548 THE PHYSIOLOGY OF REPRODUCTION 



estimation), and found further that in women who were 

 accustomed to bleed freely at the menstrual periods the amount 

 of the lochial discharge was beyond the average. According 

 to Gassner, the discharge is generally less in women who suckle. 



The uterus after delivery becomes rapidly reduced in size. 

 This process is known as the involution of the uterus ; it is 

 completely effected in from five to eight weeks, the greatest 

 reduction taking place in the first few days. Thus the freshly 

 delivered uterus weighs on an average 1000 grams (or about 

 2 pounds), a week later it weighs only half that amount, at 

 the close of the second week 375 grammes, and at the end 

 of the puerperal period as little as 60 grammes (or about 2 

 ounces). Its decrease in size is such that by the tenth day 

 after parturition the organ is once more confined to the cavity 

 of the pelvis proper, and cannot be felt above the symphysis. 



The process of uterine involution is the result chiefly of 

 changes occurring in the muscle walls. 1 The size of the in- 

 dividual cells becomes very markedly diminished, but there is 

 little or no reduction in their number. Fatty degeneration does 

 not take place in the muscular tissue. It is stated that the 

 retraction of the muscle fibres produces a compression of the 

 vessels, and that the comparatively anaemic condition of the 

 puerperal uterus, especially in the earlier stages, is due to this 

 cause. Subsequently the uterus becomes more vascular again. 



The remains of the decidua which are not expelled at partu- 

 rition undergo degeneration and are discharged in the lochia, 

 leaving only the fundi of the glands and a certain amount of con- 

 nective tissue from which the uterine stroma is renewed. The 

 epithelium is re-formed from that of the glands, as shown by 

 Friedlander, 2 Kundrat and Engelmann, 3 Leopold, 4 Kronig, 5 



1 The account given of the changes in the uterus during the puerperium 

 is based largely on that given by Williams (Obstetrics, New York, 1904). 

 See also Sellheim, " Das Wochenbett," in Nagel's Handbuch der Physiologic 

 des Menschen, vol. ii., Braunschweig, 1906, where further references are given. 



2 Friedlander, Physiologische und Anatomische Untersuchungen iiber den 

 Uterus, Leipzig, 1870. 



3 Kundrat and Engelmann, " Untersuchungen iiber die Uterusschleim- 

 haut," Strieker's Med. Jahrbuch, 1873. 



4 Leopold, Studien iiber die Uterusschleimhaut, &c., Berlin, 1878. 



s Kronig, " Beitrag zum anatomischen Verhalten der Schleimhaut der 

 Cervix und des Uterus," &c., Arch. f. Gynak., vol. Ixiii., 1901. 



