Human physiology . stains pale yellow with picric acid. In a more advanced phase of absorption, the inner zone grows out beyond the nucleus, which tends to a conspicuous lengthening of the cells, so that the nucleus is pushed into the outer third of the body of the cell. Finally, in a third phase, the hyaline portion gradually liquefies or vanishes by internal absorption, till at last only the outer zone of the epithelial cells is left, at the base of which the nucleus is found almost in contact with the basement membrane. As shown in the figure, different parts may be distinguished 296 IHYSIO
Human physiology . stains pale yellow with picric acid. In a more advanced phase of absorption, the inner zone grows out beyond the nucleus, which tends to a conspicuous lengthening of the cells, so that the nucleus is pushed into the outer third of the body of the cell. Finally, in a third phase, the hyaline portion gradually liquefies or vanishes by internal absorption, till at last only the outer zone of the epithelial cells is left, at the base of which the nucleus is found almost in contact with the basement membrane. As shown in the figure, different parts may be distinguished 296 IHYSIOUHiY CIIAI1. in the same villas, showing epithelia in the first, second, or thirdphase of the process of absorption and internal secretion of the,absorbed products. It is usually the epithelia of the apex of thnvillus which show these changes most conspicuously; along thelateral walls of the villus they are less obvious, and are minimaltowards its base. According to Mingazzini, the stroma of the villi also presents. .—Yillus of small intestine of fowl during absorption. (P. Mingazzini.) Lettering as inprevious figure. In the apex of right side of villus particularly the columnar cells havebecome elongated and exhibit a zone external to the nucleus (zs) that stains deeply, and aninternal hyaline zone (zj) which contains the absorbed substance. At the apex of the villusthe inner epithelial zone is transformed into a granular substance (si). different aspects in different phases. In some cases it seems toconsist of a compact tissue; in others, on the contrary, of loosetissue. In the former it is regular in form, and of small dimensions;in the latter the form is not very regular, and the dimensions arelarger (Fig. 96). It is possible in the last case that the villi maybe swollen owing to the chyle poured out by internal secretioninto the lymph spaces of the adenoid tissue, before it reaches thecentral lacteal. The leucocytes packed between the epithelialcells are perhaps
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectphysiology, bookyear1
