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peritoneal, (2) middle, or muscular, the fibers of which are arranged in a circular or longitudinal direction, (3) internal, or mucous, covered with ciliated epithelial cells, which are always waving from the ovary toward the uterus.

The Uterus is pyriform in shape, and may be divided into a body and neck; it measures about three inches in length and two inches in breadth in the unimpregnated state. At the lower extremity of the neck is the os externum; at the junction of the neck with the body is a constriction, the os internum. The cavity of the uterus is triangular in shape, the walls of which are almost in contact.

The walls of the uterus are made up of several layers of non-striated muscular fibers, covered externally by peritoneum, and lined internally by mucous membrane, containing numerous tubular glands, and covered by ciliated epithelial cells.

The Vagina is a membranous canal, from five to six inches in length, situated between the rectum and bladder. It extends obliquely upward from the surface, almost to the brim of the pelvis, and embraces at its upper extremity the neck of the uterus.

Discharge of the Ovum.-As the Graafian vesicle matures, it increases in size, from an augmentation of its liquid contents, and approaches the surface of the ovary, where it forms a projection, measuring from onefourth to one-half an inch in size. The maturation of the vesicle occurs periodically, about every twenty-eight days, and is attended by the phenomena of menstruation. During this period of active congestion of the reproductive organs, the Graafian vesicle ruptures, the ovum and liquid contents escape, and are caught by the fimbriated extremity of the Fallopian tube, which has adapted itself to the posterior surface of the ovary. The passage of the ovum through the Fallopian tube into the uterus occupies from ten to fourteen days, and is accomplished by muscular contraction and the action of the ciliated epithelium.

Menstruation is a periodical discharge of blood from the mucous membrane of the uterus, due to a fatty degeneration of the small blood-vessels. Under the pressure of an increased amount of blood in the reproductive organs, attending the process of ovulation, the blood-vessels rupture, and a hemorrhage takes place into the uterine cavity; thence it passes into the vagina. Menstruation lasts from five to six days, and the amount of blood discharged averages about five ounces.

Corpus Luteum.-For some time anterior to the rupture of a Graafian vesicle, it increases in size and becomes vascular; its walls become thick.

ened from the deposition of a reddish-yellow, glutinous substance, a product of cell growth from the proper coat of the follicle and the membrana granulosa. After the ovum escapes, there is usually a small effusion of blood into the cavity of the follicle, which soon coagulates, loses its coloring matter, and acquires the characteristics of fibrin, but it takes no part in the formation of the corpus luteum. The walls of the follicle become convoluted, vascular, and undergo hypertrophy, until they occupy the whole of the follicular cavity. At its period of fullest development, the corpus luteum measures three fourths of an inch in length and half an inch in depth. In a few weeks the mass, loses its red color, and becomes yellow, constituting the corpus luteum, or yellow body. It then begins to retract and becomes pale; and at the end of two months nothing remains but a small cicatrix upon the surface of the ovary. Such are the changes in the follicle if the ovum has not been impregnated.

The corpus luteum, after impregnation has taken place, undergoes a much slower development, becomes larger, and continues during the entire period of gestation. The difference between the corpus luteum of the unimpregnated and pregnant condition is expressed in the following table by Dalton

Corpus Luteum of Menstruation. Corpus Luteum of Pregnancy. At the end of Three-quarters of an inch in diameter; central clot

three weeks. reddish ; convoluted wall pale. One month.

Smaller; convoluted Larger; convoluted wall wall bright yellow; clot bright yellow; clot still redstill reddish.

dish. Two months. Reduced to the condi.

Seven-eighths of an inch tion of an insignificant in diameter; convoluted wall cicatrix.

bright yellow; clot perfectly

decolorized. Four months. Absent or unnoticeable.

Seven-eighths of an inch in diameter; clot pale and fibrinous; convoluted wall

dull yellow. Six months. Absent.

Still as large as at the end of second month; clot fibrin

ous; convoluted wall paler. Nine months. Absent.

Half an inch in diameter; central clot converted into a radiating cicatrix; external wall tolerably thick and convoluted, but without any bright yellow color.

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GENERATIVE ORGANS OF THE MALE. The Generative Organs of the Male consist of the testicles, vasa deferentia, vesiculæ seminales, and penis.

The Testicles, the essential organs of reproduction in the male, are two oblong glands, about an inch and a half in length, compressed from side to side, and situated in the cavity of the scrotum.

The proper coat of the testicle, the tunica albuginea, is a white, fibrous structure, about the 25 of an inch in thickness; after enveloping the testicle, it is reflected into its interior at the posterior border, and forms a vertical process, the mediastinum testes, from which septa are given off, dividing the testicle in lobules.

The substance of the testicle is made up of the seminiferous tubules, which exist to the number of 840; they are exceedingly convoluted, and when unraveled are about 30 inches in length. As they pass toward the apices of the lobules they become less convoluted, and terminate in from 20 to 30 straight ducts, the vasa recta, which pass upward through the mediastinum and constitute the rete testis. At the upper part of the mediastinum the tubules unite to form from 9 to 30 small ducts, the vasa efferentia, which become convoluted, and form the globus major of the epididymis; the continuation of the tubes downward behind the testicle and a second convolution constitutes the body and globus minor.

The seminal tubule consists of a basement membrane lined by granular nucleated epithelium.

The Vas Deferens, the excretory duct of the testicle, is about two feet in length, and may be traced upward from the epididymis to the under sur. face of the base of the bladder, where it unites with the duct of the vesicula seminalis, to form the ejaculatory duct.

The Vesiculæ Seminales are two lobulated, pyriform bodies, about two inches in length, situated on the inner surface of the bladder.

They have an external fibrous coat, a middle muscular coat, and an internal mucous coat, covered by epithelium, which secrets a mucous Auid. The vesiculæ seminales serve as reservoirs, in which the seminal fluid is temporarily stored up.

The Ejaculatory Duct, about 34 of an inch in length, opens into the urethra, and is formed by the union of the vasa deferentia and the ducts of the vesiculæ seminales.

The Prostate Gland surrounds the posterior extremity of the urethra, and opens into it by from twenty to thirty openings, the orifices of the pros

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