. Quain's elements of anatomy . s prolonged above between the corium andcuticle. The subsequent changes consist in the elongation of the rudimentarygland, the formation of a cavity along its axis—at first without an outlet—theprolongation of its canal through the epidermis to open on the surface, and, in themeantime, the coiling up of the gradually lengthening giand-tube mto a compactball, and the twisting of the excretory duct as it proceeds to the orifice. Theplain tissue of the sweat-glands is said to be developed from some of theepithelium-cells of the rudimentary gland (Eanvier)
. Quain's elements of anatomy . s prolonged above between the corium andcuticle. The subsequent changes consist in the elongation of the rudimentarygland, the formation of a cavity along its axis—at first without an outlet—theprolongation of its canal through the epidermis to open on the surface, and, in themeantime, the coiling up of the gradually lengthening giand-tube mto a compactball, and the twisting of the excretory duct as it proceeds to the orifice. Theplain tissue of the sweat-glands is said to be developed from some of theepithelium-cells of the rudimentary gland (Eanvier). If this be so, it is the onlyknown instance, in the higher animals, of muscular tissue being developed fromthe ectodenn. The ceraminous glands in the auditory passage consist of a tube coiled into aball, like the sweat-glands (fig. 237) : and there is such a further correspondencebetween the two, in structure and mode of development, that the cenmiinousglands may be regarded as a mere variety of the sudoriferous. W-. Fig. 238.—A, SEBACEors gland fkom the nose with bkanched duct, attached to a SMALL haik-follicle. MAGNIFIED 50 DIAMETERS (froin Kolliker). «, epithelium continuous with b, the Malpighian layer of the epidermis ; c, contents of gland ; d, d, the groups of saccules on the branches of the duct ; e, hair-follicle ; /, hair. B, Terminal saccule of a sebaceous gland. Magnified 250 diameters. a, epithelium lining the saccule ; h, sebaceous matter, partly still within the cells, C, Separated cells from the interior of an alveolus, containing fattz particles of varying degrees of fineness (from Kolliker). 256 THE SKIX. The salbaceous glands (figs. 227,238, a) pour out their secretion at theroots of the hairs, for, with very few exceptions, they open into the hair-folhcles, and are found wherever there are hairs. Each has a short duct,which opens at a httle distance within the mouth of the hair-folhcle, andby its other end, leads to a chister of small rounded
Size: 1459px × 1713px
Photo credit: © Reading Room 2020 / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., boo, bookcentury1800, booksubjectanatomy, booksubjecthumananatomy
