Quain's elements of anatomy . entrated in thesecretion, and they, in certain cases, convert the matters which they hayeselected into new chemical compounds, or lead them to assume organicstructure. A cell thus charged with its selected or converted contents 224 SECRETING GLANDS. yields them up to be poured out with the rest of the secretion—the con-tained substance escaping from it either by exudation or by bursting anddestruction of the cell itself. Cells filled with secreted matter may also bedetached, and carried out entire with the fluid part of the secretion ; and,in all cases, new cells
Quain's elements of anatomy . entrated in thesecretion, and they, in certain cases, convert the matters which they hayeselected into new chemical compounds, or lead them to assume organicstructure. A cell thus charged with its selected or converted contents 224 SECRETING GLANDS. yields them up to be poured out with the rest of the secretion—the con-tained substance escaping from it either by exudation or by bursting anddestruction of the cell itself. Cells filled with secreted matter may also bedetached, and carried out entire with the fluid part of the secretion ; and,in all cases, new cells speedily take the place of those which have servedtheir office. The fluid effused from the blood-vessels supplies matterfor the nutrition of the secreting structure, besides affording the mate-rials of the secretion. Changes in the cells during activity.—Since the materials forsecretion are selected or prepared by the cells it is not surprising to findthat the cells of a secreting gland differ considerably in appearance A. Pig. 213.—Part of a ferment-forming gland ; A at rest, B after a short PERIOD OF activity, G AFTER A PROLONGED PERIOD OF ACTIVITY. (Langlej.) In the resting condition the cells of the gland are almost filled with granules (of zymo-gen). During activity these become discharged from the cells as ferment, disap^Jearingat first from the outer part of the cell, which is thereby left clear. Finally the granulesonly remain near the lumen of the alveoli, and near the surfaces of the cells which arecontiguous to one another. In A and B the nuclei of the cells are obsciired by thegranules. according as the gland is in a condition of rest or activity (). In the former case the materials for secretion may have beenaccumulating Avithin the cells and may be detected within them,whereas in the latter case, if the secretion have been proceeding forsome time, the cells may be emptied of the accumulated material, andin many instances may themselves be partially or
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Keywords: ., boo, bookcentury1800, booksubjectanatomy, booksubjecthumananatomy
