Search PubMed⌕ Search

Biomedical subjects

B P Setchell

Publications and source records attributed to B P Setchell.

At least 91 records · Page 5Linked to original sources
PubMed1983

Limitations imposed by testicular blood flow on the function of Leydig cells in rats in vivo.

Testis blood flow per testis closely follows testis weight in rats made aspermatogenic by a single exposure of the testis to 43 degrees C for 30 min or 500 rad (5 Gy) of irradiation from a caesium source, or following ligation of the efferent ducts. Aspermatogenesis following these treatments was associated with only minor changes in the concentrations of testosterone in peripheral blood before stimulation with human chorionic gonadotrophin (hCG), and a reduced responsiveness to hCG when testis weight had fallen after heating. The concentrations of testosterone in testicular venous blood was normal or above normal during aspermatogenesis resulting from heat or irradiation, and only slightly reduced following efferent duct ligation. Consequently testosterone production (defined as the product of plasma flow and the veno-arterial concentration difference for testosterone) was markedly reduced during aspermatogenesis, both before and after stimulation with hCG. It appears that the reduced blood flow limits the amount of testosterone leaving the testis, and while the Leydig cells are capable under some circumstances of compensating partially for this fall by increasing the concentration of testosterone in the testicular venous blood, this compensation is not complete when there are severe reductions in blood flow. Therefore one can conclude that the mass of the tubules is the main determinant of testis blood flow and the Leydig cells must manage with what the tubules require.

Animals↗
PubMed1983

The effects of acidic epididymal glycoprotein (AEG) and some other proteins on the motility of rat epididymal spermatozoa.

Acidic epididymal glycoprotein (AEG) had a slight stimulatory effect on the motility of spermatozoa showing low initial motility which had been removed by micropuncture from the caput and corpus epididymidis of rats. However, similar effects were seen when bovine serum albumin (BSA) or purified gammaglobulin against AEG was used instead of AEG. Furthermore, BSA, normal rabbit serum and serum from a rabbit immunized against AEG reduced the motility of spermatozoa which showed high initial motility after removal from the caput, while AEG had no effect. These studies emphasize the importance of the effects of proteins on the motility of spermatozoa but do not provide any clear evidence for a specific effect of AEG.

Animals↗
PubMed1983

Evidence for a defective seminiferous tubule barrier in testes of Tfm and Sxr mice.

The competence of the seminiferous tubule barrier was evaluated by determining the sucrose space in isolated testis preparations obtained from adult wild-type mice and from mutants having defects in spermatogenesis. The distribution of [3H]sucrose in testes from wild-type mice was in a space which constituted 18.5% of the [14C]urea space. The corresponding sucrose space in testes from Tfm/Y and Sxr/+ sterile mutants was elevated to 57.7% and 52.0%, respectively. Independent approaches to detect an impairment in the seminiferous tubule barrier of testes from Tfm/Y mice consisted of estimations of the osmotic barrier to hypertonic LiCl, using histological techniques, and determination of the testis sucrose space in vivo. With both approaches, results obtained supported the presence of an impaired barrier in testes of Tfm/Y mice. The sucrose space was within normal limits in testes of the other mutants examined, which were defective in spermatogenesis. The results do not provide any evidence for an impaired barrier in testes of mice having Movbr/Y and Gy/Y mutations, or the t6twl genotype.

Animals↗
PubMed1983

Transport of free and conjugated steroids from the boar testis in lymph, venous blood and rete testis fluid.

In 12 anaesthetized boars the concentrations of oestrone sulphate and dehydroepiandrosterone sulphate (DHAS) were 15- to 35-fold higher in lymph collected from a vessel in the spermatic cord than in testicular venous blood plasma from a vein in the spermatic cord. The concentrations of testosterone, total unconjugated oestrogens and dehydroepiandrosterone (DHA) were about twofold higher in lymph. The concentrations of all steroids studied were higher in testicular venous blood plasma than in arterial blood plasma (testosterone about sixfold; total unconjugated oestrogens about fourfold; oestrone sulphate about threefold; DHA and DHAS about twofold), but the concentrations of testosterone, total unconjugated oestrogens and oestrone sulphate in rete testis fluid were comparable to those in arterial blood plasma. Lymph flow from the pig testis was about 7% of plasma flow so that about 80% of the oestrone sulphate and DHAS produced by the testis leaves the organ in the lymph; the comparable values for testosterone, total unconjugated oestrogen and DHA were about 20%. In the 90-min period following an injection of human chorionic gonadotrophin there were substantial increases in the concentration of testosterone and smaller increases in the other steroids in arterial and spermatic venous blood plasma and in testicular lymph, but not in rete testis fluid; there were also small increases in lymph flow, but no change in blood flow.

Androgens↗
PubMed1983

Changes in testicular blood flow and testosterone production during aspermatogenesis after irradiation.

Exposure of the testes of anaesthetized adult rats to 527 rads of gamma-irradiation caused testis weight to fall slowly at first and then more rapidly from 21 days afterwards, reaching a minimum at 52 days, when spermatogenesis was severely disrupted. The weights of the accessory organs and the concentrations of testosterone in peripheral blood were slightly reduced; the concentrations in blood from the testicular veins were lower than control at shorter intervals after irradiation, but at later times tended to be similar or greater than control. Testicular blood flow per testis followed testis weight closely, and as a result the production of testosterone by the smaller testes (calculated as the product of plasma flow and the veno-arterial difference in testosterone concentration) was markedly reduced especially when the rats had been stimulated with human chorionic gonadotrophin (hCG). Serum FSH and LH rose appreciably as testis weight fell but there was a proportionately greater rise in FSH than LH, in comparison with surgically castrated animals. Increased amounts of extratubular, extracellular fluid were found in the aspermatogenic testes, but injection of hCG still caused increases in capillary permeability and the amount of fluid in the testis. These results indicate that during aspermatogenesis following irradiation (as with heat and efferent duct ligation) the capacity of the testes to secrete testosterone is severely limited by decreased testicular blood flow, not by the ability of the Leydig cells to release testosterone into their immediate environment.

Animals↗
PubMed1982

A comparative study of carnitine and acylcarnitine concentration in semen and male reproductive tract fluids.

1. L-carnitine and its short-chain acyl derivatives were measured in semen of boar, man, rooster, bull, squirrel monkey and ram. 2. Carnitine was present in concentrations of 220, 476, 540, 1880, 3330 and 3820 muM respectively, and acetylcarnitine concentrations were 2, 191, 354, 709, 259 and 2750 muM. Propionyl and C4-acyl carnitines were found in small quantities. 3. Analysis of sequential "Split-ejaculate" samples of boar semen showed that carnitine concentration correlated with sperm count, suggesting an epididymal origin for this substance in this species. 4. Bioautographic analysis of samples obtained from ram and rat indicated that carnitine and acetylcarnitine were present in epididymal fluid and in fluids from accessory glands of the male reproductive tract.

Animals↗
PubMed1982

Influence of androgens on inositol secretion and sperm transport in the epididymis of rats.

The effects of unilateral efferent duct ligation, bilateral castration or testosterone replacement on the spermatocrit and inositol concentrations in luminal fluid removed by micropuncture from the rat epididymis were investigated. By 5 days after efferent duct ligation, there were substantial falls in the spermatocrit in the caput and corpus, but no change in the cauda. After 7 days there was an increase in the spermatocrit in the cauda. After castration there were more marked reductions in the spermatocrit in the caput and corpus but there was no change in the cauda. The spermatocrit in the corpus, but not in the caput, remained normal when castrated animals were treated with testosterone. The inositol concentrations in luminal fluid from all three sites were not changed after ligation of the efferent ducts but were greatly reduced after castration; this fall was prevented by testosterone treatment. The results support the suggestion that inositol is secreted in the rat epididymis and also indicate that the secretory process is controlled by androgens.

Androgens↗
PubMed1982

Secretion of free and conjugated steroids by the horse testis into lymph and venous blood.

In 3 testes of 2 adult Pony stallions under halothane anaesthesia, catheters were inserted into a vein and a lymphatic vessel in the spermatic cord and into a vein on the surface of the testis. Lymph and venous blood were collected from the catheters in the cord and p-aminohippurate (2% w/v, 0 . 1 ml/min) was infused into the vein on the testis to determine blood flow by dilution. After 1 h, 6000 i.u. hCG was injected i.v. and collections continued for 45 min. The testes weighed 126-176 g. Lymph flow was 20-150 microliter/min before hCG and 100-270 microliter/min after hCG; the range of blood flow, with a haematocrit of about 22%, was unchanged (27-47 ml/min) after hCG. The concentration of testosterone in spermatic venous blood rose from 6-20 ng/ml to 160-270 ng/ml within about 30 min after hCG. Peripheral levels rose from about 2 to 6 ng/ml and lymph levels increased from 9-20 to 34-150 ng/ml after hCG. In contrast, the concentrations of oestrone sulphate in spermatic venous blood were about 400 ng/ml, compared with about 250 ng/ml in peripheral blood, while lymph values ranged from 600 to 1500 ng/ml; hCG had no consistent effect. DHA and its sulphate were present in spermatic venous blood at concentrations (about 3 and 5 ng/ml respectively) slightly higher than in peripheral blood (1 . 7 and 2 . 5 ng/ml), but the sulphate was at a very much higher concentration in lymph (about 5 and 200 ng/ml respectively). These results indicate that testicular lymph is an important route for the secretion of conjugated steroids by the horse testis.

Animals↗
PubMed1981

Labelling of membrane glycoproteins on rat spermatozoa collected from different regions of the epididymis.

The major glycoprotein on the plasma membrane of testicular spermatozoa labelled with the galactose oxidase/NaB3H4 technique has mol.wt. 110 000. As spermatozoa pass through the epididymis, labelling of this glycoprotein disappears and is replaced by labelling of a 32 000-mol.wt. protein. The latter protein is a major component of epididymal secretions. The evidence suggests that it is inserted into or absorbed on to the plasma membrane, and since its appearance on spermatozoa correlates with the acquisition of fertilizing capacity it should serve as a good marker for assessing maturation in vitro.

Animals↗
PubMed1981

The concentration of some inorganic ions and organic compounds in the luminal fluid of the human ductus deferens.

The concentrations of some inorganic ions (sodium, potassium, chloride and phosphate) and organic compounds (carnitine, myo-inositol, glycerophosphocholine, phosphocholine and total phosphate) were estimated in the luminal fluid collected from sections of human ductus deferens removed at vasectomy. From the data presented it would appear that in contrast to non-primate species, in the human the inorganic ions contribute more to the total osmolarity of the luminal fluid than do the organic compounds.

Adult↗
PubMed1981

The utilization of lactic acid by sheep in late pregnancy.

The irreversible loss of lactate and the respiratory exchange in four conscious ewes that were about 138 days pregnant were measured at least seven days after surgery. In addition, the uptake and net output of lactate and the net uptake of glucose and alanine by the gravid uterus and an upper hind limb (primarily skeletal muscle) were measured. Calculated heat production of the ewes was 496 kJ/d.kg 3/4; irreversible loss of lactate was 9.5 mumol/min.kg of which 73% was oxidized to CO2, contributing 9% to the ewes' CO2 production. About 2% of the glucose and 65% of the alanine was derived from lactate. Lactate was taken up by both the gravid uterus and the upper hind limb; output of lactate could have accounted for from 8-12% of glucose uptake by the gravid uterus but from 35-50% of that by the upper hind limb. The carbohydrate/O2 quotient was 1.07 for the gravid uterus and 0.35 for the upper hind limb.

Alanine↗
PubMed1981

Effects of carnitine and some related compounds on the motility of rat spermatozoa from the caput epididymidis.

Spermatozoa were collected from the rat caput epididymidis by micropuncture and their motility assessed after dilution in physiological saline containing carnitine or related compounds. L(+)-Carnitine caused, 2 min after dilution, a transient stimulation of the motility of spermatozoa with low initial motility. No stimulatory effects were seen on spermatozoa which had high initial motility. The D-isomer inhibited the motility of spermatozoa with high initial motility after 2 min and all compounds tested appeared to inhibit, at 20 min after dilution, the motility of spermatozoa with high initial motility. Acetyl-L-carnitine and acetyl-D-carnitine stimulated the motility of spermatozoa with low initial motility. This study suggests that carnitine may be important in the development by spermatozoa of the potential for motility and also to maintain mature spermatozoa in a quiescent state.

Acetylcarnitine↗
PubMed1981

Frequency and duration of the stages of the cycle of the seminiferous epithelium of the nine-banded armadillo (Dasypus novemcinctus).

The majority of the cross-sections of seminiferous tubules of nine-banded armadillos show only one type of cellular association as in most eutherian and metatherian mammals with scrotal testes. The spermatogenic cycle was divided into 8 stages, in relation to the shedding of the spermatozoa. The relative frequencies (%) of stages 1-8 were, respectively: 16.6, 7.5, 12.9, 9.1, 9.7, 18., 11.7 and 13.6. The duration of the cycle was 8.15 days, as determined by intratesticular injection of [3H]thymidine and removing the tissue at different times after injection.

Animals↗
PubMed1981

Effects of obstruction of the flow of seminiferous tubule fluid on the germinal epithelium in the rat.

Blocking the lumen of a single seminiferous tubule by introducing a plug of non-toxic latex produced a lesion in that tubule, but not in immediately adjacent tubules. The lesion extended for up to 50 mm from the end of the latex. Nearest to the block the tubule was completely aspermatogenic; further along the tubule, the lesion was less severe, involving disorganization and reduction in germ cell numbers, with the cells showing vacuolation, pycnosis and karyolysis. Binucleate and giant cells were common, and cells were often exfoliated into the lumen. The lesion tended to increase in length with longer times after introduction of the plug, but there appeared to be no preferential involvement of the shorter segment of the tubule between the block and the rete. The transition from damaged to healthy tubule was abrupt.

Animals↗
PubMed1981

Effect of injected human chorionic gonadotrophin on capillary permeability, extracellular fluid volume and the flow of lymph and blood in the testes of rats.

The subcutaneous injection of human chorionic gonadotrophin (HCG) into adult male rats caused appreciable rises in capillary permeability and lymph flow in the testis, accompanied by smaller rises in the volume of extratubular, extracellular fluid. Most of these changes were already apparent 8 h after injection, but became progressively greater during the next 12 h. Testicular blood flow was unchanged at 12 h but increased slightly between 12 and 6 h after injection. The primary effect is probably the increase in capillary permeability. The timing of these changes suggests that HCG does not affect the capillaries directly, but it would seem that the changes are due to some substances secreted by the testis in response to the HCG. It is clear that these changes will have important influences both on the access to the testicular cells of peptide hormones in the blood and also on the passage into the venous blood of hormones secreted by the testis.

Animals↗