Quail

About: Quail is a research topic. Over the lifetime, 5908 publications have been published within this topic receiving 110618 citations.

Astrocytes induce blood–brain barrier properties in endothelial cells

Abstract: The highly impermeable tight junctions between endothelial cells forming the capillaries and venules in the central nervous system (CNS) of higher vertebrates are thought to be responsible for the blood-brain barrier that impedes the passive diffusion of solutes from the blood into the extracellular space of the CNS. The ability of CNS endothelial cells to form a blood-brain barrier is not intrinsic to these cells but instead is induced by the CNS environment: Stewart and Wiley demonstrated that when avascular tissue from 3-day-old quail brain is transplanted into the coelomic cavity of chick embryos, the chick endothelial cells that vascularize the quail brain grafts form a competent blood-brain barrier; on the other hand, when avascular embryonic quail coelomic grafts are transplanted into embryonic chick brain, the chick endothelial cells that invade the mesenchymal tissue grafts form leaky capillaries and venules. It is, however, not known which cells in the CNS are responsible for inducing endothelial cells to form the tight junctions characteristic of the blood-brain barrier. Astrocytes are the most likely candidates since their processes form endfeet that collectively surround CNS microvessels. In this report we provide direct evidence that astrocytes are capable of inducing blood-brain barrier properties in non-neural endothelial cells in vivo.

Mesenchymal derivatives of the neural crest: analysis of chimaeric quail and chick embryos.

Abstract: SUMMARY Interspecific grafts of neural tube and associated neural crest (NC) have been made between quail and chick embryos. Structural differences of the interphase nucleus in the two species make it possible to identify quail from chick cells in the chimaeras after FeulgenRossenbeck's staining and at the electron microscope level. Owing to the stability of the natural quail nuclear marker labelling, migration pattern and developmental fate of the grafted NC cells could be followed in the host embryo. In previous work it has been demonstrated that the visceral skeleton derives entirely from NC mesenchyme and the various levels of the neural axis from which visceral cartilages and bones originate have been established. In the present work, the contribution to the lower jaw and pharynx of NC mesenchymal derivatives other than bones and cartilages has been studied. It is shown that the dermis in the face and ventrolateral side of the neck has a neural origin. The wall of the large arteries deriving from the branchial arches (systemic aorta, pulmonary arteries, brachiocephalic trunks and common carotid arteries) are entirely made up of mesectodermal cells except for the endothelial epithelium which is mesodermal in origin. The presence in the wall of the common carotid arteries of fiuorogenic monoamines-containing cells is demonstrated using the formol-induced-fiuorescence technique. Like the secretory cells of the carotid body, the fluorescent cells of the carotid artery wall originate from the rhombencephalic NC. Connective tissue of the lower jaw, tongue and ventrolateral part of the neck originate from the neural crest. Mesectoderm participate in the formation of the glands associated with the tongue and pharynx (lingual gland, thymus, thyroid, parathyroids) giving their mesenchymal component. On the other hand, as demonstrated previously by our group, NC cells are the main cellular component of the UB since they give rise to the calcitoninproducing cells. The wall of the oesophagus and trachea is of mesodermal origin, but adipose tissue around the trachea and parasympathetic enteric ganglia of the digestive tube derives from NC. NC cells participate in the formation of striated muscles of the branchial arches and differentiate there into connective and muscle cells. It appears from this study that the differentiating capabilities are similar in mesenchymal and mesectodermal cells with the exception of blood vessel endothelia which in our experiments are always of host origin in mesectoderm-derived tissues. The capacity of the NC to give rise to mesenchymal derivatives is restricted to the cephalic neural axis down to the level of the 5th somite in both chick and quail embryos. 1 Authors' address: Laboratoire d'Embryologie, Universite de Nantes, B.P. 1 044, 44037

The migration of neural crest cells to the wall of the digestive tract in avian embryo.

Abstract: Isotopic and isochronic grafts of quail neural primordium in chick embryos have been made. Due to the particular structure of their nuclei, quail cells can be distinguished from chick cells and so be used as natural markers to study the migration of neural crest cells. We have been able to demonstrate by this technique that the parasympathetic enteric ganglion cells arise from two different levels of the embryonic neural axis which correspond to the vagal and lumbo-sacral parasympathetic centres. The main source of the enteric neuroblasts is located at the level of the somites 1–7. It gives rise to ganglion cells which migrate in the whole gut including the large intestine and rectum. The other region from which enteric neuroblasts originate is situated behind the level of the 28th somite and gives rise only to some post-umbilical gut ganglion cells. In this region of the intestine the ganglia are made up of a mixture of cells arising from the vagal and the lumbo-sacral levels of the neural axis. The part of the neural primordium between the 8th and the 28th somite does not participate in the formation of the enteric ganglia. The chronology of the enteric neuroblast migration has been studied. Most cells of vagal origin leave the neural crest before the 13-somite stage but the migration lasts sometimes until after the 16-somite stage. Those cells which have to reach the hind-gut level accomplish a long-term migration which can be evaluated at 6 days or more. The presumptive neuroblasts of lumbo-sacral origin are not found in the hind-gut before the 7th day of incubation. In our experiments we have never observed the migration of any quail cells into the endoderm of the chick host embryo. Therefore we consider that enterochromaffin cells of the digestive epithelium are not derived from the levels of the neural crest concerned in these experiments (i.e. rhombencephalic and medullary Anlagen).

Hair cell regeneration after acoustic trauma in adult Coturnix quail.

Abstract: Recovery of hair cells was studied at various times after acoustic trauma in adult quail. An initial loss of hair cells recovered to within 5 percent of the original number of cells. Tritium-labeled thymidine was injected after this acoustic trauma to determine if mitosis played a role in recovery of hair cells. Within 10 days of acoustic trauma, incorporation of [3H]thymidine was seen over the nuclei of hair cells and supporting cells in the region of initial hair cell loss. Thus, hair cell regeneration can occur after embryonic terminal mitosis.