. Kirkes' handbook of physiology . IN 393 and tear to which it is subjected. The columnar cells of the deepest layerof the rete mucosum elongate, multiply by division, the new cells producedbeing pushed toward the free surface of the skin. There is thus a constantproduction of fresh cells in the deeper layers, and a constant throwing off ofold ones from the free surface. When these two processes are accuratelybalanced, the epidermis maintains its thickness. When by intermittentpressure a more active cell-growth is stimulated, the production of cells ex-ceeds their waste and the epidermis incre
. Kirkes' handbook of physiology . IN 393 and tear to which it is subjected. The columnar cells of the deepest layerof the rete mucosum elongate, multiply by division, the new cells producedbeing pushed toward the free surface of the skin. There is thus a constantproduction of fresh cells in the deeper layers, and a constant throwing off ofold ones from the free surface. When these two processes are accuratelybalanced, the epidermis maintains its thickness. When by intermittentpressure a more active cell-growth is stimulated, the production of cells ex-ceeds their waste and the epidermis increases in thickness, as we see in thehorny hands of the laborer. The dermis, or cutis vera or true skin, is a dense and tough, but yieldingand highly elastic structure supporting the epidermis. It is composed ofareolar connective tissue interwoven in all directions and forming numerousspaces by its interlacements. These areohe in the deeper layers of the cutisare usually filled with little masses of fat, figure 305. Unstriped muscu-. Fig. 306.—Terminal Tubules of Sudoriferous Glands, Cut in Various Directions. From theskin of the pigs ear. (V. D. Harris.) lar fibers are also abundantly present, especially in the skin of animals whicherect the hairs with greater ease than is usually the case with man. There is a rich network of blood-vessels to the dermis. In the dermalpapilla? and about the sweat glands there are special loops of fibers are also distributed to the papillae. The special nerve terminations in the skin have been described on page 72. Glands of the Skin. The skin possesses glands of two kinds:Sudoriferous or Sweat Glands, and the Sebaceous or Oil Glands. A Sudoriferous or Sweat Gland consists of a small lobular mass, formedof a coil of tubular gland-duct, surrounded by blood-vessels, and embeddedin the subcutaneous adipose tissue, figure 305, C. The duct ascends fromthis coiled mass for a short distance in a spiral manner through the cutisand the
Size: 1701px × 1468px
Photo credit: © Reading Room 2020 / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1900, bookdecade1900, booksubjectphysiology, bookyear1
