Human physiology (1913) (14779338362)

Identifier: humanphysiology02luci (find matches)

Title: Human physiology

Year: 1913 (1910s)

Authors: Luciani, Luigi, 1842- Welby, Frances A. (Frances Alice) Camis, Marie Holmes, Gordon, Sir, 1876-1965 Pembrey, M. S. (Marcus Seymour), 1868-1934

Subjects: Physiology

Publisher: London : Macmillan and Co.

Contributing Library: MBLWHOI Library

Digitizing Sponsor: MBLWHOI Library

Text Appearing Before Image:

ng the substance into smalllobules of unequal form and size. When cut into, a yellow,sticky fluid escapes from the surface, which had previously beencontained in a multitude of closed vesicles or follicles surrounded i INTERNAL PEOTECTIVE SECRETIONS 7 by areolar connective tissue, and richly provided with blood andlymph vessels. The size of the vesicles varies considerably; thelargest may be one millimetre in diameter, so that they arevisible to the naked eye. They are rounded or oval in form,with a wall consisting of a single layer of cubical or columnar O O */ epithelial cells, which are the secreting elements (Fig. 2).According to Langendorff two kinds of cells can be dis-tinguished : Hauptzellen, which have sharp outlines and shin-ing, finely granulated protoplasm ; Colloidzellen, which haveindefinite outlines and protoplasm filled with large granules,shown by their affinity for certain pigments to consist of colloidalsubstance. The first are young cells that secrete by exudation;

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p(o. •_>.—Thyroid gland of infant. Vesicles of various sizes, lined with single layer of cubical epithelial cells. the second are older and exhibit a marked secretory activity,during which they liquefy and break up, so that both protoplasmand nucleus pass into the secretion. In fact, the colloidfluid of the alveoli contains both the old disintegrated epithelialcells, and leucocytes that have emigrated from the bloodcapillaries, as well as erythrocytes in process of destruction anddiscoloration. Liibcke (1902) concluded from histological observations, moreparticularly of fresh preparations of the gland, that the so-calledcolloid cells are only artificial products, due to the diffusion of thecontents of the vesicle in and around the atrophied epithelial cells.In any case they would not represent the secreting cells. Accord-ing to this author the thyroid vesicles contain a homogeneous fluid,which is not shiny, and is quite distinct from the protoplasm,being watery or gelatinous in

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