XV.] MUSCULAR TISSUE. 189 



LESSON XV. 

 MUSCULAR TISSUE. 



Muscle histologically occurs in two varieties (i.) Non-striped; 

 (2.) Striped. Non-striped muscles are involuntary, \vhile striped 

 muscles, as a rule, are voluntary ; but the heart-muscle is an 

 exception, for though striped it is involuntary. 



Non-Striped (smooth, involuntary). Occurs in the outer coats 

 of the lower half of oesophagus ; muscular coat and muscularis 

 mucosse of stomach and intestines ; villi ; ureter, bladder, and 

 urethra ; pelvis and capsule of kidney ; trachea (trachealis muscle) ; 

 bronchi ; oviduct ; uterus ; iris, ciliary muscle ; erector pili muscles 

 of skin, sweat glands ; coats of blood- and lymph- vessels ; capsule 

 and trabeculse (lymphatics, spleen), and ducts of some glands, sali- 

 vary, bile-ducts, &c. 



It consists of nucleated elongated fusiform contractile cells, held 

 together by a clear cement. The cells taper towards their extremities, 

 and although they appear homogeneous in reality they seem to consist 

 of longitudinally arranged fibrils held together by a sarcoplasm, or at 

 least a transparent material. The nucleus is oval or rod-shaped. 

 Some state that the cells have an elastic sheath. Each cell is from 

 4 to jo /* GroVrr- 25*00 inch ) in breadth and 40-200 //, (^-^ 

 inch) in length. 



1. Non-Striped Muscle (H). Place thin strips of the muscular 

 coat of the intestine for forty-eight hours in a 25 per cent, solution 

 of nitric acid, which softens the connective tissue and renders the 

 tissue yellow. Wash it thoroughly in water. Tease a small part 

 in glycerine or Fun-ant's solution. Or macerate a small piece of 

 intestine in | per cent, bichromate of potash for 48 hours. Cells 

 can then be readily isolated. 



(a.) Select an isolated fibre. It is spindle-shaped, elongated, or 

 fusiform, tapering to both ends, and in its centre there is an oval 

 nucleus, distinguished by its being rather more refractive than the 

 rest of the cell (fig. 162). At the poles of the nucleus there may 

 b<- a few granules. 



It is very difficult to stain these cells after the action of nitric 

 acid, but this may be done with magenta, provided the nitric acid 

 be entirely washed out of the tissue beforehand. Each cell is said 

 to have a sheath, but that cannot be seen in fibres prepared in this 

 way. 



