The wall of the cyst is composed of fibrous tissue containing elastic and unstriped muscular fibers. Traces of normal ovarian tissue may be discovered in the cyst-wall. Sometimes a corpus luteum is found in the wall of a cyst of large size, showing that ovarian follicles may ripen and rupture, and that conception may take place even though the ovary is grossly diseased.
The thickest portion of the cyst-wall is that in the region of the pedicle. The thinnest portion is usually opposite the peduncular attachment.
By careful dissection the wall may generally be divided into three layers—an external and an internal layer of fibrous structure, and a middle layer of loose connective tissue. This differentiation is best marked in the region of the pedicle. In the thinnest part of the cyst the coats become blended into a thin, homogeneous, fibrous structure.
The outer surface of the cyst is covered with a layer of endothelial cells. This is not a peritoneal investment. It is intimately connected with the outer fibrous coat of the cyst, and cannot be stripped off. In this respect these cysts differ from some hereafter to be described, in which there is a distinct detachable peritoneal covering.
The blood-vessels of the tumor are distinguished throughout the fibrous wall. When three lamellæ are present, the large arteries are found in the middle layer. Lymphatics, often of large size, are also found in the cyst-wall.
The glandular cyst is always, at first, multilocular; the tumor is made up of several cyst-cavities. As the tumor increases in size the pressure causes atrophy of intervening septa, so that two or more cavities are thrown into one, and the number of loculi becomes correspondingly diminished. As the cyst grows, therefore, the tendency is toward the unilocular form. Careful examination of a unilocular glandular cyst will usually reveal the remains of atrophied septa upon the walls.
The epithelial lining of these cysts is usually composed of columnar cells. In cavities of large size the cells are flattened by pressure, and in cavities of the largest size fatty degeneration and atrophy may have taken place, so that the lining cells entirely disappear.
The cavities are often lined with a soft, velvety membrane, microscopically similar to mucous membrane. The columnar epithelium dips below the surface to form complex mucous glands. These glands may become obstructed, and secondary mucous retention-cysts are formed in the walls of the parent cyst. Such a mass of secondary cysts is often seen projecting into the main cyst-cavity or forming a lobulated prominence upon its outer surface.
Follicular cystic degeneration, such as has already been described, may occur in the ovarian tissue of the wall of the glandular cyst, so that a secondary group of small cystic cavities may be formed.
It is thus seen that the structure of an oöphoritic glandular cyst may be very complex. There may be one or more chief cyst-cavities, on the walls of which may be discovered the remains of septa which had formerly subdivided them. Projecting into the cavities may be seen honeycomb-like masses of secondary mucous retention-cysts; while in the walls of the tumor, perhaps rendering the surface lobulated, may be seen minor cyst-cavities formed by beginning glandular cystic degeneration or by simple cystic degeneration of ovarian follicles ([Fig. 167]).