THE FEMALE REPRODUCTIVE ORGANS 



535 



the mouths of the uterine glands. In the course of a few days the mucosa 

 regains its former quiescent condition. The complete cycle includes 28 

 days, of which the menstrual process occupies about seven. 



The Gravid Uterus 



In the event of conception the uterine changes are more pronounced 

 than during menstruation. These alterations include the same processes of 

 hypertrophy and thickening as occur in the decidua menstrualis; they in- 

 volve the musculature as well as the mucosa but are not followed by regres- 

 sive changes, hemorrhage, desquamation, etc. until parturition occurs. 



The muscular wall undergoes an 

 enormous increase both in the num- 

 ber and size of its fibers. The rela- 

 tively short (30 to 60 /m) smooth 

 muscle fibers of the uterine wall 

 gradually increase in size to as much 

 as eleven times their former length 

 and two to five times their breadth 

 (Kolliker). The connective tissue of 

 the muscular coat also increases in 

 volume and becomes more distinctly 

 fibrous. After parturition, fat drop- 

 lets appear within the muscle cells, 

 and the muscular wall by gradual 

 atrophy returns to its former condi- 

 tion. 



In the mucosa the formation of 

 a decidual membrane goes forward 

 in a manner similar to the develop- 

 ment of the decidua menstrualis, but 

 the process is exaggerated. The tu- 

 nica 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 vascular 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 polymorphonu- 

 clear 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 cdls. Though it is frequently asserted that 



FIG. 469. A GROUP OP DECIDUAL 

 CELLS FROM THE HUMAN UTERUS 

 DURING THE EARLY STAGES OF PREG- 

 NANCY. 



One of the cells contains two nuclei 

 and a number of fat vacuoles. Three 

 nuclei of the connective tissue stroma 

 are also shown. X 750. 



