816 FEMALE ORGANS OF GENERATION. 



longitudinal column, from which proceed a number of small oblique columns, 

 giving the appearance of branches from the stem of a tree, and hence the name 

 arbor vitas uterinus applied to it. These folds usually become very indistinct 

 after the first labor. 



Structure. The uterus is composed of three coats : an external serous coat, a 

 middle or muscular layer, and an internal mucous coat. 



The serous coat is derived from the peritoneum ; it invests the fundus and the 

 whole of the posterior surface of the body of the uterus ; but only the upper 

 three-fourths of its anterior surface. 



The muscular coat forms the chief bulk of the substance of the uterus. In 

 the unimpregnated state, it is dense, firm, of a grayish color, and cuts almost 

 like cartilage. It is thick opposite the middle of the body and fundus, and thin 

 at the orifices of the Fallopian tubes. It consists of bundles of unstriped 

 muscular fibres, disposed in layers, intermixed with areolar tissue, bloodvessels, 

 lymphatic vessels and nerves. In the impregnated state, the muscular tissue 

 becomes more prominently developed, and is disposed in three layers : external, 

 middle, and internal. 



The external layer is placed beneath the peritoneum, disposed as a thin plane 

 on the anterior and posterior surfaces. It consists of fibres, which pass trans- 

 versely across the fundus, and, converging at each superior angle of the uterus, 

 are continued on the Fallopian tubes, the round ligament, and ligament of the 

 ovary ; some passing at each side into the broad ligament, and others running 

 backwards from the cervix into the recto-uterine ligaments. 



The middle layer of fibres presents no regularity in its arrangement, being 

 disposed longitudinally, obliquely, and transversely. 



The internal, or deep layer, consists of circular fibres arranged in the form 

 of two hollow cones, the apices of which surround the orifices of the Fallopian 

 tubes, their bases intermingling with one another on the middle of the body of 

 the uterus. At the cervix these fibres are disposed transversely. 



The mucous membrane is thin, smooth, and closely adherent to the subjacent 

 tissue. It is continuous, through the fimbriated extremity of the Fallopian 

 tubes, with the peritoneum ; and, through the os uteri, with the mucous mem- 

 brane lining the vagina. 



In the body of the uterus, it is smooth, soft, of a reddish color, lined by 

 columnar-ciliated epithelium, and presents, when viewed with a lens, the orifices 

 of numerous tubular follicles arranged perpendicularly to the surface. They 

 are of small size in the unimpregnated uterus, but shortly after impregnation 

 they are enlarged, elongated, presenting a contorted or waved appearance to- 

 wards their closed extremities, which occasionally dilate into two or three 

 sacculated extremities. The circular orifices of these glands may be seen on 

 the inner surface of the mucous membrane, many of which during the early 

 period of pregnancy are surrounded by a whitish ring formed of epithelium 

 which lines the follicles. 



In the cervix, the mucous membrane between the rugas and around the os 

 uteri is provided with numerous mucous follicles, and glands. The small, trans- 

 parent vesicular elevations, so often found within the os and cervix uteri are 

 due to closure of the mouths of these follicles, and their distension with their 

 proper secretion. They were called the ovula of Nabotli. The mucous mem- 

 brane covering the lower half of the cervix presents numerous papillae. 



Vessels and Nerves. The arteries of the uterus are the uterine, from the internal 

 iliac; and the ovarian, from the aorta. They are remarkable for their tortuous 

 course in the substance of the organ, and for their frequent anastomoses. The 

 veins are of large size, and correspond with the arteries. In the impregnated 

 uterus these vessels are termed the uterine sinuses, consisting of the lining mem- 

 brane of the veins adhering to the walls of canals channelled through the sub- 

 stance of the uterus. They terminate in the uterine plexuses. The lymphatics 

 are of large size in the impregnated uterus, and terminate in the pelvic and 



