Teratogenic studies of fenitrothion on white leghorn chick embryos

1976 ◽  
Vol 15 (2) ◽  
pp. 223-229 ◽  
Author(s):  
B. S. Paul ◽  
V. P. Vadlamudi
Keyword(s):  
Chick Embryos ◽  
White Leghorn ◽  
White Leghorn Chick

Neuroectodermal origin of avian hypothalamo-hypophyseal complex: the role of the ventral neural ridge

Development ◽  
1975 ◽  
Vol 34 (2) ◽  
pp. 311-325
Author(s):  
T. Takor Takor ◽  
A. G. E. Pearse
Keyword(s):  
The Other ◽  
Avian Embryo ◽  
Chick Embryos ◽  
White Leghorn ◽  
Optic Chiasma ◽  
Somite Stage ◽  
White Leghorn Chick ◽  
Caudal Portion ◽  
Neuroectodermal Origin

Embryonic discs from White Leghorn chick embryos (presomite to 12-somite stages) were examined in serial transverse and longitudinal sections. Later stages, up to 21 days, were also examined. The following observations were made: (1) Lateral folding rather than head folding is the mechanism by which the avian embryo is delimited. The process takes place at two terminal points, one cephalic the other caudal. (2) Thickening of the ventral ectoderm around the tip of the presumptive anterior neuropore, beginning at the 4-somite stage, subsequently extends the dorsal neural ridge to form a ventral neural ridge. (3) The cephalic portion of the ventral neural ridge, extending from anterior neuropore to optic chiasma, is mainly incorporated into the alar plates of the diencephalon. (4) The caudal portion, extending from optic chiasma to the stomodeum, gives rise to Rathke's pouch and thus to the adenohypophysis. We conclude that the latter is to be regarded as of neuroectodermal rather than ectodermal (stomodeal) origin, and that some or all of the neuroendocrine nuclei of the hypothalamus are similarly derived from the neuroectoderm of the neural ridge. The hypothalamo-hypophyseal complex is thus to be regarded as a single rather than a composite entity.

The Fine Structure of the Normal Chorio-Allantoic Membrane of the Chick-Embryo

1962 ◽  
Vol s3-103 (61) ◽  
pp. 17-23
Author(s):  
S.R. S. RANGAN ◽  
SATYAVATI M. SIRSAT
Keyword(s):  
Fine Structure ◽  
Chick Embryo ◽  
Potassium Permanganate ◽  
Osmium Tetroxide ◽  
Cell Membranes ◽  
Chick Embryos ◽  
White Leghorn ◽  
White Leghorn Chick ◽  
Lipid Inclusions ◽  
General Appearance

The chorio-allantoic membranes of White Leghorn chick embryos at 10 to 12 days after laying were fixed in Palade's buffered osmium tetroxide or in Luft's potassium permanganate. After fixation in these two ways the general appearance is similar, but there are differences in certain tissue elements. Cell membranes are well preserved after fixation in KMnCv Certain lipid inclusions in the cytoplasm of the cells of the allantoic layer are well seen after fixation by OsO4, but not after KMnO4; in their places empty vacuoles are seen. Details of the structure of the red blood-corpuscles are more clearly seen after fixation in KMnO4.

Dexamethasone Effect on Embryonic Chick Respiratory Epithelium

1982 ◽  
Vol 40 ◽  
pp. 248-249
Author(s):  
M.R. Richter ◽  
R.V. Blystone
Keyword(s):  
Lung Development ◽  
Critical Role ◽  
Respiratory Epithelium ◽  
Chick Embryos ◽  
Embryonic Chick ◽  
White Leghorn ◽  
Lung Maturation ◽  
Synthetic Analogs ◽  
Lung Physiology ◽  
Avian Lung

Dexamethasone and other synthetic analogs of corticosteroids have been employed clinically as enhancers of lung development. The mechanism(s) by which this steroid induction of later lung maturation operates is not clear. This study reports the effect on lung epithelia of dexamethasone administered at different intervals during development. White Leghorn chick embryos were used so as to remove possible maternal and placental influences on the exogenously applied steroid. Avian lung architecture does vary from mammals; however, respiratory surfactant produced by the lung epithelia serves an equally critical role in avian lung physiology.

Thyroid hormone effects on chick scale morphogenesis and keratinization

Development ◽  
1970 ◽  
Vol 24 (1) ◽  
pp. 65-71
Author(s):  
Nancy K. Lawrenz ◽  
Leland G. Johnson
Keyword(s):  
Thyroid Hormone ◽  
Scale Development ◽  
New Hampshire ◽  
Chick Embryos ◽  
White Leghorn ◽  
Endocrine Effects ◽  
Hormone Effects ◽  
Hormone Responsiveness

The effects of thiourea injection on scale development were studied in New Hampshire Red × White Leghorn Cross chick embryos. Normal morphogenesis and keratinization of scales were significantly delayed in thioureatreated specimens. Subsequent thyroxine injection resulted in normal or even precocious scale development. The thyroid hormone responsiveness of scale development is discussed in relation to other studies of endocrine effects on differentiation of skin and skin derivatives.

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