UTERUS (NORMAL ANATOMY). 



633 



largest portion, while in the cervix the fibrous 

 element predominates, and the muscular fibre 

 is proportionally less abundant. 



Course of the muscular fibres. Regarding 

 the precise plan of arrangement of the consti- 

 tuent tissues of the middle uterine coat, and 

 especially of its muscular element, in the 

 unimpregnated state, numerous microscopic 

 examinations have satisfied me that it is not 

 possible to do more than to indicate these in 

 a very general manner. Mine. Boivin at- 

 tempted to describe the special course of the 

 muscular fibres in the unimpregnated organ ; 

 but she appears to have abandoned the at- 

 tempt alter giving an account of what is seen 

 upon the surface of the organ when the peri- 

 toneum has been stripped off after prolonged 

 maceration. More recently the course of 

 these fibres has been described by Kolliker, 

 Gerlach, and others, in the deeper seated, as 

 well as in the superficial layers. 



In investigating this part of the subject it 

 appears to me that a sufficient distinction has 

 not been made between the course of the in- 

 dividual fibres, and the arrangement of the 

 lamina,' or bundles into which they are col- 

 lected, for these are by no means necessarily 

 the same. 



According to my observations the contrac- 

 tile fibre-cells are not distributed in equal pro- 

 portions through all parts of the muscular 

 coat, nor are they found everywhere in the 

 same condition. It has been already stated, 

 that no strict line of demarcation is discern- 

 ible by the microscope between the three 

 several coats, of which the uterus is said to 

 consist. And this is particularly the case in 

 respect of the muscular fibres which permeate 

 all of them. In the so-called mucous mem- 

 brane the muscular fibre-cells are loosely ar- 

 ranged in an amorphous tissue, in which they 

 lie embedded, intermixed with the elementary 

 nuclear corpuscles, constituting their embry- 

 onic condition. Here the fibre-cells form 

 bundles, situated between the ramified canals 

 or utricular glands of the uterus, and take a 

 direction more or less oblique or perpendicular 

 with regard to the inner uterine surface. But 

 at the level of the base of the uterine follicles, 

 where the proper muscular coat is considered 

 to begin, and the mucous membrane to termi- 

 nate, the contractile fibre-rells assume a dif- 

 ferent direction and arrangement. Here at 

 once they begin to exhibit a certain order of 

 stratification, the strata being very closely su- 

 perimposed, and arranged for the most part in 

 such a manner as to lie parallel with the walls 

 of the uterine cavity, which is therefore sur- 

 rounded by them. 



These strata exhibit certain differences of 

 composition and arrangement sufficient, for 

 the sake of description at least, to justify an 

 artificial division of them into three orders. 



The innermost of these may be termed the 

 dense muscular strata. They commence im- 

 mediately external to the mucous membrane, 

 and extend outwardly through about half or 

 two thirds of the thickness of the muscular 

 coat. 



When preparations that have been preserved 

 in weak spirit, or those that have been finely 

 injected, are examined by the naked eye, or 

 with a hand lens, a peculiar mottled appear- 

 ance is presented by sections of this part, 



Fig. 4-35. 



Tltin section of a portion of the uterine ivalls, com- 

 mencing from the peritoneum and extending inwards, 

 showing the irregular course of the strata of uterine 

 filire, and the divided vessels between them. (Ad 

 Nat.) 



caused by the intermixture of numerous mi- 

 nute white lines ramifying within a darker 

 substance, and dividing it into a multitude of 

 small lozenge-shaped spaces. The whiter lines 

 mark the course of the finer uterine vessels, 

 together with the bundles of white fibrous 

 tissue which accompany them. The browner 

 lozenge-shaped spaces consist of the fusiform 

 contractile fibre- cells, united together by 

 amorphous tissue into short bundles, which 

 by their superposition constitute the lamina; 

 just mentioned. When horizontal sections 

 are made of this portion of the muscular 

 coat, such as are represented mjig. 4-28., these 

 bundles or strata are seen to be arranged in a 

 concentric manner, forming interrupted circles 

 surrounding the uterine cavity. But this ap- 

 pearance must not be regarded as indicative 

 of any corresponding direction of the muscu- 

 lar fibre-cells, within these bundles or lami- 

 nae, for all appearance of a concentric plan, as 

 regards the fibres, at once vanishes under the 

 use of the microscope. 



Fig. 436., representing a fine section taken 

 from the inner muscular lamina;, serves to 

 exhibit the mode in which the contractile 

 fibre-cells are arranged in this portion of the 

 uterine walls. The individual fibres and em- 

 bryonic corpuscles are imbedded in an amor- 

 phous substance (the unformed connective 

 tissue already described), by which they are 

 aggregated together, so as to form bundles 

 and lamina;. In these strata the fibre-cells 

 appear to remain distinct, and to be separated 

 from each other by a distance not greater 

 usually than their own diameters. 



