Intrinsic forces alone are sufficient to cause closure of the neural tube in the chick

An isolated neural plate or a postnodal piece of early chick embryos, when cultured under appropriate experimental conditions, can undergo morphogenetic movements and form tubular structures closely resembling neural tubes of early chick embryos.     

Mast cells are present during angiogenesis in the chick extraembryonic vascular system

The extraembryonic vascular membranes of 3-day-18-day chick embryos were examined for the presence of mast cells. As early as 3.5 days mast cells were found on the area vasculosa. It is suggested that these cells have a role in angiogenesis of the chick extraembryonic vascular system.     

Mast cells are present during angiogenesis in the chick extraembryonic vascular system

Summary The extraembryonic vascular membranes of 3-day-18-day chick embryos were examined for the presence of mast cells. As early as 3.5 ddays mast cells were found on the area vasculosa. It is suggested that these cells have a role in angiogenesis of the chick extraembryonic vascular system.The work is supported by The Wellcome Trust.     

Lipid droplets of neuroepithelial cells are a major calcium storage site during neural tube formation in chick and mouse embryos

In situ precipitation of calcium (Ca²⁺) with fluoride and antimonate shows that Ca²⁺-specific precipitate is localized almost exclusively within lipid droplets of neuroepithelial cells during neural tube formation in chick and mouse embryos. The density of Ca²⁺ precipitate within lipid droplets is generally greater in the apical ends of cells situated in regions of the neuroepithelium that are actively engaged in bending. These findings suggest that lipid droplets, in addition to providing a source of metabolic fuel for developing neuroepithelial cells, also serve as Ca²⁺-storage and-releasing sites during neurulation.This study was supported by grants from the NIH (NS23200), the BRSG fund of UMDNJ, and the Busch Fund of Rutgers University. Dr Bush was supported by a New Jersey State Postdoctoral Fellowship.     

Lipid peroxidation caused by chinoform-ferric chelate in cultured neural retinal cells

Incorporation of chinoform-ferric chelate was demonstrable in cultured neural retinal cells of chick embryos after 1 h of incubation, and the lipid peroxide level in the cells was increased strikingly 1 h thereafter. On the other hand, free ferric ions were scarcely incorporated into the cells, and a significant increase in the lipid peroxide level in the cells was not observed. These data indicate that chinoform is carrier of iron for its passage through cell membranes and that the incorporated iron induces lipid peroxidation which in turn leads to neural cell degeneration.     

Application of chemicals in early chick embryos in ovo: A precaution

Summary A passive diffusion method is described and is compared with other methods for the application of chemicals in early chick embryos in ovo.Acknowledgments. We thank Mrs Irene Panagopoulou for expert technical assistance.     

Ventral neural tube cells differentiate into hepatocytes in the chick embryo

A population of ventral neural tube cells has recently been shown to migrate out of the hind brain neural tube via the vagus nerve and contribute to the developing gastrointestinal tract. Since liver is also innervated by the vagus nerve, we sought to determine if these cells also migrate into the liver. Ventral neural tube cells in the caudal hindbrain of chick embryos were tagged with a replication-deficient retroviral vector containing the LacZ gene on embryonic day 2. Embryos were processed for detection of labeled cells on embryonic day 5 and 11. Labeled cells were seen in the liver on both days and identified as hepatocytes. Previously, it was believed that all hepatocytes develop from the gut endoderm. Results of the present study show an additional source for the formation of liver cells. Received 25 August 1998; received after revision 5 November 1998; accepted 5 November 1998     

The early differentiation of the perinotochordal connective tissue. A scanning and transmission electron microscopic study on chick embryos (author's transl)]

The early differentiation of the connective tissue was investigated in the perinotochordal zone of 2-3 day-old chick embryos. After characterizing the different tissue components by transmission electron microscopy, their arrangement and distribution were examined by SEM. The results are discussed with regard to the role of the extracellular material in embryonic tissue interactions.     

Elektronenmikroskopischer Nachweis spezifischer Grana in den Sympathicoblasten der Grenzstrangganglien von Hühnerembryonen

Summary With regard to the cytodifferentiation of neurones in the developing CNS and the spinal ganglia, only the sympathoblasts of the primary and secondary sympathic trunk of chick embryos contain a varying amount of catechol amine-containing granules. The formation of these granules takes place in rather early stages of development.     

Lipid peroxidation caused by chinoform-ferric chelate in cultured neural retinal cells

Summary Incorporation of chinoform-ferric chelate was demonstrable in cultured neural retinal cells of chick embryos after 1 h of incubation, and the lipid peroxide level in the cells was increased strikingly 1 h thereafter. On the other hand, free ferric ions were scarcely incorporated into the cells, and a significant increase in the lipid peroxide level in the cells was not observed. These data indicate that chinoform is carrier of iron for its passage through cell membranes and that the incorporated iron induces lipid peroxidation which in turn leads to neural cell degeneration.This work was supported in part by a grant from the Ministry of Health and Welfare of Japan     

Molecular and Cellular Basis of Regeneration and Tissue Repair

Although early after birth the central nervous system is more plastic than in the adult, it already displays limited regenerative capability. This becomes severely impaired at specific stages of embryonic development; however, the precise cellular and molecular basis of this loss is not fully understood. The chick embryo provides an ideal model for direct comparisons of regenerating and non-regenerating spinal cord within the same species because of its accessibility in ovo, the extensive knowledge of chick neural development and the molecular tools now available. Regenerative ability in the chick is lost at around E13, a relatively advanced stage of spinal cord development. This is most likely due to a complex series of events: there is evidence to suggest that developmentally regulated changes in the early response to injury, expression of inhibitory molecules and neurogenesis may contribute to loss of regenerative capacity in the chick spinal cord.     

Toxicity of Phytophthora infestans and Alternaria solani to chick embryos

None of the extracts and culture filtrates from growth of 9 races of Phytophthora infestans on living potato tissue and potato dextrose broth are toxic to chick embryos. Chloroform extracts of 4 out of 10 isolates of Alternaria solani grown on potato dextrose broth showed some toxicity to chick embryos.     

Direct demonstration of production of transforming growth factor activity by embryonic chick tissue

Summary The presence of transforming growth factor activity in early chick embryos was directly demonstrated by the ability of limb and tail buds to induce anchorage independent division in NRK 49f cells. Colony number increased with limb bud number and developmental stage. Medium conditioned by tail buds contained some stimulating effect, and strongly promoted the action of other transforming growth factors.     

Direct demonstration of production of transforming growth factor activity by embryonic chick tissue

The presence of transforming growth factor activity in early chick embryos was directly demonstrated by the ability of limb and tail buds to induce anchorage independent division in NRK 49 f cells. Colony number increased with limb bud number and developmental stage. Medium conditioned by tail buds contained some stimulating effect, and strongly promoted the action of other transforming growth factors.     

Neural inducing capacity of cyclic AMP on post-nodal pieces of early chick blastoderms

Summary Cyclic AMP (0.5 mM) induced neural differentiation in post-nodal pieces of early chick blastoderms, at least in part, through promoting cell movement, tissue condensation, and assembly of microtubules.This study was supported in part by grants from the Rutgers University Research Council.     

Étude comparée de la multiplication des cellules germinales à la fin de la première semaine de la vie embryonnaire chez trois espèces de Gallinacés (Gallus domesticus,Meleagris gallopavo,Coturnix coturnix japonica)

Summary Counts were made of the numbers of germ cells in quail embryos aged 4–7 days' incubation. The rate of growth in the population of gonocytes was compared to these of chick and turkey embryos during the same period. The increase is exponential in the three species and the rates are more similar between quail and turkey than between each of them and the chick.     

A procedure for the rapid freezing of whole embryos.

A procedure for the rapid freezing of whole chick embryos for histochemical treatment is described. The problems of deformation during preparation for quenching and orientation for sectioning have been largely overcome by placing embryos inside lengths of chicken trachea. The subsequent disorientation of tissues that follows cracking and shattering due to the rapid freezing of whole embryos is avoided. The method permitted a more precise identification of the position and time of appearance of formaldehyde-induced fluorescence and myosin antibody immunofluorescence in serially sectioned embryos.     

Development of rhythmic melatonin synthesis in cultured pineal glands and pineal cells isolated from chick embryo

The chick pineal gland exhibits circadian rhythms in melatonin synthesis under in vivo and in vitro conditions. A daily rhythm of melatonin production was first detectable in pineal glands isolated from chick embryos at embryonic day 16 and incubated under a LD cycle. All pineal glands isolated from 17-day-old and older embryos were rhythmic while no gland isolated at embryonic day 14 and 15 exhibited a daily rhythm in melatonin synthesis. Melatonin production in static cultures of embryonic pineal cells was rhythmic over 48 h if the cells were kept under a LD cycle. When embryonic pineal cells were incubated in constant darkness the rhythm in melatonin production was damped within 48 h. These results suggest that chick pineal cells from embryonic day 16 onwards are photosensitive but that the endogenous component of the melatonin rhythm is not completely developed at that age. A soluble analogue of cAMP stimulated and norepinephrine inhibited melatonin synthesis in cultured embryonic pineal cells. These findings indicate that the stimulatory and inhibitory pathways controlling melatonin synthesis in the mature pineal gland are effective in pineal cells isolated from chick embryos at least 2 days before hatching.     

Innervation of the ovarian interstitial cell of the chick embryo

Summary Electron microscopic examination of the developing ovary of 15–20-day chick embryos revealed that the interstitial cells were well innervated. Nerve fibres and nerve endings were observed in close contact with steroid-producing cells.