SECT. 71.] 



SUDORIPAROUS GLANDS. 



I29 



Fig. 56. 



glands and upon the thickness of the skin. The commencement 

 of the duct is, without exception, narrower than the canal in the 

 glandular coil; it measures o - ooo/" to o - oi2'", and remains so until 

 it enters the mucous layer, where it enlarges to double (up to 

 0024.'" to 0028'") of its former size; thus wide, it passes 

 through the epidermis, and terminates by an opening -£~" to -fa"' 

 in diameter. In the corium, the sweat-ducts have always a distinct 

 cavity, an outer investment of connective tissue with elongated 

 nuclei (in the glands of the axilla, 

 also, muscles, at least in the lower 

 part), and an epithelial lining of 

 at least two layers of polygonal, 

 nucleated cells, without pigment 

 granules. At the point where 

 the sweat-ducts enter the epider- 

 mis they lose their covering of 

 connective tissue, which coalesces 

 with the outermost layer of the 

 corium, and are thenceforth 

 hounded by nothing but layers of 

 cells, which are nucleated in the 

 mucous laver, but without nuclei 

 in the horny layer. Both chemi- 

 callv and structurallv, these en- 

 tircly resemble the cells of the 

 epidermis, excepting only that 

 they are set more perpendicularly, 

 particularly in the horny layer. 

 In the epidermis, the ducts have 

 frecpiently a distinct cavity; at 

 other times, instead of it, a gra- 

 nular streak extends along the 

 duct, and is probably to be re- 

 garded as a secretion, or the 

 sediment of a secretion. The sweat-pores, whose position, in con- 

 formity with that of the sudoriparous glands, is sometimes regular, 

 sometimes more irregular, may be seen with the unaided eye on 

 the palm of the hand and sole of the foot ; but in other places, 

 •can only be recognised with the microscope. Occasionally, the 

 excretory ducts of two glands unite to form one canal (Krause). 



§ 71. Development of the Sudoriparous Glands. — The sudori- 



Perpendieular section of the epidermis and ex- 

 ternal part of the corium of the extremity of the 

 thumb, carried transversely through two ridges. 

 The preparation being treated with acetic acid 

 and seen as magnified 50 times, a. Horny layer 

 of the epidermis ; b. mucous layer; c. corium; d. 

 simple papilla; e. compound papilla; /. epithe- 

 lium of a sweat-duct passing into the mucous 

 layer ; g. cavity of the same in the corium ; h. in 

 the horny layer ; t. sweat- pore. 



