In order to determine the localization and volume of the prechordal lamina derivatives the initial stages of histogenesis of the cephalic gut epithelium lining were studied in embryos of chickens and mammals (rabbits, rats, mice) in early terms of the formation of the fore-part of their digestive tube. It has been established that the derivatives characteristics of the prechordal lamina such as the cephalic end of the chordal, larval mesodermal somites, are formed by the real enterocelic means only from the entodermal epithelium of the Seessel's pouch walls which is the most cranial end of the cephalic gut. In other parts of the dorsal wall of the pharynx, the more of the oesophagus, the prechordal lamina derivatives fail to be determined. This fact shows that the localization of the prechordal lamina coincides with the disposition of the Seessel's pouch lining, the histological nature of its material being identical to the entoderm.
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Cell Tissue Res
February 2015
Department of Human Morphology and Developmental Biology, Faculty of Medicine, Semmelweis University, Tűzoltó Str. 58, Budapest, 1094, Hungary.
We provide evidence for the compartmentalization of the avian thymic medulla and identify the avian thymic dendritic cell. The thymic anlage develops from an epithelial cord of the branchial endoderm. Branches of the cord are separated by primary septae of neural crest origin.
View Article and Find Full Text PDFJ Morphol
May 2014
Department of Vertebrate Paleontology, American Museum of Natural History, Central Park West, New York, New York, 10024-5192.
Doliodus problematicus is the oldest known fossil shark-like fish with an almost intact dentition (Emsian, Lower Devonian, c. 397Ma). We provide a detailed description of the teeth and dentition in D.
View Article and Find Full Text PDFDev Dyn
July 2001
Department of Biology, Loras College, Dubuque, Iowa 52004-1078, USA.
This study describes a whole embryo and embryonic field analysis of retinoic acid's (RA) effects upon Xenopus laevis forebrain development and differentiation. By using in situ and immunohistochemical analysis of pax6, Xbf1, and tyrosine hydroxylase (TH), gene expression during eye field, telencephalon field, and retinal development was followed with and without RA treatment. These studies indicated that RA has strong effects upon embryonic eye and telencephalon field development with greater effects upon the ventral development of these organ fields.
View Article and Find Full Text PDFJ Anat
August 1993
Department of Anatomy and Embryology, Ruhr-Universität Bochum, Germany.
The axial mesoderm of the anterior head region was investigated in young chick and quail embryos by light and electron microscopy. Semithin sections showed that the axial head mesoderm consists of the head process and prechordal mesoderm. At the anterior end of the prechordal mesoderm, a group of columnar epithelial cells formed a pit-like structure.
View Article and Find Full Text PDFThe chondrocranium at stage 23 (27-32 mm C.-R., 8 postovulatory weeks) was studied in detail to fill the descriptive gap between 7 and 9 weeks.
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