Artificial Parthenogenesis in Starfish Eggs: Production of Parthenogenetic Development Through Suppression of Polar Body Formation by Methylxanthines

Methylxanthines such as caffeine, theophylline, and theobromine at 6 to 10 mM activated eggs of the starfish, Asterina pectinifera. Up to one hour of methylxanthine treatment induced parthenogenetic development in more than 80% of the eggs that failed to form the second polar body. Eggs that formed two polar bodies did not cleave. Compared with normally fertilized eggs the first cleavage in parthenogenetically developing eggs was delayed by 2 h in eggs lacking a polar body, and by 3 h in eggs with one (first) polar body. The intervals between successive cleavages were identical to those of normally fertilized eggs. Examination of the chromosome number revealed that most parthenogenetic embryos develop as tetraploids. The possible significance of centriolar material in initiating parthenogenetic development is suggested.