Nil. OBQAVI 01 HIE OITER GEUM-LAYEK. 



I | r. , : t M the very beginning of the discussion the following 



pn>po>iti..n, which is of importune.- in int.-i -pi -, ting the conditions 



fon i. -ilk ijl-iif! in Man it not a simple organ, like an ear- 



I or a submaxillary salivary gland, with a simple outlet, but 



glandular complex. Its earliest fundament has been 



observe! in the human embryo at the end of the second month as * 



considerable thickening of the epidermis (fig. 295) upon the right 



an<l of the breast. It has arisen as the result of a special 



prl: t' (ho mu con Inch has sunk into the derma 



in the form of a henii>pli-Tieal knob (40- '''" "."'li^-.'tioni arise 



A.mls in the corneous layer also, by its becoming thickened and 



projecting as a corneous plug into the p n of tlio mucous 



< h-dinarily there i- found 



u Mnall depression (g) at tin- V 9 



middle of the whole epithelial 

 fundament. 



The proli relation of the epi- 

 dermis that first appears is not 

 precisely, as assumed by K i: i x , t h 

 lirst t'uiulament of the glandular 

 parenchyma; it therefore does 

 not correspond to the epithelial 

 plugs which >ink into the derma 

 in the development of the sweat ^ ^ 



and sebaceous glands, because the miik- land of * remote k*a Mkry 

 the further course of develop- v^^f2^ M ., tm ^ 

 ment and especially coin para dqpwkm at its turf**, 



anatomical studies show, that by 

 the thick, mm: of the epidermis there is only an early delimit 



tract of the skin, which is subsequently metamorphosed into the 

 nipple area and papilla, and from the floor of which the separate 

 milk producing glands at length sprout forth. 



The correctness of this view is shown by the following changes : 

 In older embryos the lens-shaped th produced by the 



proliferation of the epidermis has increased at t hcry and 



has thereby become flattened (fig. 296 (//*). At the same time 

 more sharply defined at the surface, owing to the derma becoming 

 thickened and elevated into a wall (dw) the cutis-wall. Therefore 

 the whole fundament now has the form of a shallow depression (df} 

 of the skin, for which the name glandular area is very appropriate. 

 For there early grow out from its mucous layer into the derma solid 



