. The development of the frog's egg; an introduction to experimental embryology. Embryology. 156 DEVELOPMENT OF THE FROG'S EGG [Cii. XIV plate is first formed. It is well marked at the time when the medullary folds have rolled in, but have not yet fused. A thickening of the somatic layer of the lateral mesoderm near the second mesoblastic somite marks the beginninir of the prone- phros (Fig. 48, A). At a later stage, the mesodermic thick- ening becomes larger, and the anterior end arches over toward the coelomic cavity, to form the first 7iephrostome. The ventro- posterior part of the nephrost
. The development of the frog's egg; an introduction to experimental embryology. Embryology. 156 DEVELOPMENT OF THE FROG'S EGG [Cii. XIV plate is first formed. It is well marked at the time when the medullary folds have rolled in, but have not yet fused. A thickening of the somatic layer of the lateral mesoderm near the second mesoblastic somite marks the beginninir of the prone- phros (Fig. 48, A). At a later stage, the mesodermic thick- ening becomes larger, and the anterior end arches over toward the coelomic cavity, to form the first 7iephrostome. The ventro- posterior part of the nephrostomal thickening is continued backward as a thickening of the somatic wall as far as the seventh somite, to form the segmental duct. A canalization now takes place in the nephrostomal portion and in the seg- mental duct. Three short tubes or canals appear in the pronephric mass running outward from the coilom (Fig. 41). Constrictions appear between the first and second, and between the second and third canalized tracts (Fig. 48, B), and short. 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 Morgan, Thomas Hunt, 1866-1945. New York, The Macmillan company; [etc. , etc. ]
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Keywords: ., bookcentury1800, bookdecade1890, booksubjectembryology, bookyear1
