340 



HUMAN UTERUS AND FETAL APPENDAGES. 



ten days; (2) menstruation proper, about four days; (3) restoration of the resting 

 mucosa, about seven days. The times given are approximate only. The whole 



cycle of changes covers about sixteen 

 days. Since the monthly period is about 

 four weeks, the period of rest, as thus 

 calculated, is only about twelve days. 



1. Tumefaction. A few days be- 

 fore the menstrual flow the mucosa 

 gradually thickens; the surface becomes 

 irregular; the openings of the glands lie 

 in depressions. The connective-tissue 

 cells are increased in number, and it 

 is said by some authors in size, but 

 the increase in size is doubtful; the 

 number of round cells increases; the 

 glands expand and become more irreg- 

 ular in their course; a short time before 

 hemorrhage begins, the blood-vessels, 

 especially the capillaries and veins, be- 

 come greatly distended. We must as- 

 sume that the connective-tissue cells 

 proliferate, but we have no satisfactory 

 observations upon their division. It was 

 formerly asserted that the menstrual 

 decidua contains decidual cells, but in 

 all the specimens the author has studied 

 there were none present. 



2. Menstruation. When the changes 

 just described are completed, the decidua 

 menstrualis is fully formed, and its 

 partial disintegration begins.. The 

 process commences with an infiltration 





of blood into the subepithelial tissues. 

 This infiltration has hitherto been com- 

 monly explained as due to the rupture 

 FIG. 225. UTERINE GLAND OF A VIRGIN OF EIGHTEEN of the capillaries; but as no ruptures at 

 YEARS, WITH A PORTION OF THE SURFACE EPI- this period have been observed, we may 



THELIUM. WAX RECONSTRUCTION BY C. A. . ,, > ., , , 



,. uistly regard this explanation as mad- 



HEDBLOM. X 50 diams. J * 



missible, and account for the infiltration 



per diapedesin. It lasts for a day or two, and is apparently the immediate cause 

 of a very rapid molecular disintegration of the superficial layers of the mucosa, 

 which in consequence are lost; the superficial blood-vessels are now exposed, and, 



