Biomedical subjects

R P Amann

Publications and source records attributed to R P Amann.

At least 19 recordsLinked to original sources

PubMed1992

Effects of microgravity or simulated launch on testicular function in rats.

Testes from flight rats on COSMOS 2044 and simulated-launch, vivarium, or caudal-elevation control rats (5/group) were analyzed by subjective and quantitative methods. On the basis of observations of fixed tissue, it was evident that some rats had testicular abnormalities unassociated with treatment and probably existing when they were assigned randomly to the four treatment groups. Considering rats without preexisting abnormalities, diameter of seminiferous tubules and numbers of germ cells per tubule cross section were lower (P less than 0.05) in flight than in simulated-launch or vivarium rats. However, ratios of germ cells to each other or to Sertoli cells and number of homogenization-resistant spermatids did not differ from values for simulated-launch or vivarium controls. Expression of testis-specific gene products was not greatly altered by flight. Furthermore, there was no evidence for production of stress-inducible transcripts of the hsp70 or hsp90 genes. Concentration of receptors for rat luteinizing hormone in testicular tissue and surface density of smooth endoplasmic reticulum in Leydig cells were similar in flight and simulated-launch rats. However, concentrations of testosterone in testicular tissue or peripheral blood plasma were reduced (P less than 0.05) in flight rats to less than 20% of values for simulated-launch or vivarium controls. Thus spermatogenesis was essentially normal in flight rats, but production of testosterone was severely depressed. Exposure to microgravity for greater than 2 wk might result in additional changes. Sequelae of reduced androgen production associated with microgravity on turnover of muscle and bone should be considered.

Animals↗

PubMed1992

Ultrasonographic and quantitative histologic assessment of sequelae to testicular biopsy in stallions.

A sample of testicular parenchymal tissue, approximately 2 x 7 x 7 mm, was aseptically removed from 1 testis in each of 9 stallions on day 0. Slight to moderate hemorrhage from the tunica albuginea was observed in 8 stallions, but bleeding from the parenchyma was detected in only 2 stallions. Stallions were castrated 27 days later. Normal development of granulation tissue was evident at the biopsy site, but hematomas were not observed. In situ measurement of the widths of the right and left testes, total scrotal width, and evaluation of testicular echogenicity during ultrasonography were variables used to monitor changes in the testicular parenchyma from 14 days before biopsy through 27 days after biopsy. The control testis was consistently larger than the biopsied testis, except for day 3. Ultrasonography revealed signs of a localized change in the parenchyma of the biopsied testis in 4 stallions, but each lesion decreased in size by day 27. Tissues removed during biopsy enabled an excellent appraisal of spermatogenesis at that time. Detailed examinations of seminiferous tubules in the testes were performed to assess for damage to testicular function. At castration, samples were taken from 6 sites in each testis. Quantitative histologic evaluations of testicular tissues revealed low numbers of spherical spermatids and pachytene spermatocytes in biopsied testes, compared with control testes. It was concluded that there was a transitory increase in degeneration of preleptotene spermatocytes and B spermatogonia at the time of biopsy. A mild inflammatory response at the biopsy site in some testes was evidenced by an increased number of leukocytes at the biopsy site and at a dorsal site.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1991

Effect of pulsatile or continuous administration of GnRH on reproductive function of stallions.

Gonadotrophin-releasing hormone (GnRH) was administered subcutaneously to reproductively normal stallions, either in a pulsatile manner (10 micrograms GnRH/2 h; n = 6) or as a continuous infusion (10 micrograms GnRH/2 h; n = 6), and in a pulsatile manner to 9 reproductively abnormal stallions, from February to July, 1988. Hormonal secretion patterns, testicular parameters and semen characteristics were monitored before and during treatment. In general, pulsatile GnRH caused a significant increase (P less than 0.05) in luteinizing hormone (LH) concentrations in the peripheral blood of normal stallions. LH levels also appeared to increase in abnormal stallions but the rise was not significant (P greater than 0.05). Stallions given GnRH by continuous infusion and the untreated control stallions did not show an increase in LH concentrations during the treatment period. None of the treatments resulted in significant increases in peripheral blood concentrations of testosterone, although individual stallions that showed an increase in LH secretion appeared to show some increase in testosterone secretion rate. In general, and for individual stallions, none of the treatments resulted in increased total scrotal width, total number of spermatozoa per ejaculate or the percentage of progressively motile spermatozoa in the ejaculate. It was concluded that although pulsatile administration of GnRH may increase the secretion rate of LH and, consequently, testosterone, this adjustment does not increase testicular size or output and motility of spermatozoa.

Animals↗

PubMed1990

Morphological features of principal cells in the ovine epididymis: a quantitative and qualitative study.

Functions of the epididymis differ by region, and this may be reflected in epithelial structure. Therefore, tissues from the initial segment (IS), proximal and central caput (PCap, CCap), and proximal and central corpus (PCor, CCor) epididymidis were examined by light and transmission electron microscopy. The proportion of principal cells in the epithelium was highest (p less than 0.05) in the CCap (74%) and lowest in the CCor (68%), whereas proportions of basal cells (25%), apical cells (1.4%), and white blood cells (2%) were similar in all regions. Volume density (VD) of the nucleus was lower (p less than 0.05) in principal cells in the IS (7%) than in other regions (10%). There was no regional difference in VD of the Golgi complex (14%) or endoplasmic reticulum (19%) in principal cells. The VD of mitochondria averaged 4% in the IS through CCap, but only 2.5% in PCor or CCor (p less than 0.05). The VD of clear vesicles + multivesicular bodies (8%) and dense vesicles (6%) were higher (p less than 0.05) in the CCap than in other regions (1% each), while there were more lipid droplets (12%) in the PCor than in other regions (less than or equal to 2%). Most quantitative differences in VD of organelles within principal cells were small even though significant. However, there were profound differences in the morphological features of the Golgi complex, endoplasmic reticulum, and mitochondria among regions.

Animals↗

PubMed1990

Oxytocin in the ovine ductuli efferentes and caput epididymidis: immunolocalization and endocytosis from the luminal fluid.

The presence, possible biosynthesis, and uptake of oxytocin from luminal fluid in the ductuli efferentes and caput epididymidis of the ram were studied. Specific immunostaining for oxytocin, but not neurophysin, was observed in the ductuli efferentes as well as caput epididymidis. This indicates the presence, but not production, of oxytocin in epithelial cells of these ducts. Staining was predominantly present in the epithelium, especially in the middle lobules of the ductuli efferentes and initial segment of the epididymis. Endocytosis of oxytocin was studied by electron microscopy after intraluminal microinjections of oxytocin conjugated to colloidal gold (8-10 nm), a 20-fold excess of oxytocin followed by oxytocin-gold, or plain colloidal gold into the ductuli efferentes and four successive regions of the caput epididymidis. Specific uptake by a receptor-mediated process was evidenced by the presence of more gold particles within epithelial cells after oxytocin-gold injections than after control injections. The quantity of oxytocin-gold endocytosed was 3.7-fold greater in the ductuli efferentes than in the initial segment of the epididymis. Within the caput epididymidis, more oxytocin-gold was endocytosed in the initial segment and proximal caput epididymidis than in two distal regions. We conclude that localization of oxytocin in epithelia of the excurrent ducts is a consequence of endocytosis (predominantly receptor mediated) of luminal oxytocin entering in rete testis fluid; however, uptake of blood-borne oxytocin cannot be excluded. Although oxytocin may have a role in sperm transport via action on smooth muscle in the ductal wall, the regional pattern of endocytosis of oxytocin is suggestive of a role for oxytocin in epithelial function in the ductuli efferentes and proximal portions of the caput epididymidis.

Animals↗

PubMed1990

Testicular growth, hormone concentrations, seminal characteristics and sexual behaviour in stallions.

Puberty was studied using 15 colts of Quarter Horse phenotype. Total scrotal width was measured every 8 weeks from 48 to 96 weeks. Blood samples were taken from 8 colts at 8, 16 and 24 weeks and then every 4 weeks until 100 weeks to measure changes in LH, FSH and testosterone concentrations. Seminal collections were attempted monthly from 48 to 64 weeks and every 2 weeks thereafter until puberty resumed every 3rd day from 96 weeks for 15 ejaculates. For all collections, times to erection, mount and ejaculation and seminal characteristics were recorded. Age at puberty was defined as the first ejaculate containing 50 x 10(6) spermatozoa, with greater than or equal to 10% motile. Colts were castrated at 2 years to enable determination of daily sperm production (DSP), epididymal sperm reserves and normality of spermatogenesis. Total scrotal width increased linearly from 48 to 96 weeks. Age at puberty averaged 83 weeks (56-97 weeks). Changes in serum concentrations of LH and FSH were parallel, rising at 36-40 weeks, declining after 40 weeks and rising again at 68-80 weeks. Testosterone was low until 68 weeks after which concentrations rose slowly to 80 weeks and increased rapidly to a plateau at 92 weeks. Sexual behaviour and seminal characteristics differed (P less than 0.05) between puberty and 2 years, except for time to erection, time to mount, and percentage of motile spermatozoa. DSP at 2 years averaged 1.7 x 10(9) and daily sperm output (DSO) averaged 1.1 x 10(9). The correlation between DSP and DSO was 0.83 (P less than 0.01). There were 9.57 x 10(9) spermatozoa/epididymis of which 67% were in the cauda.

Animals↗

PubMed1990

Effect of maternal treatment with altrenogest on pituitary response to exogenous GnRH in pubertal stallions.

The pituitary response to exogenous GnRH was studied in 8 colts of Quarter Horse phenotype from 32 to 96 weeks of age. Colts were from dams treated daily from Day 20 to 325 of gestation with (1) 2 ml neobee oil per 50 kg body weight (controls); or (2) 2 ml altrenogest per 50 kg body weight. GnRH challenges (5 micrograms/kg body weight) were administered every 8 weeks from 32 to 96 weeks of age to estimate pituitary content of LH. Blood samples were collected every 20 min for 4 h before GnRH and 15, 30, 45, 60, 90, 120, 180, 240 and 360 min after GnRH. Serum concentrations of LH and FSH were determined for the 2 pre-GnRH and all post-GnRH samples. Baseline concentrations (mean of 2 pre-GnRH samples) of LH and FSH were not affected by treatment (P greater than 0.05). Serum concentrations of LH declined from 40 to 56 weeks and rose again between 72 and 80 weeks. Basal concentrations of FSH declined from 32 to 56 weeks, and varied widely after 56 weeks. The maximum LH response to GnRH (highest concentration after GnRH minus baseline) declined steadily in both groups for 48 to 64 weeks but remained relatively constant in both groups after 64 weeks. The maximum FSH response to GnRH declined from 32 to 64 weeks then remained relatively constant in both groups. The GnRH-induced gonadotrophin release remained low with a transient increase at 72 weeks for both hormones.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1989

Optimal replication for histometric analyses of testicular function in rats or rabbits.

Quantitative evaluations of testicular histology can provide sensitive endpoints for determining toxicity of chemicals to the male reproductive system. But, the numbers of observations per testis or number of animals per treatment group often are selected by tradition or availability, rather than from a statistical basis. Therefore, we studied the number of observations per male (sampling intensity) and number of animals per treatment (replication) needed to detect treatment effects of given magnitude, with predictable error probabilities, using data from Sprague-Dawley rats and Dutch-belted rabbits that received 0.0, 0.94, 1.88, 3.75, 7.5, or 15.0 mg/kg body wt of 1,2-dibromo-3-chloropropane (DBCP). Data for one testis from 102 rats and 34 rabbits were available. For each testis, observations included measurement of the minor diameter of 50 seminiferous tubules, counts of the number of leptotene primary spermatocytes per 250 Sertoli cells, and counts of spherical spermatids within 20 seminiferous tubular cross sections. Tabular data are presented showing optimal numbers of observations per testis and animals per treatment group as a function of the difference to be detected and selected probabilities for Type I and II errors. In general, precise assessments required far fewer observations per testis than are used routinely. However, due to the inherent variability among animals, the number of animals required per treatment tended to be greater for experiments with the rabbit, and increased substantially for both species when detection of small differences had to be ensured. The data presented should enable investigators to design experiments of chosen sensitivity and precision while making cost-effective use of animals and labor.

Animals↗

PubMed1989

Immunolocalization and concentrations of inhibin alpha in the ovine testis and excurrent duct system.

Inhibin was localized in the ovine testis, excurrent ducts, and accessory sex glands by using a rabbit antiserum against a synthetic polypeptide representing the first 30 amino acids of porcine inhibin alpha-subunit. Concentrations of inhibin in fluids entering and leaving the epididymis also were determined in a radioimmunoassay using the same antibody. In the testis, immunostaining of inhibin was conspicuous in the seminiferous epithelium. Leydig cells occasionally were stained and the tunica media of blood vessels always was stained. Intense staining was observed in the epithelia lining the rete testis and ductuli efferentes. Staining also was intense in the epithelium of the initial segment and proximal caput epididymidis, and became less intense along the length of the epididymis. These observations were consistent with concentrations of inhibin in rete testis fluid (8.2 pmol/ml) entering the ductuli efferentes and in cauda epididymal plasma (0.67 pmol/ml) leaving the epididymis. Epithelia of ampullary and vesicular glands and of some prostatic acini were positively stained, but bulbourethral glands were never stained. Adrenal cortex, some proximal convoluted tubules in the kidney, and transitional epithelium of the urethra also were stained. Based on radioimmunoassay data and fluid flow rates for the ram, it was concluded that almost all of the 328 pmol inhibin that enters the ductuli efferentes daily is endocytosed in the proximal parts of the excurrent duct system. The physiological role(s) for inhibin, or inhibin-like peptides, in the excurrent duct system remains speculative.

Adrenal Glands↗

PubMed1989

Localization of androgen receptors in ram epididymal principal cells.

Androgen receptor was immunolocalized in the epididymal epithelium of rams and in isolated cells using an antibody against a synthetic polypeptide representing a portion of the androgen receptor. Immunostaining was predominant in the epithelium in tissue sections. Concentrations of androgen receptor were determined in cells from the central caput, distal caput, and central corpus epididymidis enzymically dissociated and elutriated to provide two fractions. On the average (n = 18), Fraction I contained 8% principal cells while Fraction II contained 71% principal cells; the stromal cells in each fraction were primarily smooth muscle and fibroblasts. For each sample, the number of DHT receptors (fmol) per 10(6) total cells was greater in Fraction II than in Fraction I. Few cells in Fraction I were immunostained for androgen receptor, whereas most cells in Fraction II were intensely stained. The numbers of DHT receptors per cell, or per principal cell, were similar for the central caput and distal caput, but lower in the central corpus epididymidis. The results support our hypothesis that most epididymal DHT receptors are localized in principal cells and confirm that the region between the central caput and proximal corpus of the ram epididymis is most dependent on androgen stimulation.

Animals↗

PubMed1989

Influences of season and artificial photoperiod on stallions: pituitary and testicular responses to exogenous GnRH.

Effects of season and photoperiod on the anterior pituitary gland and testes were studied by responses to exogenous GnRH. Stallions were assigned to one of three treatments: 1) control, exposed to natural day length; 2) S-L, 8 h of light and 16 h dark (8:16) for 20 wk beginning July 16, 1982 then 16:8 from December 2, 1982 until March 5, 1984; or 3) S-S, 8:16 from July 16, 1982 until March 5, 1984. Approximately every 8 wk, stallions were administered GnRH (2 micrograms/kg BW) and blood was sampled at 20-min intervals for 2 h before and 8 h after GnRH administration. Concentrations of LH, FSH and testosterone were determined. Baseline concentrations (mean of pre-GnRH samples) of all hormones fluctuated seasonally (P less than .05), but only LH and testosterone displayed seasonal changes (P less than .05) in maximum response to GnRH (highest concentration above baseline after GnRH). The FSH response to GnRH was not affected (P greater than .05) by season, photoperiod or the season X treatment interaction. Exposure of S-L stallions to 16:8 in December resulted in early recrudescence of baseline concentrations of LH, FSH and testosterone. Maximum concentration of testosterone in response to GnRH was stimulated by 16:8, but the increase in baseline LH concentrations in S-L stallions was not associated with an increase in maximum LH response to GnRH. Seasonal patterns of baseline concentrations of FSH and testosterone and maximum LH response to GnRH in S-S stallions were similar to those for control stallions.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1988

Use of a monoclonal antibody to evaluate integrity of the plasma membrane of stallion sperm.

Transmission electron microscopy was used to confirm that a monoclonal antibody (F79.3E2; class IgG1 kappa) was specifically localized to an antigen in the acrosomal ground substance of stallion sperm. This antibody was used to develop and validate an indirect immunofluorescent procedure to evaluate integrity of the plasma-acrosomal membranes of stallion sperm. The concept was that primary monoclonal antibody would be "shielded" from its acrosomal antigen by an intact plasma membrane. Conversely, sperm with damaged plasma-acrosomal membranes would exhibit green acrosomal fluorescence when viewed with an epifluorescence microscope. A lipophilic counterstain (red fluorescence) was used to insure that all sperm were visualized. Sperm in fresh-extended or frozen-thawed semen were incubated with hybridoma supernatant containing monoclonal antibody for 30 min at 37 degrees C, then a second antibody (rabbit anti-mouse IgG-FITC) was added for 30 min at 37 degrees C. Unbound antibody was removed by dilution and centrifugation. Sperm were resuspended in phosphate-buffered saline containing Evan's blue as a counterstain. All sperm fluoresced bright red, regardless of the status of cell membranes, except that in cells with damaged plasma-acrosomal membranes, the green fluorescence associated with antibody was overriding for the rostral portion. By counting fluorescent and nonfluorescent "acrosomes", the percentage of sperm with intact plasma-acrosomal membranes was easily determined. Evaluation of five mixtures of undamaged and damaged sperm by this procedure gave a correlation of 0.91 between the percentage of damaged sperm in a mixture and the percentage of sperm with a fluorescent acrosome. Intra- and interassay coefficients of variability were less than 6%.

Acrosome↗

PubMed1988

Effects of exogenous melatonin prior to the breeding season on testis weight and epididymal androgen receptors in rams.

Rams were randomly assigned to an experiment that evaluated effects of treatment (2.5 mg melatonin/d for 45 d vs control; MEL vs CON) in mid-May through June on testis weight and concentration of epididymal androgen receptor in July or September (Sept). Mean testis weight of MEL and CON rams was not different in July (332 vs 283 g), but in Sept was less (P less than .05) for MEL rams than CON rams (268 vs 382 g). Testis weight of MEL rams was less (P less than .05) in Sept than in July. Caput, corpus and cauda epididymal tissues were used to prepare extracts which were analyzed for concentration of dihydrotestosterone (DHT) receptor using a new standard curve method. A standard extract was characterized using four independent 8-point Scatchard analyses and found to contain 6.0 fmol DHT receptor/mg wet tissue (Ka = 3.5 X 10(8).M-1); this extract was used to establish standard curves for assays of unknown samples. Data on concentration of DHT receptors measured by Scatchard analysis and the standard curve method were highly correlated (r = 0.99; P less than .01; n = 8). Concentrations of DHT receptor were not affected by treatment, month of castration, or their interaction. However, for data pooled across treatment and month, concentration (fmol/mg protein) of DHT receptor was greater (P less than .05) in caput or corpus (125 or 122) than in cauda (92) epididymidis. The regional distribution of epididymal DHT receptors in this study confirmed our previous findings.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1988

Regional and seasonal differences in concentrations of androgen and estrogen receptors in ram epididymal tissue.

Dihydrotestosterone (DHT) is essential for sperm maturation within the epididymis, but the roles of estradiol-17 beta (E2) and progesterone (P) in epididymal function are unknown. To identify sites of potential action of these hormones, and any effect of season on their concentrations, specific binding of steroids to receptors in extracts of ram epididymal tissue was quantified in two studies. Tissue was taken from three broad regions of the epididymis (caput, corpus, and cauda; Study 1) or from seven discrete regions of the epididymis (Study 2) in February to May (nonbreeding season; NBS) or late August to October (breeding season; BS). Specific binding of P was not detected. Saturable high-affinity binding sites specific for DHT (Ka = 2.6 x 10(8).M-1) and E2 (Ka = 5.4 x 10(8).M-1) were detected. Binding was not to androgen-binding protein, testosterone-estradiol-binding globulin, or sperm nuclei. There was no regional or seasonal difference in affinity of DHT or E2 binding. In both studies, concentration of DHT-binding sites (fmol/mg protein for low- plus high-salt extracts) was higher (p less than 0.05) in the BS than NBS. In Study 1, mean concentration of DHT-binding sites was higher (p less than 0.05) in the caput than in the corpus and cauda. The more definitive localization possible in Study 2 revealed that concentration of DHT-binding sites was highest in the distal caput, lowest in the proximal cauda (p less than 0.05), and intermediate in other regions. For E2, however, concentration of binding sites was higher (p less than 0.05) in the BS than NBS only in Study 1, and was higher (p less than 0.05) in the cauda or corpus than in the caput epididymidis. In Study 2, the season by region interaction was significant (p less than 0.05); concentration of E2-binding sites was higher in the distal cauda during the NBS. These data support the concept that the central caput through proximal corpus epididymidis are most dependent on androgenic stimulation, whereas distal regions may respond to estrogenic stimulation.

Animals↗

PubMed1988

Evidence for the presence of oxytocin in the ovine epididymis.

The testes of several species contain oxytocin and/or neurophysin, but the content or localization of oxytocin in epididymal tissue has not been studied. The present study was undertaken to localize oxytocin and neurophysin in epididymal tissue of the ram, and to quantify oxytocin in the ductus epididymidis and fluids entering and leaving the ductus epididymidis. Neurophysin was not detected in the epididymis; thus, synthesis of oxytocin by the epididymis is unlikely. Immunohistochemical localization of oxytocin was confined to the epithelium and capillaries. Oxytocin immunostaining was most intense for epithelium of the caput and declined in corpus and cauda regions. However, based on radioimmunoassay, no difference in oxytocin concentration was detected among regions of the epididymis. Since rete testis fluid entering and cauda epididymal fluid leaving the epididymis contained at least fourfold more oxytocin than testicular venous plasma, it was concluded that regional differences in epithelial concentration of oxytocin may have been masked by oxytocin contained in the luminal fluid. It was concluded further that the epididymis of the ram does not synthesize oxytocin, but about 22 ng/day enters the epididymis in rete testis fluid. Most of this luminal oxytocin apparently is absorbed by the epithelium of the caput epididymidis, with additional adsorption in the corpus and cauda. Although a role for oxytocin in ductal contractility cannot be excluded, it is more likely that the luminal oxytocin influences epithelial or sperm function.

Animals↗

PubMed1988

Influences of season and artificial photoperiod on stallions: luteinizing hormone follicle-stimulating hormone and testosterone.

Influence of day length on seasonal endocrine responses were studied using stallions (seven per group). Treatments included 1) control, with natural day length; 2) 8 h light and 16 h dark (8:16) for 20 wk beginning July 16, 1982 then 16:8 from December 2, 1982 until March 5, 1984 (S-L); or 3) 8:16 from July 16, 1982 until March 5, 1984 (S-S). Blood was sampled hourly for 5 h every 4 wk; sera were pooled within horse, and luteinizing hormone (LH), follicle-stimulating hormone (FSH) and testosterone were quantified. Blood was collected every 20 min for 24 h every 8 wk and 2 wk before and after the December light shift. Samples were assayed for LH. Stallions in all groups underwent seasonal changes (P less than .05) in concentrations of LH, FSH, testosterone and basal concentrations of LH and amplitude of LH pulses. Season X treatment (P less than .05) reflected on early recrudescence of LH, FSH and testosterone concentrations in S-L stallions followed by earlier regression. Except for FSH hormone concentrations were depressed in S-S stallions. Number of LH pulses per 24 h was unaffected by season, treatment or their interaction. Mean amplitude of LH pulses was affected (P less than .05) by season X treatment; maximal values occurred in April vs February for control and S-L stallions, and minimal values occurred in December vs April. The season X treatment interaction (P less than .05) similarly affected basal concentrations of LH. Thus, seasonal changes in concentrations of LH, FSH and testosterone can be driven by photoperiod. Increased peripheral concentrations of LH during seasonal recrudescence of reproductive function apparently results from more LH secreted per discharge without an increased frequency of LH discharges.

Animals↗

PubMed1987

Effects of exposing bovine sperm to bovine serum albumin, or freeze-thawing, on sperm-bound amidase activity.

Isolation of a self-selected population of motile spermatozoa is possible by using a gradient of bovine serum albumin (BSA). We determined if exposure to BSA altered the sperm or if isolated sperm differed from nonisolated cells in terms of motility or activity of sperm-bound amidase, either before or after subsequent cryopreservation. Exposure of sperm to 6% BSA in egg yolk Tris extender induced changes in the plasma and acrosomal membranes of sperm that resulted in exposure and activation of sperm-bound amidase (P less than .01). In experiment 2, semen extended in egg yolk Tris was cooled to 5 degrees C or layered onto a solution of 6% BSA in extender at 37 degrees C, from which the sperm that had swum into the BSA solution were recovered 2 h later and cooled to 5 degrees C. Sperm in both treatments were cryopreserved. The percentage of progressively motile sperm was determined visually and by track motility. Activity of sperm-bound amidase exposed to substrate was evaluated. After recovery of sperm from the 6% BSA solution, 81% were progressively motile as compared to 59% in the starting samples (P less than .01). However, the amount of exposed sperm-bound amidase also was greater (P less than .05); this was a deleterious change. Immediately after thawing, more (P less than .01) sperm were motile in samples of isolated sperm than for nonisolated cells (43 vs 24%), but after incubating the thawed sperm for 1 h at 37 degrees C there was no difference.(ABSTRACT TRUNCATED AT 250 WORDS)

Amidohydrolases↗

PubMed1987

Testicular development, daily sperm production and epididymal sperm reserves in 15-mo-old Angus and Hereford bulls: effects of bull strain plus dietary energy.

Bull calves (n = 143) were obtained from two strains of Angus and two strains of Hereford cattle for which replacements were selected on the basis of superior feedlot growth performance on either high- or medium-energy diets. From weaning to slaughter at 15 mo of age, bulls were fed either the high-energy (80% grain + 20% forage) or medium-energy diet (100% forage) corresponding to their strain. Bulls in high-energy diet groups had a greater (P less than .05) scrotal circumference at 12 mo, but not 15 mo of age, than bulls in medium-energy diet groups. Compared with Hereford bulls, Angus had greater (P less than .01) scrotal circumference (36.1 vs 33.9 cm) and greater (P less than .05) paired testes weight (570 vs 464 g) at 15 mo of age. Daily sperm production per gram testicular parenchyma (DSP/g) was affected by strain-diet (P less than .01) but not by breed. Bulls in medium-energy diet groups had 12% greater DSP/g than did high-energy diet bulls (17.4 X 10(6) vs 15.5 X 10(6)). Daily sperm production (DSP) was 9% and 30% greater (P less than .01) for medium-energy diet bulls in 1980 (8.2 X 10(9) vs 7.5 X 10(9)) and 1981 (8.0 X 10(9) vs 6.2 X 10(9)), respectively, compared with high-energy diet bulls. The effect (P less than .01) of breed on DSP was attributed to breed differences in paired testes weight.(ABSTRACT TRUNCATED AT 250 WORDS)

Animal Nutritional Physiological Phenomena↗