588 



PHYSIOLOGY OF GONADS 



able pituitary lactogen at nursing, found no 

 decrease when pentobarbitalized mothers 

 were injected with physiologic doses of oxy- 

 tocin intravenously. When the dosage was 

 increased 30 to 60 times there was appar- 

 ently some moderate discharge, but the au- 

 thors regard it as insignificant. 



C. EFFECT OF THE UTERUS ON 

 LUTEAL FUNCTION 



This subject has been reviewed by Brad- 

 bury, Brown and Gray (1950). In three 

 species (Fig. 8.13) hysterectomy results in 

 significant prolongation of the functional 

 life-span of corpora lutea (guinea pig, Loeb, 

 1927; rabbit, Asdell and Hammond, 1933; 

 rat, Bradbury, 1937). In each case the pe- 

 riod of luteal function approximates that of 

 normal pregnancy. The fact that corpora lu- 

 tea in the pseudopregnant ferret normally 

 function as long as in the pregnant animal 

 may be a clue to the noncffect of hysterec- 

 tomy in that species (Deanesly and Parkes, 



19331. Ahhough Burford and Diddle (1936) 

 rej^orted that in monkeys total hysterec- 

 tomy was followed by vaginal cycles of nor- 

 mal length, examination of their protocols 

 shows that during the several postoperative 

 months just 1 corpus luteum was produced 

 among all 5 animals. The experiment thus 

 seems inconclusive. Impairment of pelvic 

 circulation seems to be a common factor 

 complicating the results of hysterectomy in 

 women and may have been one cause of the 

 failure of luteinization in these monkeys. 



An interpretation given by Loeb (1927) 

 and Bradbury, Brown and Gray (1950) for 

 the prolongation of luteal function by hys- 

 terectomy is that in species in which the ef- 

 fect is demonstrable the uterus secretes a 

 specific substance which abbreviates the life 

 of the corpus luteum. Hechter, Fraenkel, 

 Lev and Soskin (1940) found in rats that 

 grafts of estrous uteri shortened the pseudo- 

 pregnancies of hysterectomized animals to 

 normal length. Implantation of similar tis- 



Fi(i. 8.13. Reliilive duiation.s of p.seiulopicgnaiicy in normal and hysterectomizeil animals 

 of four species in relation to the duration of j^ostation characteristic of each. Gestation 

 plotted as a common unit of time. (After J. T. Bradbury, W. E. Brown and L. A. Gray, 

 Recent Proj,n-. Hormone Res., 5, 151-194, 1950.) 



