. Comparative anatomy of vertebrates. Anatomy, Comparative; Vertebrates -- Anatomy. FiG. ii.—Different types of glands; .4, to D, tubular; E, F, acinous; A, simple; B, coiled; C—F, branched. Glands.—The chief kinds of glands may be mentioned here. All have for their function the extraction and elaboration of certain products from the blood, consequently they have a good blood supply. Glands may be unicellular or multi- cellular according as they consist of isolated cells or of many cells. In unicellular glands (abundant in the digestive tract) each cell passes its own secretion directly to the
. Comparative anatomy of vertebrates. Anatomy, Comparative; Vertebrates -- Anatomy. FiG. ii.—Different types of glands; .4, to D, tubular; E, F, acinous; A, simple; B, coiled; C—F, branched. Glands.—The chief kinds of glands may be mentioned here. All have for their function the extraction and elaboration of certain products from the blood, consequently they have a good blood supply. Glands may be unicellular or multi- cellular according as they consist of isolated cells or of many cells. In unicellular glands (abundant in the digestive tract) each cell passes its own secretion directly to the place where it is to be used (fig. 19, «). Multicellular glands occur where a large amount of secretion is necessary in a limited space, hence they are not on the surface but at some deeper point, and their product is conveyed to the desired place by a duct. Multicellular glands are of two structural kinds. In the tubular gland the whole is approximately of the same diameter throughout, with little differentiation of gland and duct. It may be simple (A) or coiled (B) or branched (C, D), these modifications serving to in- crease the secreting surface. In acinous glands (D, E) there is a marked differ- ence between gland and duct, the glandular part forming an enlargement (acinus) on the end of the duct. Both simple and compound acinous glands are common. Still another type of gland, the ductless or 'internal secretion' gland occurs. In this there is no duct, the secretion elaborated by the cells passing by osmose into the blood-vessels. These secretions, collectively known as hormones, have recently acquired great prominence from their influence on different 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 Kingsley, J. S. (John Sterling), 1854-1929. Philadelphia, P. Blakiston's son & co.
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectanatomy, bookyear1912
