THE SKIN AND ITS APPENDAGES. 



26l 



CHAPTER XV. 



THE SKIN AND ITS APPENDAGES. 

 THE SKIN. 



THE skin consists of two parts : the superficial epithelial layer 

 the epidermis or the cuticle, derived from the ectoderm and the 

 deeper connective-tissue layer the corium or the cutis vera, de- 

 rived from the mesoderm. Blended with the corium and separated 

 from it by no sharp demarcation, the subcutaneous tissue exists 



FIG. 298. 



Section of human skin : a, stratum corneum ; b, stratum lucidum ; c, stratum 

 granulosum ; d, stratum Malpighii ; e, f, papillary and reticular layers of corium ; 

 g, stratum of adipose tissue ; h, i, spiral and straight portions of duct of sweat- 

 gland ; k, coiled portion of sweat-gland ; A vascular loops occupying papillae of 

 corium. 



usually as a stratum of considerable thickness, which forms a loose 

 attachment between the skin and the adjacent structures. The in- 

 tegument varies in thickness from .3 to 3.75 mm., being thicker 

 on the back of the head, the neck, and the trunk than on their 



