10/27/2022 0 Comments 96 Hour Chick Embryo Serial Section![]() ![]() A number of descriptive studies have summarized and discussed the accumulated knowledge of forebrain ontogeny and regional development based on morphological observations and neurogenetic patterns (Altman and Bayer, 1986 Puelles et al., 1987 Easter et al., 1993). The anterior neuroepithelium undergoes a progressive process of regionalization which is initiated at the neural plate stage by the region-specific expression of different genes. While the optic field evaginates bilaterally to develop the optic vesicles (between stages HH10–14 in chick and E9.5–11.5 in mouse embryos), which then produces the retina and the optic nerve, the telencephalic field, bulges dorsally to generate the telencephalic hemispheres (between stages HH13–20 in chick and E10.5–12.5 in mouse embryos). Later, four spherical vesicles protrude from the secondary prosencephalon. ![]() At neural plate stages (Hamburger and Hamilton 4–8 in chick and embryonic day 7–8.5 in mouse embryos), the neuroepithelium of the anterior neural plate is an almost flat structure which, after dorsal folding, develops into the prosencephalic vesicle at the neural tube stage (HH9 in chick and E9.5 in mouse embryos). The prosencephalic morphogenetic process has not yet been fully characterized because of important anatomical transformations occurring mainly in the optic and telencephalic epithelial domains that have not yet been studied in detail. Comparative analysis of the two maps has allowed us to descriptively characterize the morphogenetic transformations of the alar prosencephalic regions during neurulation and to establish the topologic evolution of the principal areas of the vertebrate telencephalon. Since we have previously reported the fate map of the prosencephalon at the neural plate stage, in the present work we report the corresponding fate map at the neural tube stage. In order to better characterize morphogenetic transformations of the prosencephalon, we have realized and comparatively analyzed neuroepithelial fate maps before and after neurulation using quail/chick chimerical experiments. Although the principal processes of neurulation have been well characterized, the growth patterns and evolution of topological relations between internal prosencephalic regions have not been experimentally analyzed. Later in development, two bilateral areas (the optic and telencephalic vesicles) progressively protrude from the prosencephalon, generating the eyes and the cerebral hemispheres, respectively. The almost flat epithelium of the rostral neural plate becomes transformed into a spherical region, the prosencephalic vesicle, in the neural tube. After gastrulation, during the process of neurulation, the anterior neural region undergoes important morphological transformations. ![]()
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