Fibroid tumors are loosely attached to the surrounding uterine wall. They are usually invested by loose cellular tissue, forming a capsule from which they may easily be enucleated. Blood-vessels, usually of small size, connect the tumor with its capsule. Dense adhesion between the tumor and its capsule is the result of inflammatory action. The loose connection of the fibroid tumor with the surrounding structures explains the ease with which these tumors travel and are squeezed out of the uterine wall. It will be remembered that in this respect the fibroid differs from the nodule of cancer and of sarcoma. [Illustration: FIG. 131.--Interstitial fibroid tumor of the uterus. A small submucous fibroid appears in the uterine cavity.] [Illustration: FIG. 132.--Subperitoneal fibroid tumors of the uterus.] To the naked eye fibroid tumors present a white or rosy appearance. The intensity of the red color is, as a rule, proportional to the amount of muscular tissue. On section the bundles of fibrous tissue, arranged more or less concentrically about many axes, may be apparent. The vessels in the tumor itself are usually small and few in number. The large arteries and venous sinuses are found in the capsule. Fibroid tumors vary in hardness from the soft myoma to dense stony nodules composed almost entirely of fibroid tissue. Fibroid tumors vary in size from the smallest nodule in the uterine wall to a solid mass weighing one hundred and forty pounds. The tumors that usually come under observation weigh from one to ten pounds. Fibroid tumors occur most frequently in the body of the uterus. As has already been mentioned, however, they are sometimes found in the infra-vaginal portion of the cervix, and a peculiarly dangerous form of fibroid grows from the supra-vaginal cervix. Fibroid tumors are multiple in the great majority of cases. It is unusual to find a single fibroid nodule or tumor in the uterus. Sometimes one tumor far outgrows the rest, but if the uterine wall is carefully examined other small nodules will usually be found in its substance. Fibroid tumors originate in the muscular wall of the uterus, and extend thence in various directions. When they are situated in the muscular wall they are said to be interstitial (Fig. 131). When they grow outward, so that they project beneath the peritoneum, they are called subperitoneal (Fig. 132). When they project into the uterine cavity they are called submucous (see Fig. 131). When they grow from the side of the uterus, and especially from the supra-vaginal portion of the cervix, and extend outward into the cellular tissue between the folds of the broad ligaments, they are said to be intra-ligamentous (Fig. 133).