STRUCTURE OF MUSCULAR TISSUE. 



801 



650. Putting aside these cases, however, all the sensible movements of the 

 body are effected by one or other of two forms of tissue to which the term 

 muscular has been applied. The first of these, termed the smooth or un- 

 striped variety of muscle, consists of flattened bands, which are stated by 

 Kolliker to be composed of long, fusiform cells (Fig. 282), with one or often 

 two elongated oval nuclei, which become staff-shaped after death. 1 Around 

 the nucleus is a little finely granular protoplasm, which extends for some 

 distance in the axis of the fibre; the length of the cells varies from 712 s tn 

 to g' th of an inch, and their breadth from -g-g"^^ 1 to y-pj-g-th of an inch. 

 This form of muscular tissue is found in a nearly pure state, unmixed with 

 other tissue, in the nipple, corium, intestinal canal, bladder, prostate, vagina, 



and in the smaller arteries, veins, and lym- 

 phatics ; and mingled with much areolar, 

 fibrous, and elastic tissue in the trabeculse of 

 the spleen and corpora cavernosa, the dartos, 

 the circular fibres of the larger arteries and 

 veins, the urethra, Fallopian tubes and uterus, 

 in the trachea and bronchi, and in the ciliary 

 muscle of the eye, the choroid coat, and the 

 iris. 



FIG. 283. 



FIG. 282. 



FIG. 282. Fusiform cells of Smoolh Muscular Fibre, from 

 the renal vein of Man : a, Two cells in their natural state, 

 one of them showing the staff-shaped nucleus ; 6, a cell 

 treated with acetic acid, with its nucleus c brought strongly 

 into view. 



FIG. 283. Muscular Fibre broken across, showing 

 untorn Sarcolemma, connecting the fragments. 



the 



657. The second variety of Muscular tissue presents transverse striae 

 under the microscope, and occurs in all those muscles that are usually 

 termed "voluntary," though its presence in the heart, rectum, and pharynx 

 shows that it is not limited, to these alone. On examining the structure of a 

 striated muscle it is found to be easily separable into coarser or finer fasciculi 

 connected by means of areolar tissue, and these on more minute dissection 

 can be shown to consist of transversely striated polygonal fibres with three 

 or five angles, having, in Man, an average diameter of ^-g-jjth f an inch. 

 The fibres frequently terminate by free pointed extremities in the muscle, 

 and occasionally divide ; at other times they become continuous, either ab- 

 ruptly or by imperceptible gradation, with tendinous or strong connective- 

 tissue fibres. 2 In the case of the heart, the tissue is stated by Eberth 3 and 



p. 288), as extending from the base of each cilium to the nucleus and attached ex- 

 tremity of the cell, are to be regarded as representing extremely fine muscular fibres. 

 Dr. Stuart's observations were made on the cells of the ciliated epithelium of certain 

 species of Eolis. He has counted from 40 to 60 bands in each cell, and describes the 

 nucleus of the cell as being moved hither and thither by their contraction 



1 Schwalbe, Schultze's Archiv f. Microscop. Anat., Bd. iv, p. 392, pi. xxiv. 



* As in the tongue, Hyde Salter, in Cyclop. Anat. and Phys., vol. iv, p 1132. 

 Hoyer, however, maintains that in such instances the transparent fibres in which the 

 muscular fibres apparently terminate are in reality contractile. See Keichert's Archiv, 

 1859, p. 481. 



8 Virchow's Archiv, 1866, Bd. xxxvii, p. 100. 



