258 



SPECIAL HISTOLOGY. 



softer and presents, in its tissue, well marked, easily isolated, 

 utricular glands, 1 — 3"' long and 0*036 — 0-04"' broad, and nu- 

 merous immature, round and fusiform cells. The blood-vessels 

 of the mucous membrane, which chiefly afford the menstrual 

 flux, are, throughout the uterus, and particularly in its body 

 and fundus } extremely numerous and much distended, and this 

 is especially the case with the superficial capillary plexus; 

 whence also, the mucous membrane presents a bright red 

 colour. With the escape of the blood from the superficial, 

 ruptured capillaries, the epithelium of the mucous membrane 

 is, in great measure, thrown off, except that of the cervix, and 

 may always be found in large quantity in the mucus mixed 

 with blood, which fills the cavity of the uterus; it is not, 

 however, to be regarded as normal, if, after the menstrual 

 period, or during it, the whole uterine mucous membrane 

 Figt 267. or portions of it are detached. 



After the menstrual period, the 

 parts rapidly regain their pris- 

 tine condition, and the epithe- 

 lium is restored. 



Changes of a totally different 

 kind are induced in the uterus 

 by pregnancy, among which, 

 however, in a microscopical 

 point of view, the increased 

 bulk of the organ only, is of 

 interest. This enlargement, as 

 is well known, depends upon a 

 great augmentation of the cir- 

 cumference and of the cavity; 

 at first with increased, and 

 afterwards (usually from the 

 fifth month onwards) with a 

 diminished thickness of the 

 walls, and an increase in bulk, 

 amounting on the average to 

 twenty-four times the original size (J. F. Meckel, ' Anat./ IV, 



Fig. 267. Muscular elements from the uterus, in the fifth month of pregnancy: a, 

 formative cells of the muscular fibres ; b, younger; c, developed, fibre-cells ; x 350 

 diam. 



