THE 



283 



erce are found in the skin of all parts of the body except that 

 of the glans penis and margin of the lips. They are most nu- 

 merous in the palms of the hands and the soles of the feet, 

 where they number, according to Krause, 2,685 to 2,736 to the 

 square inch. 



A sweat-gland is composed of two parts, viz.: the gland 

 proper, or secreting part, and an excretory duct. The gland 

 proper lies in the subcutaneous tissue, 

 and consists of the lower part of the sweat- 

 gland rolled and coiled upon itself into a 

 more or less globular form, the tube ter- 

 minating in a cul-de-sac, the blind extrem- 

 ity generally lying in the centre of the coil. 

 The diameter of the secreting tube is 

 greater than that of the excretory duct. 

 The former is composed of secreting cells, 

 unstriped muscular fibres, and a basement- 

 membrane. The cells (glandular or secret- 

 ing epithelial cells) are polygonal in shape 

 and form only a single layer. They are 

 strongly granular in appearance and have 

 a very distinct nucleus. Their basal end 

 is sometimes notched where they are in- 

 serted into the basement-membrane. In 

 normal conditions these bodies are never 

 found in the sweat-fluid, but in inflamma- 

 tion of the surrounding connective tissue 

 they frequently become separated from 

 the basement-membrane. Oil-globules are frequently seen in 

 the cell- body, and are to be regarded as a normal constituent 

 of the corpuscles. 



The basement-membrane is a thin, transparent structure, 

 lying beneath the epithelial cells and composed of flat endo- 

 thelial elements, as shown by the action of silver nitrate on 

 the fresh tissue. 



In certain glands, especially those of the axilla, a layer of 

 unstriped muscular fibres is found external to the basement- 

 membrane. These fibres are present in only a small number 

 of sweat-glands ; by their contraction they assist in the expul- 

 sion of the secreted sweat. They are the smallest unstriped 

 muscular fibres met with in the human body. 



FIG. 121. Lower part of a 

 sweat-gland : a, excretory duct ; 

 6, coil of secreting-tube ; c, sc- 

 creting-tube cut transversely; 

 d blood-vessels cut across. 



