THE PLACENTA. 



667 



the foetus with the membranes attached to it. It is, however, 

 only the superficial layer of the maternal placenta (which is 

 intimately connected with the fcetal placenta) that is cast off, 

 the deeper layer remaining in the uterus, and undergoing 



FIG. 258. 



Antero-posterior section through a gravid uterus and ovum of five weeks (semi-dia- 

 grammatic). (Allen Thomson.) o. Anterior wall of uterus, p. Posterior wall of uterus. 

 m. Muscle substance, g. Glandular layer, ss. Decidua serotina. r. Decidua reflexa. 

 v. Decidua vera. c*. Chorion. u.u. Uterine cavity, c. Cavity of the cervix. 



various changes during the reduction of this organ to its normal 

 size. 



After ligature of the umbilical cord, the intimate relationships 

 of the maternal and fcetal circulations cease, and it is thought 

 that this causes the inlets of the uterine sinuses to contract, so 



