Development of Mammary Glands in the Rabbit. 535 



influence which causes the growth changes and also the glandular phase of 

 the gland is essentially the same and not different, as Ancel and Bouin have 

 supposed.* 



Many methods of research have been used to eliminate the various factors 

 which might possibly cause this development. These are described under 

 the headings of the various tissues or organs which were suspected of being 

 the originators of the stimulus. 



Tlie Myometrial Gland. 



Ancel and Bouinf state that the myometrial gland occurs in the uterus of 

 the rabbit during the second half of pregnancy. They describe it as 

 consisting of clumps of cells of an epithelioid appearance, lying under the 

 placental cells and between the muscle cells of the circular and longitudinal 

 muscular coats in close proximity to the blood-vessels. They suggest that it 

 is a gland of internal secretion which takes on the functions of the corpus 

 luteum during the second half of pregnancy, controlling the glandular phase 

 of the mammary gland^ and also the tolerance of the uterus for the fcetus.§ 



Fraenkel , has verified their observations as to the presence of the gland 

 in rabbits. He could not find it, however, in the uteri of many other species 

 of animal examined. On this account, and also on account of its slender 

 vascularity (for a gland of internal secretion), he does not accept their theory 

 as to its function. 



MercierT identifies the myometrial gland with cells described by him as 

 nephro-phagocytes, and states that the normal connective tissue of mammals 

 contains these cells, which have the property of phagocytosis, absorbing solid 

 substances and fixing soluble substances injected into the organism. He found 

 that these cells occur only in the pregnant and not in the normal uterus.** 



The uteri of many rabbits between the 16th and 30th days of pregnancy 

 have been examined by cutting serial sections across a large number of 

 pieces from each uterus. Epithelioid cells, which correspond to those 

 described by Ancel and Bouin as the myometrial gland, have been found 

 only in one or two cases. In every case they have been found beneath the 

 small yellow patches which are seen in the region of the uterine mucosa 



* Ancel and Bouin, ' Journ. de Phys. et de Path, generale,' vol. 13 (1911). 

 t Ancel and Bouin, ' Compt. rend. Assoc. des Anat,,' 13e. reunion, Paris, 1911. 

 I Ancel and Bouin, 'Compt. rend. Soc. Biol., ; vol. 72 (1912). 

 § Ancel and Bouin, 'Compt. rend, de TAcad. des Sci.,' vol. 154 (1912). 

 || Fraenkel, 'Arch, fur Gynaek.,' vol. 99 (1913). 

 IT Mercier, ' Compt. rend. Soc. Biol.,' vol. 74 (1913). 

 ** Mercier, 'Compt. rend. Soc. Biol.,' vol. 72 (1912). 



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