DISEASES OF THE GENERATIVE ORGANS
GENERAL DISCUSSION.—The study of the organs concerned with the reproduction of the species is essential in order to acquire a knowledge of their several functions. It is only through an understanding of these functions that we can prepare ourselves to correctly recognize, and successfully treat, or prevent, such diseases as may involve the organs of generation. A knowledge of the structure and function of the generative organs of the female is of greater importance from the standpoint of disease, than is a similar knowledge of the generative organs of the male. The female is concerned with the complete reproductive process, which may be divided into four stages. These are copulation, fecundation, gestation and parturition. The male is concerned only with copulation and fertilization of the ovum by the spermatozoa, while the female must protect and nourish the embryo and foetus until it has become sufficiently developed to live independently of the protection and nourishment afforded it within the womb. When the final stage of gestation is reached, birth or the act of parturition occurs.
GENITAL ORGANS OF THE FEMALE.—The female generative organs are the ovaries, fallopian tubules, uterus, vagina, vulva and mammary glands.
The ovaries are analogous to the testicles of the male. Their function is to secrete ova. This pair of glands is suspended from the superior region (sublumbar) of the abdominal cavity by folds of the lining membrane. Leading from the ovaries, but connected with the surface of these glands only during the period of oestrum or heat, are the fallopian tubules. Their function is to carry the ovum from the ovaries to the uterus.
The uterus or womb is a membranous sack situated in the sublumbar region and at the inlet to the pelvic cavity. It is held in position by numerous folds of the lining membrane of the abdominal cavity. We may divide the womb into three divisions, cornua, body and cervix.
The cornua or horns are long and cylindrical in shape. This portion of the womb is greatly developed in animals, like the sow and bitch, that give birth to several young. In the impregnated animal the wall of the cornua that contains one or several foetuses, and the body as well, becomes greatly thickened and the lining membrane more vascular.
The body is short in all domestic animals and connects the horns with the cervix or neck. The latter is represented by a narrow portion that projects backward into the vagina. In the cow the cervix is less prominent than in the mare and the tissue that forms it, quite firm. In the cow the opening in the cervix, the os, is very small.
The vagina is a musculo-membranous canal that leads from the womb. In the mare and cow it is about one foot in length. Its function is to take part in copulation and parturition.
The vulva is the external opening of the maternal passages. It shows a vertical slit enclosed by lips, and interiorly it forms a passage that is continuous with the vagina. This passage is about six inches long in the larger animals. The different features that should be noted are the clitoris, a small erectile organ located at the inferior portion of the opening, the meatus urinaris, the external opening of the urethra, situated in a depression in the floor of the vulva, and the hymen, an incomplete membranous partition that may be found separating the vulva from the vagina.
The mammary glands or udders secrete the milk that nourishes the young. The glands vary in number. The mare has two, the cow four (Fig. 17), the ewe two and animals that give birth to several young, eight or more. Each gland is surmounted by a teat or nipple. The glandular tissue consists of caecal vesicles that form grape-like clusters around the milk tubules. The milk tubules from the different portions of the gland converge and form larger tubules that finally empty into small sinuses or reservoirs at the base of the teat. Leading from these sinuses are one or several milk ducts that open at the summit of the teat.