The adhesion of the peritoneum to the uterus is closest along the median line, and over the whole of the fundus, at which points its separation by dissection from the tissues beneath cannot be effected without the aid of prolonged maceration ; but towards either side of the organ the connection is less inti mate, so that here the membrane may be made to glide to a limited extent over the sub-lying structures. At the two upper uterine angles the peritoneum is continued on to the uterine appendages ; viz., the Fal lopian tubes, round ligaments and ligaments of the ovaries. After sending off extensions to invest these parts, the portions of mem brane which cover the anterior and posterior faces of the uterus respectively come nearly into apposition along the lateral borders of the organ (fig. 427.), where they are con joined by a quantity of lax fibrous tissue, which serves to bind them loosely together, and at the same time to give support and protection to the numerous blood vessels entering the uterus on either side along the whole of this border.
A similar portion of lax fibrous tissue serves to connect the anterior wall of the uterine cervix, where it is uncovered by peri toneum with the posterior surface of the bladder, with which it lies in contact.
The sectional views of the uterus in three directions already given serve to explain the whole of the relations of the outer or peri toneal coat of the uterus to the muscular or proper coat.
Fig. 426. shows the mode of attachment of this membrane to the anterior and posterior surface and fundus along the median line, and also the parts which are left uncovered by peritoneum. Commencing from the os uteri the vaginal portion of the cervix forming the anterior lip (a) receives an investment of mucous membrane as far as its point of at tachment to the anterior wall of the vagina (v a). Beyond this the whole of the reinain ing portion of the anterior wall of the cervix, measuring above one inch in length (b b), is left uncovered either by mucous or serous membrane. At the termination of this space the peritoneum, reflected off' from the bladder, reaches the uterus, and after investing the organ, is continued down to and beyond the fornix of the vag,ina (f). But at this point the mass of loose connective tissue before re ferred to separates the peritoneum from the posterior cervical wall to a great extent (c), while finally a much larger portion of the cer vix is contained within the vagina, posteriorly than anteriorly, and is consequently covered by mucous membrane(p), because the vaginal walls are attached at a much higher point here than anteriorly.
Fig. 431. serves to exhibit the relations of the peritoneum to the fundus, and the absence of that membrane from the lateral borders of the uterus, while figs. 427.-430. exhibit the
relative proportions of the covered and un covered parts as seen in a series of horizontal sections of different portions of the organ.
The middle or smooth-muscular coat, upon which depends the remarkable firmness and solidity of the uterus, constitutes the prin cipal bulk of the organ. This coat upon sec tion appears of a pale pink colour, mottled with irre,,0ular white lines, and permeated by vessels which are particularly numerous near its lateral borders. The following are the compo nent tissues of the middle uterine coat, viz.:— 1st. Smooth-muscular fibres.— These are found in every portion of this coat, and con sist of fusiform fibres of the kind termed by Kolliker contractile fibre-cells, in which a single elongated oval nucleus may be occa sionally brought into view with difficulty. They all contain minute dark granulos easily distinguished, and they sometimes exhibit upon their surface slight longitudinal folds or tnarkings. These fibres have an average length of and breadth of vdtm".
They are deeply imbedded in the uterine substance from which they are with difficulty obtained separate, but they may be commonly seen projecting to the extent of about half their length from the torn margin of the preparation, and they are easily rendered visible in its substance by the aid of dilute acetic acid. These fibres do not apparently possess any distinct cell membrane. In very thin sections the ends of the fibres which have been transversely divided are seen as if solid, and the cut fibres do not collapse, nor have I ever been able to detect any appear ance of a flowing out of fluid contents, which would be the case if the individual fibres con sisted of a cell wall containing fluid (fig. 431. a).
2. Round and oval nuclei, or elementary corpuscles. —These measure wdr,u" in diame ter. They are found in many parts inter mixed with the fusiforin fibres, but they are most abundant towards the inner layers of the muscular coat. They are apparently the elementary or embryonic condition of the fusiform fibre-cells just described. For al though the two extreme forms of round cor puscles and fusiform fibres are the conditions under which these constituents of the mus cular coat are most numerously seen, there may yet be traced a sufficient number of apparently intermediate stages to justify the conclusion that the one is but the embryo fortn of the other ; the round corpuscles becoming at first oval, and then being length ened out into the fusitbrin state (fig. 434. b).