The development of the human body; a manual of human embryology . ching non-elastic fibers, sometimes of yellow, branching, elasticfibers; of white, branching, but inelastic fibers whichform a reticulum, or of a soft gelatinous substancecontaining considerable quantities of mucin, as in the tis-sue which constitutes the Whartonian jelly of the umbili-cal cord. Again, in cartilage the matrix is compact andhomogeneous, or, in other cases, more or less fibrous,passing over into ordinary fibrous tissue, and, finally, in 174 THE CONNECTIVE TISSUES. 175 bone the organic matrix is largely impregnated
The development of the human body; a manual of human embryology . ching non-elastic fibers, sometimes of yellow, branching, elasticfibers; of white, branching, but inelastic fibers whichform a reticulum, or of a soft gelatinous substancecontaining considerable quantities of mucin, as in the tis-sue which constitutes the Whartonian jelly of the umbili-cal cord. Again, in cartilage the matrix is compact andhomogeneous, or, in other cases, more or less fibrous,passing over into ordinary fibrous tissue, and, finally, in 174 THE CONNECTIVE TISSUES. 175 bone the organic matrix is largely impregnated with saltsof lime. Two views exist as to the mode of formation of thematrix, some authors maintaining that in the fibrous tis-sues it is produced by the actual transformation of themesenchyme cells into fibers, while others claim that itis manufactured by the cells but does not directly repre-sent the cells themselves. Fibrils and material out of whichfibrils could be formed have undoubtedly been observedin connective-tissue cells, but whether or not these are. Fig. 87.—Portion of the Center of Ossification of the ParietalBone of a Human Embryo. later passed to the exterior of the cell to form a connective-tissue fiber is not yet certain, and on this hangs mainlythe difference between the theories. Recently it has beenheld (Mall) that the mesenchyme of the embryo is reallya syncytium in and from the protoplasm of which thematrix forms; if this be correct, the distinction which theolder views make between the intercellular and intra-cellular origin of the matrix becomes of little importance. Bone differs from the other varieties of connective tis-sue in that it is never a primary formation, but is always 176 THE DEVELOPMENT OF THE HUMAN BODY.
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