INHIBITION OF FERTILIZATION IN ARBACIA BY BLOOD EXTRACTS

¹ Marine Biological Laboratory, Woods Hole, Massachusetts, and Department of Zoology, Pomona College, Claremont, California

1. Whole perivisceral fluid (blood) of Arbacia contains a substance capable of inhibiting fertilization.

2. Contrary to the conclusions of previous investigators, this inhibitor is not normally present in the serum. Rather certain blood cells, particularly the amoebocytes with yellow spherules, are the ultimate source of the inhibitor.

3. The inhibitor believed by Lillie and Just to be found in the serum of Arbacia blood actually entered their samples as a contaminant from the outside of their animals.

4. The external application of tap water causes the inhibitor to appear in the drainage from the test. Under these conditions the inhibitor emanates from yellow bodies found in the hypodermis of the tube feet.

5. The supposedly variable potency of inhibitor reported by previous workers can be explained by the technique used in obtaining samples, and the methods used in testing its strength. In reality former workers were testing inhibitor in varying dilutions rather than testing the potency of a standard amount of inhibitor.

6. This inhibitor does react with the egg's jelly layer and can modify the fertilization membrane in proportion to concentration and duration of exposure. Eggs that are inhibited for short intervals of time (1-4 hours) can be fertilized and will develop normally (i.e. with membranes, etc.), provided they are rinsed thoroughly in fresh sea water.

7. Fertilizin is believed to have little influence on the activity of the inhibitor beyond a simple dilution effect. On the other hand, the sperm-agglutinating power of fertilizin-bearing solutions can be reduced or nullified by the addition of sufficient inhibitor.

8. It is suggested that this blood inhibitor may be related to an egg-agglutinin extracted from the egg itself.