424 THE FEMALE KEPKODUCTIVE ORGANS 



five times their breadth (Kolliker *). The connective tissue of 

 the muscular coat also increases in volume and becomes more dis- 

 tinctly fibrous. After parturition, fat droplets appear within the 

 muscle cells, and the muscular wall by gradual atrophy returns to 

 its former condition. 



In the mucosa the formation of a decidual membrane goes for- 

 ward in a manner similar to the development of the decidua men- 

 strualis, but the process is exaggerated. The tunica propria soon 

 becomes divisible into two distinct, though not sharply defined, 

 layers, a deeper cavernous portion which is permeated by broad 

 vascular channels together with the atrophied remains of the 

 uterine glands, and a superficial compact layer in which the vascu- 

 lar channels, except for the thin-walled venous spaces, are smaller 

 and the connective tissue cells more closely packed. 



Many of the connective tissue cells attain a large size and their 

 nuclei are frequently multiple, or they may acquire an irregular 

 polymorphonuclear form. Giant cells are thus produced in the 

 compact layer of the mucosa of the gravid uterus ; they are highly 

 characteristic of this tissue and are known as decidual cells. 

 Though it is frequently asserted that similar cells occur in the 

 decidua menstrualis, this is denied by Minot,f who states that in a 

 considerable number of menstrual decidua examined, no such cells 

 were ever found. 



The superficial epithelium is soon desquamated and the tunica 

 propria comes into contact with the fetal chorion. The glandu- 

 lar epithelium is also partially degenerated, often becoming flat- 

 tened and of irregular shape. It is frequently desquamated into 

 the glandular lumen; this lumen is thus reduced to a narrow 

 crevice, which is so elongated during the dilatation of the uter- 

 ine wall that the axis of the glandular remnant becomes nearly 

 parallel to the surface of the decidua. 



The decidual membrane which is thus formed is divisible into 

 three portions, according to its relation to the tissues of the em- 

 bryo : 1, that portion upon which the developing ovum directly 

 rests, which is known as the decidua serotina or decidua basalis 

 but later forms the placenta uterina or maternal portion of the 

 placenta ; 2, at the margins of the implanted ovum the decidual 

 tissues grow up around the ovum which is thus surrounded by 

 the so-called decidua reflexa or decidua capsularis, which, after 



* Handbuch, iii, 574. 



f Laboratory Text-book of Embryology, 1903. 



