Number Of Pregnant Females Research Articles

Aspectos reprodutivos de Poecilia vivipara (Bloch & Schneider) (Poeciliidae) da Lagoa Rodrigo de Freitas, Rio de Janeiro, Brasil

Poecilia vivipara (Bloch & Schneider. 1801) is a species that lives in the Rodrigo de Freitas lagoon, a coastal lagoon in the city of Rio de Janeiro. The objective of this study was to increase the knowledge about reproductive aspects of P. vivipara population including: the female size when it begins reproduction, the number of offsprings per gestation, embrionary development stages and the number of pregnant females. The results show that P. vivipara reproduces throughout the whole year with its first maturation occurring at 29 mm. The proportion found of females to males was 3:1. Embryos showed four developmental stages until birth with sexual differentiation occurring after 15mm.

Effects of extremely low frequency magnetic field on fertility of adult male and female rats.

To investigate the effects of an extremely low-frequency (ELF) magnetic field on their fertility, adult male and female Sprague-Dawley rats were exposed to a 50 Hz sinusoidal magnetic field of approximately 25 microT (rms) for 90 days before they were mated with unexposed counterparts. Exposure to a 50 Hz field reduced male rat fertility. The number of pregnant females was reduced when mated with exposed males, and the number of resorptions increased. The effects of magnetic field on male fertility were shown to be partly reversible, when the same exposed group of males were remated 45 and 90 days after being removed from the fields. Exposure of adult female rats to 50 Hz magnetic fields for 90 days before mating significantly reduced their fertility. The mean numbers of implantations and living fetuses per litter were statistically significantly decreased in the 50 Hz group. These results suggest that low frequency magnetic fields have some adverse effects on fertility of male and female rats.

Effect of Ferula hormonis extract on social aggression, fertility and some physiological parameters in prepubertal male mice.

The effects of an aqueous extract of Ferula hormonis on social aggression, fertility and some physiological and biochemical parameters were investigated in male mice. The ingestion of 3 mg/kg of aqueous extract of F. hormonis for six weeks clearly inhibited social aggression. Body wet weight and other sex accessory organ weights were significantly reduced by this treatment. The ingestion of this extract by male mice resulted in a significant reduction of their fertility. This treatment caused a significant decrease in the number of pregnant females, number of implantations and viable fetuses in females impregnated by males that ingested this extract. Additionally, the numbers of epididymal sperm and their motility were dramatically reduced in F. hormonis-treated mice. Concomitant increases in sperm abnormalities were also observed when compared with control. These data indicate that F. hormonis exposure during this period puts the exposed animals at significant risk for reduced reproductive capacity in adulthood.

Male subfertility induced by acute scrotal heating affects embryo quality in normal female mice.

The aim of this experiment was to design a suitable mouse model for male subfertility in which to study the effect of decreased sperm quality on embryo quality in vivo and in vitro. To achieve male subfertility, testes of adult male mice were immersed in water at either 42 degrees C (heated) or 33 degrees C (controls) during 20 min. Twenty-eight days after treatment, all heat stressed males showed a significant decrease in relative testis weight [384.7 mg in controls (286.7-460.6) versus 323 mg in stress heated groups (117.9-405.6); P < 0.001], sperm concentration [3.75 x 10(6)/ml (2.75-7.25) versus 1.00 x 10(6)/ml (0-4.00); P < 0.001] and progressive sperm motility [57.5% (48.0-79.0) versus 42.5% (14.0-66.0); P < 0.001]. Moreover, after mating to heat exposed males, not only the number of pregnant females (20/22 versus 18/30) but also the weight of their embryos [275.4 mg (78.7-339.4) versus 261.8 mg (68.1-339.0); P < 0.001] was significantly lower at 14.5 days post coitum when compared to controls. Neither the number of resorption sites nor the number of viable embryos per pregnant female was significantly different between groups. Also, the in-vitro fertilization rate of oocytes, fertilized by spermatozoa collected from heat stressed males, was significantly lower (44.9%; P < 0.0001) when compared to controls (65.1%; P < 0.0001). In conclusion, the results of this study suggest that male subfertility induced by acute scrotal heating may result in impaired sperm quality, reduced embryo weight in vivo and decreased fertilization rate in vitro.

Characterization of pregnancy outcome following thiram-induced ovulatory delay in the female rat

A single injection of the dithiocarbamate fungicide, thiram, suppresses the proestrous surge of LH and delays ovulation for 24 h. In this study, we examined fertility after a thiram-induced delayed ovulation. Females were injected with thiram (50 mg/kg, IP) on proestrus (1300 h) and mated on the following evening. Control and thiram-treated, but nondelayed, females were injected and mated on the same day. The number of females in the thiram-delayed group that became pregnant was reduced and litter size on GD 20 was reduced; however, no obvious morphological anomalies were seen. The number of pregnant females and litter size was not altered in the thiram-nondelayed rats, indicating that it is the thiram-induced delay in ovulation and not the exposure to thiram per se that was responsible for altered pregnancy outcome. On GD 7 and 11, the number of live fetuses per litter was reduced in the delayed females, but the number of implantation sites was not different from controls. On GD 11 the mean developmental score, head length, crown-rump length, and somite number in the delayed group were also reduced, indicating retarded development of live embryos. These results demonstrate that delayed ovulation induced by a single thiram exposure does not alter the number of oocytes released or the number that implant. However, the concepti from these females are compromised during midgestation.

Dominant lethal studies in male mice after exposure to a 50 Hz magnetic field

The potential mutagenicity of power frequency magnetic fields was investigated using a dominant lethal assay in mice. A total of 42 male mice were exposed for 8 weeks to a 50 Hz sinusoidal magnetic field at 10 mT (rms) and 47 males acted as simultaneous cage controls. Each male was subsequently mated with two females on weeks 1, 3, 5, 7, and 9 post-exposure. The numbers of pregnant females, corpora lutea, and live and dead implants were recorded. Multiple logistic regression analyses examined the effects of exposure on pregnancy rate, pre-implantation survival and post-implantation survival. There were no statistically significant differences in overall response between exposed and control groups, nor was there any significant effect of exposure in any post-exposure week. Thus, exposure to power frequency magnetic fields at 10 mT for the approximate period of spermatogenesis did not appear to induce dominant lethal mutation in the germ cells of male mice.

Clastogenicity of diepoxybutane in bone marrow cells and male germ cells of mice.

The bifunctional metabolite of 1,3-butadiene, 1,2:3,4-diepoxybutane (DEB), was tested in the mouse bone marrow micronucleus assay and in male mouse germ cell tests, namely the analysis of first cleavage divisions and the dominant lethal assay. All experiments were performed with single intraperitoneal treatment of the animals. In the micronucleus test, DEB doses of 4.5, 9.0, 18.0 and 36.0 mg/kg body weight were tested at a sampling interval of 24 h for bone marrow. The dose response for the induction of micronuclei in polychromatic erythrocytes was linear with the lowest effective dose of 9.0 mg/kg body weight. No sensitivity difference was observed between male and female mice. the cytogenetic analysis of first cleavage division chromosomes was performed after treatment of male mice with 17, 26, 34, 43 and 52 mg/kg body weight of DEB and mating the males to hormonally stimulated females on days 7, 14, 21 and 28 after treatment. The two higher doses caused general toxicity evidenced by the poor mating behavior of the males. Only 13 and 20% of the mated females were fertilized on day 7 after treatment of the males with 43 and 52 mg/kg body weight of DEB, respectively. An increased number of unfertilized oocytes was obtained from fertilized females on day 7 after treatment of the males with 34 mg/kg body weight of DEB. With a dose of 26 mg/kg body weight, it was demonstrated that chromosomal aberrations were only induced in spermatozoa (mating on day 7 after treatment) while spermatids (mating on days 14 and 21) and spermatocytes (mating on day 28) were not susceptible to the clastogenic effect of DEB. The response in spermatozoa in the dose range 17-34 mg/kg body weight was linear up to 26 mg/kg body weight and reached a plateau thereafter. The results of the dominant lethal experiments performed in the dose range 18-54 mg/kg body weight gave results similar to the cytogenetic study. With the highest dose tested, the toxicity and cytotoxicity during the first 8 mating days after treatment dramatically reduced the number of pregnant females and, consequently, the total implantations, so that no significant dominant lethal effect could be assessed. During mating days 9-12 (treated late spermatids), a significant dominant lethal effect was observed. With the two lower doses (18 and 36 mg/kg body weight), the dominant lethal effect was restricted to spermatozoa. The good correlation of the chromosomal aberrations with dominant lethal mutations confirms the chromosomal origin of dominant lethal effects. The clastogenic effect of DEB in somatic cells and in germ cells of mice was of the same order of magnitude.

Pregnancy Alterations Following Xenobiotic-Induced Delays in Ovulation in the Female Rat

Pregnancy Alterations Following Xenobiotic-Induced Delays in Ovulation in the Female Rat. Cooper. R. L., Barrett, M. A., Goldman, J. M., Rehnberg, G. L., McElroy, W. K., and Stoker, T. E. (1994). Fundam. Appl. Toxicol. 22, 474-480.Chlordimeform [N′-(4-chloro-o-tolyl)-N,N-dimethylformamidine] has been shown to cause a 1-day delay in the surge of luteinizing hormone (LH) in ovariectomized, steroid-primed female rats, presumably through its ability to block CNS α-noradrenergic receptors and consequently CNS regulation of anterior pituitary function. In the present study, we determined whether a chlordimeform-induced delay in the ovulatory surge of LH would alter pregnancy outcome in intact females. Chlordimeform (50 mg/kg) or sodium pentobarbital (35 mg/kg), as a positive control, was administered in order to delay ovulation 24 (1-day delay) or 48 hr (2-day delay). Females were then housed with proven fertile males on the evening of proestrus (0-day delay group), the following evening (1-day delay group), or the evening after that (2-day delay group). The number of receptive females in each group, the mean lordosis quotient, and the number of sperm-positive females in each group were recorded. All females were killed on Gestation Day 20. The number of pregnant females in the 1- or 2-day delay groups was reduced with both chlordimeform and pentobarbital. Also, delaying ovulation for 1 or 2 days with either compound resulted in a significant reduction in the number of live pups present on Gestation Day 20 and a decrease in the number of implantation sites. Litter size was not affected if the females were mated on the same day that treatment was administered (0-day delay). Pentobarbital did not alter the proportion of females showing sexual behavior or the mean lordosis quotient in the 0- and 1-day delay groups, although fewer 1-day females were sperm positive. The number of sexually active and sperm-positive females was reduced in the 2-day pentobarbital-delayed group. However, the lordosis quotient of those that were sexually active was not different than that of control. Similarly, in CDF-treated groups, the proportion of females showing sexual activity was reduced in the 0- and 2-day delayed groups. In contrast, sexual behavior was lower in the 0-day delayed females when tested 2 hr after lights out. These females did eventually mate, however, as confirmed by the high incidence of sperm positive smears the following morning. The number of sperm positive females was lower in both the 1- and 2-day chlordimeform-induced delay groups. Thus, brief exposures to compounds such as formamidine pesticide chlordimeform will result in not only a delay in breeding but, more importantly, a significant reduction in litter size.

Dominant lethal assay of 2,4-pentanedione vapor in Fischer 344 rats.

2,4-Pentanedione (2,4-PD: CAS No. 123-54-6) is a volatile industrial chemical of moderate acute toxicity, centrally neurotoxic by repeated exposure to high vapor concentrations, fetotoxic, and clastogenic. Its wide use and known toxicology indicated the conduct of a dominant lethal assay. Male Fischer 344 rats, 20 per group, were exposed to 2,4-PD vapor concentrations (mean +/- SD) of 0, 99.1 +/- 2.2, 412 +/- 12.6 and 694 +/- 9.1 ppm, for 6 hr/day for 5 consecutive days. The day following the final exposure they were bred to unexposed female Fischer 344 rats, 2 per week for 8 consecutive weeks. Weight loss occurred with males during 2,4-PD exposure for the 412 and 694 ppm groups, with compensatory increased weight at 694 ppm, for the first two weeks postexposure. No histopathological change was seen in brain, testes or thymus from high concentration males sacrificed after eight weeks of mating. Minor transient reproductive and gestational effects were present at 412 and 694 ppm. At week 2 there was a reduction, not statistically significant, in the number of corpora lutea and total and viable implants per dam at 694 ppm, and a slight increase in preimplantation loss. At week 3 the number of pregnant females was slightly reduced at 412 and 694 ppm, causing a lowered female fertility index. At week 4 there was a slight reduction in the number of total and viable implants per litter and a significant preimplantation loss at 694 ppm. The dominant lethal factor (FL%) was increased slightly at 694 ppm for weeks 2 and 4. Thus, the "no observable effect" level for dominant lethal effects was 99 ppm. The results, although not statistically significant, are dose-related and compatible with a transient slight dominant lethal effect at the spermatid stage of spermatogenesis.

Long-term exposure of the male mouse to lead: Effects on fertility

Sexually mature male mice, exposed to lead in the drinking water for 3 months, attained a mean blood level of 32 micrograms/100 ml. In control mice, given deionized water, blood lead levels were less than 0.5 microgram/100 ml. At the end of the exposure period, each male was caged with three untreated females. On Day 17 after mating, the frequency of pregnant females and the number of fetuses and resorptions were recorded. Females without implantations were significantly more numerous (P less than 0.05) in the group that had been mated with the lead-exposed males. The frequencies of resorptions and fetal malformations were similar in the two groups. The two groups of males were compared with respect to body weight, plasma level of testosterone, number of epididymal sperms, and weight of reproductive organs. No statistically significant differences were found. Increased tissue concentrations of lead were noted for all the male reproductive organs, as well as the hypothalamus. It cannot be decided at present whether the decrease in the number of pregnant females was due to a reduction in the ability of spermatozoa from the lead-exposed males to fertilize or to a preimplantation loss of fertilized ova.

Cyclophosphamide in the seminal fluid of treated males: Transmission to females by mating and effect on pregnancy outcome

Cyclophosphamide is an anticancer and immunosuppressant drug administered to men of reproductive age. In the present study the ability of cyclophosphamide and/or its metabolites to enter secretions of the male reproductive tract, to be transmitted to the female partner upon mating, and to alter progeny outcome was assessed. [ 14C]Cyclophosphamide was given intravenously to adult male Sprague-Dawley rats; radiolabel (greater than 96% cyclophosphamide) was first found in seminal vesicle fluid within 10 min and equilibrated with plasma radioactivity within 30 min. Furthermore, radiolabel from cyclophosphamide given to the male was transmitted to the female upon mating up to 5 hr post-drug treatment. To study possible consequences of paternal treatment with cyclophosphamide on pregnancy outcome, male rats were administered a single dose of cyclophosphamide, 10, 30, or 100 mg/kg, or saline immediately prior to cohabitation with females in proestrus. There was no effect on the number of pregnant females per sperm-positive females but there was a significant decrease in the number of implantations per pregnant female per male and in the number of live fetuses per pregnant female per male. There was a twofold increase in preimplantation loss. There was no increase in postimplantation loss or number of abnormal fetuses. These results demonstrate that cyclophosphamide not only penetrates the male reproductive tract but that it can be transmitted to the female partner and can affect progeny outcome.

Dominant lethal testing of theobromine in rats

Theobromine (TBR) 3,7-dimethylxanthine, the major purine alkaloid present in chocolate and cocoa products, was evaluated for dominant lethality in male Sprague-Dawley rats after administration of subacute oral doses of 0, 50, 150 and 450 mg/kg. Dominant lethal mutations were assessed weekly for a 10-week period by killing the females 13 days after the midweek of presumptive mating with treated males and counting total implants (living and dead), corpora lutea and number of pregnant females. Dead implants per total implants and preimplantation loss per total corpora lutea were evaluated statistically. No significant dose-dependent effects were observed in the % dead implants of preimplantation loss throughout the study; pregnancy rate averaged 94%. These results indicated no induction of dominant lethal mutations or adverse effects on pregnancy rate after TBR doses equivalent to 25–225 times the maximum human consumption level.

Teratogenicity of 2-Ethoxxethanol by Dermal Application

Undiluted 2-ethoxyethanol or water (control) was applied to the skin of pregnant Sprague-Dawley rats on days 7--16 of gestation (sperm = day 1). Applications were made 4 times daily in volumes of 0.25 or 0.50 ml 2-ethoxyethanol. Females exhibited ataxia following treatment of the high-dose group, and weight gain was significantly (p less than u. 0.001) reduced in the last half of gestation. Litters were collected by caesarian section on day 21 of gestation, and fetuses were examined for external defects. Half of the fetuses were cleared and stained in alizarin red S for skeletal examinations, and half were examined for visceral defects by the Wilson technique. Intrauterine death was 100% in the high-dose group. In the lower dosage group, there was a significant increase in the number of pregnant females with 100% dead implants (p less than 0.001), a significant reduction in the number of live fetuses per litter (p less than 0.001), a significant reduction in fetal body weight (p less than 0.001), and a significant increase in the incidence of skeletal variations (p less than 0.05) and cardiovascular malformations (p less than 0.05).

ChemInform Abstract: SYNTHESIS AND EVALUATION OF THE MALE ANTIFERTILITY PROPERTIES OF A SERIES OF N‐UNSUBSTITUTED SULFAMATES

AbstractDie Diole (I) werden in die Sulfamate (III)‐(VI) übergeführt.

Synthesis and evaluation of the male antifertility properties of a series of N-unsubstituted sulfamates.

A series of six aliphatic and one carbocyclic N-unsubstituted sulfamates have been synthesized and evaluated as potential male antifertility agents. Three of the aliphatic sulfamates, 1,2-ethanediyl sulfamate (1), 1,3-propanediyl sulfamate (2), and 1,4-butanediyl sulfamate (3), when administered orally to male rats caused a decrease in the number of pregnant females and/or implantation coupled with increased embryonic and fetal resorption. The compounds were prepared by treating the appropriate glycol salt with sulfamoyl chloride or by the cleavage of a tert-butylsulfamate with trifluoroacetic acid.

The effect of in vitro storage of hamster sperm on fertilization and early development

AbstractThe effects of storage of hamster sperm in vitro at temperatures above freezing on fertilization and early development were studied. Initially, female hamsters were inseminated artificially with epididymal sperm stored up to five days at 5°, 16°, or 23–25°C. Eggs were examined at the pronuclear stage for evidence of fertilization. The best conditions for the storage of hamster sperm were found to be 16°C in a 5% CO2 in air gas phase. Pre‐ and postimplantation development were then assessed following insemination of females with sperm stored at 16°C. An increased frequency of eggs with three pronuclei, a decrease in the number of pregnant females, and an increase in the number of resorption sites were found with increasing sperm storage time. Chromosome mosaicism and triploidy were encountered in 9.5‐day embryos resulting from eggs fertilized by stored sperm. No chromosome abnormalities were found in a control group of embryos. Thus, storage of hamster epididymal sperm resulted in decreased fertility and an increased frequency of abnormal development.

The effect of mitomycin on the fertility and the induction of meiotic chromosome rearrangements in mice and their first generation progeny.

The dose dependent effects of chronic application of Mitomycin C(MC) on the induction of chromosomal translocations in treated animals and F1 males and on their fertility have been examined. The C3H strain mice used in the present experiments were treated with MC during eight successive weeks in doses of 0.05 mg/kg and 0.1 mg/kg of body weight. 75 males were treated (25 males per dose and 25 males as controls). Immediately after the chronic treatment they were mated with normal females and were tested for their reproductive performance. The fertility of males was estimated from the number of pregnant females after one week of being together. After that all males were sacrificed and prepared for cytological analysis. No chromosomal translocations were found in diakinesis-metaphase I of meiosis. Data from the study of fertility showed that all treated males were fertile, but all females were not pregnant. The tests of all sterile, semisterile and fertile F1 males showed that F1 males could not be identified as heterozygous translocation carriers.