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Multiple subpopulations of avian neural crest cells arising in culture
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THE NEURAL CHEST HYPOTHESIS: A REFUTATION REFUTED. J. McCredie, Department of Surgery, University of Sydney, N.S.W., 2006, Australia. Strecker and Stephens (Teratology 27: 159-167, 1983) tested the hypothesis that congenital limb reduction defects result from damage to the neural crest or peripheral nerves. They inserted foil barriers into 2 day chick embryos to separate wing bud from neural tube. Barriers placed lateral to mesonephros caused reduction deformities of the wings. Barriers placed between neural tube and somites resulted in normal wing development. The conclusion, that skeletal morphogenesis is independent of innervation, is challenged. Both experiments separated neural tube from limb bud, but only the first experiment could have separated neural crest from limb bud. The published results provide evidence in support of, rather than against, the neural crest hypothesis.
SORTING OF CELLS DESCENDED FROM SINGLE BLASTOMERES OF XENOPUS EARLY EMBRYOS. T.Mikawa and C.Koseki. Department of Molecular Physiology, National Institute for Physiological Sciences, Okazaki, 444, Japan. Bovine serum albumin (m.w.68,000) covalently labelled with fluorescein isothiocyanate (FITC), as a cell lineage linked tracer, were injected into single cells in a series of Xenopus blastulae. Embryos were allowed to develop to the appropriate stage and were pulse-labelled with J5S-methionin. They were transferred into the medium free of calcium ions. All the cells of embryos were dispersed to single cells after surgical removal of vitelline membrane. FITC-labelled cells which were descended from single blastomeres were collected by cell sorter (FACS II). Proteins containing 35S-methionin were separated by two dimensional gel electrophoresis and were identified by the autoradiography. We have found that several peptides were synthesized specifically to the descendent cells of blastomeres which were localized at the animal-dorsal part of blastulae.
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RETINAL DEVELOPMENT IN THE LIZARD CALOTES VERSICOLOR: I. CHRONOHISTOMORPHOMETRY OF 5~TOSIS, REGiONALIZATION AND CELL DEATH.S. L.Shinde and S.C.Goel. MACS Research Institute, Pune 411 004, and Zoology Department,Poona University,Pune 411 O07,1ndia. The neural retina during its development passes through four overlapping phases: proliferation(stage 25-35),regionalization(stage 32-37),celi death(stage 35+ -37, and 41) and cell differentiation(stages 39-42). The development proceeds from the central to the peripheral region of the optic cup. The mitotic nuclei are located towards the pigment epithelium and interkinetic nuclear redisposition occurs before regionalization. During regionalization eight layers,including the three nuclear layers are formed. The first wave of cell death sweeps across the inner nuclear layer(INL) and ganglion cell layer(GCL), and at the peak time up to 15% nuclei in GCL and 9% nuclei in INL are pycnotic. This perhaps contributes to the appearance of a transient 'split-line' in the INL. The second wave of cell death is mild and restricted to peripheral areas of INL. This is the most detailed light microscopic study so far on any vertebrate;it provides quantitative data on cell death,and highlights new features.
MULTIPLE SUBPOPULATIONS OF AVIAN NEURAL CREST CELLS ARISING IN CULTURE. K. Vogel and J.A. Weston, Department of Biology, University of Oregon, Eugene, Oregon, 97403. The embryonic neural crest gives rise to a wide variety of cell types, including sensory and autonomic neurons. To investigate the generation of this phenotypic diversity, quail neural crest cell cultures were immunocytochemically stained with the mo~ioclonal antibody A2B5, which recognizes a n e u r o n - s p e c i f ~ ganglioside, and with a monospecific antiserum against the autonomic marker tyrosine hydroxylase (TH). Although some crest cells were both A2B5+ and TH+, other cells exhibited immunoreactivity for only one of either of the two markers. Similar results were obtained when crest cell cultures were doublelabelled using A2B5 and the glyoxylic acid-induced fluorescence technique for catecholamines. We interpret these results to be indicative of the phenotypic heterogeneity present in early crest cell populations in vitro. Supported by NSF Fellowship RCD8450115 to K.V.
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THE NEURAL CHEST HYPOTHESIS: A REFUTATION REFUTED. J. McCredie, Department of Surgery, University of Sydney, N.S.W., 2006, Australia. Strecker and Stephens (Teratology 27: 159-167, 1983) tested the hypothesis that congenital limb reduction defects result from damage to the neural crest or peripheral nerves. They inserted foil barriers into 2 day chick embryos to separate wing bud from neural tube. Barriers placed lateral to mesonephros caused reduction deformities of the wings. Barriers placed between neural tube and somites resulted in normal wing development. The conclusion, that skeletal morphogenesis is independent of innervation, is challenged. Both experiments separated neural tube from limb bud, but only the first experiment could have separated neural crest from limb bud. The published results provide evidence in support of, rather than against, the neural crest hypothesis.
SORTING OF CELLS DESCENDED FROM SINGLE BLASTOMERES OF XENOPUS EARLY EMBRYOS. T.Mikawa and C.Koseki. Department of Molecular Physiology, National Institute for Physiological Sciences, Okazaki, 444, Japan. Bovine serum albumin (m.w.68,000) covalently labelled with fluorescein isothiocyanate (FITC), as a cell lineage linked tracer, were injected into single cells in a series of Xenopus blastulae. Embryos were allowed to develop to the appropriate stage and were pulse-labelled with J5S-methionin. They were transferred into the medium free of calcium ions. All the cells of embryos were dispersed to single cells after surgical removal of vitelline membrane. FITC-labelled cells which were descended from single blastomeres were collected by cell sorter (FACS II). Proteins containing 35S-methionin were separated by two dimensional gel electrophoresis and were identified by the autoradiography. We have found that several peptides were synthesized specifically to the descendent cells of blastomeres which were localized at the animal-dorsal part of blastulae.
469
470
RETINAL DEVELOPMENT IN THE LIZARD CALOTES VERSICOLOR: I. CHRONOHISTOMORPHOMETRY OF 5~TOSIS, REGiONALIZATION AND CELL DEATH.S. L.Shinde and S.C.Goel. MACS Research Institute, Pune 411 004, and Zoology Department,Poona University,Pune 411 O07,1ndia. The neural retina during its development passes through four overlapping phases: proliferation(stage 25-35),regionalization(stage 32-37),celi death(stage 35+ -37, and 41) and cell differentiation(stages 39-42). The development proceeds from the central to the peripheral region of the optic cup. The mitotic nuclei are located towards the pigment epithelium and interkinetic nuclear redisposition occurs before regionalization. During regionalization eight layers,including the three nuclear layers are formed. The first wave of cell death sweeps across the inner nuclear layer(INL) and ganglion cell layer(GCL), and at the peak time up to 15% nuclei in GCL and 9% nuclei in INL are pycnotic. This perhaps contributes to the appearance of a transient 'split-line' in the INL. The second wave of cell death is mild and restricted to peripheral areas of INL. This is the most detailed light microscopic study so far on any vertebrate;it provides quantitative data on cell death,and highlights new features.
MULTIPLE SUBPOPULATIONS OF AVIAN NEURAL CREST CELLS ARISING IN CULTURE. K. Vogel and J.A. Weston, Department of Biology, University of Oregon, Eugene, Oregon, 97403. The embryonic neural crest gives rise to a wide variety of cell types, including sensory and autonomic neurons. To investigate the generation of this phenotypic diversity, quail neural crest cell cultures were immunocytochemically stained with the mo~ioclonal antibody A2B5, which recognizes a n e u r o n - s p e c i f ~ ganglioside, and with a monospecific antiserum against the autonomic marker tyrosine hydroxylase (TH). Although some crest cells were both A2B5+ and TH+, other cells exhibited immunoreactivity for only one of either of the two markers. Similar results were obtained when crest cell cultures were doublelabelled using A2B5 and the glyoxylic acid-induced fluorescence technique for catecholamines. We interpret these results to be indicative of the phenotypic heterogeneity present in early crest cell populations in vitro. Supported by NSF Fellowship RCD8450115 to K.V.
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