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Results for “Organizers, Embryonic”

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At least 19 recordsLinked to original sources
PubMed1994

SEM observation and GABA immunoreactivity of human embryonic organ of Corti tissue culture.

Scanning electronic microscopy (SEM) observation and GABA immunoreactivity of the tissue culture of 6 human embryonic organs of Corti are reported. The normal structural appearance of the hair cells and the facts that there were no bulging of cuticular plates, and cytoplasmic protrusion proved that the hair cells were healthy. After GABA immunostaining, radial bundles, innerspiral bundles, and the ending of inner and outer hair cell regions displayed typical GABA-positive reactivity. The results indicate that the human embryonic organ of Corti is well developed differentiated, and mature at 19 gestational weeks and can continue to grow and differentiate in vitro. The study offers an ideal and important biological model for further research into the human ear.

Culture Techniques↗
PubMed1978

[Differentiation of hematopoietic cells in explants of embryonal organs of Rana temporaria L].

The potencies of isolated embryonic hemopoietic organs (pronephros and liver) of Rana temporaria L. to the formation of the foci of hemopoiesis were studied. The pronephros and liver rudiments were explanted at the early developmental stages (late neurula and early tail bud) and cultivated in vivo in the diffusion chambers. The blast hemopoietic elements and differentiated blood cells are found in the explants within 7 to 10 days of cultivation. A suggestion is put forward that the differentiation of hemopoietic cells in the embryonic hemopoietic organs proceeds from the local cells-precursors.

Animals↗
PubMed1987

Teratological research using in vitro systems. III. Embryonic organs in culture.

A search of literature published through the spring of 1986 yielded approximately 95 citations for the following embryonic organs in culture: kidney, pancreas, skin, palate, craniofacial tissue, tooth, lens, bones, digits, and liver. However, only the in vitro organ culture of the palate and tooth are reviewed in this paper. The other organ culture systems were not reported as teratogenic screens. Although some organs may have the potential for such use, many are currently used for evaluation of the pathogenesis associated with congenital abnormalities, cancer, or transplacental carcinogenesis, or in studies of the structure and function of differentiating organs, and will not be included in this review.

Animals↗
PubMed2001

MAPK signaling by the D quadrant embryonic organizer of the mollusc Ilyanassa obsoleta.

Classical experiments performed on the embryo of the mollusc Ilyanassa obsoleta demonstrate that the 3D macromere acts as an embryonic organizer, by signaling to other cells and inducing them to assume the correct pattern of cell fates. We have discovered that MAP kinase signaling is activated in the cells that require the signal from 3D for normal differentiation. Preventing specification of the D quadrant lineage by removing the polar lobe disrupts the pattern of MAPK activation, as does ablation of the 3D macromere itself. Blocking MAPK activation with the MAP Kinase inhibitor U0126 produces larvae that differentiate the same limited complement of tissues as D quadrant deletions. Our results suggest that the MAP Kinase signaling cascade transduces the inductive signal from 3D and specifies cell fate among the cells that receive the signal.

Animals↗
PubMed1997

Glycosaminoglycan analysis in amniotic fluid and in cultured fibroblasts from normal and holoprosencephalic human embryonic organs.

Glycosaminoglycans are polysaccharides involved in epithelial-mesenchymal interaction and cell differentiation and provide a meshwork which is essential to maintain a proper intercellular milieu. The development of embryonic organs can be accompanied by alterations in the glycosaminoglycan pattern. In pregnancies with malformed fetuses, there are alterations in total glycosaminoglycans and their components (chondroitin 4-6 sulphate, dermatan sulphate, and hyaluronic acid) in amniotic fluid. We examined total glycosaminoglycans and the percentage variations of the single classes in both amniotic fluid and culture medium of fibroblasts from heart, lung, and skin obtained from five normal human fetuses and one with holoprosencephaly. In the amniotic fluid total glycosaminoglycans and their sulphate classes were increased, whereas hyaluronic acid was decreased, compared with controls. The extracellular glycosaminoglycans showed hyaluronic acid reduction in skin, while chondroitin 4-6 sulphate plus dermatan sulphate and heparan sulphate were higher in skin and heart. Our data demonstrate that variations in the glycosaminoglycan pattern are associated with alterations of the cellular environment, which can prevent normal organogenesis.

Amniotic Fluid↗
PubMed1999

Ovalbumin in developing chicken eggs migrates from egg white to embryonic organs while changing its conformation and thermal stability.

Ovalbumin was detected in developing chicken eggs. The large majority of these ovalbumin molecules was found to be in a heat-stable form reminiscent of S-ovalbumin. About 83 and 90% of the ovalbumin population was in a heat-stable form in day 14 or stage 40 amniotic fluid and day 18 or stage 44 egg yolk, respectively, whereas ovalbumin in newly deposited eggs was in the heat-unstable, native form. Purified preparations of stable ovalbumin from egg white and amniotic fluid showed a less ordered configuration than native ovalbumin, as analyzed by circular dichroism and differential scanning calorimetry. In addition, mass spectrometric analysis exhibited distinct size microheterogeneity between the stable and native forms of ovalbumin. Immunohisotochemical study revealed that ovalbumin was present in the central nervous system and other embryonic organs. These results indicated that egg white ovalbumin migrates into the developing embryo while changing its higher order structure.

Amino Acid Sequence↗
PubMed2001

Multiple-site optical recording reveals embryonic organization of synaptic networks in the chick spinal cord.

We examined embryonic expression of postsynaptic potentials in stages 26-31 (E5 to E7) chick spinal cord slices. Slow optical signals related to the postsynaptic potentials which were evoked by electrical stimulation of afferent fibers were identified in the dorsal grey matter and the ventral motoneuronal area. In cervical spinal cord (C13) preparations, the dorsal slow signal appeared from stage 28 (E6), whilst the ventral slow signal was recognized from stage 29. At stages 26 and 27 (E5), no slow signal was observed in either the dorsal or ventral regions. On the other hand, in lumbosacral spinal cord (LS5) preparations, the dorsal, as well as ventral, slow signals appeared from stage 29; at stage 28 no slow signal was detected in the dorsal or ventral regions. These results suggest that there are differences in the ontogenetic expression of synaptic functions between the dorsal and ventral regions, and between the cervical and lumbosacral spinal cords. In embryos older than stage 29, removal of Mg2+ from the bathing solution markedly enhanced the amplitude and incidence of the ventral slow signal. In addition, in C13 preparations at stage 28, removal of Mg2+ elicited small slow signals in the ventral region in which no synaptic response was evoked in normal Ringer's solution. The slow signals induced in the Mg2+-free solution were blocked by 2-amino-5-phosphonovaleric acid (APV), showing that they are attributable to N-methyl- D-aspartate (NMDA) receptors. These results suggest that functional synaptic connections via polysynaptic pathways are already generated on motoneurons, but are suppressed by a Mg2+ block on the NMDA receptors at developmental stages when synaptic transmission from the primary afferents to the dorsal interneurons is initially expressed in the dorsal region.

Animals↗
PubMed1992

Human embryonic organ of Corti in tissue culture and NSE expression.

For the first time ever, the cochlear tissue of the human embryo has been successfully grown in vitro in two cases, and neuro-specific enolase (NSE) immunoreactivity was studied in one of these tissues. The outer hair cells were arranged in three rows, and the inner hair cells in one row and in better order than the outer hair cells. After NSE immunostaining, the outer spiral bundle, tunnel fiber, outer hair cells, inner hair cells, and the spiral ganglion cells showed positive staining. This data suggests that the human embryonic cochlea has nearly reached complete maturation by 16 weeks, and that the tissue of the Corti organ can be differentiated and matured in vitro.

Cochlea↗
PubMed1993

Sequential expression of HNF-3 beta and HNF-3 alpha by embryonic organizing centers: the dorsal lip/node, notochord and floor plate.

Axial patterning in the nervous system of vertebrate embryos depends on inductive signals that derive from the organizer region (the dorsal lip in amphibians and the node in birds and mammals) and leter from the notochord and floor plate. Previous studies have shown that Pintallavis, a member of the HNF-3/fork head transcription factor family, is expressed selectively by these cell groups in frog embryos and may be involved in regulating neural development. We report here that in early rat and mouse embryos, the embryonic endoderm, the node, the notochord and the floor plate express two related transcription factors, HNF-3 alpha and HNF-3 beta, which also function in the control of liver cell differentiation. Early embryonic tissues express variant forms of HNF-3 beta which derive from the use of 5' alternative exons. Within the organizer region and notochord, HNF-3 beta and HNF-3 alpha have distinct temporal patterns of expression and appear in partially overlapping domains. The early expression pattern of mammalian HNF-3 beta in the node, notochord and midline neural plate cells is similar to that of Pintallavis in frog embryos. There does not appear to be a Pintallavis homologue in mice. This prompted us to isolate and analyze the expression of the frog HNF-3 beta gene. In frog embryos, HNF-3 beta is expressed in the dorsal lip, pharyngeal endoderm and floor plate. In contrast to mammalian HNF-3 beta, the onset of frog HNF-3 beta expression in neural tissue occurs after neural tube closure. Thus, the combined expression patterns of Pintallavis and HNF-3 beta in frogs is equivalent to that of HNF-3 beta in rats and mice. Within neural tissue, the onset of expression of these regulatory genes define successive stages in the differentiation of floor plate cells. The results reported here show that closely related members of the HNF-3/fork head gene family are expressed by axial midline cell groups involved in neural induction and patterning and suggest the involvement of these genes in the development of the vertebrate neuraxis.

Amino Acid Sequence↗
PubMed1995

Cytoplasmic HSP70 homologues of pea: differential expression in vegetative and embryonic organs.

Eukaryotes express several cytoplasmic HSP70 genes, and their encoded proteins participate in diverse cellular processes. Three cDNAs encoding highly expressed cytoplasmic HSP70 homologues from Pisum sativum were cloned and characterized. They were designated PsHSP71.2, PsHSC71.0, and PsHSP70b. These HSP70 genes have different expression profiles in leaves: PsHSP71.2 is observed only in response to heat stress, PsHSC71.0 is present constitutively, and PsHSP70b is weakly constitutively expressed, but induced strongly in response to heat stress. In addition to being heat induced, the PsHSP71.2 mRNA is also expressed in zygotic, but not maternal organs of developing pea seeds, while PsHSC71.0 and PsHSP70b mRNAs are present in maternal and zygotic organs throughout seed development. Immunoblot analysis of parallel protein samples detects a 70 kDa polypeptide in all samples, and a 72 kDa polypeptide that corresponds to the PsHSP71.2 gene product is observed in cotyledons beginning at mid-maturation and in axes beginning between late maturation and desiccation. This polypeptide is not detected in the seed coat. The 72 kDa polypeptide remains abundant in both cotyledons and axes through germination, but declines substantially between 48 and 72 h after the onset of inbibition. Differential control of HSP70 expression during heat stress, seed maturation, and germination is consistent with the hypothesis that there are functional distinctions between cytoplasmic HSP70s.

Amino Acid Sequence↗