HYBRIDIZATION AND EARLY DEVELOPMENT 



PURPCSE : To demonstrate the effects upon early development of the egg when activated 'by- 

 foreign spermatozoa, and to determine the relative influence of the maternal and pa- 

 ternal factors in hybrids which pass the critical period of gastrulatlon. 



MATEBIALS : 



Biological : 



Ovulating females of any Amphibian species, and sexually mature males of 

 a variety of species. ( Pre- breeding, sexually mature females of any 

 species of Amphibia can be induced to ovulate by pituitary injection.) 



Technical : Standard equipment- 



METHOD : 



Precautions : 



1. Avoid contamination with sperm suspensions other than that intended for use. All 

 instruments and glassware should be sperm-sterile. 



2. Examine sperm suspensions under the microscope for motile spermatozoa. 



5. Cleaving eggs should be separated from others, and placed in finger bowls of 



Standard Solution (or Urodele Growing Medium) at cool temperatures, not more than 

 25 eggs per 50 cc. of medium per finger bowl. 



Controls : 'Egga inseminated with spermatozoa of the same species. This should be done 

 after the hybridization experiments, to avoid contamination. 



Procedure : A summary (Moore, 19'*1) of the hybrid crosses between American species of 

 Bana follows : 



NO 



CLEAVAGE 



OCCUBS 



FEMALE 



Bana clamitans 

 Bana clamitgins 

 Bana clamitans 

 Bana clamitans 

 Bana clamitans 

 Bana clamitans 

 Bana septentrionalis 

 Bana septentrionalis 



MALE 



X 



X 

 X 



X 

 X 

 X 

 X 

 X 



X 

 X 

 X 

 X 



X 

 X 

 X 

 X 

 X 



X 

 X 



X 

 X 

 X 

 X 

 X 

 X 



Bana palustris 

 Bana sphenocephala 

 Bana pipiens burns i 

 Bana pipiens 

 Bana palustris 

 Bana pipiens 

 Bana palustris 

 Bana pipiens 



If 5yla or Bufo eggs or sperm are available, hybridization with Bana should be at- 

 tempted. In most, if not all, cases these hybrids would fall into the second group above. 



-556- 



