CHANGES IN THE NON-PREGNANT UTERUS 99 



Van Herwerden is certain that the changes observed could 

 not be ascribed to a puerperal condition, as in the case of Tupaia, 

 but must have been the result of a normal proosstrum. The 

 periodicity of the changes is unknown. 



THE CYCLE IN CARNIVORES 



The histological changes in the non-pregnant uterus have 

 been studied in the dog 1 and in the ferret. 2 The periods into 

 which the uterine cycle is divided are identical with those 

 adopted by Heape for the monkey : 



(1) Period of rest Anoestrum. 



(2) Period of growth and congestion . ) Prooestrum. 



(3) Period of destruction . ) 



( (Estrus. 



(4) Period of recuperation . . ' j M t t 



It is seen that oestrus, or the time of desire, begins normally 

 about the close of the period of destruction. With the ferret 

 it may be very prolonged, extending until the end of the 

 recuperation period, or even considerably beyond it. Conse- 

 quently there may be no metcestrum (strictly speaking) with 

 the ferret, since the period during which copulation can occur 

 is liable to persist until the uterus has reached the resting stage. 



(1) Period of Rest. The uterine mucosa in both the dog and 

 the ferret is bounded at the surface by an epithelium consisting 

 of a single row of columnar or cubical cells, and is continuous 

 with that of the glands. The stroma is a connective tissue, 

 containing numerous fusiform cells. Blood-vessels of small 

 size are fairly common. Leucocytes do not appear to occur in 

 the mucosa outside of the vessels. Pigment is not present at 

 this stage, at least ordinarily. 



(2) Period of Growth and Congestion. The mucosa at this 

 period becomes slightly thickened, and tends to be more compact. 

 This is effected by cell divisions, but mitoses have not been 



1 Marshall, and Jolly, " Contributions to the Physiology of Mammalian 

 Reproduction: Part I. The (Estrous Cycle in the Dog," Phil. Trans., B ., 

 vol. cxcviii., 1905. 



2 Marshall, " The (Estrous Cycle in the Common Ferret," Quar. Jour. Micr. 

 Sci. vol. xlviii., 1904. 



