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Results for “Embryonic Development”

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At least 217 records · Page 12Linked to original sources

PubMed2003

In vivo imaging of embryonic development in the mouse eye by ultrasound biomicroscopy.

PURPOSE: New imaging tools now provide an unprecedented opportunity to visualize anatomic and functional development of the mouse eye. In this study, normal embryonic development of the mouse eye was studied by ultrasound biomicroscopy (UBM), with a focus on the formation of the retina, lens, and cornea. METHODS: The growth of 65 embryonic eyes from timed-pregnant CD-1 mice was examined at various stages of development between embryonic day (E)11.5 and E18.5, using 40-MHz UBM. RESULTS: The morphogenesis of ocular tissues including the lens, retina, and orbit were revealed from the earliest stages of development. The major axis of the CD-1 lens grows at a rate of 68 micro m/d, whereas that of the globe grows at a rate of 122 microm/d, with a concomitant exponential increase in volume. CONCLUSIONS: UBM allows noninvasive assessment of ocular morphogenesis in vivo and can be used to calculate relative growth rates of ocular structures.

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PubMed2005

Gli1 is not required for Pdgfralpha expression during mouse embryonic development.

Pdgfra is expressed in the mesenchyme of multiple organs during embryonic development and Pdgfralpha is involved in cell proliferation, differentiation, migration, and apoptosis in many tissues. A fine-tuned regulation of gene transcription is required to achieve these effects. To investigate if the Shh signaling pathway is involved in the tightly regulated Pdgfra expression during embryogenesis, we systematically compared Gli1 and Pdgfralpha mRNA expression patterns in vivo from mouse embryonic day 9.5 to 14.5. We found that an initial partly overlapping expression of Gli1 and Pdgfralpha in the mesenchyme of foregut and somites was changed to different expression patterns when the mesenchyme differentiated into specialized structures such as intestinal villi and chondrocytes. Gli1 and Pdgfra were also expressed differently in the developing lung, heart, central nervous system, skin, tooth, and eye. Importantly, neither Pdgfralpha mRNA patterns nor levels were altered in Ihh mutant embryos although Gli1 and Ptc mRNA levels were dramatically reduced. Our results demonstrate that Gli1 is not required to induce Pdgfra expression during embryonic bone development, and are consistent with previous findings that Pdgfralpha and Hh pathways serve different functions in, e.g., bone, gut, and lung development. However, we cannot exclude the possibility that Glis can have more complex regulatory effects on Pdgfra gene activity, nor can we exclude such effects in pathological conditions.

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PubMedDate not supplied

Pre-implantational timetable of embryonal development of Myocastor coypus (Coypu).

The purpose of the present study was to determine the chronology of the pre-implantation embryonic development in Myocastor coypus (coypu). It was carried out by daily colpocytological examination and controlled mating of 33 females. Oocytes and embryos were obtained by flushing from day 0 to day 10 post-coitus (p.c.). On day 1 p.c., oocytes predominated whereas on day 2 p.c. zygotes were predominant. The cleavage period was from day 3 to day 6 p.c.. Morulae were collected from day 6 to day 9 p.c., whereas blastocysts were collected on days 8 and 9. From oviduct flushing, the embryos in the zygote stage and up to the morula stage with less than a 30-cell stage were recovered. Embryos in the morula stage with 30 or more cells and up to the growing blastocyst stage were collected from the flushing of hemiuteri.

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PubMed1994

Inhibition of in vitro fertilization and early embryonic development in hamsters by gossypol.

We have previously reported an inhibitory effect of gossypol and its metabolite on bovine and mouse early embryonic development. In the present study, eggs were collected from oviducts of superovulated hamsters. Epididymal sperm were used for in vitro fertilization (IVF). Gossypol at 5, 10, and 30 micrograms/ml significantly inhibited the formation of 2 pronuclei by 45, 65 and 95%, respectively. On the first day of pregnancy, hamsters were given an intrauterine treatment of 200 micrograms of gossypol in 100 microliters of corn oil per uterine horn. On day 3, embryos from controls were in morula (65%) and early morula (17%) stages, while less than 2% of embryos from the gossypol-treated hamsters were in the morula stage. The numbers of embryo implantation sites on day 8 and pups in controls (14 +/- 2.0 and 12 +/- 1.5, respectively) were significantly higher than those in the gossypol-treated hamsters (8.5 +/- 2.0 and 4.0 +/- 1.5, respectively). Our results suggest that gossypol is able to affect fertilization, embryonic development, embryo implantation, and the number of pups in hamsters through a not-yet-defined mechanism.

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PubMed1997

Differential responsiveness of somatotrophs to growth hormone-releasing hormone and thyrotropin-releasing hormone during chicken embryonic development.

This study was designed to evaluate responsiveness and sensitivity of pituitaries from chickens to growth hormone (GH) secretagogues during late embryonic development. Anterior pituitary cells from 16-, 18- and 20-day-old chicken embryos were subjected to reverse hemolytic plaque assays (RHPAs) for GH in the presence of GH-releasing hormone (GHRH) and thyrotropin-releasing hormone (TRH). The proportion of somatotrophs detected increased between embryonic days 16 and 20, from 16 to 19.5% of all pituitary cells. Sensitivity to GHRH and TRH was similar and increased between embryonic days 16 and 20. On embryonic day 16, about 50% of somatotrophs that were not detected under basal conditions released GH in the presence of GHRH at 2 and 6 h. In contrast, only 15 and 30% of day 16 somatotrophs released GH by 2 and 6 h, respectively, following exposure to TRH. Thus, at least one of five somatotrophs responded to GHRH but not to TRH. By embryonic day 20, the proportions of somatotrophs that responded to GHRH and TRH were approximately equal at about 40%. These results provide additional evidence that GHRH and TRH may be involved in hypothalamic regulation of GH secretion during chicken embryonic development. Furthermore, it appears that full differentiation of functional chicken somatotrophs does not occur abruptly but rather gradually between embryonic days 16 and 20, during which a subpopulation of GH cells undergoes changes in sensitivity and responsiveness to TRH.

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PubMed1992

The post-embryonic development of cell properties and synaptic drive underlying locomotor rhythm generation in Xenopus larvae.

In the first 24 h of post-embryonic development, the motor rhythm underlying swimming in Xenopus laevis tadpoles changes from brief (ca. 7 ms) ventral root discharge in each cycle to bursts of activity lasting around 20 ms (Sillar et al. 1991). Because individual motoneurons in the spinal cord of newly hatched embryos normally fire only a single impulse per cycle, two possible changes underly the transition to motor bursts seen in larval ventral roots; desynchronization of neurons in a given ventral root which continue to fire once per cycle, or the developmental acquisition of a multiple spike capability in individual motoneurons. Here we have recorded intracellularly from ventrally positioned spinal neurons, presumed to be myotomal motoneurons, in stage 37/38 embryos and 24 h later in development in stage 42 larvae. We find that (i) larval neurons are able to fire more than one impulse per cycle of fictive swimming activity; (ii) unlike in the embryo, they generally will fire multiple impulses in response to injected depolarizing current; (iii) the synaptic drive to motoneurons during swimming increases dramatically in complexity, although it still consists of alternating phases of synaptic excitation and chloride-dependent inhibition, superimposed upon tonic synaptic depolarization. The results therefore suggest a developmental change in the membrane properties of rhythmically active neurons as a major factor in the post-embryonic development of swimming in Xenopus larvae. This change appears to occur in premotor rhythm generating interneurons as well as in the motoneurons themselves and may satisfy a demand for behavioural flexibility that allows larvae to survive in a complex and changing environment.

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PubMed1983

Silver positivity of the NORs during embryonic development of Xenopus laevis.

Transcriptional activity of ribosomal RNA (rRNA) genes is detectable around blastula-gastrula transition during the embryonic development of amphibians and other non-mammalian systems. The silver staining reaction, known to selectively stain transcriptionally active nucleolus organizer regions (NORs) both in interphase and metaphase chromosomes allowed us to follow the activation of the NORs during the embryonic development of Xenopus laevis.

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PubMed1987

The effect of a carbon dioxide pneumoperitoneum on rabbit follicular oocytes and early embryonic development.

The effect of a carbon dioxide (CO2) pneumoperitoneum and its duration on rabbit follicular oocytes was assessed by evaluating fertilization and subsequent embryonic development rates. CO2 may cross the plasma membrane and form carbonic acid, which liberates H+, thus lowering the intracellular pH. There were no significant differences in arterial pH and [HCO3-] between CO2 and air treatment groups, whereas arterial pCO2 and pO2 were significantly increased in the CO2 treatment group. We found that the duration of pneumoperitoneum, irrespective of type of gas used, was negatively correlated with success of embryonic development. These findings necessitate that more attention be given to the gas used for creation of a pneumoperitoneum during egg retrieval for in vitro fertilization and an attempt be made to minimize duration of the pneumoperitoneum.

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PubMed1999

Apolipoprotein E (ApoE), a Bmp-2 (bone morphogenetic protein) upregulated gene in mesenchymal progenitors (C3H10T1/2), is highly expressed in murine embryonic development.

Apolipoprotein E (ApoE) was identified as upregulated by Bmp-2 (bone morphogenetic protein-2) in the murine mesenchymal progenitor cell line C3H10T1/2 by a subtractive cloning strategy. Expression of recombinant Bmps in mesenchymal C3H10T1/2 progenitors results in the differentiation into the osteogenic, the chondrogenic, and the adipogenic lineage. In addition, ApoE is also expressed in primary osteoblasts isolated from murine calvariae late in the in vitro osteoblast developmental sequence. To infer possible roles of ApoE in organogenesis and tissue differentiation, ApoE expression during mouse embryonic development was analyzed in murine midgestation and late embryonic development by in situ hybridization. ApoE is highly expressed at many sites of organ development (liver, brain, heart, eye, lung), probably in a subset of neural crest cells and ectodermal derivatives suggestive for important functions of ApoE during embryonic differentiation and organ development.

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PubMed2003

Temperature influence on embryonic development of Anopheles albitarsis and Anopheles aquasalis.

Temperature influence on the embryonic development of Anopheles aquasalis and An. albitarsis was investigated. At 26 degrees C, 75% and 60% of respectively An. aquasalis and An. albitarsis eggs hatched, with one peak of eclosion, between the 2nd and 3rd day after oviposition. At 20 +/- 2 degrees C, around 66-70% of An. aquasalis eggs hatched, with one eclosion peak, on the 5th day. On the other hand, An. albitarsis eclosion at 21+/- 2 degrees C decreased to 10-22%, with two eclosion peaks, on the 4th-5th day and on the 9th-12th day. These data indicate a stronger temperature influence over An.albitarsis than over An. aquasalis embryos.

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PubMed1981

Dynamics of the neurosecretory cells of the brain of Amsacta collaris Hampson (Lepidoptera: Artiidae) during post embryonic development.

A comprehensive account of the dynamics of the neurosecretory cells of the brain of Amsacta collaris Hampson, during post embryonic development has been given using largely PARF, as well as PF and PAVB techniques in whole mounts sections. On the basis of staining properties the neurosecretory cells have been distinguished into principal A, B and C types. These cell types have been further classified into A-1, A-2, A-3, and A-4; B-1, B-2, and C-1, C-2 subtypes. Occurrence of paired medial, lateral, optic, posterior, ventral and tritocerebral groups containing different types of cells in the brain of Amsacta collaris in specific development stages have been reported. It has been observed that in the 1st instar larvae, there is no distinction of subtypes of cells. The distinction of cells into respective subtypes starts from 2nd instar and onward. The number of cells are minimum in the 1st instar, which increases upto the sixth instar larva, and remain almost constant in the prepupa, and diapausing pupa. The maximum number of cells have been observed in the adult individuals. In addition to number and distribution, the secretory activity of different types of cells during post embryonic development have also been described.

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PubMed1983

[Ultrastructural study of embryonic development in Grantia compressa F. (Porifera, Calcarea)].

The embryonic development of Grantia compressa is studied by means of the electron microscope from the blastula inside the mesenchyme to the mature amphi-blastula released in the excurrent canals. The study of the different cellular categories of the embryon shows the distribution of the vitellin inclusions and their evolution. The ultrastructure of the "cellules en croix" is not in favour of a photoreceptor part.

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PubMed2004

Phosphatidylinositol 3-kinase signaling is involved in neurogenesis during Xenopus embryonic development.

Phosphatidylinositol 3-kinase (PI3K) has numerous cellular functions, including cell survival and proliferation. In this study, we demonstrated that the expression of the active form of PI3K induced dorsal differentiation and axis duplication and strongly induced the expression of neural markers. In contrast, the inhibition of PI3K activity by its dominant negative mutant induced the phenotype of losing posterior structures and the expression of ventral markers. Akt is an essential target of PI3K for neurogenesis. The expression of the active form of Akt induced axis duplication and increased the expression of neural markers. Inhibition of the Akt activity abolished the PI3K-induced double heads and axes. This signal transmits through its target, glycogen synthase kinase 3beta, which is known to mediate Wnt signaling for Xenopus development. These results identify a new function of PI3K/Akt signaling in axis formation and neurogenesis during Xenopus embryonic development and provide a direct link between growth factor-mediated PI3K/Akt signaling and Wnt signaling during embryonic development.

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PubMed2005

Effect of copper exposure during embryonic development on chemosensory function of juvenile fathead minnows (Pimephales promelas).

Fish rely on chemosensation to alert them of nearby predators. Recent evidence suggests that metals disrupt this chemical communication system. Our objective was to determine the chemical alarm response of juvenile fathead minnows after embryonic copper (Cu) exposure. Embryos were randomly assigned to one of two treatments: clean water or water containing 10 microg/L Cu. Once hatched, half of the Cu-exposed embryos were transferred to clean water (after hatch), while the other half remained in the Cu-contaminated water. Fish were tested using a triumvirate maze at the age of 84-96 d post-hatch. Fish reared in clean water significantly avoided the alarm cue. However, fish reared under continuous Cu exposure and those that were only exposed to Cu during embryonic development were unable to respond to the chemical alarm stimulus. Fish from all treatments did not respond to two control stimuli. Results from this study suggest that fish exposed to elevated Cu concentrations during embryonic development is sufficient to impair chemosensory function during later life stages. This could result in an inability to detect nearby predators by olfaction, which could lead to important ecological perturbations in populations inhabiting metal-contaminated systems.

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PubMed2006

Characterization of the human PAP1 gene and its homologue possible involvement in mouse embryonic development.

We have identified PAP1 gene, a novel member of the immunoglobulin superfamily (IGSF) from U251-pTet-p53 cell line, which carried a wild-type p53 transgene. The gene has been localised to chromosome 16p12-13. Alignment of the predicted protein sequence for Human, Pan troglodytes, Canis, Mus musculus and Gallus gallus revealed it was highly conserved. Its homologue, IGSF6, possible involves in mouse embryonic development. The presence of IGSF6 specific transcript was detected by Northern blot in the RNAs extracted from 11 to 14 day postconception. IGSF6 expression is different in mouse embryos of the different ages. In situ hybridization performed on mice embryos sections showed the differential presence of IGSF6 in developing lung and kidney. This structure and differential expression suggests a function involvement in embryonic development, perhaps involvement in cell proliferation.

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PubMed1996

Metamorphosis: an exquisite model for hormonal regulation of post-embryonic development.

Metamorphosis in invertebrates and vertebrates, a process highly conserved throughout evolution, is an ideal model for studying mechanisms of post-embryonic development regulated by external signals. Amphibian metamorphosis also shares many similarities with mammalian development in the perinatal period. The precocious induction in vivo and in culture of insect and amphibian metamorphosis by exogenous thyroid hormones, and its retardation or inhibition by prolactin (PRL), have allowed the analysis of such characteristic features of post-embryonic development as morphogenesis, tissue remodelling, gene reprogramming, and programmed cell death. Recent studies on metamorphosis have revealed the important role played by such processes as auto-and cross-regulation of thyroid hormone receptor (TR) genes and by cell death or apoptosis, as in the maturation of the central nervous system, tissue restructuring and organolysis.

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PubMed2007

Cytoplasmic glutathione regulated by cumulus cells during porcine oocyte maturation affects fertilization and embryonic development in vitro.

It is generally accepted that cumulus cells support the nuclear maturation of mammalian oocytes. In the present study, we examined relationships between the cytoplasmic glutathione (GSH) content of porcine oocytes, and oocyte nuclear maturation, fertilization or subsequent embryonic development. Cumulus-oocyte complexes (COCs; control group) and oocytes denuded of cumulus cells after collection (DO 0h group) were cultured for 24h with dibutyryl cAMP, eCG and hCG (first culture step) and then for a further 20h without supplements (second culture step; 44h total culture). After the first culture step, some of the COCs were denuded, either completely (DO 24h group) or partly (H-DO 24h group), and then matured by the second culture step. Also, in the second culture step, some DOs were co-cultured with cumulus cells that had been pre-cultured for 24h (DO 24h+CC group). The maturation rates of all the cumulus-removed groups (DO 0h, DO 24h, H-DO 24h and DO 24h+CC groups) were lower (34.3-45.0%) than that of the control group (64.5%; P<0.05). The GSH contents of matured oocytes in the completely denuded groups (DO 0h, DO 24h and DO 24h+CC groups) were lower (4.03-5.26pmol/oocyte) than that of the control group (9.60pmol/oocyte; P<0.05); however, the H-DO 24h group had an intermediate value (7.0pmol/oocyte). The male pronuclear formation rates of completely denuded oocytes were lower (41.4-59.3%) than that of the control group (89.4%; P<0.05), whereas the H-DO 24h group had an intermediate rate (80.0%). The blastocyst formation rates of the completely denuded oocytes were lower (3.0-4.5%) than that of the control group (19.9%; P<0.05), and the H-DO 24h group again had an intermediate rate (11.6%). The GSH content was correlated with the rates of male pronuclear formation (P<0.01) and blastocyst formation (P<0.01), and also with the number of cells per blastocyst (P<0.01). In conclusion, we inferred that GSH synthesized by intact cumulus cells during maturation culture improved oocyte maturation and played an important role in fertilization and embryonic development.

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PubMed2004

Ovca1 regulates cell proliferation, embryonic development, and tumorigenesis.

Loss of OVCA1/DPH2L1 correlates with ovarian and breast cancer. To study its in vivo role, we generated Ovca1 mutant alleles in mice. Ovca1 heterozygotes spontaneously develop cancer. Ovca1 mutant mice die during embryonic development and at birth with developmental delay and defects in multiple organ systems. Cell proliferation defects were observed in Ovca1 mutant mouse embryonic fibroblasts (MEFs). p53 deficiency can rescue these Ovca1 mutant MEF proliferation defects and partially rescue Ovca1 mutant embryonic phenotypes. Furthermore, Ovca1; p53 double heterozygotes developed tumors quicker than p53 heterozygotes and with an increased carcinoma incidence. Multiple tumor burden in Ovca1 heterozygotes that were also p53 deficient was significantly higher than in p53 homozygous mutants. These in vivo findings demonstrate that Ovca1 is a tumor suppressor that can modify p53-induced tumorigenesis and suggest that it acts as a positive regulator for cell cycle progression. The close linkage of OVCA1 and p53 on human Chromosome 17 suggests that coordinated loss may be an important mechanism for the evolution of ovarian, breast, and other tumor phenotypes.

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