Effect of actinomycin D on protein synthesis by delayed implanting mouse embryos in vitro.
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Animals↗
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Results for “Embryo Implantation, Delayed”
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The effect of oestrogen and progesterone on CO2 production by 'delayed implanting' mouse embryos.
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Animals↗
Effect of implantation delay on transfer of rat embryos to mice.
Rat and mouse blastocysts were transferred to the uteri of ovariectomized mice, maintained by progesterone for a few days and induced to implant by oestradiol administration. Mouse implantation sites contained normal embryos; all rat embryos were retarded, although some had developed to the egg-cylinder stage.
Animals↗
Diapause of mouse blastocysts transferred to oviducts of immature mice.
Mouse blastocysts transferred to the oviducts of immature females entered a period of diapause from which they could be activated by culture in vitro or by transfer to pseudopregnant recipients. In the tract of immature females, embryos hatched from the zona pellucida, increased cell number to a maximum that is comparable to that of blastocysts delayed by ovariectomy, and some moved to the uterus. Viability of blastocysts retained in the non-progestational, immature tract remained high for 4 days but dropped after 5 or 6 days. This new method of producing a delay in implantation offers precision in determining survival and viability rates and in determining the requirements of diapausing embryos.
Animals↗
Regulation of glycolysis in the mouse blastocyst during delayed implantation.
The rate of oxidation of glucose is reduced in mouse embryos in the prolonged free living phase associated with delayed implantation and increases when the embryos are reactivated by estrogen. To determine how these changes in metabolism are regulated, several aspects of glucose metabolism were evaluated in dormant and reactivated blastocysts: 1) Embryos were exposed to 14C-pyruvate in vitro and evolved 14CO2 was measured. It was found that the rate of production of CO2 was equal in the two types of blastocysts, suggesting that aerobic pathways are fully functional during delayed implantation. 2) Production of lactate in the presence of O2 was measured and a decrease of 30% was found in delayed implanting embryos, suggesting that the overall regulatory mechanism for glucose metabolism resides in the glycolytic portion of the pathway. 3) Capacity for uptake and phosphorylation of glucose was evaluated using 3H-2-deoxyglucose and was found to be equal in the two types of embryos. 4) Total amounts of the rate-controlling enzymes for glycolysis (i.e., hexokinase and phosphofructokinase) in lysates of delayed and reactivated embryos were found to be equal, indicating that amounts of these enzymes are not limiting in delayed implantation. 5) Lactate production, measured under anaerobic conditions, was found to be equal, demonstrating that it is not the capacity for glycolysis but a difference in the degree of allosteric inhibition that is responsible for reduced glucose oxidation in delayed implantation. 6) Levels of ATP, ADP, and hexose-6-phosphates were found to be consistent with allosteric inhibition of the glycolytic pathway at phosphofructokinase during delay and a release of this inhibition with reactivation.(ABSTRACT TRUNCATED AT 250 WORDS)
Aerobiosis↗
[Relation between the corpus luteum & the blastocyst during delayed nidation in the European badger].
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Blastocyst↗
Influence of the embryo on the distribution of maternal immunoglobulins in the mouse uterus.
The effect of the embryo on the distribution of IgA, IgG and IgM was studied by an immunoperoxidase technique on mouse uterine sections, (1) during the first part of pregnancy and pseudopregnancy, and (2) in delayed implantation combined with different progesterone-oestradiol treatments designed to extend the delay or induce implantation, and in nonpregnant ovariectomized mice similarly treated. The number of glandular lumina containing IgA increased particularly from the implantation period, but in pseudopregnancy this number decreased from the morning of Day 4, and afterwards continued to decline. In delayed implantation, the number of glandular lumina containing IgA also rose considerably when implantation was induced by oestradiol, whereas under the same progesterone-oestradiol treatment, nonpregnant ovariectomized animals displayed no such increase. Significant staining for IgG in the stroma was observed on Day 4 of pregnancy and pseudopregnancy but prolonged staining for IgG was observed only during pregnancy. In addition, significant numbers of IgA-plasma cells in the stroma were observed mostly in uteri containing embryos. These results indicate that embryos might affect the process by which ovarian hormones regulate IgA and IgG distribution.
Animals↗
A sporadic case of delayed implantation after in-vitro fertilization in the human?
A possible case of delayed implantation after in-vitro fertilization (IVF) is described. The patient was sterilized in 1981, and made fertile again by tubal anastomosis in 1988. In 1990 and 1992 the patient had two right-sided tubal pregnancies, the first was treated with prostaglandin instillation, the second with salpingectomy. In connection with the salpingectomy in 1992, the left tube was observed to be constricted in the middle part and with phimosis of the ostium. In 1994 three IVF embryos were transferred, but 15 days after the transfer, serum human chorionic gonadotrophin (HCG) was negative (< 10 IU/ml). Seven weeks after the embryo transfer, menstruation was still missing, and the serum HCG was now positive (329 IU/ml). Subsequent ultrasound scans were compatible with an intrauterine pregnancy, progressing normally, but 5 weeks delayed compared with the oocyte aspiration. The pregnancy was successfully carried to term. Such a long delay in detection of HCG, in association with a normal pregnancy, has not been described in the literature before.
Adult↗
Expression and regulation of stanniocalcin 1 and 2 in rat uterus during embryo implantation and decidualization.
Stanniocalcin-1 (STC-1) is a recently discovered polypeptide hormone, while stanniocalcin-2 (STC-2) is a subsequently identified homologue of stanniocalcin-1. Although previous studies have shown that both STC-1 and -2 are involved in various physiological processes, such as ion transport, reproduction and development, their expression in the uterus and roles in implantation and early pregnancy are unclear. Here we have investigated the expression and regulation of both STC-1 and STC-2 in rat uterus during early pregnancy under various physiological conditions. We show that only basal levels of STC-1 and STC-2 mRNA were detected in the uterus from day one (D1) to day five (D5) of pregnancy. STC-2 immunostaining was gradually increased in the glandular epithelium from day two (D2), with a peak occurring on D5. High levels of both STC-1 and STC-2 mRNA were observed in the stoma cells at the implantation site on day six (D6) of pregnancy, whereas their immunostaining signals were also significant in the luminal epithelium. Basal levels of both STC-1 and STC-2 mRNA and STC-1 immunostaining were detected in the uterus with delayed implantation. After the delayed implantation was terminated by estrogen treatment, both STC-1 and STC-2 mRNA signals were significantly induced in the stroma underlying the luminal epithelium at the implantation site, and STC-2 immunostaining was also observed in the luminal epithelium surrounding the implanting blastocyst. Embryo transfer experiments further confirmed that STC-1 and STC-2 expression at the implantation sites was induced by the implanting blastocyst. Both STC-1 mRNA and immunostaining were seen in the decidualized cells from day seven (D7) to day nine (D9) of pregnancy. STC-2 mRNA was also found in the whole decidua from D7 to D9 of pregnancy; STC-2 protein, however, was strictly localized to the primary deciduas on D7 and D8, with a weak expression in the whole deciduas on D9. Consistent with the normal pregnancy process, strong STC-1 and STC-2 mRNA signals were detected in the decidualized cells under artificial decidualization, whereas only basal levels of STC-1 mRNA and immunostaining were observed in the control horn. These data suggest, for the first time, that STC-1 together with STC-2 may play important roles in the processes of implantation and decidualization in the rat.
Animals↗
[Effects of gossypol acetic acid on transport and development of fertilized eggs in rats].
The effects of gossypol acetic acid on the transport and development of fertilized eggs have been observed in rats. The results showed that gossypol acetic acid apparently delayed egg transport and retarded early development of the embryo in the oviduct. It is suggested that these two effects may be important causes of the antiimplantation action of gossypol.
Animals↗
The effect of ethanol upon early development in mice and rats. IV. The effect of acute ethanol intoxication of day 4 of pregnancy upon implantation and early postimplantation development in mice.
Acute ethanol intoxication in albino mice (RAP) induced by intravenous administration of ethanol on day 4 of pregnancy delayed or inhibited implantation in about 25 per cent of the cases. The noxious action upon the implantation process showed a clear-cut "litter effect" and the mean litter was not affected by the experimental intervention. In very early postimplantation stage (day 6 of pregnancy) a statistically significant advance of some main morphogenetic indices was detected in treated specimens. As a possible explanation of this finding, a "selection" of more resistant and viable embryos by the acute ethanol intoxication is presumed. The data discussed in the present paper, together with authors' previous findings suggest a possible noxious action of acute ethanol intoxication during preimplantation stages upon implantation.
Animals↗
Epidermal growth factor--induced implantation and decidualization in the rat.
Effects of epidermal growth factor (EGF) on blastocyst implantation and experimentally-induced decidualization were examined in the rat. Intraluminal injection of EGF into each uterine horn induced implantation in the ovariectomized progesterone-treated delayed implanting rat in a dose-dependent manner. This induction was inhibited by indomethacin, an inhibitor of prostaglandin synthesis. Intraluminal injection of EGF on day 5 of pseudopregnancy elicited a greater decidual response when compared to the vehicle-injected contralateral uterine horn. These results suggest that EGF may play important roles in the process of implantation and decidualization in the rat.
Animals↗
Apposition of uterine luminal epithelium during implantation in senescent golden hamsters.
Closure of the uterine luminal epithelium was examined with light and electron microscopy in 3 to 5-month-old and 14 to 15-month-old golden hamsters at 3 1/2, 4, and 4 1/2 days of pregnancy. Apposition of the uterine luminal epithelium and the subsequent changes occurring during the early stages of implantation were delayed approximately 12 hrs in senescent females. However, the sequence of events and the degree to which the uterine epithelium closed and made contact with implanting blastocysts were similar in both age groups. It does not appear that closure of the uterine luminal epithelium or blastocyst attachment to the epithelium is impaired in 14 to 15-month-old hamsters but that other factors are responsible for the declining litter size.
Aging↗
Embryonic/fetal growth following suckling-induced delay of implantation.
In rats fertilized during the first or second day post partum (second consecutive pregnancy), suckling induces delay of implantation for 8 to 22 days. However, pregnancy is prolonged for only 3 to 17 days because accelerated embryonic and early fetal growth makes up 4 to 5 days of the implantation delay. After implantation, embryonic/fetal growth is accomplished within 11 to 12 days for a second consecutive pregnancy, whereas 16 days are required for first or second-spaced pregnancies. After weaning, increased function of the intestinal tract and liver is not needed anymore for mammary milk synthesis, and abundant nutrients can be shifted to the uteroplacental unit for rapid embryonic/fetal growth. Because the exponential curves for fetal growth are similar for first, second consecutive, and second-spaced pregnancies, it seems that, besides an increased supply of nutrients, an as yet unidentified maternal or a placentofetal factor(s) may play a role for embryonic/fetal growth.
Animals↗
Growth and role of the corpus luteum throughout delayed gestation in the potoroo, Potorous tridactylus.
The growth cycle of the corpus luteum (CL) of the potoroo is similar to that of other macropodids. During delayed gestation, the post-partum CL remains quiescent until it is reactivated by removal of the sucking pouch young. The CL then undergoes a period of growth, rapid from Day 6 until Day 12, followed by a gradual decline from Day 21 to Day 27. Excision of the CL before Day 6 of pregnancy either inhibited embryonic development or failed to support it. Excision of the CL between 6 and 21 days after removal of pouch young did not prevent embryos developing to full term but interfered with parturition. Excision on Day 25 after removal of pouch young allowed birth but impaired lactation, neonates dying within 2 days. By Day 27, the CL appeared to be no longer essential for embryonic development, birth or neonate survival. It is suggested that the CL of the potoroo is required for a slightly greater proportion of pregnancy than in most larger kangaroos because the birth canal must be prepared before each parturition.
Animals↗
Establishing the timing of implantation in the Harlan Porcellus Dutch and New Zealand White rabbit and the Han Wistar rat.
The purpose of this study was to establish the timing of the onset of implantation in both the Harlan Porcellus Dutch and New Zealand White rabbit and the Han Wistar rat. Implantation was initiated on Day 5 (rat) and 7 (rabbit) and established by Day 7 and 8 of gestation in the rat and rabbit, respectively. Recent guidelines on toxicity testing during embryo-fetal development studies require that maternal exposure to pharmaceutical compounds does not occur until after implantation has taken place. In order to ensure that this is the case, female Harlan Porcellus Dutch and New Zealand White rabbits and Han Wistar rats were sacrificed on different days of gestation, over the expected periods of implantation. The presence of preimplantation blastocysts in the uterus was investigated, and evidence of established implantation sites was assessed.
Animals↗
Impaired expression of importin/karyopherin beta1 leads to post-implantation lethality.
Importin beta1 (Impbeta)/karyopherin beta1 (Kpnb1) mediates the nuclear import of a large variety of substrates. This study aimed to investigate the requirement for the Kpnb1 gene in mouse development, using a gene trap line, B6-CB-Ayu8108(GtgeoIMEG) (Ayu8108(geo)), in which the trap vector was inserted into the promoter region of the Kpnb1 gene, but in reverse orientation of the Kpnb1 gene. Ayu8108(geo/geo) homozygous embryos could develop to the blastocyst stage, but died before embryonic day 5.5, and expression of the Kpnb1 gene in homozygous blastocysts was undetectable. We also replaced the betageo gene with Impbeta cDNA through Cre-mediated recombination to rescue Impbeta expression. Homozygous mice for the rescued allele Ayu8108(Impbeta/Impbeta) were born and developed normally. These results demonstrated that the cause of post-implantation lethality of Ayu8108(geo/geo) homozygous embryos was impaired expression of the Kpnb1 gene, indicating indispensable roles of Impbeta1 in early development of mice.
Animals↗
Cell lineage and differentiation during growth of the early mammalian embryo.
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Animals↗