48 



CHANGES IN THE UTERUS, 



whilst others are special to that part (d. serotina) which enters into the construction 

 of the placenta. The following is a brief account of these changes. 1 



"With the supervention of pregnancy the mucous membrane lining the uterus 

 becomes thickened and the tubular glands become both dilated and greatly elongated. 



Fig. 51. ANTEROrPOSTERIOR SECTION OF TflE GRAVID 



UTERUS AND OVUM OF FIVE WEEKS. (Semi-dia- 

 grammatic.) (Allen Thomson.) 



a, anterior ; p, posterior uterine wall ; m, mus- 

 cular substance ; u, placed in the cavity of the uterus ; 

 <7, the glandular layer of the decidua vera ; r, the 

 decidua reflexa ; .?, decidua serbtina ; c, cervix uteri ; 

 ck, chorion with its villi, which are more highly deve- 

 loped on the placental side ; c, the embryo enclosed 

 in the amnion, with the allantoic vessels passing along 

 a short allantoic stalk into the placenta, and the 

 umbilical vesicle lying free in the space between 

 aranion and chorion. 



Fig. 51*. DIAGRAMMATIC SECTIONS OF THE UTERINE MUCOUS MEMBRANE, SHOWING THE CHANGES WHICH 

 THE GLANDS UNDERGO WITH THE SUPERVENTION OF PREGNANCY (from Kundrat and Engelmann). 



A, Diagram of the glands of the non-pregnant uterus ; m, muscular layer ; B, condition of the 

 glands at the beginning of pregnancy ; c, compact layer near free surface of decidua : the glands are 

 here somewhat enlarged but not very tortuous, and the mucous membrane is rendered compact by 

 hypertrophy of the interglandular tissue ; sp, spongy layer, containing the middle portion of the 

 glands greatly enlarged and tortuous, producing a spongy condition in the mucous membrane ; d, deepest 

 portion of the glands, elongated and tortuous, but not much enlarged. 



This thickening of the membrane and enlargement of the glands goes on until the 

 fifth month, so that by this time the decidua vera is nearly half an inch in thickness 

 and its glands have undergone so considerable an elongation that they now no longer 

 pass nearly straight through the membrane but run in a tortuous manner from the 



1 For a more complete account of the changes in the uterus, and of the placenta, ths reader is 

 referred to the list of papers at the end of this section, but especially to the works of Kundrat and 

 Engelmann, Leopold, and Minot, and for the comparative structure of the placenta to the classical 

 investigations of Turner. 



