106 



INDUCED BREEDING 



sphere Is uppennost within about an hour and by 2^ hours the eggs should be In 

 the 2 -cell stage at laboratory "temperatures of 23° - 25°C. 



(a) Egg of Raina plplens at the 

 moment of insemination. 



(b) Egg of Rana plpiens 29 minutes 

 after Insemination, showing 

 grey crescent. 



5. Care of the material : Aa the jelly membranes swell (by Imbibition) the egg mass 

 will expand sind It may become necessary to add some water to cover. The Jelly 

 mass generally sticks to the bottom of the container but may be separated by means 

 of a stiff, clean section lifter. This may be done as soon as 1 hour after in- 

 semination. The Jelly should be allowed to swell to its maximum and then the egg 

 mass should be cut up Into small groups of eggs. This should be done before the 

 first cleavage. The optimum ratio is about 25 eggs per finger bowl of 500 cc. 

 water. 



The optimum temperature for the normal development of the eggs of Bana 

 plpiens is 18° - 25°C. Development can be slowed down without the production of 

 abnormalities if the eggs are kept at the lower temperatures, but never lower 

 thein 10°C. ?y retarding the developmental rate of some eggs it is possible to 

 have various stages of development available at all times. Eemember, however, 

 that when eggs are removed from a cold to a warm environment, sufficient time 

 must be allowed for the adjustment before the eggs are to be used for experinen- 

 tal procedures. Eggs and embryos should never be transferred suddenly fKjm one 

 temperatiure level to another. 



INDUCED BREEDING IN OTHER AMPHIBIA 



There is reason to believe that any amphibian which Is sexually mature and which has 

 not recently undergone its normal breeding reaction, will respond to the pituitary hormone 

 by ovulation (female) or by the release of spermatozoa (male). In general, the Anura will 

 respond to pituitaries from other Amphibia but not from mammalian extracts of the pituitary 

 hormone. Exceptions to this statement are Bufo and Xenopus. The Urodela, in contrast, 

 will respond readily to the pituitary hormone from almost any source. 



There follows an alphabetical list of the more common Amphibia which have responded to 

 pituitary treatment In the manner described for Sana plpiens. The references given are 

 not complete but represent one of the major sources of other references for the particular 

 form. 



Amblystoma tigrlnum 

 Bomblnator pachypus 

 Bufo americanus 

 Bufo arenaxnim 

 Bufo calami ta 

 Bufo D'Orblgnyl 

 Bufo fowls rl 

 Bufo vulgaris 

 Desmognathus fuscus 

 Dlscogloseus plctus 

 Eurycea blslineata 

 Grylnophllus porph. 

 ^la aurea 



Bums & Buyse, 1951 



Moskowska, 1955 



Wills, Riley, & Stubbs, 1955 



Novelli, 1952 



Cunningham & Smart, I95U 



Houssay, 1950 



Rugh, 1955 



Rostand, 1954 



Noble & Evans, 1925 



Kehl, 1950 



Noble & Richards, 1950 



Noble & Richards, 1952 



Creaaer & Gorbman, 1955 



