PRINCIPAL INVESTIGATOR (S ): Richard S. Young, and John W. Tremor 



EXPERIMENT TITLE/NUMBER : Frog Egg Growth, S003 



PROGRAM/MISSION : Gemini 8, 12 



CLASSIFICATION : Animal - Bullfrog eggs ( Rana pipiens ) 



DISCIPLINE(S) : Cell biology, Genetics 



OBJECTIVES : To determine the effect of weightlessness on the ability of a 

 fertilized frog egg to divide normally and to differentiate and form a normal 

 embryo. 



PROTOCOL : Eggs were obtained from female frogs after they were injected with 

 pituitary gland extract at F-48 hrs. The eggs were fertilized and placed in 

 10 cc of spring water in four chambers, with five eggs per chamber at 43 F. 

 Two sets of ground controls were used, one simultaneous and one with a two hr 

 delay. A temperature of 66 to 74 F was maintained inflight. Two chambers 

 were fixed with formalin after 41 hrs of flight, one was fixed after 85 hrs 

 and one chamber was unfixed with embryos being recovered alive. 



EQUIPMENT : Experiment package with four chambers, a temperature control 

 system and two handles for fixative activation. 



RESULTS : On Gemini 8, early cleavage was achieved but the flight was too 

 short to achieve later developmental stages. On the Gemini 12 experiment, ten 

 embryos in 41 hr. fixation were morphologically normal when compared to 

 controls. Embryos at 85 hr. fixation were well developed and morphologically 

 normal tadpoles. Five unfixed embryos were live swimming tadpoles. Three of 

 these were morphologically normal, two were abnormal, but consistent with 

 ground controls. These live tadpoles died for unknown reasons several hours 

 after recovery. 



CONCLUSIONS : A gravitational field is not necessary for frog eggs to divide 

 normally, nor is it necessary for differentiation and morphological changes in 

 later stages of embryonic development. 



PUBLICATIONS : 529, 530, 580, 581 



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