BISECTIONS FOB LABORATORY WORK 777 



VII. MUSCULAR TISSUE 



(A) SMOOTH (Unstriped, Plain, Non-striated, Involuntary Smooth). 



(1) Sketch (.84) several isolated cells from a macerated preparation 

 of smooth muscle from the wall of the bladder, stomach or intestines of 

 the cat, or from a teased .fresh preparation of bladder of frog. Note 

 shape of cell, position of nucleus, fibrillar and granular content of cyto- 

 plasm, pcrinuclear coarsely granular sarcoplasm, and cell membrane 

 (sarcolemma). 



(2) Study smooth muscle in a stained section of the stomach or 

 intestines. Make l.p. sketch (85) of area including fibers cut trans- 

 versely and longitudinally. Sketch (86) h.p. a small area of cross-cut 

 fibers. Note variations in shape of cross sections and the position of 

 the nucleus. Why do not all of the cross sections of the fibers contain 

 a nucleus? Sketch (87) h.p. small area of longitudinally cut fibers. 

 Note the manner in which the fibers are joined into membranes. Why 

 do many of these cells appear much shorter than the isolated cells? 

 Study wall of one of the blood vessels of the umbilical cord. Sketch (88) 

 a few cells. Is an intercellular cement present? intercellular bridges? 

 Study also smooth muscle of bladder, and of a pregnant uterus. Where 

 in the body are the longest smooth muscle cells found ? Study the nerve 

 supply of the smooth muscle of the intestine in a demonstration prep- 

 aration. 



(B) CARDIAC (Involuntary striped). 



(1) Sketch (89) a fragment of the cardiac syncytium (myocardium) 

 from a macerated preparation of the heart ; or from a teased fresh speci- 

 men. Note the branching of the muscle trabecula?, position of nuclei, 

 fibrils, sarcoplasm, cross striations, and sarcolemma. 



(2) Make sketch (90) of small area of a stained section including 

 both transversely and longitudinally cut trabecula? ('fibers'). Note posi- 

 tion of the nucleus, myofibrils, cross striations (ground membranes, Z 

 lines, or telophragmata) and intercalated discs. What is the relation- 

 ship between the telophragmata and the sarcolemma? between the telo- 

 phragmata and the nuclear membrane? Are other striations present 

 besides the Z-stripes? 



(3) Sketch (91) small area of a specially prepared demonstration 

 slide (Zimmermann's techuic) to show the several types of intercalated 

 discs. Tease in glycerin a fragment from a hemalum-stained block of 

 myocardium. Determine the complete form of the intercalated discs. 



