RETROGRADE DEVELOPMENT OF THE UTERUS. 635 



Fig. 232. 



MCSCITLAR FIBRES OF U NIMPREG.V ATED 

 UTERUS; from a woman aged 40, dead of phthisis 

 pulmonalis. 



brane. It unites at the os inter urn, by a linear cicatrix, with the 

 mucous membrane of the cervix, and the traces of its laceration at 

 this spot afterward cease to be visible. At the point, however, 

 where the placenta was at- 

 tached, the ^regeneration of 

 the mucous membrane is 

 less rapid; and a cicatrix- 

 like spot is often visible at 

 this situation for several 

 months after delivery. 



The only further change, 

 which remains to be de- 

 scribed in this connection, 

 is the fatty degeneration 

 and reconstruction of the 

 muscular substance of the 

 uterus. This process, which 

 is sometimes known as the 

 'involution" of the uterus, 

 takes place in the following 

 manner. The muscular 

 fibres of the unimpregnated 

 uterus are pale, flattened, 

 spindle-shaped bodies (Fig. 

 232) nearly homogeneous 

 in structure or very faintly 

 granular, and measuring 

 from 5 J C to jjfl of an inch 

 in length, by T u Jos to ffu'&u 

 of an inch in width. During 

 gestation these fibres in- 

 crease very considerably in 

 size. Their texture becomes 

 much more distinctly granu- 

 lar, and their outlines more 

 strongly marked. An oval 

 nucleus also shows itself in 



the central part of each fibre. The entire walls of the uterus, at 

 the time of delivery, are composed of such muscular fibres as 

 these, arranged in circular, oblique, and longitudinal bundles. 



About the end of the first week after delivery, these fibres begin 



Fig, 233. 



MUSCULAR FIBRES op HUMAW UTERUS, ten 

 days after parturition ; from a woman dead of puer- 

 peral fever. 



