Lastly, it may be observed, in reference to tumours which are commonly termed polypi, that the present state of pathology demands a separation of these, according to their struc tural differences, such as has long been esta blished, upon a similar basis, among those objects of the animal kingdom whose sup posed reserablance, distant indeed, and at the best fanciful, has given a name to this form of tumour. For, as in that prototypal group of animal forms, once termed polypi, three widely separated classes at least are now known to have been conibined, so those pathological for mations, which are still familiarly. termed po lypi, exhibit a more than equal number of va rieties, each marked by distinct differences of structure. These may be distinguished as the fibrous, including the cellular, which are com posed of a looser fibrous tissue ; the muscular ; the mucous, also frequently containing much fibrous tissue, and the cancerous or nzolignant polypi.- And to these have been added the so-called fibrinous or blood poly pi.
The fibrous polypus has been already de scribed, and the second, or muscular, may here also be classed with it, as having its origin in the middle coat of the uterus, but consisting of muscular rather than of fibrous tissue.
These muscular polypi are comparatively rare. Their structure, as exhibited in the ac companying fig. 477., is precisely that of the proper muscular coat of the uterus.
The malignant polypi, and those which are formed of hypertrophied mucous structure, belong to another category, and will be de scribed hereafter.
4. Pathological conditions of the mucous coat. —a. First under this head may be noticed simple hypertrophy of the uterine mucous membrane, followed often by a partial shed ding of that structure in the form of the so called Dysmenorrhyeal menzbrane.—The term men strual decidua would probably forin a more appropriate title for these structures, which consist of a greater or less thickness of the mucous membrane lining the uterus, differing in no respect from that membrane in its ordi nary condition*, except in the one particular, that it has undergone a certain degree of hypertrophy. (Fig. 443.) The hypertrophies which the mucous membrane of the uterus undergoes in various circumstances form a most interesting subject for study', but all of them are not pathological. The most familiar example of normal hypertrophy of the uterine mucous membrane is that which occurs in ordinary pregnancy. Here, no sooner does the uterus begin to enlarge, than the mucous lining also expands, and its tissues become opened up by an in creased flow of blood, and a consequent rapid development of the simple elements composing this structure. This hypertrophy
occurs in every pregnancy where the ovum enters the uterus. But it also happens very generally in those cases where the ovum never enters the uterus at all, but is developed externally to that cavity (extra-uterine gesta tion). Here a most perfect decidua is usually found lining the uterus. The exceptions are few in which the uterine mucous membrane, under these circumstances, does not exhibit any increase of thickness, but retains or nearly so, its ordinary characters But a state of pregnancy is 'not necessary to produce evolution of the uterine lining, for this may occur when the body of the uterus is enlarged from other causes. Thus, in an example in my possession of uterine fibroid, in 'which the body of' the uterus has undergone the hypertrophy already described (p. 491.), as common in that state, the hypertrophy has extended to the mucous membrane, so that the uterine cavity, which had also been occupied by one of these tumours, exhibits a delicate decidual lining.
The decidual membranes occasionally cast off' from the uterus under circumstances of dysinenorrhcea, consist of fragments, or, more rarely, of entire membranes forming casts of the uterine cavity. The structure of all these is nearly similar, and they differ chiefly in the greater or less thickness of membrane de tached. All present upon their inner surface the peculiar cribriform markings already de scribed as constituting the orifices of the uterine glands, while their outer surfaces are rough and shaggy, like the outer surface of aborted ova, for this surface has been de tached or torn off from the uterus. Fig. 443. represents a portion of such a membrane, as seen from its inner or cribriform surface. The microscopic characters of these membranes are precisely those of ordinary decidua.
b. Hypertrophy of the follicular structures of the uterine mucous membrane. Follicular polypi. Mucous polypi. Cysts.— The patho logical formations which take their origin in the mucous membrane lining the uterus, con sist chiefly in hypertrophic growths of that membrane, and of its follicular structures. They present usually two varieties, according as the follicular or the ordinary mucous tissue abounds in their composition. Many of these growths acquire a peduncle, and then consti tute the mucous or follicular polypi.