. Text-book of normal histology: including an account of the development of the tissues and of the organs. extending through-out the osseous tissue, are filled with the highly vascular marrow,which genetically is an extension of the osteogenetic layer of theperiosteum, since the primary marrow is a direct ingrowth and ex-tension of this latter tissue. The marrow of all bones in very younganimals is red in color; after a certain time, however, that con-tubular and the spaces of someother bones assumes a lightertint, finally becoming of astraw color, owing to the;--, accumulation of fat within■
. Text-book of normal histology: including an account of the development of the tissues and of the organs. extending through-out the osseous tissue, are filled with the highly vascular marrow,which genetically is an extension of the osteogenetic layer of theperiosteum, since the primary marrow is a direct ingrowth and ex-tension of this latter tissue. The marrow of all bones in very younganimals is red in color; after a certain time, however, that con-tubular and the spaces of someother bones assumes a lightertint, finally becoming of astraw color, owing to the;--, accumulation of fat within■ . ■■ ■ the marrow-cells. Depend-ing upon this difference, twovarieties—the red marrowand the yellow marrow—are recognized : it is to beremembered that the redmarrow is genetically theolder and represents theprimary elements of the red marrow comprise a delicate connective-tissue reticulum supporting a rich vascular distribution, composed ofarterioles breaking up into numerous capillaries, which, in turn, giveplace to venous radicles of large size and extremely thin walls. The. Elements of red marrow ; stained and highly magni-fied, a, forms of marrow-cells : 6, eosinophilicceil; c, mast-cell ; d giant-cell; e, nucleated red blood-cells ; r, red blood-cell. THE CONNECTIVE TISSUES. 51 meshes of the tissue contain great numbers of soft, plastic connective-tissue elements, the marrow-cells ; many of these, in actively-growing bone, become the osteoblasts. In yellow marrow themajority of the marrow-cells have undergone transformation intofat-cells. Additional huge, irregular, multinucleated, protoplasmicmasses are occasionally encountered; these are the giant-cells, ormyeloplaxes (Robin), and are of interest as being elements es-pecially concerned in the absorption of osseous tissue, being iden-tical with the osteoclasts (KoUiker). These cells, with their nuclei,offer an example of what formerly was described as the endogenousmode of cell-formation.
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Keywords: ., bookcentury1800, bookdecade1890, bookpublisherphiladelphiajblipp
