i86 INTERNAL SECRETIONS OF THE OVARY 



found in the ordinary unmated cycle. Long and Evans also 

 introduced the technique of inserting a small loop of surgical 

 silk transversely through the uterus as a means of providing the 

 mechanical stimulation. If the stitch passes through the mucosa, 

 the stimulus which it set up is found to be a§ effective as that 

 of an actual incision through the muscle and mucosa. The 

 uterus was found to be most sensitive in the rat about four 

 days after ovulation. These results have been extended and 

 confirmed by various workers. Loeb (381), Gasbarrini (236), 

 Hammond (263), and Nielsen (474) have induced deciduomata 

 formation during pseudo-pregnancy in the rabbit, while Krainz 

 (335) has obtained a like effect in the bitch. Results agreeing 

 exactly with those of Long and Evans (425) on the rat have been 

 obtained (501) on the mouse, although in this animal the 

 maximum sensitivity occurs somewhat sooner after copulation. 

 Evidence of luteal control. The evidence that the corpora 

 lutea are responsible for this sensitization of the uterus is so 

 strong that its absence during the ordinary unmated cycle in the 

 rat is additional evidence that the corpus luteum of ovulation 

 in this animal does not function. This fact is comparable with 

 the lack of change in the periodicity of oestrus following oblitera- 

 tion of the corpora lutea in the unmated mouse. In the rat and 

 mouse, therefore, the corpus luteum of the unmated animal 

 possesses neither a sensitizing nor an oestrus-inhibiting function. 

 Additional evidence of the luteal control of the sensitization of 

 the uterus has recently been obtained from the fact that 

 sensitivity does not appear even after copulation in sterilized 

 mice possessing no corpora lutea (501 ) . Interesting experiments 

 have been reported by Teel (610) showing that the corpus 

 luteum in the rat is responsible for the sensitization of the 

 uterus. It has been described above how the injection of 

 anterior pituitary extracts will bring about the luteinization of 

 the ovary. Teel was able to show that with this treatment 

 the consequent luteinization of the ovary of the rat made 

 possible the production of deciduomata even in the unmated 

 animal. The deciduomata were produced most readily when 

 the operation was made on the fifth day of injection. The 

 reaction, however, did not occur in the ovariectomized animal 

 and cannot, therefore, have been directly due to the anterior 



