74 INTRODUCTION TO SEXUAL PHYSIOLOGY 



dyes of a similar kind, if injected into the mother become 

 aggregated in the trophoblast, the rest of the tissues, both of the 

 mother and of the fnetus, being left colourless (Goldmann). 



Changes tn thp: Matf:rnal Organism 



The changes in the uterine mucosa and the formation of the 

 placenta have been already described. In addition to these 

 changes the uterine muscles also undergo a great development 

 during pregnancy. The weight of the virgin uterus is only about 

 30 grams, while that of the uterus at the time of parturition, 

 apart from the foetus and foetal membranes, is as much as 

 1,000 grams. Of the other characteristic changes which occur 

 during pregnancy the development of the corpus luteum in the 

 ovary has been already outlined. This structure develops to far 

 greater size than the " corpus luteum spurium," though it begins 

 to degenerate in the later stages, lipoid substances becoming 

 deposited in great quantity in the luteal cells, but the corpus 

 luteum does not finally disappear until after parturition. The 

 breasts begin to swell early in pregnancy, and may even yield 

 a few drops of milky fluid in the first months. In some animals 

 (cow), however, there is quite a considerable amount of fluid 

 which changes in character in the course of pregnancy, being 

 at first thin and then thick and honey-like, subsequently becoming 

 thinner again. The factors contributing to the mammary 

 development and their functional correlation with the ovaries 

 are discussed in a later chapter. The nipples increase in size 

 and often become pigmented, and the area around them assumes 

 slight granular elevations. 



One of the earhest indications of pregnancy, apart from the 

 cessation of menstruation, is the softening of the cervix uteri. 

 It is not, however, until after the third month that the dimensions 

 of the uterus have increased to such an extent that the organ 

 rises from the pelvic cavity so as to reach the cavity of the 

 abdomen, where it can be felt in external examination. By the 

 end of the fifth month the uterus has extended as far as the 

 umbilicus, and by the seventh month it has reached midway 

 between the end of the sternum and the navel. At the end of 

 pregnancy the uterus has reached the ribs and the pit of the 

 stomach, the alimentary canal and other viscera being pushed 



