. A practical treatise on diseases of the skin, for the use of students and practitioners. layer of the epidermis encircle in a spiraldirection both nervous and vascular papillae. At the apices of thelatter these threads completely surround the connective-tissue fibres. The name of this portion of the derma is intended to describe itschief characteristic, the existence of numerous digital prolongations ofthe corium, made up of delicate connective-tissue fibres, which do not ANATOMY AND PHYSIOLOGY OF THE SKIN. 23 interlace, and which are abundantly provided with nuclei. The papillaespring each
. A practical treatise on diseases of the skin, for the use of students and practitioners. layer of the epidermis encircle in a spiraldirection both nervous and vascular papillae. At the apices of thelatter these threads completely surround the connective-tissue fibres. The name of this portion of the derma is intended to describe itschief characteristic, the existence of numerous digital prolongations ofthe corium, made up of delicate connective-tissue fibres, which do not ANATOMY AND PHYSIOLOGY OF THE SKIN. 23 interlace, and which are abundantly provided with nuclei. The papillaespring each from a single, or several from a common, ovoid base; theirbulbous, conical, or blunt apices reach into the rete, which also dipsdown between them. The papillae differ in size in different parts ofthe body, and also in their disposition and shape, being in placesarranged in linear series, and in other in concentric whorls, with defi-nite centres, thus producing crossing-furrows, visible to the naked eyeas markings upon the outer surface of the epidermis. Fig. 5. wmmmmm WHOM 1M1M! I b—. :mmm:> Vascular and nervous papillae: a, vessel; b, nervous papilla , c, vessel; d. nerve-fibre; e, corpus-culum tactus ; /, transversely divided nervous filaments ; g, epithelia of rete. (After Biesiadecki.) In horizontal sections of the skin the papillae, being transverselydivided, appear as circular or ovoid areas, in which can be recognizedcentrally a transversely or obliquely divided capillary loop. Betweenthese areas is seen the interpapillary reticulum of the mucous layer. According to Unna, who bases his statements upon the wide variationbetween the largest sized papillae and their entire absence in someregions, the papillary layer of the corium represents merely anextremely variable border-phenomenon/ Certain it is that the growthof the rete downward and of the corium upward results in mutualeffects of pressure and counter-pressure whose equilibrium is constantlyadjusted by the mecha
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