The Pituitary Stalk and Ovulation 



71 



Infusion of Median Eminence Extracts into Rats 



Concurrently with the above study, Dr. M. Nikitovitch-Winer, working 

 in this department, has been investigating the effect of intrapituitary infusions 

 of median eminence, and other extracts in rats in which spontaneous 

 ovulation has been blocked with nembutal. The procedure used is as follows. 



Adult female rats (Wistar strain), whose vaginal cycles had been found to be 

 regular for at least two weeks, were anesthetized early in the day of proestrus 

 and a fine platinum or platinum-iridium cannula (SWG 27) was inserted in 

 the right half of the pars distalis with a stereotaxic machine. In general 

 principle the technique used was similar to that described above for the rabbit. 

 Later on the same day, the spontaneous release of LH, and subsequent 

 ovulation, was blocked by intraperitoneal injections of 30 mg/kg body weight 

 "nembutal" (pentobarbitone sodium) at 1 1.00 a.m. and 2.00 p.m. (see Everett 

 and Sawyer, 27). In the afternoon, usually between one and three o'clock, the 

 brain extracts (from cattle) were infused either into the pituitary gland 

 directly (at a rate of 0.005-0.006 ml/hr or 0.008-0.009 ml/hr for one to two 

 hours) or intravenously (0.016-0.019 ml/hr) for the same period. The 

 following morning, the animals were anesthetized, the pituitary glands 

 infused with a dye solution at the same rate and for the same period as 

 perfused on the previous day, and the ovaries and Fallopian tubes removed. 



Table 1. Induction of Ovulation by Direct Intra-pituitary Infusion of Median 

 Eminence Extracts into "Nembutal-blocked" Proestrous Female Rats 



* 0.44 mg infusion. 



t Fast infusion over a period of 1 min. 



After kiUing the animal, the cranium was opened and the position of the tip 

 of the cannula and the spread of the dye was observed. The ovaries were 

 examined for fresh rupture points, and the ampullae of the oviducts searched 

 for ova. The results obtained are shown in Table 1 . It may be seen that median 

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