Discussions 191 



Sprague-Dawley rats were hypophysectomized when 29 or 30 days of age. They 

 were injected subcutaneously with a FSH preparation made by trypsin digest method 

 (W. H. McShan and R. K. Meyer, J.B.C. 132: 783, 1940). This preparation causes the 

 development of follicles in the hypophysectomized rat, and when administered over a 

 period of 10 days repairs ovarian interstitial cells and causes localized thecal luteiniza- 

 tion and occasionally one to few corpora lutea. The FSH was injected once in the 

 afternoon of the first day and twice daily for the next four days, a total of nine injec- 

 tions. At the time of the last injection, an intravenous injection was made of an 

 unfractionated gonadotropic preparation, which was relatively rich in FSH and LH 

 activity. 



At varying times after the ovulator was injected, animals were killed and the ovarian 

 bursa, oviducts, uterus and body cavity were flushed with saline. The number of ova in 

 the washings was recorded. 



The data are presented in terms of the number of ova recovered from the oviducts 

 between 12 and 35 hr after the injection of the ovulator (Fig. 1). The maximum 

 number of ova recovered was found between 16 and 20 hr. Between 20 and 24 hr 

 the number of ova found in the oviduct was much smaller. It was during this time that 

 one to five eggs were recovered from the body cavity of a few of the rats; ova were 

 not recovered from the uterus before 48 hr after the ovulator was injected. We believe 

 that when large numbers of ova are ovulated some of them accumulate in the 

 bursa and are extruded through the bursal pore into the body cavity, thus accounting 

 for the decrease found between 20 and 24 hr. A second peak in the number of ova was 

 found between 23 and 26 hr. We do not have a satisfactory answer for this unexpected 

 second peak. It has been suggested that ova found during this time are from a second 

 group of follicles which were ovulated some hours after those which shed the eggs 

 accumulating in the bursa and oviduct between 16 and 20 hr. 



It is suggested that under the conditions of this experiment, and in similar experiments 

 in which superovulation is experimentally induced in rats, the function of the 

 oviduct is aberrant due to abnormal estrogen-progesterone levels. The practical 

 implication of this concept is that in comparative studies of ovulators of different kinds 

 the amount of gonadal hormones produced by different ovulators may vary, thus 

 affecting the function of the oviduct, and the distribution of the ova in the different 

 parts of the tract. It is also probable that when large numbers of ova are rapidly ovulated 

 they accumulate in the bursa and many of them are forced through the bursal pore 

 into the body cavity. This and/or the hormonally induced dysfunction of the oviduct 

 are factors which should be considered in the development of methods which depend 

 upon the recovery of ova for evaluating the effectiveness of ovulators. 



