CHAPTER XX 

 THE SKIN AND ITS APPENDAGES 



The Skin 



The skin or cutis consists of two parts: (i) The derma, corium, 

 or true skin, and covering this, (2) the epidermis or cuticle. The 

 derma is a connective-tissue derivative of the mesoderm, the epider- 

 mis an epithehal derivative of the ectoderm. 





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ig|p?a 



>>«;«1 





Fig. 271. — Vertical Section of Thin Skin, Human. X60. (Technic 2, p. 391.) a 

 Epidermis; b, pars papillaris of derma; c, papilla; d, pars reticularis of derma; e, duct of 

 sweat gland;/, sweat gland; g, subcutaneous fat. 



The Derma. — This is divided into two layers which blend 

 without distinct demarcation. The deeper is known as the pars 

 reticularis, the more superficial as the pars papillaris (Fig. 263). 



The pars ^''cularis is made up of rather coarse, loosely arrai -red 



386 



