84 



NORMAL HISTOLOGY. 



FIG. 67. 



a distinct intranuclear reticulum of chromatin. The intercellular 

 substance is a mere cement of homogeneous character. 

 rpj ie ce j] s are arrail g e( j w ith 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. 68). 



Smooth muscular tissue occurs in the form of bundles 

 or layers, in each of which the cells or fibres run in the 

 same direction. The tapering ends of the individual cells 

 interdigitate with each other, masking the intercellular 

 substance, so that the tissue appears as though wholly 

 composed of cells. Surrounding the muscular bundles or 

 between the layers of that tissue is vascularized areolar 

 tissue, giving it support and containing its nerve-supply. 



The microscopical appearances of sections of smooth 

 muscular tissue depend upon the direction in which the 

 individual cells have been cut. A brief analysis of the 

 different appearances that may result will be useful as an 



FIG. 68. 



Smooth muscular tissue. 



Fig. 67. An isolated fibre from the muscular coat of the small intestine. (Schafer.) The 

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

 extended state. 



Fig. 68. 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 and is studied under a high power of the microscope. 



illustration of the way in which microscopical appearances must be 

 interpreted in order to gain a correct conception of the structure 



