Abstract
The ovary in the guinea pig, as in most other mammals, frequently presents a cystic condition. The cysts are the result of a proliferation of the cuboidal epithelium which lines the epididymal portions of the embryonic Wolffian duct. The epididymal tubules are located towards one pole of the ovary and are connected with similar tubules lying outside the body of the ovary between it and the oviduct.
Under certain conditions the walls of these blind tubules begin to proliferate, apparently forming a number of new tubules. A fluid accumulates in the interior of the tubules and distends them into spheroidal shapes. They become greatly distended and break into one another or fuse, thus forming large “ovarian cysts” in the case of those tubules lying within the ovary or “parovarian cysts” in the tubules lying outside.
Thus the ovarian and parovarian cysts are similar in structure and their formation is of the nature of a tumorlike growth of the cuboidal epithelium which lines them. The accumulation of fluid which is essential to the formation of typical cysts is not to be considered their primary cause.
In studying a great many ovaries for cystic conditions during several years we have never observed a follicular cyst. Large atretic follicles may be confused at times with small cysts, but such follicles always begin to disappear or atrophy before attaining significant dimensions.
The uterine glands occasionally become cystic. Such cysts usually break into the lumen of the uterus when their epithelial lining becomes greatly distended. These are similar to the ovarian cysts in that both occur under identical conditions in tubules lined by epithelium. The fact that the uterine glands open directly into the lumen of the uterus makes the occurrence of such cysts exceptional.
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