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PubMed2002

Skeletal muscle fibre type specification during embryonic development.

In the last 10 years an increasing number of studies have provided an insight in the signalling mechanisms underlying myogenesis and fibre type specification during embryonic development: this paper aims to review the most relevant findings. In vertebrates a central role in muscle differentiation is played by the MyoD family, a group of transcription factors which activate transcription of muscle specific genes. In turn MyoD family is expressed in response to inductive signals coming from tissues adjacent to somites, in the first place the notochord and the neural tube. Hedgehog and Wnt are among these inductive signals and they find in the future myoblasts a response pathway which includes Ptc, Smu and Gli. The signalling mechanisms have been analysed in model organisms: mouse, chick. zebrafish and Drosophila. For some factors the orthologs in different species have been found to accomplish similar function, but for some other factors important differences are present: for example in Drosophila twist codes for a transcription factor which promotes myogenesis, whereas its ortholog in mouse tends to prevent or inhibit myogenesis. Conversely, nautilus which is the orholog of MyoD in Drosophila does not have a general function in muscle differentiation, but is required for the differentiation of a limited group of muscle fibres.

Animals↗

PubMed1993

Expression of vasopressin V1a and V2 receptor messenger ribonucleic acid in the liver and kidney of embryonic, developing, and adult rats.

The ontogenic expression of mRNAs encoding the V1a and V2 vasopressin receptors (V1aR and V2R) was visualized in liver and kidney of embryonic, developing, and adult rats using in situ hybridization histochemistry. Transcripts were detected at 16 and 19 days gestational age in kidney, with V1aR mRNA predominating in the developing cortex and V2R in the medulla. V1aR transcripts in 1-day-old kidneys were in vascular elements, in cells of developing medullary collecting ducts, and over mesangial cells of deep glomeruli, consistent with a role for the V1aR in regulating cellular growth. Expression of V1aR mRNA in the adult was found mainly in medullary vascular elements, arcuate and interlobular arteries, short segments of the cortical distal tubule, and transitional epithelium and smooth muscle of the pelvic wall and ureter. V2R mRNA, at 16 and 19 days gestational age, was in cells of developing medullary and cortical collecting ducts and, after birth, in cells of differentiating thick limbs of the loops of Henle, papillary surface epithelium, overlying macula densa, and short distal nephron segments. This distribution is in accord with the known role of V2 receptors in regulating water excretion. In contrast to kidney, liver did not express V2R mRNA and expressed V1aR transcripts only after birth. V1aR mRNA labeling was over cells bordering central veins on day 1 and surrounding central veins by day 5. A gradient was maximal on postnatal day 21, with V1aR mRNA most abundant in hepatocytes surrounding central veins and virtually absent in periportal hepatocytes. By day 60, most hepatocytes expressed V1aR transcripts, and the gradient was reduced. The ontogenic expression and receptor mRNA gradient are consistent with a role for hepatic V1a receptors in glucoregulation. These experiments confirm the presence of both V1a and V2 receptors in kidney and show that vasopressin receptor mRNA expression is developmentally regulated and tissue specific.

Aging↗

PubMed1994

Cadherins and catenins: interactions and functions in embryonic development.

During the past year, the family of cadherin cell-adhesion molecules has increased in number and diversity. Recent studies have also emphasized how cadherin activity can be regulated by the dynamic association with intracellular components, the catenins, and with extracellular molecules that are linked to different cell-signaling pathways. Finally, the initial steps have been taken towards identifying the function of cadherins in vivo, including their potential roles in early embryonic development.

Amino Acid Sequence↗

PubMedDate not supplied

[The potential fertility, embryonic development and hormonal status of rats selected for their estrous cycle reaction to constant illumination].

Illumination responsiveness (IR) is studied by selection experiments with outbred Wistar rats. Under selection is estrous cycles under permanent illumination (PI) condition, changes in hormonal status, potential fertility, and embryonic developments ats different stages are registered and compared with control. Results indicate significant changes in endocrine regulatory system in the lines exposed to PI. Functional potentiality of reproductive system gets more weak as a result of this selection, which leads to decreasing in number of ovulations, defective development of placenta, less embryo weights, higher embryo mortality. The opposite conditions are observed in rats undergone selection of stability of estrous cycle. It is concluded that the above selection reveals formation of regulatory mechanisms of reproduction on different genetical physiological bases.

Animals↗

PubMed1996

Morphological and biochemical effects of excessive amounts of biotin on embryonic development in mice.

Pregnant mice received excessive amounts of biotin either subcutaneously (sc) or orally during gestation. There were no differences in the successful pregnancy rates and number of dead or resorbed fetuses between the control and biotin-treated groups. In biotin-treated groups no increased incidence of fetuses with external malformations was clearly demonstrable. However, biotin accumulated in maternal and embryonic organs; especially, the serum biotin level in the biotin-treated dam was 200-fold higher than that in the control dam. There was a difference in biotinidase activity in maternal serum and placenta between the control and biotin-treated groups. It was concluded that excessive amounts of biotin affected the specific activity of biotinidase in pregnant mice, but did not disturb normal reproductive functions and embryonic development.

Abnormalities, Drug-Induced↗

PubMed2006

RBP-Jkappa-dependent notch signaling is dispensable for mouse early embryonic development.

The Notch signaling pathway is an evolutionarily conserved signaling system which has been shown to be essential in cell fate specification and in numerous aspects of embryonic development in all metazoans thus far studied. We recently demonstrated that several components of the Notch signaling pathway, including the four Notch receptors and their five ligands known in mammals, are expressed in mouse oocytes, in mouse preimplantation embryos, or both. This suggested a possible implication of the Notch pathway in the first cell fate specification of the dividing mouse embryo, which results in the formation of the blastocyst. To address this issue directly, we generated zygotes in which both the maternal and the zygotic expression of Rbpsuh, a key element of the core Notch signaling pathway, were abrogated. We find that such zygotes give rise to blastocysts which implant and develop normally. Nevertheless, after gastrulation, these embryos die around midgestation, similarly to Rbpsuh-null mutants. This demonstrates that the RBP-Jkappa-dependent pathway, otherwise called the canonical Notch pathway, is dispensable for blastocyst morphogenesis and the establishment of the three germ layers, ectoderm, endoderm, and mesoderm. These results are discussed in the light of recent observations which have challenged this conclusion.

Animals↗

PubMed2005

Effect of protein supplement source on porcine oocyte maturation and subsequent embryonic development after parthenogenetic activation.

The aim of this study was to compare the effect of purified GPBoS and commonly used FCS on porcine oocyte maturation and subsequent embryonic development after their parthenogenetic activation. COCs were obtained from dissected follicles and cultured for 18, 24, 30, 36, 42 and 48 h in M-199 medium either with GPBoS or FCS. After 24 h with GPBoS, 91% of oocytes reached MI stage while in the medium supplemented with FCS, only 29% of oocytes reached the same stage (P < 0.05). The majority of oocytes from the FCS group (61%) reached MI stage approximately 6 h later. In the time periods between 36 to 48 h both groups of oocytes reached the same stage of maturation. After 48 h of culture the oocytes with extruded polar bodies were activated by a single electric pulse and then cultured with 4 mM 6-DMAP. Activated oocytes were cultured in PZM-3 medium supplemented with 3 mg/ml of BSA. After 7 days, the development and the quality of embryos were evaluated. The results showed that the maturation of oocytes in the presence of GPBoS significantly increased their subsequent developmental ability when compared with FCS supplementation (27% vs. 19% of blastocysts, P < 0.05). However, differential staining revealed that once blastocysts were formed in either group, they had the same total cell number (40 vs. 41) and also the ICM/total cell ratio (0.27 vs. 0.29).

Animals↗

PubMed1989

In situ localization of mRNA for the interferon, ovine trophoblast protein-1, during early embryonic development of the sheep.

The embryonic interferon, ovine trophoblast protein-1 (oTP-1), is considered to be the major protein signal by which the developing ovine conceptus communicates its presence to the mother in order to provide extension of luteal progesterone secretion critical for the establishment of pregnancy. The objective of the present study was to examine the distribution of mRNA for oTP-1 in developing ovine embryos by using in situ hybridization. A total of 11 ovine embryos were collected on days 11, 13, 15, 17, and 23 of gestation (n = 1, 2, 3, 3, and 2, respectively) and were subjected to either immediate paraformaldehyde fixation or culture for 24 h followed by fixation. Fixed embryos were embedded in paraffin and oTP-1 mRNA levels determined by in situ hybridization with a 35S-labeled cDNA probe specific for the 3'-untranslated region of the oTP-1 mRNA. Controls included parallel hybridizations with a 35S-labeled gamma-actin cDNA to detect actin mRNA (positive control) and with 35S-labeled plasmid cDNA (negative control). Hybridization signals were detected by autoradiography and quantified by computer-assisted video image analysis. Ovine TP-1 mRNA levels in tissue were low but detectable on day 11, rose 6.5-fold to peak concentrations on day 13, and declined in a linear fashion through day 23. A low, detectable signal was present in portions of chorionic tissue on day 23. Messenger RNA was localized solely to the trophectoderm and did not appear in the extraembryonic endoderm, yolk sac, and embryonic disc. The relative hybridization signal for actin mRNA was approximately 12-fold lower than that for oTP-1 mRNA on day 13. However, by day 17 oTP-1 and actin mRNA hybridization signals were similar. In conclusion, oTP-1 mRNA is localized in the trophectoderm of the developing embryo, being produced between days 11 and 23 of gestation with peak amounts produced per cell at approximately day 13 of gestation.

Animals↗

PubMed1993

Correlations between serum oestradiol level on day of HCG and speed of embryonic development in in-vitro fertilization.

The number of embryos transferred, ease of embryo transfer, and rate of embryo cleavage are significant factors affecting the success of IVF. High levels of oestradiol occurring when HCG is given may reduce implantation and pregnancy rates. A discrepancy between the stage of embryonic development and the phase of endometrial maturation at embryo transfer may be responsible for IVF failure in some cases.

Chorionic Gonadotropin↗

PubMed1983

Tumor promoter actions on rat embryonic development in culture.

The many embryonic and developmental features associated with tumor promotion have prompted us to investigate the effects of a series of phorbol esters and related diterpene tumor promoters on mammalian embryogenesis. A culture system which supports the normal development of 10.4 day organogenesis-phase rat conceptuses was utilized. In this system, 12-O-tetradecanoylphorbol-13-acetate (TPA), a potent Stage I and II promoter, disrupted the morphology and function of the embryonic visceral yolk sac (dose required to affect 50% of conceptuses, 18 nM). The effect was characterized by an abnormal, progressive separation of the two cellular layers of the yolk sac, but cellular differentiation appeared to be uninterrupted. Parallel log dose-response lines for this effect were produced by phorbol-12,13-dibenzoate (dose required to affect 50% of conceptuses, 200 nM) and phorbol-12,13-diacetate (dose required to affect 50% of conceptuses, 300 nM) which are consistent with structure-activity relationships for other promotional actions of these compounds. In addition, the weak Stage I promoter, 4-O-methyl-12-O-tetradecanoylphorbol-13-acetate, produced identical effects but was 1400 times less potent than was TPA, while mezerein, a potent Stage II promoter, was as potent as was TPA. These observations support the hypothesis that embryonic cells may be differentially sensitive to early- and late-stage promoters. Ethylphenylpropiolate, a nonpromoting hyperplastic agent in mouse skin, had no effect on yolk sac morphology or function at its maximum solubility (1.85 mM). Yolk sac disruption by TPA was potentiated by heat inactivation (56 degrees, 30 min) or 0.45-micron filtration of the culture medium. A more advanced stage of yolk sac development was less sensitive to TPA disruption since 11.4 day conceptuses, which were cultured for 30 hr, developed identical lesions, but TPA was at least 5-fold less potent. Thus, the tumor promoter-induced lesions of the rat yolk sac have some features consistent with late-stage tumor promotion and do not appear to be associated with general toxicity, hyperplasia, or alterations in cellular differentiation. We postulate that rat conceptuses maintained in vitro may provide an important model system for the study of the proposed mechanisms involved in chemical tumor promotion.

Animals↗

PubMedDate not supplied

[Embryonic development of guppies in weightlessness].

The program of the Cosmos-1514 flight included an experiment the purpose of which was to study the effect of weightlessness on the embryonic development of the live-bearing guppy fish: three pregnant females were flown for 5 days. Prelaunch their embryos were at the stage of cerebral vesicle differentiation and somite formation; this implies that the basic stages of organogenesis developed in weightlessness. One female was fixed in Bouin's fluid two days postflight and the second fish was fixed nine days postflight. Fourteen days after flight the third female gave birth to 25 normal fry. Thereafter that fish was mated 6 times more, each time delivering normal offspring. In addition, the offspring of the second generation was normal. Histological analysis of the embryos that were developing in weightlessness revealed no abnormalities. It can be concluded that weightlessness produced no effect on the fish development, beginning with the stage of the axial complex formation.

Animals↗

PubMed1979

[The effect of repeated applications of carbutamide on the embryonic development of the rat (author's transl)].

The present paper will check the effects of repeated applications of the oral "antidiabeticum" Carbutamide (substitute of the "sulfonylurea") on the embryonic development of wistar rats. The agent was given the pregnant animal by the means of a throat sonde at the 5th, 6th and 7th day post coitum suspended in Tween 80 in a dosage of 800 mg/kg bodyweight. In order to value the intrauterine development the following parameters were used: mean implantation rate, resorptions rate, bodyweight of fetuses, statemend of animalies by an accurate inspection of the body surface shape, of the skeleton and the inner organs. The rates of implantation do not differ from that of the control group. The rate of resorption increases dependend on the beginning of the treatment. The later the treatment begins the higher the resorptions rate. The body weight of surviving fetuses is diminished strongly. Damage of the skeleton appears as the presence of 14th ribs at one or each side or as ossifications at the 7th neck vertebra (neck rib). Also this results depend on the beginn of the treatment.

Abnormalities, Drug-Induced↗

PubMed1995

Transgene detection during early murine embryonic development after pronuclear microinjection.

The polymerase chain reaction (PCR) technique was used to detect a whey acidic protein (WAP) gene and transgene presence in mouse ova cultured to various stages of development after pronuclear microinjection at the one-cell stage. The PCR technique detected an endogenous 442 bp WAP DNA sequence in 78% of one-cell, 88% of two-cell and 94% of four-cell ova, and in 95% of morulae and 97% of blastocysts. The heterologous WAP-human protein C transgene was detected in 88% of one-cell, 88% of two-cell and 44% of four-cell ova, and in 40% of morulae and 29% of blastocysts. For comparison, the integration frequency for transgenic mouse production using the same DNA construct was 22%. After five days of in vitro culture, embryos that were either developmentally arrested or fragmented were tested for the presence of the transgene. The injected construct was detected in 83% of arrested one-cell, 85% of arrested two-cell, and 85% of fragmented ova. In culture, only 28% of zygotes microinjected with DNA developed to the blastocysts stage compared to 74% of noninjected zygotes, while 63% of zygotes developed to the blastocyst stage after injection of buffer alone. Pronuclear injection of the transgene at concentrations of 1.5, 15 and 50 micrograms ml-1 resulted in 28, 11 and 9% development to blastocysts and 29, 86 and 88% transgene detection, respectively. Transgene detection was 85, 96 and 97% in degenerate embryos at the respective doses of DNA. These data show that pronuclear microinjection of the transgene is detrimental to subsequent embryonic development.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1991

[Hereditary memory: genomic imprinting and its importance for embryonal development and carcinogenesis].

When the mammalian oocyte is fertilized, a unit is formed which requires the collaboration of the parental cell genomes. In this collaboration, however, a fraction of the autosomal parental genes are provided with different values by a memory from the germ cell maturation process. In the article the importance of genomic imprinting by the parental cell genomes is discussed in terms of the regulation of embryonic development and with regard to tumourigenesis.

Cell Differentiation↗

PubMed2001

Carboxypeptidases from A to z: implications in embryonic development and Wnt binding.

Carboxypeptidases perform many diverse functions in the body. The well-studied pancreatic enzymes (carboxypeptidases A1, A2 and B) are involved in the digestion of food, whereas a related enzyme (mast-cell carboxypeptidase A) functions in the degradation of other proteins. Several members of the metallocarboxypeptidase gene family (carboxypeptidases D, E, M and N) are more selective enzymes and are thought to play a role in the processing of intercellular peptide messengers. Three other members of the metallocarboxypeptidase gene family do not appear to encode active enzymes; these members have been designated CPX-1, CPX-2 and AEBP1/ACLP. In this review, we focus on the recently discovered carboxypeptidase Z (CPZ). This enzyme removes C-terminal Arg residues from synthetic substrates, as do many of the other members of the gene family. However, CPZ differs from the other enzymes in that CPZ is enriched in the extracellular matrix and is broadly distributed during early embryogenesis. In addition to containing a metallocarboxypeptidase domain, CPZ also contains a Cys-rich domain that has homology to Wnt-binding proteins; Wnts are important signaling molecules during development. Although the exact function of CPZ is not yet known, it is likely that this protein plays a role in development by one of several possible mechanisms.

Amino Acid Sequence↗

PubMed1975

Effects of hypoxia on early pregnancy and embryonic development in the mouse.

The efficacy of gestation during early pregnancy was investigated in mice exposed to either 14% or 7% oxygen environments. At Day 8 postinsemination, animals were killed and reproductive tracts were examined. Embryonic development was decelerated and an increased frequency of embryo death and resorption was apparent. At the 7% oxygen level, implantation was almost always blocked as evidenced by free blastocysts and uterine debris of embryonic origin. This blockage of nidation is attributed to altered progestational support due to ovarian luteolysis as demonstrated by decreased uterine volumes. These studies indicate that reproduction is impaired by hypoxia during preplacental stages. Abnormal gestation may be attributed to the direct effects of hypoxia on the conceptus and to its indirect effects which alter the tropic and endocrine support provided by the maternal system.

Animals↗

PubMed1995

[Effects of the maturity of human oocytes on fertilization and embryonic development: application of oocyte maturation in medium containing follicle-stimulating hormone].

A total of 2,145 oocytes from 355 IVF cycles were classified as overmature (O), mature (M), transitional (T), immature (I) and abnormal (A) according to the morphology of the corona radiata. The rates of fertilization (%F) and embryonic development (%D) per oocyte were the highest in the M group, and decreased significantly with the decreasing maturity of the oocytes (T and I) and were the lowest in the A group. Decreases in %F and %D were also observed in the O group. %F and %D were significantly higher in oocytes with a polar body (PB) than without a PB. Mature oocytes classified according to the morphology of the corona radiata had significantly higher %F and %D than those classified according to the morphology of the cumulus oophorus. %F and %D were increased when T-oocytes without a PB and I-oocytes were matured in vitro for 18-24 hours in medium supplemented with FSH. A normal female baby was delivered, following IVF-ET of two T-oocytes matured in vitro with FSH.

Adult↗

PubMed2001

Exposure to lead during critical windows of embryonic development: differential immunotoxic outcome based on stage of exposure and gender.

Previous rat studies with lead (Pb) have shown that exposure throughout the full gestational period results in persistent immunotoxicity detectable in both juvenile and adult offspring. Gender differences are also evident. However, little is known about the persistent immunotoxic effects of Pb when administered during specific stages of embryonic development. Adult Sprague-Dawley female rats were administered Pb acetate (or control acetate) in their drinking water early in gestation (days 3-9) or late in gestation (days 15-21). Significantly depressed delayed type hypersensitivity (DTH) responses as well as elevated IL-10 production, relative monocyte numbers, and increased relative thymic weights were observed in late-gestation Pb-exposed female offspring assessed as adults. In contrast, late-gestation Pb-treated male offspring had significantly increased IL-12 production and decreased IL-10 production, while the DTH response, relative monocyte numbers and thymic weights were unchanged. With early exposure, the primary alteration was decreased nitric oxide production in Pb-treated males, whereas in Pb-treated females nitrite production was unaltered. These results suggest that at the Pb dosage employed, the embryo may be more sensitive to the full range of Pb-induced immunotoxic effects with late gestational Pb exposure, and the effects of Pb on DTH function are more pronounced in females. The data also indicate that adherent splenocytes (probably macrophages) and T lymphocytes are the primary immune cells affected during fetal Pb exposure, and that gender may influence the impact of Pb exposure on these cells. Therefore, additional developmental immunotoxicity studies are needed to examine critical windows of immune development for immunotoxicity and differential susceptibility based on gender.

Adjuvants, Immunologic↗