Histology Of Reproductive Organs Research Articles

GC–MS analysis of Moringa oleifera leaf extract and effects of administration on histology of reproductive organs and liver of female rats exposed to chronic unpredictable stress

Exposure to several stressors and other lifestyle factors converge to affect the chemistry, structure, and function of body tissues over time. Chronic unpredictable stress (CUS) protocol has been widely used to study the impact of stress exposure in several animal models. Moringa oleifera leaf extract (MOLE) is known to have hepatoprotective and antioxidant properties. The study aimed to determine the effect of the administration of MOLE during conditions of chronic stress on the histology of reproductive organs, heart and liver. Twenty mature inbred healthy virgin female Wistar rats were randomly placed into four groups of five rats per group as follows: Group One (water and normal rat chow ad libitum), Group Two (CUS protocol only), Group Three (CUS protocol + 200 mg/kg MOLE), Group Four (CUS protocol + 300 mg/kg of MOLE). CUS protocol was applied unpredictably for two weeks. The chromatogram of the GC–MS analysis indicated the presence of 41 compounds. Photomicrograph examination of the uterus, ovaries, and liver showed severe alterations in the histology of the tissues. Consumption of MOLE during chronic stress has shown deleterious effects and is not advised for consumption during stress conditions.

Effects of moringa stenopetala (Baker f.) Cufod leaf on reproductive organs and serum biochemical levels in male rats: An in vivo reproductive toxicity study

BackgroundMoringa stenopetala (Baker f.) Cufod. (Moringaceae) leaves are a common food source and traditional medicine used to treat a variety of illnesses, including malaria, hypertension, stomach discomfort, diabetes, elevated cholesterol, and the removal of the retained placenta. Its reproductive toxicity studies are limited. Therefore, the objective of the current study was to examine the toxicity of a 70% ethanol extract of Moringa stenopetala leaf on the reproductive organs and serum biochemical levels in male Wistar rats. MethodFresh leaves of Moringa stenopetala were extracted using 70% ethanol. For this study, five groups of animals, each containing twenty rats, were used. Groups I - III were treated with 250, 500, and 1000 mg/kg body weight of Moringa stenopetala leaf extract, respectively. Groups IV and V were pair-fed and ad libitum control groups. The extract was given for ten weeks. Data about body weights, weights and histology of reproductive organs, testosterone, LH, and FSH, levels, and serum chemistry were analyzed using one-way ANOVA, Tukey's test, and Dunnett's test. ResultsCompared to the pair-fed control group, the sex hormones like testosterone, FSH, and LH levels increased in the 1000 mg/kg body weight treated rats. Significant differences were not seen in the weight and histology of the testis, epididymis, prostate gland, or seminal glands. However, the serum ALT, AST, ALP, HDL, and creatinine levels were significantly raised in the high-dose-treated group. ConclusionMoringa stenopetala may increase reproductive hormones in male rats. Consuming Moringa stenopetala leaves could therefore help to increase male reproduction.

Moderate doses of Mucuna pruriens seed powder is safe and improves sperm count and motility

BackgroundConventional remediation techniques involving male fertility include hormonal therapy, in vitro fertilization and surgery. However, the use of natural products continues to be a popular option. Emerging new products that have not been well investigated is the use of Mucuna pruriens seed powder. AimThis study aimed at determining the efficacy and safety of Mucuna pruriens (MP) seed powder on the male fertility using normal animal models. MethodologyFour groups of seven (7) male Sprague-Dawley rats were used. Groups comprised Control (distilled water), Low dose (500 mg/kg b.wt MP), Medium dose (1000 mg/kg b.wt MP) and high dose (2000 mg/kg b.wt MP). Test groups were administered aqueous crude extract of MP by gavage over 90 days. Upon sacrifice, the following assays were performed: FSH, testosterone, oestrogen, PSA, semen analyses, histology of reproductive organs, and general haematological and biochemical analyses. ResultsFSH increased, whilst oestrogen decreased, across groups: however, it was not statistically significant between groups. Although testosterone increases were not statistically significant, increases were dose-dependant. Sperm count increased significantly between the Control and Medium dose groups (p<0.001). Motility significantly increased with the Medium and High dose groups compared to Control group (p = 0.022, p = 0.029, respectively). Additionally, immotility significantly decreased in all treatment groups compared to control group (p = 0.013). No abnormality was observed in biochemical, haematological and histological analyses. ConclusionThis study demonstrates a margin of safety and improved spermogram pattern between the low and medium dose administration of Mucuna pruriens seed powder.

Effect of methylphenidate on the onset of puberty and reproductive organ development in rats

Methylphenidate (MPH) is the first-line therapy for attention deficit hyperactivity disorder (ADHD) in children and adolescents. The aim of this study was to investigate the effects chronic MPH administration on reproductive parameters in both male and female pre-pubertal rats and reversibility of these effects. Sprague-Dawley rats were administered with 5 mg/kg MPH or saline orally from postnatal day (PND) 21 to PND60 and from PND21 to PND90. In addition, recovery groups from both sexes, in which MPH administration was stopped from PND60 to PND90 were included. Puberty onset, serum luteinizing hormone (LH), follicle stimulating hormone (FSH), testosterone and estradiol levels were determined. Histopathology of male and female reproductive organs was examined. Puberty onset was significantly early in the males (p<0.01), but late in females (p<0.05). In males, serum LH and FSH levels were similar. Testosterone levels tended to decrease in MPH-treated animals. Morphology of testes, epididymis and vas deferens was disrupted in MPH-treated animals, while it was improved in the recovery group. In females, estradiol levels decreased in MPH-treated group compared to controls, and elevated LH levels were detected in recovery group. Similar to the males, disruption in the reproductive organ histology was seen with morphological deterioration in basement membrane of the ovaries of MPH-treated groups. These adverse effects of MPH were recovered after drug cessation for 30 days. The present results demonstrate that MPH could affect the reproductive functions in both male and female rats. However, our findings also suggest that those effects are transient.

Assessment of non-target toxicity effects of synthetic estradiol, quinestrol, in chickens.

Fertility control agents for the management of rodent populations are developing and maturing. Investigating the impacts on non-target species of consumption of these agents is essential. The present study assessed the non-target toxicity effects of quinestrol, a synthetic estrogen-based antifertility agent for managing rodent populations. Various quinestrol doses administered to male and female (n= 60 each) chickens through single oral gavage were 0 (A), 10 (B), 50 (C), and 150 (D) mg/kg body weight. Chickens were assessed for effect on body weight, weight of vital and reproductive organs, reproductive hormones, histology of reproductive organs and egg laying rates after 15, 30, and 135 days of treatment. Quinestrol did not induce mortality in chickens and its effects were time and dose dependent. The 90% egg-laying rates were delayed by 30, 60 for groups B and C compared with the control group, and group D did not reach the 90% egg-laying rate by 135 days. Reproductive organs in males and females returned to normal levels within 30 and 135 days, respectively. With the exception of the FSH concentration in group D, reproductive hormones of both sexes were similar to controls by 30 days. No other significant effects were found. The present research demonstrated the safety of quinestrol on non-target species and facilitates recommendations for the general administration of quinestrol for rodent pest management.

Anti-fertility and antisteroidogenic activity of Clerodendrum serratum in mature male rats

Background and Aims: The study was designed to evaluate the anti-fertility effect of methanolic extract of Clerodendrum serratum (MECS) on mature male rats. Methods: The vehicles and MECS were administered orally to four groups of forty male albino rats on consecutive days for 30 days. At the end of the experimental period, five animals from both the control and experimental groups were given anesthesia and the animal reproductive organs were collected and anti-fertility effect evaluated by studying the following parameters (i) Body and reproductive organ weight (ii) Biochemical estimation (iii) Reproductive hormone analysis (iv) Abnormalities in reproductive organ histology. Another five rats in each group were subjected to fertility testing. Results: This study shows that female rats which mated with MECS treated male rats delivered fewer pups than those which mated with the control rats. An antisteroidogenic effect was revealed through the increased concentration of testicular cholesterol and ascorbic acid in MECS treated rats. However, testicular Δ5 -3β-hydroxysteroid dehydrogenase (Δ5 -3β-HSD), glucose-6-phosphate dehydrogenase (G-6-PD); serum reproductive hormones testosterone, FSH and LH were significantly reduced. Conclusion: The present investigation discovered the antisteroidogenic effect of MECS, which confirms the male antifertility effect of this plant. This encourages the traditional use of this plant in the Indian subcontinent as a male contraceptive.

Re-evaluation of reproductive cycle and fecundity of finetooth sharks Carcharhinus isodon (Valenciennes 1839) from the Northwest Atlantic Ocean, with new observations on ovarian cycle and reproductive endocrinology of biennially reproducing sharks.

To provide updated information on life history for improved fishery management, the reproductive cycle of the finetooth shark Carcharhinus isodon from Northwest Atlantic (NWA) populations was investigated by examining temporal changes in morphology and histology of reproductive organs. Changes in plasma concentrations of gonadal sex hormones in relation to reproductive stage were also examined. Increases in testis width, epididymis head width, plasma testosterone concentrations and occurrence of mature spermatozoa were observed in male sharks between December and April, suggesting a seasonal pattern in reproduction that culminates with copulatory activity in May. Increases in maximum follicular diameter, oviducal gland width, plasma 17β-estradiol concentrations and occurrence of vitellogenic follicles were observed in non-pregnant female sharks during the same time period along with the occurrence of newly pregnant females in May, demonstrating strong synchronicity between male and female reproductive cycles. Pregnant females bearing full-term embryos were also observed in May, indicating that parturition occurs between mid-May and early June and gestation requires 12 months. Only transient temporal changes in follicle size and oviducal gland width were observed in pregnant females, indicating that reproductive periodicity is biennial; nonetheless, a single female exhibiting signs of concurrent vitellogenesis and pregnancy was observed. Mean brood size ± S.D. was 3.9 ± 0.9 offspring/female. Fecundity was not significantly correlated with female size, in part due to an unexpectedly high rate of early embryo mortality, which occurred in 11% of pregnant females, and was more common in larger individuals. Changes in ovarian activity during mid-pregnancy were observed, suggesting possible roles for the ovary in regulating some aspects of early to mid-gestation. This study confirms that earlier characterizations of the reproductive cycle and fecundity in NWA finetooth sharks remain valid for use in fishery management. This study also highlights unusual features of finetooth shark pregnancy (e.g., early embryo death, mid-pregnancy changes in ovarian function) that may have broader relevance to understanding elasmobranch reproduction.

Reproductive cycle and fecundity of the bonnethead Sphyrna tiburo L. from the northwest Atlantic Ocean.

The present study examined temporal changes in plasma sex hormone concentrations and the morphology and histology of reproductive organs in mature northwest Atlantic (NWA) bonnetheads Sphyrna tiburo L. to characterize reproductive cycle, breeding periodicity and fertility in this still poorly studied population. Progressive increases in testis width, epididymis head width, plasma testosterone (T) concentrations, and occurrence of mature spermatozoa were observed in male S. tiburo from June to September, demonstrating that spermatogenesis occurs during the summer. Nonetheless, increases in maximum follicle diameter, oviducal gland width, plasma 17β-estradiol and T concentrations, and occurrence of vitellogenic follicles were not observed in mature females until between October and April, demonstrating non-synchronous patterns of gametogenesis in males and females. Fresh copulatory wounds were observed in females collected during late September along with histological evidence for sperm presence in the oviducal gland between September and April, confirming a 6- to 7 month period of female sperm storage. Ovulation occurred between mid-April and early May in concert with increases in female plasma progesterone concentrations. Gestation occurred during a 4.5- to 5 month period between May and early September, and 97% of mature females collected during this period were gravid, indicating a highly synchronized, annual reproductive periodicity. Brood size was significantly correlated with maternal size and ranged from 1 to 13 pups with a mean ± S.D. of 8.1 ± 2.2, which was significantly lower than reported in Gulf of Mexico (GOM) populations. The occurrence of non-fertile offspring was observed in 17% of broods with a range of 1-7 non-fertile eggs present in individual females. Thus, as previously reported in GOM S. tiburo, this unusual form of infertility also appears to be prevalent in the NWA population and requires further study. This study has demonstrated meaningful differences in reproductive biology of these populations, emphasizing the need for region-specific approaches for population management.

Effects of Lepidium sativum Seed on Reproductive Characteristics in Rabbit Bucks

Lepidium sativum (LS) has been documented to possess numerous properties but little is known as regards its mechanism on male reproductive features which the study aimed to clarify by evaluating its effects on luteinizing hormone, testosterone, sperm characteristics, and histology of reproductive organs in rabbit bucks. Twenty mature, intact bucks were randomly assigned into four treatment groups and fed either normal rabbit feed or diets containing LS seeds powder at varying levels for 63 days. Blood samples were collected from each rabbit weekly to determine LH and testosterone levels. Semen was collected three times for evaluation of sperm characteristics; weight and histological examination of reproductive organs were evaluated at the end of the experiment. Inclusion of LS seed in the feed of rabbit bucks significantly increased plasma LH concentrations in a bimodal dose-dependent manner with no significant difference in the levels of testosterone. Percentage motility and live sperm percent were significantly reduced in all rabbits fed LS based diet while the control rabbits showed an increasing pattern in percentage motility and live sperm. Sperm abnormality percent was significantly increased in all rabbits in LS dose-dependent manner. There were no significant effects of LS on the relative weights of all bucks accessory glands but significantly affected the relative weights of paired testis and caudal epididymis. Marked alterations in the testis were also noted. The findings suggest that mechanism underlying the effects of LS seed on reproduction is mediated through multiples pathways which depend greatly on the amount of LS seed ingested.

Oviduct morphology and estrogen receptors ERα and ERβ expression in captive Chinchilla lanigera (Hystricomorpha: Chinchillidae)

Chinchilla lanigera is a hystricomorph rodent from South America whose reproductive biology presents particular characteristics that distinguishes it from other Rodentia species, such as low reproductive rate, seasonal breeding pattern, and long estrous cycle. Nevertheless, reproductive features in female chinchillas are still poorly investigated, with a scarce knowledge concerning the estrous cycle and the histology of reproductive organs. In this study, we investigate the morphology, histomorphometry, secretory activity, and immunolocalization of estrogen receptors ERα and ERβ in oviducts of nulliparous chinchillas, euthanized at fall season in Brazil. Follicular phase of estrous cycle of all studied animals was characterized by ovary and uterine morphology inspection, as well as vaginal cytology. Similar to other mammals, the oviduct wall of infundibulum, ampulla and isthmus was composed of mucosa, muscle, and serosa layers. Morphometric data of oviduct layers were used for identifying each oviduct segment. In the follicular phase, the oviduct was characterized by intense secretory activity, mainly in the ampulla, and expression of ERα and ERβ throughout the oviduct epithelium. Both ERα and ERβ were also detected in the connective tissue and smooth muscle cells. Our findings point out to the important role of estrogen in this female organ. Similar wide distribution of both ER proteins has been described for human Fallopian tube. Taken together, our data add to the understanding of the reproductive biology of female chinchillas, and may assist in the intensive breeding of this species and any eventual endeavor for conservation of chinchillas in the wild.

Oral administration of Tridax procumbens aqueous leaf extract attenuates reproductive function impairments in L-NAME induced hypertensive male rats

Abstract Objective In this study, we investigated effect of Tridax procumbens aqueous leaf extract (TPALE) on reproductive function in N nitro- l -arginine-methyl ester (L-NAME) induced hypertensive rats. Methodology Twenty healthy, adult male rats (150–190 g) were divided into four groups of five. Group 1 (control) received normal saline (0.6 ml/kg of 0.9% NaCl) orally; groups 2, 3 and 4 received L-NAME (40 mg/kg) orally to induce hypertension for a period of three weeks. Treatments were continued for another 3 weeks with groups 3 and 4 being further treated orally with 100 and 200 mg/kg of TPALE respectively. Blood pressure, body and reproductive organs weight, histology of reproductive organs, fertility success, plasma testosterone and luteinizing hormone (LH) and seminal analysis were determined. Results TPALE decreased systolic, diastolic and mean arterial blood pressure in L-NAME + 100/200 mg/kg TPALE treated groups when compared to L-NAME (40 mg/kg) group. Relative prostate and seminal vesicle weight were significantly reduced in L-NAME group. Motility, viability and count were reduced in L-NAME group when compared to control and TPALE treated group. Fertility success was 100% in all groups except for L-NAME group (0%) with no significant differences in average litter size and weight. Testosterone level increased significantly in TPALE treated group. There was mild interstitial congestion of the epididymis in L-NAME treated groups; tubular diameter also appeared reduced with heightened epithelium for TPALE treated groups. No visible lesions were seen in the testis of all treated groups. Conclusion TPALE exhibits pharmacotherapeutic and protective role on hypertension and reproductive functions in L-NAME induced hypertensive male rats.

EFFECT OF PARTIAL REPLACEMENT OF MONOSODIUM GLUTAMATE BY 5΄-INOSINE MONOPHOSPHATE ON THE FERTILITY OF MALE RATS

This work aimed to study the effect of partial replacement of monosodium glutamate (MSG) by 5΄ inosine monophosphate (5΄-IMP) on the fertility of male rats after oral administration for 90 days. Before the biological treatment, a half amount of MSG as flavor enhancer in chicken burger was replaced by 5´IMP. The sensory assessment of cocked chicken burger confirmed that this used mixture (1:1 w/w) had a synergistic effect and led to improve the flavor intensity compared to that with MSG. Treatments were applied by stomach tube (mg/kg BW); (i) MSG, [60 for adult; 30 for weaned rats]; (ii) Mixture (1:1; w/w) of MSG and 5΄-IMP [30:30 for adults; 15:15 for weaned rats] and (iii) 5΄-IMP [30 for adult; 15 for weaned rats]. Body weight gain (BWG%) and weight of some reproductive organs including testes, prostate, cauda epididymes and seminal vesicles were measured. Serum testosterone and interstitial cell-stimulating hormone (ICSH) and seminal fructose content were assayed. Spermatozoa activity and the histology of reproductive organs were also studied in adult and weaned male rat groups. Severe negative effects on most studied parameters were demonstrated in MSG-groups, where the lowest fructose content in prostate, testosterone levels and spermatozoal activities were recorded. Reduction in the weight of cauda epididymes and testes was recorded in MSG-treated weaned rats. Histologically, all studied reproductive organs were dramatically affected by MSG-treatment. Considerable enhancements in the studied parameters and normal histological profiles were obtained due to the partial replacement of MSG by 5΄-IMP. In conclusion, 5΄-IMP has a potential protective effect against MSG-hazards in reproductive organs.

Immunocontraception in Eastern Gray Squirrels (Sciurus carolinensis): Morphologic Changes in Reproductive Organs

Eastern gray squirrels (EGS) (Sciurus carolinensis) damage trees through bark stripping or gnawing due to territorial marking or agonistic gnawing behavior in concert with higher densities. This study was conducted to determine the effects of a contraceptive vaccine on EGS and its reproductive organ histology. Free-ranging urban EGS were vaccinated with the immunocontraceptive GonaCon. All EGS were > or = 6 mo of age as determined by a combination of pelage characteristics and body weights. The vaccine was administered by injection at a dosage rate of 0.4 ml containing 400 microg of GnRH-mollusk protein conjugate i.m. in the thigh to 33 EGS (17 male [m], 16 female [f]) in trapping session 1 (TS1), 23 (14 m, 9 f) in trapping session 2 (TS2), and 11 (8 m, 3 f) in trapping session 3 (TS3). A sham injection containing 0.4 ml saline-AdjuVac was given as control to 22 EGS (16 m, 6 f) in TS1, 20 (12 m, 8 f) in TS2, and 8 (4 m, 4 f) in TS3. In the last trapping session (TS4), 35 EGS (16 treated, 19 control) were killed for necropsy to evaluate histologic changes in testes and ovaries. Treated EGS males had testicular, prostatic, and epididymal atrophy compared with control EGS males. The tubuli seminiferi and prostatic glandular lumen of treated EGS males were atrophic, and the epididymal lumen contained no sperm cells. No histologic changes were observed in treated EGS females; however, females likely were not collected when changes due to GonaCon would have been observed. There were no observable histologic differences in the pituitary gland of treated and control EGS. There were no statistically significant differences in either testosterone or progesterone concentrations between control and treated EGS. Although there were no serious side effects to the vaccine, six EGS developed injection site abscesses. GonaCon may be a potential tool for EGS population control.

Maternal exposure to aqueous extract of Jacaranda decurrens: Effects on reproductive system in male rats

Context: Jacaranda decurrens subsp. symmetrifoliolata Farias & Proença (Bignoniaceae) is a species widely used for their medicinal properties. At least to our known, no study has been conducted concerning its toxicological profile after gestational and lactational exposure.Objective: The present study was carried out to evaluate the effects of J. decurrens on development of the reproductive system in male rats.Materials and methods: Pregnant rats were treated daily (gavage) with 250 or 500 mg/kg/day of aqueous extract of J. decurrens or vehicle, from day 12 of pregnancy to day 21 of lactation.Results and Discussion: Both doses of J. decurrens significantly anticipated (p < 0.05) the age of testicular descent to the scrotum, a parameter indicative of puberty initiation. Furthermore, at puberty, there was a significant reduction (p < 0.05) in testicular and epididymis weights in the offspring exposed to the higher dose of extract, without effect on sperm production and the histology of reproductive organs. On the other hand, at adulthood, the reproductive parameters analyzed did not differ among groups.Conclusions: J. decurrens, in this experimental model, interfered with the initial development of the reproductive system, but without lasting effects on sperm production in adulthood.

Betacellulin Overexpression in the Mouse Ovary Leads to MAPK3/MAPK1 Hyperactivation and Reduces Litter Size by Impairing Fertilization1

The epidermal growth factor receptor (EGFR) and its ligands are emerging as key molecules in regulating female reproduction. Here, we used a transgenic mouse model to evaluate whether and at which level of the reproduction cascade higher-than-normal levels of the EGFR ligand betacellulin (BTC) in the reproductive organs affect fertility. Western blots and immunohistochemistry revealed increased BTC levels in uterus and ovaries from transgenic females, particularly evident in granulosa cells of antral follicles. Onset of puberty, estrous cyclicity, and the anatomy and histology of reproductive organs at puberty were not altered as compared to control females. Fertility tests revealed a reduction (~50%) in litter size as the major reproductive deficit of transgenic females. Embryo implantation was delayed in transgenic females, but this was not the reason for the reduced litter size. Transgenic females produced a normal number of oocytes after natural ovulation. The in vivo fertilization rate was significantly reduced in untreated transgenic females but returned to normal levels after superovulation. Impaired oocyte fertilization in the absence of superovulation treatment was associated with MAPK3/MAPK1 hyperactivation in BTC transgenic ovaries, whereas similar levels of MAPK3/MAPK1 activation were detected in transgenic and control ovaries after superovulation treatment. Thus, tight regulation of MAPK3/MAPK1 activity appears to be essential for appropriate granulosa cell function during oocyte maturation. Our study identified hitherto unknown effects of BTC overabundance in reproduction and suggests BTC as a novel candidate protein for the modulation of fertility.

Alloxan-induced and insulin-resistant diabetes mellitus affect semen parameters and impair spermatogenesis in male rats.

The purpose of this study was to determine the effects of diabetes mellitus and insulin resistance on semen parameters, histology of reproductive organs and serum concentrations of testosterone and luteinizing hormone (LH). Male Sprague-Dawley rats weighing 180 - 200g were made diabetic by intravenous injection of alloxan (40 mg/kg): and insulin resistant by chronic fructose feeding (25% fructose) for 12 weeks. Rats were anaesthetized, followed by laparatomy. Blood was obtained by cardiac puncture for measurement of testosterone and LH concentrations by radioimmunoassay. Semen analysis was carried out; reproductive organs were isolated, fixed in Bouin's fluid and processed for histological studies. All semen parameters analyzed were significantly reduced (P < 0.05) in the diabetic and insulin resistant rats compared to control rats. Body weight and weight of reproductive organs were also significantly reduced (P < 0.05). Furthermore, tissue fixation studies revealed changes in the cytoarchitecture of reproductive organs in the diabetic and insulin resistant rats compared to control rats. However, serum concentrations of testosterone and LH were not significantly different in all the groups. We conclude that diabetes mellitus and insulin resistance affect semen parameters and impair distinct phases of spermatogenesis in male rats. Some mechanisms responsible for this impairment are suggested.

Reproductive effects of fenoxycarb on sheep.

Fenoxycarb (ethyl [2-(4-phenoxyphenoxy)-ethyl] carbamate) is an insect growth regulator used for long-term fire ant control. Because of its effects on insect reproduction and its potential use on pasturage consumed by food animals, a reproductive study was conducted using Rambouillet sheep. The sheep were dosed daily with a placebo or with fenoxycarb at 0.69 or 1.38 mg/kg/day, representing ten (10x) and 20 times (20x) the maximum amounts of fenoxycarb in forage or hay treated at recommended levels for fire ant control. Parameters that were measured included rates of weight gain of adults, serum clinical chemistry profiles of adults, spermatozoal morphology and motility, estrus cycling, pregnancy rates, maintenance of pregnancies to term, numbers of live births, and rates of weight gain of lambs to 28 days. There were no statistically significant (P < or = 0.05) differences between the exposed and control groups of sheep in any of these facets of the study. No clinical signs associated with exposure to fenoxycarb were observed in any animal at any time, and no exposure-related pattern of pathologic lesions or reproductive organ histology was observed. Means of hepatic fenoxycarb residues in the rams followed a statistically significant (P < or = 0.05) dose-related pattern. No fenoxycarb was detected (detection limit of 5 ppb) in any neonatal liver, despite the presence of hepatic fenoxycarb residues in the treated ewes, indicating that transplacental transport of fenoxycarb was minimal. No fenoxycarb was detected in any lamb liver at 28 days, although both the colostrum and the milk of exposed ewes were found to contain fenoxycarb at levels proportional to the treatments. Based on the lack of significant findings in this study, it is unlikely that use of fenoxycarb, according to label instructions (currently applicable to homeowner and registered agricultural usage) for fire ant control in pasturage or hay fields, will affect ruminant reproduction.