Repetitive Procurement of Mature Gametes from Individual Sea Stars and Sea Urchins

The various conventional methods of procuring ripe gametes from sea stars (1, 2), and sea urchins (3, 4, 6) are well suited for experiments in which large quantities or pooled lots of gametes from different individuals are required . It is often desirable, however, to perform experiments on a few cells, under well controlled conditions and from a single individual . For this purpose I have devised methods which permit repetitive procurement of healthy echinoderm eggs from a single animal for periods of a week or more . In addition, for various microscopic methods of observation and measurement, one may wish to select and use females whose eggs possess few light scattering or birefringent inclusions . The degree of optical clarity of eggs is fairly uniform for one individual, but can vary widely from one individual to another .