共查询到20条相似文献,搜索用时 15 毫秒
1.
2.
Nonbred and pregnant heifers were examined ultrasonically on alternate days from Days 10 to 22 in three experiments. The goal was to define criteria that could be used for identification of the early conceptus. The location and size of circular and elongated nonechongenic structure (apparently free intrauterine luminal fluid) were recorded (Experiment 1). On Day 12, there was a significantly greater number of circular nonechogenic structures in the ovarian half of the uterine horn ipsilateral to the corpus luteum in pregnant heifers than in nonbred heifers (means, 5.1 vs 3.5). Therefore, the embryonic vesicle was apparently detected on Day 12, but was not distinguished from circular nonechogenic structures representing free luminal fluid. The number of circular nonechogenic structures decreased after Day 14, with a corresponding increase in elongate nonechogenic structures associated with luteal regression (nonbred heifers) or elongation of the blastocyst (pregnant heifers). On Day 16, there were more elongated than circular nonechogenic structures in pregnant heifers than in nonbred heifers. In nonbred heifers, there was no evidence of a local utero-ovarian relationship between the amount of intrauterine luminal fluid and the location of either the corpus luteum or the next ovulatory follicle. Uterine luminal fluid in each horn increased several fold between Days 16 and 18 in nonbred heifers; there was significantly more lumina fluid in nonbred than in pregnant heifers on Days 18 and 20. In pregnant heifers, intrauterine luminal fluid area increased first in the ovarian end of the uterine horn ipsilateral to the corpus luteum; this was apparently due to detection of the elongating blastocyst. The length of the longest specular reflector on the endometrial surface of the uterine lumen increased over Days 10 to 22 in nonbred and pregnant heifers, but was not a useful criterion for detection of the conceptus (Experiment 2). The accuracy of a 7.5 MHz transducer for pregnancy diagnosis was not greater than a guess (50%) before Day 16 (Experiment 3). Results indicated that early pregnancy diagnosis in heifers was confounded by the presence of intrauterine fluid. 相似文献
3.
T E Spencer A G Stagg T L Ott G A Johnson W S Ramsey F W Bazer 《Biology of reproduction》1999,61(2):464-470
Interferon tau (IFNtau) is the antiluteolytic signal produced by the conceptus of ruminants. Intrauterine administration of recombinant ovine IFNtau suppresses expression of endometrial estrogen receptor (ER) and oxytocin receptor (OTR) in the luminal and superficial glandular epithelia to abrogate the production of luteolytic prostaglandin F(2alpha) (PGF(2alpha)) pulses. Subcutaneous (s.c.) injections of recombinant ovine (o) IFNtau appear to extend the interestrous interval by altering uterine PGF(2alpha) response to oxytocin. The present study tested the hypothesis that antiluteolytic effects of roIFNtau injected into the uterine lumen (paracrine) or s.c. (endocrine) are equivalent in suppressing expression of endometrial ER and OTR and inducing uterine expression of type I IFN-regulated Mx and ubiquitin cross-reactive proteins (UCRP). Sixteen cyclic ewes were fitted with uterine catheters on Day 5 (Day 0 = estrus), were assigned randomly to receive treatment with control proteins or roIFNtau (2 x 10(7) antiviral units/day) by either intrauterine or s.c. injections from Days 11 to 15, and were ovariohysterectomized on Day 16. Results indicated that expression of ER and OTR mRNAs in endometrial epithelium was suppressed by intrauterine but not by s.c. injections of roIFNtau. Intrauterine injections of roIFNtau increased expression of Mx and UCRP mRNA in the endometrium. Subcutaneous injections of roIFNtau increased endometrial Mx mRNA levels but not UCRP mRNA. Unexpectedly, intrauterine and s.c. injections of roIFNtau were equally effective in inducing expression of Mx and UCRP mRNA in the corpus luteum. Although s.c. injections of roIFNtau induced Mx mRNA in the endometrial epithelium, s.c. injections of roIFNtau did not abrogate activation of the uterine luteolytic mechanism by suppressing epithelial ER and OTR expression. Therefore, results of this study failed to support the assumption that endocrine roIFNtau mimics antiluteolytic effects of paracrine IFNtau to improve pregnancy rates in sheep. 相似文献
4.
M Shemesh W Hansel 《Proceedings of the Society for Experimental Biology and Medicine. Society for Experimental Biology and Medicine (New York, N.Y.)》1975,148(1):123-126
Prostaglandins F (PGF) were measured in uterine vein, ovarian artery, and jugular vein plasma and in the endometrial tissues at various times during the bovine estrous cycle, and were compared to peripheral plasma progesterone levels. Four groups of heifers at days 1-5, 10-14, 15-17 and 20-0 of the estrous cycle were studied. Low levels of PGF (48 plus or minus 12 ng/g dry tissue were measured in the endometrium on days 1-14 of the cycle. Higher values (131 plus or minus 9.0) were found at days 15 until the day of estrus (p less than 0.001). Similarly, very low levels of PGF were observed in the uterine vein plasma at days 1-14 (0.162) plus or minus 0.044) ng/mlM plus or minus S.E.), whereas on days 15 until the day of estrus the levels ranged from 1.5 to 3.0 ng/ml. The increases in uterine vein PGF on day 15 occurred even while peripheral plasma progesterone levels were still high. However, PGF was not elevated in either the ovarian artery or the jugular vein at any time during the cycle, even when uterine vein levels were greatly elevated. No differences in PGF content were detected in endometrial tissue from uterine horns adjacent or opposite to the functional corpus luteum. 相似文献
5.
Paula Tríbulo Leandro Balzano‐Nogueira Ana Conesa Luiz G. Siqueira Peter J. Hansen 《Molecular reproduction and development》2019,86(1):75-87
The uterine microenvironment during the first 7 days after ovulation accommodates and facilitates sperm transit to the oviduct and constitutes the sole source of nutrients required for the development of preimplantation embryos. Knowledge of the composition of uterine fluid is largely incomplete. Using untargeted mass spectrometry, we characterized the uterine metabolome during the first 7 days of the estrous cycle. Bovine uteri were collected on Days 0 (N = 4), 3 ( N = 4), 5 ( N = 3), and 7 ( N = 4) relative to ovulation and flushed with Dulbecco’s phosphate‐buffered saline. A total of 1,993 molecular features were detected of which 184 peaks with putative identification represent 147 unique metabolites, including amino acids, benzoic acids, lipid molecules, carbohydrates, purines, pyrimidines, vitamins, and other intermediate and secondary metabolites. Results revealed changes in the uterine metabolome as the cow transitions from ovulation to Day 7 of the estrous cycle. The majority of metabolites that changed with day reached maximum intensity on either Day 5 or 7 relative to ovulation. Moreover, several metabolites found in the uterine fluid have signaling capabilities and some have been shown to affect preimplantation embryonic development. In conclusion, the metabolome of the bovine uterus changes during early stages of the estrous cycle and is likely to participate in the regulation of preimplantation embryonic development. Data reported here will serve as the basis for future studies aiming to evaluate maternal regulation of preimplantation embryonic development and optimal conditions for the culture of embryos. 相似文献
6.
Endometrial explants obtained from cows between Days 13 and 29 of pregnancy were cultured for 24 h in modified minimum essential medium in the presence of [35S]methionine or [3H]leucine. Proteins synthesized and released into medium were analyzed by two-dimensional polyacrylamide gel electrophoresis and fluorography. Uterine luminal flushings were obtained from cyclic cows (Days 2-20 of estrous cycle) and early pregnant cows (Days 17-22). Endometrial tissues from cows on Days 17 and 29 of pregnancy were prepared for immunocytochemistry. A uterine secretory protein, which consisted of five isoelectric variants (pI 5.3-6.1) of identical molecular mass (23,000 Da), was shown to react immunologically with antiserum raised against bovine placental retinol-binding protein (bpRBP). Limited N-terminal sequence analysis of two major isoforms showed that the protein had nearly complete homology with bovine placental and plasma retinol-binding protein (RBP) over the first 25 amino acids. Through use of bpRBP antiserum, immunoreactive RBP was detected in uterine flushings collected from cows in the late luteal phase of the estrous cycle and early pregnancy by Western blotting, and in medium conditioned by uterine explants prepared at Days 13-29 of pregnancy by immunoprecipitation. Immunoreactive RBP was localized in endometrial surface and glandular epithelium on Days 17 and 29 of pregnancy by immunocytochemistry. These results demonstrate that RBP is a product of bovine uterine tissues. The uterine RBP may play an important role in vitamin A transport between maternal tissues and developing embryos. 相似文献
7.
To determine if increased endometrial vascular permeability (a response which precedes decidualization) could be obtained in temporally nonsensitized uteri by treatments designed to increase endometrial adenosine 3':5'-cyclic monophosphate (cAMP) concentrations, cholera toxin (an activator of adenylate cyclase) was injected into the uterine lumen of immature rats treated to be at the equivalent of day 4, 5, or 6 of pseudopregnancy. In all experiments, the rats were pretreated with indomethacin to inhibit endogenous prostaglandin (PG) synthesis. Endometrial vascular permeability, determined using 125I-labeled bovine serum albumin, was assessed 8 h later. Cholera toxin increased endometrial vascular permeability to the same level in all groups. As determined by uterine weights 5 days after the intrauterine administration of cholera toxin or its vehicle, the toxin produced the same extent of decidualization in all groups. Cholera toxin had no detectable effect on uterine cAMP concentrations in rats sacrificed 15 min after intrauterine treatment. In contrast, intrauterine administration of PGE2 increased uterine cAMP concentrations at 15 min in all groups. These data suggest that the effects of cholera toxin and of PGE2 on endometrial vascular permeability and decidualization are not mediated by cAMP. 相似文献
8.
A.J. Peterson H.R. Tervit R.J. Fairclough P.G. Havik J.F. Smith 《Prostaglandins & other lipid mediators》1976,12(4):551-558
Six non-pregnant ewes at day 12 of the estrous cycle each had a day-12 embryo transferred into the uterine horn ipsilateral to the corpus luteum, and 4 non-pregnant ewes at day 13 each had a day-13 embryo similarly transferred. Four control ewes, 2 at day 12 and 2 at day 13 received sheep serum into the uterine horn ipsilateral to the corpus luteum. Jugular blood samples were taken at 2-hourly intervals for 3 days post-surgery, then twice-daily for a further 4 days, and the plasma radioimmunoassayed for progesterone and 13,14-dihydro-15-keto-prostaglandin F. All control ewes exhibited estrus within the expected time range and pulsatile peaks of 13,14-dihydro-15-keto-prostaglandin F occurred coincident with declining progesterone levels. With one exception, the recipient ewes had prolonged cycles and those ewes found pregnant at necropsy, 30 days after transfer, showed no progesterone decline and no pulsatile peaks of prostaglandin during days 12 to 16 after estrus. These observations suggest that the presence of the embryo at a critical stage after mating suppresses the release of uterine prostaglandin F2α. 相似文献
9.
Twelve crossbred gilts, 8 to 9 months of age, were used to study the effects of prostaglandin E2 (PGE2) on luteal function during the estrous cycle. Intrauterine and jugular vein catheters were surgically placed before day 7 of the treatment estrous cycle and gilts were randomly assigned to 1 of 3 treatment groups. Groups I and II received constant intrauterine infusion of vehicle (6.0 ml/24 hr) or PGE2 (2400 micrograms/day; 6.0 ml/24 hr) respectively; while group III was given intrauterine infusions of 400 micrograms PGE2 every 4 hr. All infusions were initiated on day 7 and continued until estrus or through day 23. Jugular blood samples were collected twice daily from days 7 to 30 for progesterone analysis. Intrauterine infusion of PGE2 at the dose and frequencies given in this study delayed the decline in jugular plasma progesterone and resulted in prolongation of the estrous cycle length. The results of this study have shown that PGE2 at the dosage and frequency of administration used was capable of extending corpus luteum function. 相似文献
10.
The role of estradiol-17 beta (E2) in migration of the porcine embryo was examined (Experiment 1) by observing the distribution of Silastic (polydimethyl siloxane, Medical Adhesive Silicone Type A, Dow Corning) beads impregnated with cholesterol or E2 (n=5 gilts per treatment) after 5 days in utero (Day 12 of the estrous cycle, Day 0=1st day of estrus). Beads impregnated with E2 migrated farther (P less than 0.05) than those impregnated with cholesterol. Twenty additional gilts and sows were used to determine if histamine was involved with intrauterine migration (Experiment 2). On Day 6 of gestation the tip of each uterine horn was exposed and the subserosa of each of 5 gilts was injected with either vehicle, 8 mg of cromolyn sodium (an inhibitor of histamine release) or 8 mg of cromolyn sodium plus 1 mg of histamine. Four days later (Day 10), the excised uterus was examined for migration of embryos. An additional group of 5 gilts received 8 mg of cromolyn sodium on Days 6 and 10 and were examined on Day 12. Results from the second experiment demonstrated that cromolyn sodium treatment alone restricted (P less than 0.05) Day 10 embryos to the tip of the uterine horn but by Day 12 embryos had overcome this restriction. Injection of histamine overcame the inhibitory effects of cromolyn sodium and restored migration of Day 10 embryos. These experiments suggest that both E2 and histamine are involved in intrauterine migration of the porcine embryo. The extent to which these hormones might be interrelated during migration is not fully understood at this time. 相似文献
11.
Uterine flushings from ewes on days 0, 3, 6, 9, 12 and 15 of the estrous cycle were analyzed for total protein content. Flushings from days 9, 12 and 15 had greater (P<.01) amounts of protein than those from 0, 3 and 6. Antisera to uterine fluids from ewes at day 10 to 12 or day 14 to 15 of pregnancy detected two uterine-specific antigens in uterine flushings at day 7, 11 and 15 but not at days 0 and 3 of the cycle. A third uterine antigen was also detected in kidney tissue extracts. All three antigens were present in endometrial extracts at each stage examined. Progesterone, or estrogen plus progesterone, administration to ovariectomized ewes induced the appearance of the two uterine-specific antigens. The third antigen was detectable even in ovariectomized ewes. No pregnancy-specific antigens were detected in flushings from days 7, 11 or 15 of gestation. The effect of pregnancy on endometrial protein synthesis was examined in vitro . No differences were seen in the incorporation of (3)H-leucine in day 11 pregnant or nonpregnant or in day 14 pregnant or nonpregnant endometrium. No differences in total uterine lumenal protein were observed. Endometrial secretions, obtained by conditioning media with endometrial explant cultures, were evaluated to assess their effect on protein synthesis in day 11 embryos cultured in vitro . No significant effects of endometrial secretions or serum were observed. 相似文献
12.
The objective was to evaluate the effect of intrauterine infusion of prostaglandin E2 (PGE2) on luteal function in cattle. Heifers and cows were randomly assigned after two normal estrous cycles to either PGE2 or control treatment groups. Females in Treatment A were infused with 1 mg of PGE2 once daily into the uterine horn ipsilateral to the corpus luteum between days 7-10 of the estrous cycle with a 0.25 ml plastic semen straw and an artificial insemination pipette. Females in Treatment B were similarly infused with 1 mg of PGE2 once daily in 20 ml of a carrier vehicle via a catheter on days 10 and 11 of the estrous cycle. Control animals were infused with the carrier vehicle using either a semen straw (Treatment C) or via a catheter (Treatment D) on the same days of the estrous cycle. Blood samples were collected daily to monitor plasma progesterone concentrations during the treatment period. Females infused with PGE2 on days 7-10 of the estrous cycle returned to estrus in a mean of 23.5 days (range 22-25 days) and were similar (P > 0.05) to those infused on days 10 and 11 which returned to estrus in 23.5 days (range 22-25 days). Animals similarly infused with carrier vehicle on the same days of the estrous cycle returned to standing estrus in 20.2 days (range 17-23 days). Plasma progesterone concentrations indicated an extended period of elevated progesterone concentrations in PGE2-treated animals compared with control animals. These results indicate that short term administration of PGE2 early in the estrous cycle may result in extended luteal maintenance. 相似文献
13.
Dietary Zn-deficiency in mature female mice for 6 weeks caused a retardation of ovarian growth characterized by lack of vesicular and Grafian follicles, degenerated corpus luteum, distorted cell membranes of granulosa cells with pycnotic nuclei, poor development of theca interna, inordinate accumulation of sudanophilic granules in theca interna and interstitial cells. The vagina and uterus did not exhibit cyclic changes in their cytoarchitecture as a result of the cessation of estrous cycle after 6 weeks of dietary treatment. They displayed wide spread degenerative changes in their myometrial and endometrial layers. The uterine glands appeared collapsed with little or no secretion. The vagina lacked cornification. Their gonadotrophs reacted positive to PAS, identical to the control group observed at diestrous stage. However, they did not display a negative reaction, characteristic of the gonadotrophs at estrous stage of the control group, examined even at an interval of 1 day for 6 days in succession. These results point towards the suspension of steroidogenesis inspite of intact gonadotrophs under Zn-deficiency condition. 相似文献
14.
Twelve crossbred gilts, 8 to 9 months of age, were used to study the effects of prostaglandin E2 (PGE2) on luteal function during the estrous cycle. Intrataurine and jugular vein catheters were surgically placed before day 7 of the treatment estrous cycle and gilts were randomly assigned to 1 or 3 treatment groups. Groups I and II received constant intrauterine infusion of vehicle (6.0 ml/24 hr) or PGE2 (2400 μg/day; 6.0 ml/24 hr) respectively; while group III was given intrauterine infusions of 400 μg PGE2 every 4 hr. All infusions were initiated on day 7 and continued until estrus or through day 23. Jugular blood samples were collected twice daily from days 7 to 30 for progesterone analysis. Intrauterine infusion of PGE2 at the dose and frequencies given in this study delayed the decline in jugular plasma progesterone and resulted in prolongation of the estrous cycle length. The results of this study have shown that PGE2 at the dosage and frequency of administration used was capable of extending corpus luteum function. 相似文献
15.
Correlation of increased concentration of ovine endometrial cyclooxygenase 2 with the increase in PGE2 and PGD2 in the late luteal phase 总被引:6,自引:0,他引:6
Charpigny G Reinaud P Créminon C Tamby JP 《Journal of reproduction and fertility》1999,115(2):315-324
The effect of intraoviductal embryos on endometrial receptivity was studied by intraendometrial and intrauterine embryo transfer. Five-week-old female ICR mice were mated after superovulation; a vaginal plug confirmed day 1 of pregnancy. On day 4 (90 h after hCG injection), blastocysts were collected and transferred to pseudopregnant female mice and to recipient mice in which the uterotubal junction had been ligated bilaterally on day 1 of pregnancy. Three embryos per uterine horn, a total of six embryos per recipient mouse at days 1-6, were transferred to the endometrium or uterine cavity and implantation and pregnancy rates were calculated. The implantation rate for intraendometrial embryo transfer to recipients of days 3, 5 and 6 was significantly higher for uterotubal junction-ligated mice (72.2, 20.8 and 9.7%, respectively) than for pseudopregnant mice (55.0, 8.3 and 0.0%, respectively). The implantation rate for intrauterine embryo transfer to recipients at days 2, 5 and 6 was significantly higher for uterotubal junction-ligated mice (11.1, 25.0 and 8.3%, respectively) than for pseudopregnant mice (0.0, 3.3 and 0.0%, respectively). Uterotubal junction-ligated mice achieved implantation and bore neonates by intrauterine embryo transfer on days 2 and 6, whereas no implantation was achieved in pseudopregnant mice. The difference in implantation rate could not be explained by a difference in progesterone concentration between the groups. The distribution of proliferating cells in the endometrium was also studied immunohistochemically by use of anti-proliferating cell nuclear antigen (PCNA) antibody in the recipient mice. PCNA-positive cells were more abundant in uterotubal junction-ligated mice and demonstrated a marked extension from the epithelium to the stroma over time, in contrast to those in pseudopregnant mice. These findings indicate that an intraoviductal embryo exerts a biological effect by sending a signal to the endometrial epithelium and stroma, thus facilitating endometrial receptivity to the embryo and improving the rate of implantation. 相似文献
16.
A series of experiments were conducted to determine whether bovine blastocysts would develop beyond the blastocyst stage in the ovine uterine environment. In Experiment 1, in vitro matured, fertilized and cultured (IVM/IVF/IVC) expanded bovine blastocysts were transferred into uteri of ewes on Day 7 or 9 of the estrous cycle and collected on Day 14 or 15 to determine if the bovine blastocysts would elongate and form an embryonic disk. Springtime trials with ewes that were synchronized with a medroxyprogesterone acetate (MAP) sponge resulted in a 78% blastocyst recovery rate, and 68% of the recovered spherical or elongated embryos had embryonic disks. In Experiment 2, transfer of 4-cell bovine embryos to the oviducts of ewes at Day 3 resulted in a lower recovery (47 vs 80%) than the transfer of blastocysts at Day 7 when embryos were recovered at Day 14. However, the percentage of embryos containing embryonic disks was higher for embryos transferred at the 4-cell stage (71%) than for embryos transferred as blastocysts (50%). In Experiment 3, IVF embryos from super-ovulated cows or Day 8 in vitro produced embryos transferred to cows were collected at Day 14 and were found to be similar in size to those produced by transfer to ewes in Experiment 2. In Experiment 4, the transfer of bovine blastocysts to ewes did not prolong the ovine estrous cycle. In Experiment 5, extension of the ovine estrous cycle by administration of a MAP releasing intravaginal device allowed bovine embryos to elongate extensively and to become filamentous. In Experiment 6, uterine flushings on Day 14 or Day 16 contained elevated levels of interferon-tau when bovine blastocyst were transferred on Day 7. Transfer of bovine embryos to the reproductive tract of a ewe allows some embryos to develop normally to advanced perimplantation stages and may be a useful tool for studying critical stages of embryo development and the developmental capacity of experimental embryos. 相似文献
17.
The success rate of in vitro fertilization (IVF) in dogs is low and only early embryos have been obtained. In the present study, we investigated the use of intrauterine transfer of early-stage canine embryos to obtain pups. Twenty-three female dogs, in which the date of ovulation (based on plasma progesterone concentrations) differed by +/-1 day, were used (10 donors and 13 recipients). The uterine tube was extirpated under general anesthesia 1-4 days after mating (5-7 days after ovulation), and descending perfusion was done to collect embryos. Embryos were examined and transferred into the uterine horn of a recipient, ipsilateral to the ovary with the most corpora lutea. Pregnancy was established in one of eight bitches that received early embryos (zygote to 4-cell embryos); she received two zygotes and one 2-cell embryo and delivered two puppies. Although intrauterine transfer of early embryos (zygote to 4-cell embryos) was difficult, pregnancy was achieved, suggesting that uterine tube transfer is appropriate for these early-stage embryos. 相似文献
18.
Uteroplacental prostaglandins (PGs) play pivotal roles in the maintenance and termination of pregnancy in mammals. In the present study, we have characterized the expression of prostaglandin transporter (PGT) in placentome caruncles, intercaruncular tissues, fetal membranes, and utero-ovarian plexus during pregnancy in cattle. Pregnant bovine uteri were collected and classified into six groups covering the entire gestational length. In caruncles and intercaruncular tissues, PGT mRNA (also known as SLC02A1) and PGT protein were highly expressed at the late stage of pregnancy compared to the early and mid stages, whereas the level of expression is constant and low in fetal membranes throughout pregnancy. PGT mRNA and PGT protein were expressed at a constant level in the utero-ovarian plexus both ipsilateral and contralateral to corpus luteum throughout the course of pregnancy. Overall, the relative expression of PGT mRNA and PGT protein were higher in caruncles than in intercaruncular tissue and fetal membranes, whereas no differences were detected between intercaruncular tissues and fetal membranes at any stage of gestation. Immunohistochemistry indicated that PGT was preferentially expressed in caruncular epithelial cells of placentomes and endometrial luminal epithelial and myometrial smooth muscle cells of the intercaruncular regions. The level of PGT expression was comparatively higher in maternal components than in fetal components. In conclusion, differential spatiotemporal tissue-specific expression of PGT in uterine and intrauterine tissues suggests a role for this transporter in the exchange of PGs between the maternal and the fetal compartments, as well as for intrauterine metabolism of PGs during pregnancy. 相似文献
19.
Dose‐Dependent Effects and Reversibility of the Injuries Caused by Nandrolone Decanoate in Uterine Tissue and Fertility of Rats
下载免费PDF全文
![点击此处可从《Birth defects research. Part B, Developmental and reproductive toxicology》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Larissa Berloffa Belardin Vinícius Augusto Simão Gabriel Adan Araújo Leite Luiz Gustavo de Almeida Chuffa Isabel Cristina Cherici Camargo 《Birth defects research. Part B, Developmental and reproductive toxicology》2014,101(2):168-177
This study is the first to investigate the effects of different doses of nandrolone decanoate (ND) upon uterine tissue and fertility, and if the reproductive alterations can be restored after cessation of the treatment. Wistar female rats were treated with ND at doses of 1.87, 3.75, 7.5, and 15 mg/kg body weight, diluted in vehicle (n = 30/group), or received only mineral oil (control group, n = 45). The animals were divided into three periods of study: ND‐treated receiving a daily subcutaneous injection for 15 consecutive days (1), and treatment with ND followed by 30‐day recovery (2), and 60‐day recovery (3). At the end of each period, five females per group were induced to death to histopathological analysis and the others were allowed to fertility evaluation (at 19th gestational day). Animals that received ND followed by 30‐day recovery exhibited persistent diestrous and marked suppression of reproductive capacity. Conversely, after 60‐day recovery, only lowest doses females (1.87 and 3.75 mg/kg) exhibited restoration of normal estrous cyclicity. Uterine weights were increased after ND treatment similarly to that of the controls after 60‐day recovery. The ND‐treated groups showed histopathological changes in the endometrium, myometrium, and perimetrium, and an increase in the thickness of both muscular and serous layers. Notably, the recovery of uterine tissue after ND treatment was dose‐ and period‐dependent. We reported that administration of ND promoted damage in uterine tissue and fertility of rats, and the recovery periods were insufficient to restore all of the side effects caused by ND under a dose‐dependent response 相似文献
20.
A method for producing identical twin calves is described in which Day 7 frozen-thawed bovine embryos in 12.5% sucrose solution were bisected using a fine microsurgical blade. The resulting bisected embryos were transferred nonsurgically to the uterine horn ipsilateral to the corpus luteum of synchronous recipients (+/-1 d), two bisected embryos per recipient. The pregnancy rate when both halves remained in the same zona pellucida was 50% (5 10 ); the pregnancy rate was 1 5 for morulae and 4 5 for blastocysts. The pregnancy rate for unfrozen morulae bisected in PBS and transferred without zona pellucida was 27% (4 15 ). The in vitro survival rate of embryos bisected in 12.5% sucrose when both halves remained in the original zona pellucida was 82% (18 22 ), which was higher than when embryos were bisected in PBS (53%, 9 17 ). 相似文献