutions have then been used, with the measured concentrations of sodium, potassium, protein and testosterone in the perfusate, to calculate the concentrations of these substances in undiluted extracellular interstitial fluid of the testis. 3. Sodium, potassium and protein levels in testicular interstitial fluid calculated in this way were similar to blood plasma levels. Testosterone concentrations were certainly no greater than in testicular venous blood, and may have been even less. The results with testosterone and potassium contrast with earlier results obtained with less-physiological techniques.

Animals↗
PubMed1988

Is embryonic mortality increased in normal female rats mated to subfertile males?

Normal female rats were mated to control males or males which were subjected to unilateral testicular heating (43 degrees C for 30 min), irradiation (500 R), efferent duct ligation, arterial ligation or castration; in all males, the contralateral ductus deferens was ligated. All treatments caused reduced fertility and eventually infertility, as judged by the percentage of females becoming pregnant; the infertility was temporary after heating and irradiation. During the periods of reduced fertility, the numbers of fetuses per pregnant female and the fetus/corpus luteum ratios were reduced. In subsequent experiments, after heating of the testis, there was not only failure of fertilization despite the presence of normal numbers of spermatozoa in the uterus, but also an increased rate of embryonic degeneration in normal females. These results provide evidence that the male, while still fertile, can affect the fecundity of the female and the rate of embryo mortality.

Animals↗
PubMed1988

Gonadotrophin secretion and ovarian responses in prepubertal heifers actively immunized against androstenedione and oestradiol-17 beta.

Groups of heifer calves received a primary immunization against androstenedione (Group A; N = 11) or oestradiol-17 beta (Group E; N = 10) at 3 months of age and booster injections on 5 occasions at 2- to 3-month intervals. Controls (Group C, N = 11) were immunized against human serum albumin alone using the same protocol. Immunity was achieved against both steroids as judged by the secondary antisteroid antibody titres in Group A (1126 +/- 261; reciprocal of titre) and Group E (10,357 +/- 4067) heifers. In Groups A and E there was a general decline in the respective peak antibody titres after successive booster injections. From 3 to 9 months of age mean plasma concentrations of LH were higher (P less than 0.05) in Group E heifers (0.89 +/- 0.08 ng/ml) than in Group C (0.46 +/- 0.03 ng/ml) and Group A (0.59 +/- 0.05 ng/ml) heifers which did not differ from one another. There were no differences between groups in plasma FSH concentrations. At 10 months of age the LH response to exogenous LHRH was of higher (P less than 0.05) amplitude for heifers in Group E (2.59 +/- 0.56 ng/ml) than for those in Groups C (0.61 +/- 0.07 ng/ml) and A (1.04 +/- 0.22 ng/ml). Elevated plasma progesterone concentrations at 5 months of age were shown by 2 heifers in Group C, 10 in Group A, and 6 in Group E. From 8 to 14 months of age a consistently higher proportion of Group A heifers exhibited elevated progesterone compared with Group C and Group E heifers. After ovarian synchronization and booster injection at 15 months of age a corpus luteum was present in 2 heifers in Group C, 7 in Group A and none in Group E. The ovaries of Group A heifers were different from those of Groups C and E and were characterized by greater numbers of 2-4 mm follicles. It is concluded that active immunization against gonadal steroids influences both LH secretion and ovarian function in prepubertal heifers. Early increases in ovarian activity in androstenedione-immunized heifers are maintained after puberty and may therefore confer some lifetime reproductive advantages.

Androstenedione↗
PubMed1988

Distribution of 5 alpha-reductase in the epididymis of the tammar wallaby (Macropus eugenii) and dependence of the epididymis on systemic testosterone and luminal fluids from the testis.

The activity of 5 alpha-reductase was much higher in the caput and corpus epididymidis than in the cauda epididymidis. Orchidectomy caused a reduction in 5 alpha-reductase activity in the caput and corpus epididymidis, and regression of the epithelium and reduction in mass of all regions of the epididymis. Subsequent testosterone therapy caused a substantial increase in amount of epithelium and overall mass of the cauda epididymidis but showed little or no increase in any of the responses measured in the caput and corpus epididymidis. We concluded that the caput and corpus epididymidis of the tammar respond to factors other than testosterone, probably some constituent in the luminal fluid, and therefore are homologous with the initial segments of the epididymis in eutherians.

3-Oxo-5-alpha-Steroid 4-Dehydrogenase↗
PubMed1988

Increases in ovulation rate in lupin-fed ewes are initiated by increases in protein digested post-ruminally.

Parous Merino ewes were maintained outdoors in feedlots during the beginning of the spontaneous breeding season and fed a maintenance ration of wheaten hay. For 14 days, ewes in each of 4 groups (N = 40/group) were given supplements of lupin grain or formaldehyde-treated casein and/or wheat starch. These were calculated to supply equivalent amounts of protein post-ruminally and/or digestible energy. Supplementation with lupin grain significantly increased ovulation rate by 37% by increasing the proportion of ewes with two ovulations. Similar increases in ovulation rate were achieved by increasing the supply of digestible protein post-ruminally in the casein and casein + starch-supplement groups. Increasing the intake of digestible energy separately in the starch-supplement group did not increase ovulation rate. It is concluded that increases in ovulation rate in ewes fed a lupin supplement are the result of significant increases in the amount of protein digested post-ruminally.

Animals↗