26 INTERNAL SECRETIONS OF THE OVARY 



two animals, therefore, no cycle exists in the unmated animal, 

 except the alternation of anoestrus and breeding season. 



Diagram of Cycle where Ovulation is dependent on 

 Copulation, as in the Rabbit and Ferret. 



As has been pointed out above, cyclic changes occur in the 

 secondary organs in correlation with those in the ovary. The 

 extent to which the various accessory organs participate in the 

 oestrous cycle shows much specific variation. All species which 

 have been studied show considerable uterine changes, but 

 vaginal and mammary cycles have been less frequently described. 

 In the ferret, guinea-pig, rat, and mouse, however, vaginal 

 changes at least as marked as the uterine ones are well known, 

 while cyclic mammary changes in the unmated female have been 

 described in the rat (472, 605), guinea-pig (402), cow (265), and 

 human (159); in other species, apparently, they may be absent. 

 The extent to which the vagina participates in the cycle entirely 

 determines the application to any particular species of the 

 vaginal smear technique (see p. 95). 



The exact nature of the changes taking place in the accessory 

 organs varies very much from animal to animal, but they are 

 roughly comparable; a comparison of the ovarian and uterine 

 cycles is given on p. 27. 



For descriptive purposes it is convenient to use Loeb's (400) 

 division of the cycle into two main phases: (a) the follicular 

 phase, during which the Graafian folhcles mature and ovulate 

 (this includes prooestrus and oestrus) and {b) the luteal phase 

 (including dioestrus, pseudo-pregnancy and pregnancy) during 

 which the corpus luteum dominates ovarian activity. 



