THE CUTANEOUS GLANDS. 



1399 



Spiral part 

 of d 



scrotum, lies within the subdermal connective tissue. The coiled portion of the 

 gland is not entirely formed by the secretory segment, since, as shown by the recon- 

 structions of Huber, about one fourth is contributed by the convolutions of the first 

 part of the duct. 



On leaving the gland-coil, in close proximity to the blind end of the gland, the 

 duct ascends through the corium with a fairly straight or slightly wavy course as 

 far as the epidermis. On entering the latter its further path is marked by conspicu- 

 ous cork-screw-like windings, which, where the cuticle is thick as on the palm, are 

 close and number a dozen or more and terminate on the surface by a trumpet-shaped 

 orifice, the sweat-pore. 



In its course through FlG - Il6 4- 



the corium the duct 

 never traverses a 

 papilla or ridge, but 

 always enters the cuti- 

 cle between these ele- 

 vations. On the palms 

 and soles, where the 

 pores occupy the sum- 

 mit of the cutaneous 

 ridges, the ducts enter 

 the cuticle between the 

 double rows of papillae. 



Structure. The 

 secreting portion of 

 the gland-coil, called 

 \heampulla on account 

 of its greater diameter, 

 possesses a wall of 

 remarkable structure. 

 The thin external 

 sheath, composed of a 

 layer of dense fibrous 

 tissue andelastic fibres, 

 supports a well defined 

 mcmbrana propria. 

 Immediately within the 

 latter lies a thin but 

 compact layer of invol- 

 untary muscle whose 

 longitudinally disposed 

 spindle - shaped ele- 



: duct 



Stratum 

 "corneum 



S. lucidum 

 S. granulosum 



S.germinativutK 



Duct of 

 sweat-gland 



Corium 



-. Fat-cells 



Coiled part of 

 sweat-gland 



Section of skin from palm, showing different parts of sweat-glands extending from 

 surface into tela subcutanea. X 65. 



ments in cross-section 

 appear as a zone of 

 irregularly nucleated 

 cells that encircle the secreting epithelium and displace it from its customary position 

 against the basement membrane. This muscular tissue enjoys the distinction, sharing 

 it with the muscle of the iris, of being developed from the ectoblast. The secreting 

 cells constitute a single row of low columnar epithelial elements, that lie internal to 

 the muscle and surround the relatively large lumen. Their finely granular cytoplasm 

 contains a spherical nucleus, situated near the base of the cell, and in certain of the 

 larger glands, as the axillary, includes fat droplets and pigment granules. These 

 are liberated with the secretion of the gland and when present in unusual quantity 

 account for the discoloration produced by the perspiration of certain individuals. In 

 the case of the ceruminous glands, the amount of oil and pigment is constantly great 

 and confers the distinguishing characteristics on the ear-wax. 



The sudden and conspicuous reduction in the size of the tube which marks the 

 termination of the secreting segment and the beginning of the duct, is accompanied 

 by changes in the structure of its wall. In addition to a reduction of its diameter to 



