Incidence Of Sperm Abnormalities Research Articles

Cryopreservation-Induced Morphological Changes in Freshwater Fish Sperm: A Systematic Review.

A systematic review was performed to summarize the scientific evidence and critically evaluate the effects of cryopreservation on sperm morphology in freshwater fish, and to assess the methodologies for sperm morphology classification. The search strategy was applied to four electronic databases (CAB Direct, Pub Med, Scopus, and ISI Web of Science). The main inclusion criteria involved studies on semen from freshwater fish subjected to the cryopreservation process and evaluation of sperm quality through morphology. The risk of bias was assessed with respect to randomization, allocation concealment, blinding, incomplete outcome data, and selective reporting. A total of 6 publications reporting sperm cryopreservation from 4 species with a total 74 fish individuals were included in this review. A high methodological variability among the results of the studies was observed due to the species-specific protocols and diversity of freshwater fish species studied. All included studies reported negative effects of cryopreservation on sperm quality, especially morphology, highlighting the increase in incidence of sperm abnormalities. However, only five studies statistically compared abnormalities between groups (fresh and cryopreserved sperm). Our results suggest the need to elaborate on a new morphological classification of fish spermatozoa, by considering the structure and physiology of fish sperm. This classification should be developed based on the sperm characterization and observing damage caused by different cryopreservation protocols.

Incidence of sperm Abnormalities in Ejaculates of Breeder cocks fed Rations Containing Different Levels of Cottonseed Meal

A seven week study was conducted to determine the effect of three dietary levels of cottonseed meal (0%, 15%,30%) on the occurrence of spermatozoa morphological abnormalities in mature Rhode Island White (RIW) breeder cocks. Abnormalities of the acrosome, sperm head, cytoplasmic droplets and mid piece and sperm tail were investigated in 180 ejaculates collected between October and November. All types of abnormalities were variable between treatments and between extent of feeding (weeks). The values (2.90,5.30 and 8.63) on sperm head abnormalities were significantly different (P<0.01) between treatments and increased linearly with higher levels of cottonseed meal (CSM) in the diets. Abnormalities of the sperm tail were significantly variable (P<0.05) within treatment weeks with a linear increase from baseline value (2.00) lo about the 3r week post feeding (5.00). The mean total sperm morphological abnormalities in the treatment groups significantly increased linearly (P<0.01) as duration of feeding increased. It is suggested that breeder cocks should not be fed rations containing more than 15%CSM

PROTECTIVE EFFECT OF L-CARNITINE AGAINST CISPLATIN-INDUCED TESTICULAR TOXICITY IN RATS

Testicular damage is one of the most deleterious effects whenever cisplatin (CIS) is employed in cancer chemotherapy. Oxidative stress has been proven to be involved in CIS induced toxicity. Thus, the current study explored the possible protective effect of L-carnitine (L-CAR) against cisplatin-induced testicular damage in rats. L-carnitine (500 mg/kg/day; i.p.) was injected for 15 days, whereas cisplatin (10 mg/kg; i.p.) was injected as a single dose at the 12th day to induce testicular damage in adult male Sprague-Dawley rats. In the current study, CIS reduced the reproductive organs weight, sperm count, sperm motility and serum testosterone level beside a marked increase in the incidence of sperm abnormalities. In addition, it significantly increased malondialdehyde (MDA) and nitric oxide (NO) along with a marked decrease in testis reduced glutathione (GSH) content and superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GPx) activities. At the same time, CIS administration resulted in marked elevation in tumor necrosis factor-α (TNF-α) production and nuclear factor-kabba B (NF-κB) expression. These results were confirmed by histopathological examination. Treatment with L-CAR markedly attenuated cisplatin-induced injury by suppression of oxidative/nitrosative stress and inflammation, amendment of antioxidant defenses, as well as improvement of steroidogenesis, spermatogenesis and testicular histological features. This study suggests a novel therapeutic application for L-carnitine as a protective agent against cisplatin-induced testicular toxicity through its promising anti-inflammatory and antioxidant capacities.

Role of testosterone and photoperiod on seasonal changes in horn growth and sperm variables in the Iberian ibex: a model for polygynous wild bovids

This work examines the effect of testosterone secretion and photoperiod on seasonal changes in horn growth and sperm variables in the Iberian ibex (Capra pyrenaica), here used as a model for polygynous wild bovids. The hypothesis that high levels of testosterone provide an endocrine signal that inhibits horn growth in autumn was tested by assessing the effect of cyproterone acetate (CA), an anti-androgen, administered in October - coinciding with the period of natural increases in plasma testosterone concentrations - under different photoperiodic conditions (natural photoperiod and artificial long days). The persistence of horn growth during autumn in all ibexes held under the long-day photoperiodic conditions clearly shows that horn growth regulation in the mating season is primarily modulated by day length and not by a fall in testosterone concentration. A retrospectively designed second experiment involving testosterone propionate (TP) administration in April (when horns are growing) was then undertaken to confirm that high levels of testosterone do not inhibit horn growth. Overall, the results strongly suggest that the rise in testosterone secretion during the autumn mating season does not act as an endocrine signal for the arrest of horn growth, although the rate of horn growth before the mating season may be related to springtime testosterone levels. A direct relationship was seen between the rate of horn growth and the incidence of sperm abnormalities. Neither CA treatment in October nor TP administration in April affected the studied sperm variables. By contrast, CA treatment plus artificial long days in autumn had a negative effect on sperm motility and sperm morphology.

Effects of high and low dose of cadmium chloride on male Reproductive system in mice

Background: Cadmium is highly toxic and carcinogenic environmental contaminant exposure to cadmium has been reported to reduce male fertility and there are several hypotheses that suggest how reduced male fertility may result from incorporation of cadmium. The purpose of this study was to determined the role of testicular ascorbic acid level in cadmium mediated oxidative damage on mice testis.Objectives:To know the extent of toxicity of cadmium chloride and its adverse effects on male reproductive system in mice .Methods:Fifteen adult albino male mice were divided into three groups, group one control and two experimental groups (low dose and high dose ).the experimental groups were injected with single dose of (0.14mg/BW) cadmium chloride in low dose and with (0.28mg/BW) cadmium chloride in high dose group ,intraperitoneally (ip) . The control group has given normal saline (0.9%) only .Animals were sacrificed after 15 days.The epididiymal sperm count, sperm abnormalities, tissue level of lipid peroxidation and testicular ascorbic acid level were estimated.Results:Exposure of mice to different doses of cadmium showed a decrease in the testicular weight (0.219±0.03), sperm count (124.6±0.2), ascorbic acid level (0.023±0.04), and increase in the testicular level of lipid peroxidation (0.49±0.1) and in the incidence of abnormal sperms. Exposure to high dose of cadmium showed a significant decrease in testicular weight (0.140±0.03), sperm count, (83.8±0.5) and increase in lipid peroxidation (0.79±2.1) compared to low dose group. Ascorbic acid level decreased significantly in high dose group compared to low dose group.Conclusion: Therefore the present study suggests that cadmium has deleterious effect on spermatogenesis and one of the possible mechanism in cadmium induced oxidative damage on mice testis cell might be mediated through its effect on reducing ascorbic acid level.

Acute Testis Toxicity of Bisphenol A Diglycidyl Ether in Sprague-Dawley Rats

Bisphenol A diglycidyl ether (BADGE) is a liquid compound obtained by condensation of two molecules of epichlorohydrin with one molecule of bisphenol A. General and reproductive toxicity with BADGE has been reported higher than 1000 mg/kg/day. This study was performed to show the effects of acute exposure to BADGE below 1000 mg/kg/day on the testis in adult male rats. BADGE was administered by gastric lavage in a single dose of 500, 750, 1000, and 2000 mg/kg/day in 8-week old male SPF Sprague-Dawley rats. The right testis was processed for light microscopic analysis. The left testis was homogenized and spermatids were counted to determine the daily sperm production and daily abnormal sperm production. The sperm count, sperm motility, and incidence of abnormal sperm were estimated in the epididymis. In testicular sections, the seminiferous tubules were observed for qualitative changes. The progression of spermatogenesis was arbitrarily classified as full-matured, maturing, and immature. The specimen slide was observed at 3 points and 10 seminiferous tubules were evaluated at each point. The male rats exposed to single oral dose of BADGE at 750, 1000, and 2000 mg/kg/day were significantly increased the number of immature and maturing sperm on the testis. There were no significant differences with respect to sperm head count, sperm motility, and sperm abnormality in the BADGE treatment groups. These results suggest that single oral exposure of BADGE 750 mg/kg/day can affect adult male testis development.

Dose-Response Effects of Epichlorohydrin on Male Reproductive Function in Rats.

Present study was conducted to investigate potential effects of epichlorohydrin on testicular and epididymal function in male rats. The test chemical was administered to adult male rats by gavage at dose levels of 0, 3.125, 12.5, and 50 mg/kg/day for 7 days. Testicular and epididymal function were assessed by measurement of reproductive organ weight, testicular spermatid count, epididymal sperm count, motility and morphology, and histopathology in rats. At 50 mg/kg, a decrease in the sperm motility and an increase in the incidence of sperm abnormalities were observed. Histopatho-logical examinations revealed an increase in the incidence of histopathological changes including cell debris in the ducts, vacuolization of the epithelial cells, oligospermia, and epithelial disruption in the proximal caput epididymidis. At 12.5 mg/kg, an increase in the incidence of histopathological changes of the epididymidis was found. There were no treatment-related effects at 3.125 mg/kg. These results show that 7-day repeated oral administration of epichlorohydrin to male rats results in adverse effects on sperm motility, sperm morphology, and epididymal histology at ≥ 12.5 mg/kg/day.

An aminoglycoside antibiotic gentamycin induces oxidative stress, reduces antioxidant reserve and impairs spermatogenesis in rats

Gentamycin (GS) is an aminoglycoside antibiotic used to treat infections of various Gram-negative organisms. The present study was designed to investigate the effects of GS on oxidative stress, antioxidant levels, testicular structure and sperm parameters in the rat. Adult Wistar rats (12 week old; N=7/group) were treated (i. p.) with 0 mg/kg, 3 mg/kg and 5 mg/kg for 10 days at an interval of 24 hr between subsequent treatments. Animals were sacrificed on days 1 and 35 after the last treatment, and the reproductive organs were removed and weights of testis and seminal vesicle were recorded. The right testis was processed for light microscopic analysis. The left testis was homogenized and step 19 spermatids were counted to determine the daily sperm production (DSP) and daily abnormal sperm production (DASP). The sperm count, sperm motility and incidence of abnormal sperms were estimated in the epididymis. In testicular sections, along with the evaluation of qualitative changes, the seminiferous tubule diameter (STD) and the epithelial height (SE) were measured. The incidence of stage XIV tubules in testicular sections, meiotic figures and step 14 spermatids/stage XIV tubule, and step 19 spermatids/stage VII tubule were estimated. Intra-testicular levels of superoxide anion, lipid peroxidation and antioxidants-superoxide dismutase (SOD), catalase, glutathione peroxidase (GPx) and ascorbic acid were measured. GS did not affect the body weight, but the testis weight and DSP were decreased at 5 mg/kg dose-level on both days (p<0.05), and the weight of seminal vesicle decreased on day 35 at both dose-levels. The DASP was increased in a dose-dependent manner (p<0.05) on days 1 and 35 at both dose-levels. The sperm count was decreased at both dose-levels on day 35, whereas the sperm motility was decreased and sperm abnormality was increased on day 1 at 5 mg/kg and on day 35 at both dose-levels. GS induced structural changes such as sloughing of seminiferous epithelium, vacuoles and gaps in the epithelium, nuclear pyknosis and atrophic changes in a few tubules. The tubular shrinkage was observed as indicated by decreased STD and SE on both days at 5 mg/kg dose-level. Incidence of stage XIV tubules and step 19 spermatids/stage VII tubule decreased on all time points at all dose-levels, whereas the step 14 spermatids and meiotic figures decreased on day 35 at both dose-levels (p<0.05). The free radical- superoxide anion concentration was significantly increased on day 1 in a dose-dependent pattern (p<0.05). However, activities of all 3 enzymatic antioxidants and ascorbic acid level decreased in a dose-dependent pattern on day 1 (p<0.05), except the GPx, which was also decreased on day 35 at 5 mg/kg dose-level. There was a significant rise in the thiobarbituric acid reactive substances on day 1 indicating increased lipid peroxidation in the testis. In conclusion, GS induces an oxidative stress-status in the testis by increasing free radical formation and lipid peroxidation, and by decreasing the antioxidant reserves. These biochemical changes manifest as structural and cytotoxic changes in the testis. Further, GS also affects the spermatozoa by affecting their number, motility and morphology.

Morphological Features of Spermatozoa of Swamp Buffalo AI Bulls in Thailand

The appearance and incidence of sperm abnormalities was studied in 115 ejaculates, collected periodically over 1 year covering all seasons from five mature, healthy swamp buffalo (Bubalus bubalis) bulls reared under tropical conditions and serving as the current source of semen for artificial insemination (AI) in Thailand. Light microscopy of stained smears was used to investigate sperm head shape morphology, while unstained wet smears were used to examine other sperm abnormalities. The most commonly found morphological aberrations were pear-shaped spermatozoa, knobbed acrosomes, proximal cytoplasmic droplets, simple bent tails and coiled tails under the head, whose ultrastructure (scanning electron microscopy) corresponded to what has been found in other species of bovidae, including varieties of buffalo. The mean prevalence (as least squares mean +/- SEM) of sperm abnormalities was low (below 15%), corresponding to healthy spermiograms. The younger bulls (<10 years old, n = 3) had less abnormalities than the older ones (10.1 +/- 0.6% versus 14.1 +/- 0.8%, P < 0.001, n = 2), including abnormalities of sperm head shape (1.1 +/- 0.3% versus 3.6 +/- 0.3, P < 0.001), acrosome defects with knobbed acrosomes (1.1 +/- 0.2% versus 1.2 +/- 0.3%, P < 0.001), spermatozoa with proximal cytoplasmic droplets (2.7 +/- 0.1% versus 1.4 +/- 0.2%, P < 0.001), defective mid-pieces (0.2 +/- 0.1% versus 0.3 +/- 0.1%) and abnormal sperm tails (3.1 +/- 0.3% versus 5.7 +/- 0.4%, P < 0.001). The within-bull effect of the year solely affected the incidence of pear-shaped spermatozoa while the incidences of abnormal contour, variable size of sperm head shapes, abnormal mid-piece and simple bent tail among bulls were affected by ejaculate (week of collection). Interaction between age and ejaculate affected only the prevalence of spermatozoa with proximal cytoplasmic droplets. In conclusion, the types of defects encountered were similar to those found in other bovidae, with a very low prevalence over the year the AI sires were followed through.

An in vivo Evaluation of Induction of Abnormal Sperm Morphology by Ivermectin MSD (Mectizan®)

The in vivo effects of orally administered ivermectin (Mectizan) on sperm head morphology of albino mice were evaluated. Four different dose levels of 0.25, 0.5, 1.0 and 1.5 x the human therapeutic dose of 150 g kg(-1) body weight, were administered to the animals. The animals were exposed to a single oral treatment. The sperm of the mice from the cauda epididymes were examined 5 and 7 weeks after treatment. Ivermectin (Mectizan) induced sperm head abnormalities; however, the induction was not significantly elevated above the negative control value. Furthermore, the induction of the sperm head abnormalities was not strictly dose-dependent and there was also no correlation between dose level of administered drug and incidence of abnormal sperms. This indicates that the drug might not be mutagenic.

Studies of male reproduction in captive African wild dogs ( Lycaon pictus)

Implementation of assisted breeding in the captive African wild dog is restricted by a current lack of knowledge on their reproductive physiology and the apparent difficulty of effectively manipulating the complex social dynamic of the pack in order to conduct reproductive procedures. In this study, we describe protocols for the safe and repeated capture and restraint of the African wild dog ( n = 7) as well as techniques for assessment of male reproductive function, semen collection and preservation. In a serendipitous finding, captive African wild dogs appeared to display significant seasonal change in male reproduction. Testicular volume and tone, spermatorrhea and the ability to collect semen by electroejaculation all increased significantly during late summer and then subsequently declined by early spring. While there were no detectable seasonal changes in testosterone concentration in the population as whole, the alpha-dominant male in both years of the study, had a highly elevated testosterone concentration compared to subordinate males. Semen collection by electroejaculation during the late summer was most effective in peri-pubertal males (15 months) when all seven electroejaculates were of adequate quality for cryopreservation. In the second breeding season (27 months), there were numerous changes in the pack hierarchy and electroejaculation was not as successful (3/7). The characteristics of electroejaculated semen collected in the breeding season are described for seven animals including the first descriptions and incidence of sperm abnormalities in the species. Semen ( n = 7) was frozen using a Tris–citrate fructose buffer and final egg yolk and glycerol concentration of 20% and 4%, respectively. Sperm were loaded into 0.25 mL straws, frozen in liquid nitrogen vapor and then thawed at 37 °C. Initial post-thaw survival of spermatozoa was encouraging (% motile: 31.8 ± 5.8%; rate: 2.8 ± 0.3; % intact plasma membranes: 33.4 ± 5.3% and the % of damaged acrosomes: 4.4 ± 1.5%) but following 2 h incubation at 37 °C, post-thaw survival declined markedly.

Genotoxic consequences associated with oxidative damage in testis of mice subjected to iron intoxication

While iron-induced testicular dysfunction has been demonstrated adequately, the mechanism(s) involved and the genotoxic implications are not fully understood. In order to understand the genotoxic effects of iron intoxication, initially induction of oxidative stress response in testis of adult albino mice (CFT-Swiss) was ascertained following administration (i.p.) of acute sub-lethal doses of iron dextran (ID). Subsequently, multiple sub-lethal doses (50, 100 and 200 mg/kg bw/day) were employed to characterize effects on lipid peroxidation (LPO) in testis (homogenates, microsomal/mitochondrial fractions), DNA damage and incidence of abnormal sperms. While acute doses of ID induced only a marginal increase in LPO response in testis at 24 h of administration, multiple doses elicited a moderate (30-40%) increase in LPO in whole homogenates and significant dose-related elevation in both mitochondrial (20-45%) and microsomal fractions (25-65%). This was associated with significant increase in DNA damage in the testis as evidenced by increased single strand breaks in a fluorimetric analysis of DNA unwinding (FADU) assay. Further, evidences of oxidative damage in testis was evident in terms of increased protein carbonyls and altered antioxidant enzymic activities. The genotoxic implications were investigated by quantification of the frequency of abnormal sperms sampled at specific periods during spermatogenetic cycle. Nearly three- to seven-fold increase in percent abnormal sperms among the ID treated males were evident during the first 3 weeks although the counts were unaffected. Interestingly, in a classical dominant lethal (DL) assay, mating of ID treated (100 mg/kg bw/day for 5 days) males sequentially for a period of 5 weeks with untreated females resulted in a significant increase in male-mediated dominant lethal type mutations (the frequency of dead implants) during the first 3 weeks only indicating a stage-specific effect on post-meiotic germ cells. These findings provide an account of the early oxidative damage in testis in vivo following exposure to low levels of iron which may be wholly or in part responsible for the genotoxic consequences observed in this model of iron overload.

The effects of dietary vitamin B12 deficiency on sperm maturation in developing and growing male rats.

To evaluate the role of vitamin B12 on spermatogenesis, the effects of dietary vitamin B12 deficiency on sperm maturation in developing rat fetuses and young growing rats were examined. The vitamin B12-deficient diet was given to all the animals for three different periods: whole period (gestation to mature), gestation period (gestation to weaning), or immature period (3-12 weeks postnatal). Sperm examination revealed that the sperm count was markedly lower in male progeny (F1) that were vitamin B12-deficient during the whole period. In addition, a significantly higher number of abnormal sperm, such as tailless and amorphous sperm, was observed. In male rats that were vitamin B12-deficient during the immature period, the incidence of abnormal sperms was 14.4% and 4.8% for tailless and short tail, respectively. The motion rates, such as path velocity and straight line velocity, were decreased to 20-40% of the control value in rats that were vitamin B12-deficient both during the whole and gestation periods. However, no effects of vitamin B12 deficiency on sperm motility were observed during the immature and mature periods. From these findings, we suggest that dietary vitamin B12 deficiency during pregnancy may induce irreversible damage in the germ cells of embryos and affect the maturation of spermatozoa.

The effects of dietary vitamin B12 deficiency on sperm maturation in developing and growing male rats

To evaluate the role of vitamin B12 on spermatogenesis, the effects of dietary vitamin B12 deficiency on sperm maturation in developing rat fetuses and young growing rats were examined. The vitamin B12-deficient diet was given to all the animals for three different periods: whole period (gestation to mature), gestation period (gestation to weaning), or immature period (3-12 weeks postnatal). Sperm examination revealed that the sperm count was markedly lower in male progeny (F1) that were vitamin B12-deficient during the whole period. In addition, a significantly higher number of abnormal sperm, such as tailless and amorphous sperm, was observed. In male rats that were vitamin B12-deficient during the immature period, the incidence of abnormal sperms was 14.4% and 4.8% for tailless and short tail, respectively. The motion rates, such as path velocity and straight line velocity, were decreased to 20-40% of the control value in rats that were vitamin B12-deficient both during the whole and gestation periods. However, no effects of vitamin B12 deficiency on sperm motility were observed during the immature and mature periods. From these findings, we suggest that dietary vitamin B12 deficiency during pregnancy may induce irreversible damage in the germ cells of embryos and affect the maturation of spermatozoa.

An in vivo evaluation of induction of abnormal sperm morphology by some anthelmintic drugs in mice

Using the murine sperm-head abnormality test, the mutagenicity of pyrantel pamoate, levamisole, albendazole, mebendazole and niridazole was evaluated. Pyrantel pamoate and niridazole induced increases in sperm-head abnormalities statistically significant over the negative controls at all the dose levels that were considered; the induction was dose-dependent indicating that both drugs might be mutagenic. Levamisole, albendazole, mebendazole and thiabendazole, all were unable to induce statistically significant increases in sperm-head abnormalities over the negative controls at all the dose levels tested; there was no correlation between dose level of administered drugs and incidence of abnormal sperms, indicating that the drugs might not be mutagenic.

Influence of season, age, breed and some other factors on the variation in sperm morphological abnormalities in Swedish dairy A.I. bulls

Abstract Fifty-two dairy A.I. bulls aged from 14 months to 6 and a 1 2 years old were used to study the effects of age, breed, season and, dehorning and dihydrostreptomycin treatments on the incidence of sperm morphological abnormalities in fresh semen. The highest mean value of sperm abnormalities was recorded for abnormal heads (6.1%), but most of the recorded abnormalities only occurred in approximately 1–2% of the studied spermatozoa. Significant seasonal variation occurred in the incidences of sperm head abnormalities and total sperm abnormalities. Least-squares means for sperm abnormalities were significantly higher during the warmer seasons (spring, summer) compared with the colder ones (autumn, winter). The incidence of sperm abnormalities (abnormal heads, proximal droplets, total abnormalities) was relatively constant over time within bull (repeatability estimates varied between 0.36 and 0.54), but was significantly affected by age (abnormal heads and acrosomes, total abnormalities) and breed (abnormal heads, detached heads). The incidence of total sperm abnormalities was also found to be significantly increased in semen from a group of bulls submitted to both dehorning and double injections of dihydrostreptomycin (DHS) when comparing pre- and posttreatment periods. The results indicate that age, breed and seasonal effects as well as repeated stressful treatments influence the sperm characteristics and must be considered when evaluating bulls for sperm morphological traits.

Genotoxic effects of a synthetic pyrethroid insecticide, cypermethrin, in mice in vivo

The genotoxicity of cypermetrhin, a synthetic pyrethroid insecticide, has been studied in vivo in mice. Bone marrow chromosome aberrations were not dose, time or route dependent, but most of the results differed significantly from controls except after 6 and 24 h of treatment using the i.p. and s.c. routes, respectively. In the micronucleus test, the occurrence of polychromatic erythrocytes with micronuclei increased slightly with dose, but was significantly higher than controls at all dose levels. Only a marginal difference in the incidence of sperm abnormalities was noted with the three doses of cypermethrin tested. However, all results differed significantly from the respective control values. Chromosome aberration; Micronucleus; Sperm abnormality; Cypermethrin

Reproductive and genetic consequences of founding isolated lion populations

Species survival is critically dependent on reproductive performance, a complex physiological process under rigorous genetic control. Classical studies of inbreeding in laboratory animals and livestock have shown that increased homozygosity can adversely affect spermatogenesis, ovulation and perinatal mortality and morbidity1–3. For wild populations, the consequences of inbreeding depression have not been examined intensively, although our recent studies of the African cheetah revealed a striking degree of genetic uniformity4,5 combined with an extremely high incidence of structurally abnormal spermatozoa (>70%) in captive6 as well as free-ranging7 males. In this study, we report definitive evidence that the reproductive function of free-ranging mammals can be impaired as a result of demographic contraction followed by inbreeding. In an examination of three distinct lion populations (two from the Serengeti ecosystem in East Africa and a third descended from lions in the Gir Forest of western India), a direct correlation was observed between genetic variability and two physiological traits, incidence of abnormal sperm and circulating testosterone, a critical hormone for spermatogenesis.

Evaluation of a testicular sperm head counting technique using rats exposed to dimethoxyethyl phthalate (DMEP), glycerol alpha-monochlorohydrin (GMCH), epichlorohydrin (ECH), formaldehyde (FA), or methyl methanesulphonate (MMS).

Single dosages of DMEP (1,000-2,000 mg/kg), GMCH (50 mg/kg), ECH (25 and 50 mg/kg), FA (100 and 200 mg/kg), and MMS (100-400 mg/kg) were administered orally to 10 week old male Wistar rats. The rats were necropsied on the 11th day following dosing. The testes were weighed, homogenised and sonicated; numbers of sperm heads (total and abnormal) were counted and percentage sperm head abnormalities were calculated. Testes weights were significantly reduced only in rats exposed to 1,500 and 2,000 mg DMEP/kg. Compared with controls, there were significant increases in the incidence of abnormal sperm at all dose levels of MMS and the higher dose levels of DMEP (1,500 and 2,000 mg/kg), ECH and FA. No toxicologically significant effects upon total sperm counts were seen following the oral administration of any of the five chemicals tested. However, an additional group of rats given 100 mg MMS/kg intraperitoneally (i.p.) showed significant reductions in testes weight and total sperm head counts compared with control animals. It is concluded that this testicular sperm head counting technique is a useful tool in the detection of selective adverse effects of chemicals upon testicular sperm but requires further evaluation.

Effect of chloride ions on cock spermatozoa.

The respiration rate, rate of fructolysis and incidence of abnormal spermatozoa were studied in cock semen immediately after dilution (1:10) and after storage at 5°C. Tyrode's solution was the basic diluent, and the effect of replacement of chloride by either glutamate or phosphate was investigated. Replacement by glutamate resulted in a linear reduction of respiration and fructolysis rates of fresh semen and of the fructolysis rate of stored semen. Respiration rate of stored semen decreased nonlinearly. Replacement of chloride by phosphate had no significant effect on the metabolic rates of either fresh or stored semen. Chloride ions caused an increase in the incidence of abnormal sperm after storage. When glutamate replaced chloride this increase was reduced, whereas in phosphate replacement there was evidence of a synergistic effect between chloride and phosphate in causing abnormalities. Differences in metabolic rates could not be accounted for by changes in the incidence of dead or abnormal sperm.