. Elementary text-book of zoology, general part and special part: protozoa to insecta. Animals. Fig. 24.âGastric glands, a, their origin as in- vaginations of tlie epithelium, b, perfect gas- tric glands. it (fig. 23). If .several cells enter into the formation of a gland, they are arranged, in the simplest cases, round a central cavity, which receives the secretion. The gland then has the form of a sack or blind tube, derived from an inva- gination of the epithelium, either of the inner or the outer surface of the body, into the subjacent tissue. From this fundamental form the larger and more
. Elementary text-book of zoology, general part and special part: protozoa to insecta. Animals. Fig. 24.âGastric glands, a, their origin as in- vaginations of tlie epithelium, b, perfect gas- tric glands. it (fig. 23). If .several cells enter into the formation of a gland, they are arranged, in the simplest cases, round a central cavity, which receives the secretion. The gland then has the form of a sack or blind tube, derived from an inva- gination of the epithelium, either of the inner or the outer surface of the body, into the subjacent tissue. From this fundamental form the larger and more complicated glands are to be derived, as the result of continued regular and irregular outgrowth. While their form presents great variations, they are characterised by the transformation of their terminal portion into a duct; this diflferentiation may also appear in the simple glandular tubes, and even in the unicellular glands (figs. 23, 24). Fig. 23.ââ Unicellular glands, a, goblet cells from the epithelium of the small intestine of a vertebrate, b, unicel- lular cutaneous gland of Argulus with long duct, c, unicellular cuta- neous gland of insects with cuticular 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 Claus, Carl, 1835-1899; Metcalf Collection (North Carolina State University). NCRS. London, Swan Sonnenschein
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Keywords: ., bookcentury1800, bookdecade1890, booksubjectanimals, bookyear1892
