CHAPTER X 



THE INTERNAL SECRETION OF THE 

 CORPUS LUTEUM 



{a) INTRODUCTION 



The facts discussed in previous chapters make it clear that the 

 ovary possesses some periodicity which is quite independent of 

 the periodic production of Graafian folHcles and of corpora 

 lutea, and which is probably under the control of the anterior 

 pituitary body. This basic periodicity appears in the unmated 

 cycle of the normal mouse, because in this animal the complete 

 ablation of the periodic ovarian structures does not alter the 

 periodicity of oestrus. In most species, however, even in the 

 unmated animal, this basic cycle is disturbed by the transient 

 development of corpora lutea after each ovulation, namely, by 

 the interpolation of a luteal phase. When pregnancy leads to 

 the full development of the corpora lutea the derangement of the 

 cycle is much greater. The conditions in animals, such as the 

 rabbit and ferret, in which oestrus persists in the absence of 

 mating, are somewhat difficult to explain by this conception 

 of the ovarian function; it is necessary to suppose that the 

 factor which causes periodic oestrus in animals such as the rat 

 and mouse is persistently operative in the unmated rabbit and 

 ferret. 



The functions of the corpus Jut cum. The analysis of the 

 mechanism controlling the luteal phase of the sexual cycle has 

 not yet proceeded as far as the analysis of the mechanism of the 

 follicular phase. Nevertheless, a great deal of work has been 

 carried out on the functions of the corpus luteum, and, in spite 

 of the present tendency to minimize its importance in the 

 oestrous cycle, certain definite functions can be ascribed to it. 

 The subsequent history of the corpus luteum formed after 



173 



