Identifier: textbookofnorma1899pier (find matches)
Title: Text-book of normal histology: including an account of the development of the tissues and of the organs
Year: 1899 (1890s)
Authors: Piersol, George A. (George Arthur)
Subjects: Histology
Publisher: Philadelphia, J.B. Lippincott Company
Contributing Library: Columbia University Libraries
Digitizing Sponsor: Open Knowledge Commons

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elioidcell-plates. The deeper layers of the mucous mem-brane fade away into the surrounding areolar tissueor into the adjacent submucosa ; sometimes, how-ever, the mucosa is limited by a delicate zone ofinvoluntary muscle, the muscularis mucosae,consisting often of two distinct, although delicate,layers of muscle-cells. Mucous membranes are usually provided withglands, which in their simplest type are depressed portions of thegeneral mucous surface, Hned with modified epithelium—the secretingcells. A single cell may constitute an entire gland, instances of sucharrangement being found in the unicellular glands of the lowerforms ; the familiar goblet-cells are, in fact, such structures ; it is,however, the more developed forms of secreting apparatus whichthe term gland usually represents. Glands are of two chief varieties, tubular and saccular, eachof these occurring as simple and compound. Simple tubular Plate-like endothe-lioid connective-tissuecells constituting base-ment-membrane.
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Diagram illustrating the forms of glands: A, simple tubular; B, compound tubular; C, modified(coiled) tubular; £>, simple saccular; £, compound saccular, or racemose. glands are frequent, the peptic glands and the mucous follicles ofthe intestines being well-known examples. Compound tubularglands vary in complexity, from a simple bifurcation of the fundus, 128 NORMAL HISTOLOGY. as in many pyloric or uterine glands, to the intricate arrangementof the tubules of the kidney or the testicle. Simple saccular glands do not occur in the higher animals, butare conspicuous in the lower types, as in the integument of am-phibians. Compound saccular, or racemose, glands, on theother hand, are represented in man and mammals by such importantorgans as the pancreas and the salivary glands. In the least complex type of gland, the simple tubular, the t>vofundamental parts of all glands are distinguishable in their primi-tive form : these are the deeper actively secreting portion, the fundus,an

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