CHANGES OF THE UTERUS IN GESTATION, &c. 987 



substance of the mons Veneris. Besides areolar tissue and vessels, the 

 round ligaments contain plain muscular fibres, like those of the uterus, 

 from which, indeed, they are prolonged. Each ligament also receives a 

 covering from the peritoneum, which, in the young subject, is prolonged 

 under the form of a tubular process for some distance along the inguinal 

 canal : this, which resembles the processus vaginalis originally existing in 

 the same situation in the male, is named the canal of Nuck : it is generally 

 obliterated afterwards, but is sometimes found even in advanced life. 



Blood-vessels and Nerves. The arteries of the uterus are four in number, viz., the 

 right and left ovarian (which correspond to the spermatic of the male) and the two 

 uterine. Their origin, as well as the mode in which they reach the uterus and ovaries, 

 has been already described (pp. 414, 422). They are remarkable for their frequent 

 anastomoses, and also for their singularly tortuous course ; within the substance of 

 the uterus they seem to be placed in little channels or canals. The veins correspond 

 with the arteries ; they are very large, and form the uterine plexuses, and their thin 

 walls are in immediate contact with the uterine tissue. The course of the lymphatics 

 is described at p. 495 ; they are very large and abundant in the gravid uterus. The 

 nerves have been fully described at p. 704. They are derived from the inferior 

 hypogastric plexuses, the spermatic plexuses, and the third and fourth sacral 

 nerves. 



The changes which take place in the uterus from age, menstruation, and gestation, 

 and the characters presented by this organ after it has once performed the latter func- 

 tion, can only be very generally indicated here. 



For some time after menstruation first commences, the uterus becomes rounder 

 and slightly enlarged at each period, its os externum becomes more rounded, and 

 its lips swollen ; subsequently these periodical alterations are not so marked. The 

 organ itself, however, always becomes more turgid with blood, and the mucous mem- 

 brane appears darker, softened, and thickened. 



In gestation more extensive alterations ensue, which necessarily affect the size, shape, 

 and position of the organ, the thickness and amount of substance in its walls, the dimen- 

 sions and form of its cavity, and the character of its cervix and of its os externum and os 

 internum. Its weight increases from about one ounce to one pound and a half or even 

 three pounds. Its colour becomes darker, its tissue less dense, its muscular bundles more 

 evident, and the fibres more developed. The principal increase is in the muscular 

 tissue, and this increase takes place not only by the enlargement of already existing 

 elements, the fibre-cells becoming enlarged from seven to eleven times in' length, and 

 from two to five times in breadth (Kolliker), but also by new formation. The former 

 process is general ; the latter occurs mainly in the innermost layers, and continues 

 until the sixth month of pregnancy, when new formation ceases. The round liga- 

 ments become enlarged, and their muscular structure more marked ; the broad liga- 

 ments are encroached upon by the intrusion of the growing uterus between their 

 layers. The mucous membrane and the glands of the body of the uterus become the 

 seat of peculiar changes, which lead to the formation of the decidual membrane; 

 whilst the membrane of the cervix loses its columns and rugae. The blood-vessels 

 and lymphatics are greatly enlarged, and it is observed that the arteries become 

 exceedingly tortuous as they ramify upon the organ. The condition of the nerves in 

 the gravid uterus has been previously fully referred to (p. 704). 



After parturition, the uterus again diminishes, its enlarged muscular fibres under- 

 going oleaginous degeneration and becoming subsequently absorbed, while a new set 

 of minute fibre cells are developed. The organ, however, never regains its original 

 virgin character. Its weight usually remains from two to three ounces in those who 

 have had children ; its cavity is larger ; the os externum is wider and more rounded, 

 and its margins often puckered or fissured ; the arteries continue much more tortuous 

 than they are in the virgin, and its muscular fibres and layers remain more defined. 



Age. In the infant, the neck of the uterus is larger than the body ; and the 

 fundus is not distinguished either by breadth or by convexity of outline. These parts 

 afterwards enlarge gradually, until, at puberty, the pyriform figure of the womb is 

 fully established. The arbor vitse is very distinct, and indeed at first reaches up- 

 wards to the highest part of the cavity. 



