MENSTRUATION 



229 



into the intermenstrual, or restiufj; {)erio(l, (lurinj^ wliieh time there 

 are few changes until at the beginning of the premenstrual period, 

 when renewed pre])arations are made for reception of the ferti- 

 lized egg. Sometimes between two menstrual periods, generally 



Fig. 142 



Fig. 143 



Fig. 144 



Figs. 142, 14.3 and 144. — Three diagrams illustrating changes in mucosa of the uterus during pre- 

 menstrual period. 



Fig. 142. — Below is the myometrium. In the mucosa are simple tubular glands lined with 

 simple columnar epithelium. The tunica propria is fibrous, with many connective-tissue cells and 

 also leukocytes. The mucosa is also very vascular with many venous-like capillaries. 



Fig. 143. — The mucosa increases in thickness; the glands become elongated and more tortuous. 

 Somewhat below the internal surface, connective-tissue cells at a certain level become much en- 

 larged and are known as decidual cells. The capillaries increase in size. The epithelial cells in the 

 zone of decidual cells enlarge and secrete the mucus collecting in the adjacent lumen. 



Fig. 144. — The mucosa is much thicker (possibly twice as thick as in Fig. 142.) The decidual 

 cells are more prominent. Epithelial cells of the glands in the neighborhood of outpocketings filled 

 with secretion give way; fluid seeps out from capillary spaces in this region — the capillary walls give 

 way and the mucous secretions and blood mingle in pools. The process continues until there is a 

 general sloughing ofT of the internal lining of the mucosa. Half way through this menstrual (slough- 

 ing) period — the mucosa internal surface is lacking in epithelium. Later epithelial cells from ends 

 of glands still left in deeper portions of the mucosa migrate out to the internal surface and organize 

 a new lining and also outlets for the glands. It will be noted that the above mucosal changes do 

 not involve the deeper portions of the glands as much as external portions adjacent to the limien of 

 the uterus. 



