. A practical treatise on diseases of the skin, for the use of students and practitioners. sebaceous glands thelimits of the hair-follicle are lost in the papillary layer. It is consti-tuted of the connective tissue of the corium in three layers: an exter-nal, longitudinal, fibrous layer; a middle, transverse layer; and aninternal, homogeneous, or vitreous layer. At the base of the sac afibrous pedicle may often be traced as low as the subcutaneous tissue. If the hair-pouch were made artificially by thrusting into the skinfrom without inward a blunt-pointed pin before which the tissue wasgradu
. A practical treatise on diseases of the skin, for the use of students and practitioners. sebaceous glands thelimits of the hair-follicle are lost in the papillary layer. It is consti-tuted of the connective tissue of the corium in three layers: an exter-nal, longitudinal, fibrous layer; a middle, transverse layer; and aninternal, homogeneous, or vitreous layer. At the base of the sac afibrous pedicle may often be traced as low as the subcutaneous tissue. If the hair-pouch were made artificially by thrusting into the skinfrom without inward a blunt-pointed pin before which the tissue wasgradually pushed, it is evident that the external layer, the stratum cor-neum, of the epidermis would be the first depressed, and finally coverthe inner surface of the pouch. This represents the inner root-sheathof the hair. Next to this the pin would carry before it the mucous ANATOMY AND PHYSIOLOGY OF THE SKIN 37 layer of the epidermis, which then would form the outer root-sheathof the hair. Outside of both would lie the connective tissue of thecorium; this is the hair-follicle. Fig. Lower portion of hair-pouch from the lip of a kitten : F, follicle ; T, transverse section of con-nective-tissue bundles of derma; M, arrector pili muscle; IS, inner root-sheath ; OS, outer root-sheath ; P, papilla; C, cuticle ; R, root of hair ; H, hyaline, or so-called structureless 500 diameters. (After Heitzmann.) The Outer Eoot-sheath, or, as some prefer to call it, the prickle-layer of the hair-follicle, accompanies the involutions of the stratumcorneum and the stratum granulosuni from without into the funnel-shaped neck of the hair-pouch, as far as the openings of the ducts ofthe sebaceous glands. There, abandoned by the two other layers of theepidermis, the root-sheath is thinned in proportion as the papilla, whichrises from below and which it closely surrounds, increases in size. Itthus forms a hollow cylinder traversed by the hair and its envelopes,with a relatively w
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Keywords: ., bookauthorhydejamesnevins184019, bookcentury1800, bookdecade1890
