. Text-book of normal histology: including an account of the development of the tissues and of the organs. n size the middle, while the smallestapproach the capillary zone. The most conspicuous of the largesuperficial blood-channels are the four venae vorticosae, with theirwhorls of tributaries. These veins occupy positions around theequator at points about equidistant, towards which the smaller vesselsconverge from all directions, returning the blood not only from thechoroid but also from the ciliary body and the iris. The veins ofthe choroid are often surrounded by perivascular lymph-sheaths
. Text-book of normal histology: including an account of the development of the tissues and of the organs. n size the middle, while the smallestapproach the capillary zone. The most conspicuous of the largesuperficial blood-channels are the four venae vorticosae, with theirwhorls of tributaries. These veins occupy positions around theequator at points about equidistant, towards which the smaller vesselsconverge from all directions, returning the blood not only from thechoroid but also from the ciliary body and the iris. The veins ofthe choroid are often surrounded by perivascular of the larger arteries, in addition to the well-marked circu-larly-disposed muscle with which they are provided, are accompaniedby external longitudinal bundles of involuntary muscle. The innermost part of the stroma-layer, next the choriocapil-laris, forms a narrow stratum (lo p. in width) which is devoid, ornearly so, of pigment, and constitutes the boundary zone. Inthe eyes of many animals (horse, cow, sheep) this layer possesseswavy bundles of connective tissue, to whose peculiar arrangement. Human choroid seen from its inner surface, exhibiting surface view of cap-illary net-work, or choriocapillaris {c, c) ; b, b, large blood-vessels of stroma-layer beneath; a, a, intervening stroma-tissue. is due the metallic reflex sometimes seen from such eyes ; thisshining structure is known as the tapetum fibrosum, as distinguishedfrom the iridescent tapetum cellulosum of the carnivora which isdependent upon the presence of several layers of plate-like cellscontaining innumerable small crystals. The capillary layer, or choriocapillaris, consists oi a narrow 344 NORMAL HISTOLOGY. zone, about lo ,a in width, at the inner part of the choroid, composedof a structureless, apparently homogeneous, matrix, in which lieembedded the close capillary net-works derived from the terminalbranches of the short ciliary arteries. The vitreous lamina, or glassy membrane, forms the mostinternal la
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Keywords: ., bookcentury1800, bookdecade1890, bookpublisherphiladelphiajblipp
