Fibroglia Fibrils in the Intestinal \\:ill of Necturn 93 



lagenous fibrils. These aie quite numerous intercellularly and, in all 

 probability, arc, derived from the same cells as the fibroglia. 



Often, however, the arrangement differs from the aboYe. In Figure 6, 



taken from the connective tissue in the center of a fold or villus, the 

 connective tissue cells form a distinct syncytium. Must ol the tibi ils 

 are almost entirely embedded in the cell protoplasm. The ends of 

 some of the fibrils seem to be lying free in the intercellular substance, 

 but in most instances some granular protoplasm surrounds the fibril 

 throughout its extent. Here the condition closely resembles a develop- 

 mental stage of smooth muscle. In Figure 3, taken from just beneath 

 the epithelium, the cells are much elongated structures with rod-shaped 

 nuclei similar to those of smooth muscle. The protoplasm is directly 

 continuous from one cell with that of the next, through long anasto- 

 moses. The fibrils are very numerous and most of them run parallel 

 with the long axis of the cell. The fibrils nearest the nucleus are 

 embedded in the granular protoplasm throughout their entire length. 

 Some of the more peripheral seem to be entirely free from cell pro- 

 toplasm, but usually can be shown to be connected at some point. The 

 fibrils are both fine and coarse. The fine fibrils tend to lie near the 

 nucleus, the coarse around the periphery. The whole bundle of fibrils 

 grouped around a single nucleus forms a structure which shows a 

 striking resemblance to a smooth muscle fiber. Between this type and 

 that described by Mallory are all transitions. Not only in the base- 

 ment membrane, but scattered throughout the subepithelial connective 

 tissue are these elongated, spindle-shaped cells, which, with their sur- 

 rounding fibrils so closely resemble muscle fibers. Here, as in the base- 

 ment membranes, all transitions exist between them and the stellate 

 cells which contain such fibrils. 



From the fact that the fibroglia fibrils, by every method employed, 

 stain just as do myofibrils, and in addition, because these fibrils are 

 often arranged in bundles which morphologically resemble smooth 

 muscle fibers, it seems that, unless more evidence to the contrary can 

 be obtained, they should be considered myofibrils. The term fibroglia 

 fibril will then be unnecessary. That these fibrils arise in connective 

 tissue cells, and that the cells even when the fibrils are fully formed 



