. The elements of experimental embryology. Embryology, Experimental; Embryology. 138 organisers: inducers of differentiation positions where they are not underlain by mesoderm. If, on the other hand, they are situated in regions where mesoderm does underHe them, they become typical neural folds (see fig. 64).. Fig. 64 Effects of a lateral temperature differential on development in Urodeles. A-F, Triturus torosus, treatment by temperature-gradient in blastula stage, with 5° C. temperature difference between the two sides of each egg. A, B, Warmed on left; A, dorsal view; B, anterior view; the w
. The elements of experimental embryology. Embryology, Experimental; Embryology. 138 organisers: inducers of differentiation positions where they are not underlain by mesoderm. If, on the other hand, they are situated in regions where mesoderm does underHe them, they become typical neural folds (see fig. 64).. Fig. 64 Effects of a lateral temperature differential on development in Urodeles. A-F, Triturus torosus, treatment by temperature-gradient in blastula stage, with 5° C. temperature difference between the two sides of each egg. A, B, Warmed on left; A, dorsal view; B, anterior view; the warmed neural fold is much larger and more differentiated. C-E, Dorsal views. F, Lateral view, showing secondary neural structures on the previously warmed side, either connected with the main neural folds, or F, isolated from them. In C, D, E, the secondary formations appear to be underlain by mesoderm, and have differentiated into structures of neural fold type. In F they are not underlain, and do not show typical morphogenesis. (From Gilchrist, Quart. Rev. Biol, iv, 1929.) Another method of testing this labile determination is by inter- plantation, the grafting of portions of blastulae ( portions of tissue taken from an embryo before the invagination of the organiser) into the eye-sockets or coelomic cavities of other larvae.^ The differentiation of various structures can be obtained in this way (fig. 148, p. 316). The fact that interests us here is that neural tube may be differentiated in these circumstances from tissue which ^ Diirken, Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Huxley, Julian, 1887-1975; De Beer, Gavin, Sir, 1899-1972. New York [Hafner Pub. Co. ]
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