;8 THE PHYSIOLOGY OF REPRODUCTION 



appear in the middle of the cell at the beginning of the stage 

 of pre-menstrual swelling. 



As a consequence of these changes the mucosa becomes consider- 

 ably increased in thickness. Thus, if a woman who had been 

 menstruating regularly dies shortly before the expected approach 

 of a menstrual period, the thickness of the mucous membrane is 

 often as much as one-sixth of an inch at its thickest part, as 

 compared with a thickness of from one-tenth to one-twentieth of 

 an inch in women who died within ten days after the cessation of 

 the flow.': Leopold^ has described a growth so considerable that 

 the uterine cavity, prior to the stage of bleeding, becomes almost 

 completely obliterated. 



It should be mentioned, however, that according to some authors 

 the amount of pre-menstrual growth in the uterine mucosa is very 

 slight, while Oliver^ seems to be doubtful whether any growth 

 occurs at all, stating that he has made an examination of uteri at 

 various pre-menstrual and menstrual stages, and has failed to find 

 any evidence of changes in the mucosa tissue apart from those 

 directly associated with the phenomena of bleeding. Westphalen's 

 view appears to be similar ; for, according to this observer, there is 

 no multiplication of nuclei during this stage, the pre-menstrual 

 swelling being brought about entirely by the serous saturation of 

 the stroma. 



Tlie Destructive Stage. — At the close of the constructive period 

 the blood leaves the capillaries and becomes extravasated freely in 

 the stroma, but there has been some dispute as to how this process 

 is effected. It has been suggested that the blood transudes through 

 the walls of unruptured capillaries under the influence of congestion, 

 or that permanent openings exist from the vessels into the uterine 

 glands, these being closed normally by muscular contraction ; * but 

 the belief now generally held is that, whereas the walls of many of 

 the congested vessels break down under pressure, and so freely 

 admit of the exit of the blood corpuscles into the mucosa tissue, 

 haemorrhage also takes place partly by diapedesis. Engelmann,^ 

 Williams," and others have ascribed the breaking down of the vessel- 

 walls to fatty degeneration, but this has been denied by Moricke,' 



' Galabin, A Manual of Mid/wifery, 6th Edition, London, 1904. 



^ Leopold, " Untersuchungen fiber Menstruation und Ovulation," Arch. f. 

 Gynak., vol. xxi., 1883. 



^ Oliver, "Menstruation : its Nerve Origin," Jowr. Anat. and Phys., vol. xxi., 

 1887. 



• Galabin, loc. cit. ^ Engelmann, loo. cit. 



6 Williams (Sir J.), " The Mucous Membrane of the Body of the Uterus," 

 Ohstet. Jow. Ot. Britain, vols. iii. and v., 1875, 1877. 



' Moricke, "Die Uterusschleimhaut in der verschiedenen Altersperioden 

 und zur Zeit der Menstruation," Zeitsch. f. GehwrtahUlfe u. Gynak, vol. vii., 1882. 



