NX 



NORMAL HISTOLOGY. 



Fig. 70. 



a distinct intranuclear reticulum of chromatin. The intercellular 

 substance is a mere cement of homogeneous character. 

 The cells are arranged with their long axes parallel to 

 each other and with the tops of their minute ridges in 

 contact, So that fine channels exist between the contiguous 

 cells. This is apparently a provision for the circulation 

 of nutrient fluids between the cells (Fig. 71). 



Recent studies of the intercellular regions of smooth 

 muscular tissue cast some doubt upon the existence of the 

 minute ridges described above. The appearances taken 

 for such ridges may, in reality, be produced by a fine 

 mesh work of delicate fibrils which encircle the muscle- 

 cells and bind them together. In the spaces between these 

 fibrils there is opportunity for circulation of the tissue- 

 fluids. This view also does away with the idea of a cement- 

 substance holding the cells together. The reactions which 

 led to the belief in a cement may be due to proteids in the 

 tissue-fluids present in this situation. This conception 

 would make the structure of smooth muscular tissue, as far 



Fig. 71. 



Smooth muscular tissue. 



Pig. 70.— An isolated fibre from the muscular coat of the small intestine. (Schiifer.) The 

 nucleus is somewhat contracted, so as to appear broader and shorter than when in the 

 extended state. 



Fig. 71. -Cross-section of smooth muscular tissue : human sigmoid flexure. (Barfurth.) Two 

 of the muscle-cells have been cut in the region occupied by the nucleus, which appears 

 in round cross-section. The other cells have been cut between the site of the nucleus 

 and the end of the cell. The structural details of the cytoplasm or contractile substance 

 are not represented, but the connecting ridges of the cells, with the channels between 

 them, are shown. These minute ridges can, however, only be seen when the tissue has 

 been exceptionally well preserved ami is studied under a high power of the microscope. 



as the intercellular substances or structures are concerned, analogous 

 to those of striated and cardiac muscles. 



