238 



PHYSIOLOGY 



CHAP. 



months till the end of pregnancy it gradually diminishes until 

 it is reduced to 1-0-5 cm. in thickness. 



The increase in the surface of the uterus and of its internal 

 capacity is progressive from the beginning to the end of pregnancy ; 



FIG. 100. Smooth muscular fibres of the uterus. (Bumm.) a, fibre of non-gravid uterus ; 

 b, fibre of gravid uterus at the tenth month ; d, transverse sections of fibres. 



according to Krause its capacity becomes 519 times greater and 

 the weight increases from about 50 to 1000 grms. 



With the increase in size the uterus changes considerably in 

 shape during pregnancy. The shape of the non-pregnant uterus 

 is piriform ; in the first months of pregnancy it tends to become 

 round, and the wall which corresponds to the placental insertion 

 protrudes asymmetrically according to whether the placenta lies 

 towards the right or left tube (Fig. 103). At the fourth month 



