The Ovaries.— The ovaries are two small bodies of an almond shape, and lie on either side of the uterus. The bulk of the entire organ consists of connective tissue, in which lie imbedded the Graafian follicles or ovisacs, in which the ova are contained. These follicles or ovisacs are minute cells which are packed immediately beneath the surface, where they occur in all stages of development. With the increase in size which accompanies their development the follicles pass toward the surface, where they form a distinct projection, and at this point will occur the final rupture of the sac and the escape of the ovum. It is supposed that the ovum is grasped by the fringe-like extremity of the Fallopian tube and is carried through it by the movements of the ciliary epithelium to the uterus.
The formation of new follicles continues only for a short time after birth, when the Graafian follicles are the most numerous; the entire number contained within the ovaries of the child being estimated at over 70,000. In view of the unquestionably large number of follicles in very young ovaries, and the relatively small number of ova which reach maturity, the degeneration of many follicles after reaching a certain degree of development seems certain.
PHYSIOLOGY OF THE FEMALE GENERATIVE ORGANS.
Ovulation; Etiology of Menstruation; Uterine Nerve-supply; the Function of the Uterus; Stages of the Menstrual Cycle; Average Duration of the Menstrual Flow; Character of tahe Flow; Relation of Ovulation to Menstruation; the Menstrual Wave; Definition of Menstruation; Premomitory Symptoms of the Flow; Hygiene of Menstruution.
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Ovulation.— At birth the formation of the ova is nearly completed; the production of’ new cells probably ceases after the second year. The ovaries of the child of two years contain, therefore, the full quota of ova, although the vast majority of these cells always remain immature and undeveloped. While it is probable that a variable number of the immature ova undergo partial development before puberty, yet the advent of sexual maturity at that time marks the establishment of the regular development of the Graafian follicles and their contained ova, accompanied by the attendant phenomena of menstruation.
During the entire child-bearing period, or from about the age of fifteen to forty-five years, the development of the Graafian follicles and the discharge of the ova are continually taking place. The liberation of the ova usually takes place at definite times, which in general coincide with the menstrual epochs, one or more ova being set free at each period; but this is by no means invariable.
The ripe human ovum or germ cell is a spheric cell, about 0.2 mm. in diameter, consisting of granular protoplasm, in which lies a nucleus which contains the germinal spot. The proper cell-wall is a structure of great delicacy, outside of which is a secondary envelope.