Studies on the surface layers of oocytes and mature eggs of Psammechinus miliaris

Abstract

1. 1. Oocytes and mature eggs of Psammechinus miliaris have been subjected to the action of proteolytic enzymes (trypsin, chymotrypsin and papain), and of bee venom, whose active factor is a phospholipase A. 2. 2. The surface layers of both oocytes and eggs appear to be very sensitive to such enzymes. The oocytes seem to be more sensitive to bee venom than the mature eggs, and these latter, on the contrary, seem to be more sensitive to proteolytic enzymes than the oocytes. 3. 3. The proteolytic enzymes cause a partial dissolving in the surface of oocytes and eggs. The bee venom induces elevation of a fertilization membrane in the mature eggs. An elevation of both the vitelline layer and of the plasma membrane was observed in oocytes treated with bee venom in hypertonic solution. 4. 4. The birefringence (radially positive) of the mature eggs is not affected by proteolytic enzymes, but it disappears with bee venom. The same applies to the oocytes, which are not birefringent in normal sea water, but become birefringent (positively in the radial direction) in hypersonic solution. 5. 5. The combined action of both proteolytic and bee venom enzymes brings about a complete dissolving of the surface layers. 6. 6. The structure of the surface layers is discussed on the evidence of the experimental results.