1634 A MANUAL OF ANATOMY 



The stratum profundum lies next the muscular coat, there being 

 no submucosa in the uterine wall. It contains the deep parts of the 

 uterine glands, the blind ends of which project into the inner 

 muscular layer, after having undergone in many cases dichotomous 

 division. 



Structure of the Decidua Capsularis or Reflexa.— This contains no 

 uterine glands, except where it is in continuity with the decidua 

 vera. Essentially it consists of a matrix of connective tissue, per- 

 meated by decidual cells, and it is devoid of epithelium. 



Structure of the Decidua Basalis or Serotina. — Prior to the fifth 

 month of pregnancy the structure of the decidua basalis practically 

 resembles that of the decidua vera. As the ovum sinks into it, 

 certain changes occur. It loses its cihated columnar epithelium, 

 basement membrane, and some of the superficial cells of the corium. 

 After this loss there remain (i) the deep part of the stratum com- 

 pactum, (2) the stratum spongiosum, presenting the usual irregular 

 spaces or gland-cavities, and (3) the stratum profundum. 



The Decidua Vera, Reflexa, and Serotina after the Fifth 

 Month of Pregnancy. 



Decidua Vera. — ^This membrane is now being subjected to pressure 

 by the growing foetus, and it undergoes certain retrogressive changes, 

 (i) The ciliated columnar epithelium disappears. (2) The portions 

 of the uterine glands which lie in the stratum compactum lose their 

 epithelial lining and, becoming obliterated, entirely disappear. The 

 gland-cavities in the stratum spongiosum likewise lose their epi- 

 thelial lining, but they persist, being now converted by pressure into 

 narrow elongated clefts. (3) The gland-cavities in the portion of 

 the stratum spongiosum which adjoins the stratum compactum 

 likewise lose their epithelial lining, but those in the portion which 

 adjoins the stratum profundum retain their epithelium. All these 

 gland-cavities persist, but they now assume the form of elongated, 

 narrow clefts, which lie parallel to the uterine wall. This change is 

 brought about by the expansion of the uterus and the lateral 

 stretching of the gland-cavities. (4) The decidua vera, now very 

 thin, is joined by the decidua capsularis, or reflexa. 



Decidua Capsularis or Reflexa. — ^This membrane gradually ex- 

 pands after the fifth month of pregnancy in adaptation to the grow- 

 ing foetus, and it comes to press closely upon the decidua vera. 

 The uterine cavity thereby becomes gradually occupied by (i) the 

 foetus and its membranes, and (2) the placenta. Whatever glandular 

 elements the decidua capsularis contains disappear, the membrane 

 becomes extremely thin, and it fuses with the decidua vera. Accord- 

 ing to some authorities, the membrane entirely disappears, in which 

 case the chorion leve would come into contact with the decidua 

 vera. 



Decidua Basalis, or Serotina. — ^The changes which this membrane 

 has undergone prior to the fifth month of pregnancy have just been 



