OF THE GLANDS OF THE SKIN. 



ooq 



the cavity of the gland, which, however, never appears 



empty, but is continually filled by successive generations of cells. 



The development of the glands, up to this point, proceeds 



pretty quickly. It may be stated generally, that so long as 



Fig. 88. 



the hairs have not appeared externally, the rudiments of the 

 glands are papillary, measure scarcely more than O03"', and 

 for the most part contain cells which are still quite pale; after 

 the hairs have made their appearance externally, we find larger 

 pyriform rudiments with a thicker end, of 0*024 — 005'", the 

 cells of which arc partly still pale, partly contain fat, and which 

 now soon open into the hair-sac. In the fifth month, therefore, 

 the secretion has already begun in many places, and in the 

 sixth, it is everywhere established. At the same time, however, 

 it is to be observed that, together with the original glands, 

 which occur, one or two together to each sac, in the sixth month, 

 new rudiments are produced, which generally lie deeper, and 

 taking on the same course as that which has been described, 



Fig. 88. To elucidate the development of the sebaceous glands in a six-months' 

 foetus, x about 250 : «, hair ; b, inner root-sheath, here more closely resembling the 

 horny layer of the epidermis ; c, outer root-sheath ; d, rudiments of the sebaceous 

 glands. A, flask-shaped rudiment of the gland, with fat developed in the central 

 cells; B, larger rudiments; the development of fat has taken place also in their 

 neck, and fatty cells have been excreted into the hair-sac, giving rise to the glandular 

 cavity and the secretion. 



