. Text-book of normal histology: including an account of the development of the tissues and of the organs. um, restsupon a highly vascular and sensitive nail-bed, the posterior portionof which, covered by the root of the nail, is the matrix. The nail-root is usually lighter in color and somewhat opaque, owing to thethickness of the stratum Malpighii; on the thumb it extends beyondthe nail-fold as a pale projecting convex area, the lunula. While attached throughout the extent of the nail-bed, the growthof the nail takes place from the matrix alone, each newly-formed 266 NORMAL HISTOLOGY. increm
. Text-book of normal histology: including an account of the development of the tissues and of the organs. um, restsupon a highly vascular and sensitive nail-bed, the posterior portionof which, covered by the root of the nail, is the matrix. The nail-root is usually lighter in color and somewhat opaque, owing to thethickness of the stratum Malpighii; on the thumb it extends beyondthe nail-fold as a pale projecting convex area, the lunula. While attached throughout the extent of the nail-bed, the growthof the nail takes place from the matrix alone, each newly-formed 266 NORMAL HISTOLOGY. increment pushing before it the older already existing parts at therate of about one millimetre per week. The nail-bed comprises the cerium and that portion of theepidermis corresponding to the stratum Malpighii. The coriumconsists of the usual bundles of fibro-elastic tissue, which are arrangedsomewhat parallel to the long axis of the finger, the longitudinal bun-dles being supplemented by vertical ones extending from the perios-teum of the phalanx to the superficial layers. The minute elevations Fig. Transverse section of childs finger, including the nail: a, connective tissue of corium; i, longi-tudinally corrugated nail-bed ; c, corneous tissue constituting body of nail; rf, its thin edge coveredby tissue of nail-wall (_/); e, point where stratum Malpighii becomes continuous with nail bed. which occupy the surface of the corium in transverse section are nottrue papilhe, except posteriorly over the , but longitudinalridges. They are lowest behind and gradually increase in heighttowards the front of the nail, terminating abruptly at the point wherethe latter parts from its bed. The epithelial portion of the nail-bed is principally composed of cells belonging to the stratum Mal-pighii, whose numerous layers fill up the inequalities between thepapillae and the ridges of the corium below, and are sharply definedfrom the substance of the nail above. The transformation of t
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Keywords: ., bookcentury1800, bookdecade1890, bookpublisherphiladelphiajblipp
