310 



STOMACH AND INTESTINE. 



subjacent muscular tunic. The advantage 

 of such a yielding attachment has already 

 been alluded to. For a description of the 

 structure of this tunic, the reader is referred 

 to the articles PERITONEUM and SEROUS MEM- 

 BRANES. 



The muscular coat of the stomach consists 

 of the unstriped or organic muscular fibre ; 

 which the researches of Koelliker have shown 

 to consist of fibre-cells, such as are represented 

 in Jig. 241. The form and dimensions of these 

 long and spindle-shaped elements vary little 

 in the different parts of the intestine and 

 stomach. Their length is from 5 1 Q to -jgth of 



Fig. 241. 



or faintly striated contents. In some instances, 

 they are marked by swellings ; which, as they 

 are rarely seen in the associated fibres, are 

 probably due to casual local contractions of the 

 sarcous substance itself. The arrangement 

 of these fibre-cells is very simple; they are 

 packed together in parallel rows (fg- 242.), 

 their flattened surfaces adhering strongly 



Fig. 242. 



Fibre-cell from the unstriped muscle of the intestine. 

 Magnified about 350 diameters. ' (After Koel- 

 liker.") 



a, nucleus. 



an inch : their breadth from .^.^ to ^oWth a t 

 the middle, where they are flattened, and from 

 whence they taper off to conical and pointed 

 extremities. They contain a nucleus ; which 

 is from ^- to Y^th of an inch in length, 

 and about a sixth of this in breadth. Their tex- 

 ture is a pale substance,which generally appears 

 to be homogeneous, but is sometimes seen to 

 consist of a membrane* enclosing granulated 

 * From a comparison of very numerous observa- 

 tions, the author entertains no doubt that this 



Portion of a bundle of fibre-cells from the muscular 

 coat of the intestine. Magnified 250 diameters. 



a, nuclei of the fibre-cells. 



to each other. They thus form small 

 and broadish bundles, between which are 

 interposed the vessels for their supply, en- 

 closed in a sparing quantity of areolar tissue. 

 The union and interlacement of such fasci- 

 cles of cells, builds up the large flattened 

 strata of the muscular coat of the intestines. 

 The fibre-cells are developed by the longitu- 

 dinal extension of an oval cell ; in which is 

 deposited a special sarcous content, that soon 

 obscures the original cell-membrane. 



We shall hereafter see that these fibres sur- 

 round the intestine in two layers : an external, 



membrane is always present, being only obscured 

 by such circumstances as delicacy, adhesion, or re- 

 fractility. In the fibre-cells of the adult human 

 pylorus, he has often verified a distinct cell-wall 

 or sarcolemma. And the reappearance of this 

 membrane in the unstriped muscular fibre of the 

 human uterus, as its cells recede or degenerate 

 after parturition, is only one of many significant 

 instances, that we cannot deduce the real absence 

 of such a delicate membrane, from the mere fact of 

 its ceasing to be visible under the microscope. 



