The American journal of anatomy . are difficult to see on account of the great numberof yolk granules. This taste bud is forming in the entoderm betweenthe tongue and the teeth in the floor of the mouth. It is surroundedon all sides by entoderm crowded with yolk granules and these gran- 62 -T. B. Johnston. ules are closely packed around and among the nuclei of the cellswhich form the sense organ. It presents the same appearance as doearly taste buds in the roof of the pharynx or in any part of themouth, whether near the ectoderm or far from it. Another taste bud in a slightly later stage of de
The American journal of anatomy . are difficult to see on account of the great numberof yolk granules. This taste bud is forming in the entoderm betweenthe tongue and the teeth in the floor of the mouth. It is surroundedon all sides by entoderm crowded with yolk granules and these gran- 62 -T. B. Johnston. ules are closely packed around and among the nuclei of the cellswhich form the sense organ. It presents the same appearance as doearly taste buds in the roof of the pharynx or in any part of themouth, whether near the ectoderm or far from it. Another taste bud in a slightly later stage of development is shownin Fig. 20. It is situated in the roof of the mouth just behind themost Lateral one of the vomerine teeth. The cells immediately aroundthe tooth together with the three or four deep nuclei at the right handend of the figure (asterisk) come from the ectoderm of the dentalridge. All the rest of the cells are entoderm. At the left, several nucleivertically arranged indicate the beginning of a taste bud. It contains. Fig. 20. A. punctatuin after the formation of the mouth cleft. Sagittalsection of the roof of the mouth in the vomerine region. At the left is a tastebud forming. At the right the asterisk marks the border of the hematoxylin, fuchsin. and is surrounded on all sides by large yolk granules such as are foundin this embryo only in entoderm and in parts of the ectoderm has no yolk at all in embryos of this stage and thenervous system has very little. In Fig. 21 are shown three taste buds and one neuromast from alarva four or five days after the formation of the mouth entoderm is still clearly distinguishable from the ectoderm andextends beyond the teeth to the lips. At A in the figure is a taste budstanding near the vomerine teeth. The deep nuclei which show activenuclear changes belong to the ectoderm of the vomerine dentalridge. The two cells with dark nuclei belong to the cells and the definite out
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectanatomy, bookyear1910
