72 



J0RN Hess Thaysen 



watery secretion with a low concentration of organic material 

 (cf. Babkin, 1950). With respect to the sweat gland it is 



SWEAT 



PAROUS 



SUBMAX. 



S <EC. 



Na Na 



Z> varies with 

 Na 



secretory rate 



SUBLING. PANCREAS LACRYMAL 



k\ 



V, 



^ 



S = E.C. 



Na No 



_D», independent of 

 Na 



secretory rate 



I 



Fig. 5. Comparison between the histological structure of the six 

 main duct-possessing glands and their secretion of sodium ions. 

 Sjja = concentration of sodium in tlie secretion. E.C.Na = con- 

 centration of sodium in the extracellular fluid. The coil of the 

 sweat gland and the acini of the other glands are cross-hatched. 

 The epithelia of the ducts are illustrated by different symbols, 

 which refer to the schematic cross- sections at the bottom of the 

 figure. The cross-sections are (from left to right) : double-layered 

 epithelium of sweat duct; striated epithelium of intralobular 

 ducts ; high cylindrical epithelium of excretory ducts ; low cuboidal 

 epithelium of intercalary ducts. 



suggested that precursor formation is located in the coil, 

 whereas reabsorption of sodium takes place in the duct. 



REFERENCES 



Albrectsen, S. R., and Thaysen, J. H. (1955). Scand. J. din. Lab. 



Invest., 7, 231. 

 Araki, Y., and Ando, S. (1953). Jap. J. Physiol., 3, 211. 

 Babkin, B. P. (1950). Secretory Mechanism of the Digestive Glands, 



2nd ed. New York : Hoeber. 



