File:Hand-book of physiology (1892) (14742436956).jpg

Identifier: handbookofphysio00bake (find matches)
Title: Hand-book of physiology
Year: 1892 (1890s)
Authors: Baker, W. Morrant, (William Morrant), 1839-1896 Harris, Vincent Dormer Kirkes, William Senhouse, 1823-1864. Hand-book of physiology. 13th ed
Subjects: Physiology Human physiology
Publisher: London : John Murray
Contributing Library: Francis A. Countway Library of Medicine
Digitizing Sponsor: Open Knowledge Commons and Harvard Medical School

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Fig. 491.—The same region after the lapse of 24hours. The sprouts and cords of proto-plasm have become channelled out intocapillaries. (Arnold.) 822 DEVELOPMENT. (ch. XIX. In the development of capillaries another plan is pursued.This has been well illustrated by Kolliker, as observed in thetails of tadpoles. The first lateral vessels of the tail have theform of simple arches, passing between the main artery andvein, and are produced by the junction of prolongations, sent fromboth the artery and vein, with certain elongated or star-shapedcells, in the substance of the tail. When these arches are formedand are permeable to blood, new prolongations pass from them,join other radiated cells, and thus form secondary arches. Inthis manner, the capillary network extends in proportion as thetail increases in length and breadth, and it, at the same time,becomes more dense by the formation, according to the same
Text Appearing After Image:
Fig.492.—Capillaries from the vitreous humour of a foetal calf. Two vessels are seenconnected by a cord of protoplasm, and clothed with an adventitia, containingnumerous nuclei, a, insertion of this cord into the primary walls of the vessels.(Frey.) plan, of fresh vessels within its meshes. The prolongations bywhich the vessels communicate with the star-shaped cells, consistat first of narrow pointed projections from the side of the vessels,which gradually elongate until they come in contact with theradiated processes of the cells. The thickness of such a pro-longation often does not exceed that of a fibril of fibrous tissueand at first it is perfectly solid ; but, by degrees, especially afterits junction with a; cell, or with another prolongation, or with avessel already permeable to blood, it enlarges, and a cavity thenforms in its interior (see figs. 491, 492). This tissue is well cal-culated to illustrate the various steps in the development ofblood-vessels from elongating and b

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