i6o 



PRACTICAL HISTOLOGY. 



[X. 



transparent. The fibres are striated longitudinally, and are seen to 

 be made up of excessively delicate fine unbranched fibrils. The 

 fibres vary from 6 /u to 8 /* in diameter (-^^-^^ inch). They 

 may be round or flattened, and are of indefinite length. Amongst 

 the white fibres may be seen a few fine elastic fibres (E1F), recog- 

 nised by their sharper contour, and by the fact that they branch 

 and anastomose. . They run between, but never in the white fibres. 

 It is not often that the corpuscles are visible without the action of 

 special reagents. The corpuscles are best seen in young animals 

 (fig. 124, Bdgz). 



(b.) Irrigate with a 2 per cent, solution of glacial acetic acid ; 

 observe that the white fibres swell up, become clear, gelatinous, 



and homogeneous ; the elastic fibres 

 being unaffected, come clearly into 

 view. The latter have a sharply- 

 defined outline, branch and anasto- 

 mose, and sometimes curl at the ends. 

 The corpuscles, or at least their 

 nuclei, come into view. Observe 

 the oval or fusiform nuclei of the 

 fixed connective - tissue corpuscles 

 (Bdgz) they may be surrounded 

 with some soft protoplasm and 

 the much smaller compound nuclei 

 of the wandering cells or leucocyte* 

 (Lc). In the rat especially one is 

 very likely to find the very granular 

 nucleated cells known as granular 

 cells. They frequently lie along 

 the course of the small blood- 

 vessels. Do not preserve this 

 specimen. 



If the areolar tissue be taken from the sub-arachnoid space of 

 the brain and treated with dilute acetic acid, the fibres lose their 

 librillated structure, nuclei appear, and the fibres themselves may 

 be seen to swell up here and there, while they are constricted at 

 irregular intervals by a thin fibre. This is due to these fibres 

 being partly embraced by connective-tissue cells, which have long 

 branches which partly encircle the fibre. 



9. Fenestrated Fibrous Tissue (L and H). Harden the 

 omentum of a dog or cat in Miiller's fluid. Stain a piece in logwood, 

 and mount in balsam. 



Note the meshes bounded by areolar tissue. The fibrils which 

 compose the fibres are readily seen, and sometimes an cnclotliolial 

 cell may be seen partially detached (fig. 125, E'), for the omentum 



Flo. 125. Omentum of Dog. E', E". Par- 

 tially detached endothelial cells. E. 

 Nuclei of endothelial cells, x 130. 



