826 



SPERM, OVA, AND PREGNANCY 



TABLE 14.4 



Volume of fluid secreted by the doubly ligated rabbit 



oviduct during a three-day interval 



(After D. W. Bishop, Am. J. Physiol., 



187, 347-352, 1956a.) 



arterioles within the endometrium. 



Finally, it has been established that se- 

 cretions of the oviduct undergo changes in 

 response to hormonal variations (Table 

 14.4). Bishop (1956a) studied the rates of 

 fluid production and the secretion pressures 

 in rabbit oviducts under a variety of ex- 

 perimental conditions. Ligatures were se- 

 cured around the uterotubal junctions. Poly- 

 ethylene tubes were then inserted into the 

 fimbriated ampullae and securely tied, and 

 manometric changes in fluid pressures were 



recorded continuously for periods up to 52 

 hours. The mean rates of oviduct secretion 

 are recorded in Table 14.4 and the maximal 

 secretory pressures graphically in Fig. 14.10. 

 The data indicate that the oviducts of rab- 

 bits exhibit an active process of secretion 

 against a gradient. The variations in secre- 

 tory pressures are related to changes in hor- 

 monal activity in the normal female or to 

 hormonally induced responses in the cas- 

 trate animal. Corner (1928b) showed that 

 if the ovaries of rabbits are removed 4 to 

 8 hours after ovulation, all of the eggs are 

 transported to the uterus, but that the 

 blastocysts die soon after entering the uter- 

 ine cavity. He concluded that the presence 

 of actively secreting corpora lutea is essen- 

 tial for the continued nutrition of the free 

 blastocyst. Westman (1930) also removed 

 the ovaries of rabbits 12 hours after mating. 

 All the ova recovered from the oviducts 72 

 hours later showed some signs of degenera- 

 tion. Subsecjuently Westman, Jorpes and 

 Widstrom (1931) cauterized the corpora 

 lutea of mated rabbits and recorded a de- 

 generation of the tubal ova similar to that 



P M 



12 16 



Hours 



20 

 A M 



24 



28 



32 



Fig. 14.10. Tubular secretion pressure of right and left oviducts of rabbit under Dial anes- 

 thesia. Vertical bars indicate pulsations due to visceral movements at the time of reading. 

 (After D. W. Bishop, Am. J. Physiol., 187, 347-352, 1956.) 



