I20 OBSTETRICAL PHYSIOLOGY. 



Structure. 



These changes add to the thickness and density of the uterus ; but 

 there are others still more remarkable. While the organ is increasing in 

 volume, becoming rounder, acquiring a greater capacity, and its cervix 

 widening, its proper structure is exaggerated to an extraordinary degree. 

 This exaggeration, however, does not occur equally throughout ; it is 

 most marked in the cornua of multiparous creatures at the points where 

 the young are fixed ; in ruminant animals at the situation of the cotyle- 

 dons ; and in solipeds at the part of the body of the uterus corresponding 

 to the foetal placenta. So that, at least in the early months of pregnancy, 

 it is thinnest towards the cervix. The increased thickness of the organ, 

 however, never equals that observed in the human female, compared with 

 which the walls of the uterus of the domesticated animals are thin. 



The firmness or density of the organ is always most conspicuous in the 

 cornua, and in the operation of " spaying," or castration of the female, 

 this serves as a useful guide in enabling the operator to distinguish be- 

 tween the cornua and the intestines, which they so closely resemble in 

 appearance. 



But during pregnancy this density seems to diminish, as the organ 

 becomes more vascular, and the cervix assumes a much softer condition 

 than usual. For instance, in the fcetal cornu of a Cow advanced three 

 months in pregnancy, the thickness of the wall was only 2-5 millimetres, 

 while in the other horn it was four millimetres. In another Cow at five 

 months, it was two millimetres in the foetal horn and five millimetres in 

 the vacant one. The mucosa is thicker, redder, more pulpy and vascu- 

 lar, than before impregnation ; the longitudinal rugse it then exhibited 

 gradually disappear ; the epithelium covering it usually loses its .colum.nar 

 form ; the utricular glands enlarge — they are longer and their orifices 

 wider, and their secretion, as well as that of the other glands, is increased ; 

 the interglandular tissue is largely and rapidly augmented by multiplica- 

 tion of the cells of the surface epithelium, and proliferation of the cor- 

 puscles of the sub-epithelial connective tissue, so that the glands are 

 more widely separated ; while the uterine cotyledons grow quickly, and 

 there can be no doubt that new ones appear, Rainard speaks of exam- 

 ining the uterus of several calves and lambs, and finding only thirty or 

 forty cotyledons ; while after parturition he has ^counted more than a 

 hundred ; and more recent observers have testified to this fact. In the 

 uterus of a six months' pregnant Cow, Franck found that the horn con- 

 taining the fcetus had forty-seven cotyledons and weighed 3,54zollpfund ; 

 while the other horn had only forty-two placentae, and weighed no more 

 than 0,22 zollpfund. 



In addition to these supplementary appendages of the mucous mem- 

 branes, a new glandular apparatus, of which no trace was to be found 

 previous to gestation, now makes its appearance in the form of a large 

 number of small openings in the mucosa, each leading into a depression 

 which was for a long time regarded as the dilated mouth of the tubular 

 or utricular glands, but which is really a " crypt " formed in the hyper- 

 trophied tissue of the uterus — a kind of open follicle placed in the inter- 

 glandular part of the mucous membrane. These crypts are new struct- 

 ures, formed during pregnancy, and are for the lodgment of the villi that 

 project from the chorion of the foetus — being, in fact, the maternal coty- 

 ledons or maternal portion of the placenta. They are small straight 



