Cytochemical studies of fertilization and first mitosis of the sea urchin egg

Abstract

It has been demonstrated that the yolk granules of the sea urchin eggs give a more intense PAS reaction following than prior to fertilization. A hypothetical scheme has been proposed which accounts for the increase of α-glycol groups occurring upon fertilization (cf. scheme I and II, Fig. 13). The Feulgen staining of the pronuclei and of the syncarion has been studied. The results are given in Fig. 3. They confirm that DNA at least in its ordinary form is absent in the female pronucleus and during a certain period in the syncarion as well (cf. stage f, Fig. 3). Some additional data are given concerning the staining reactions of nucleus and chromosomes. The cytoplasm of the spindle poles is intensely PAS-positive (cf. Fig. 5). The maximum reaction occurs in the prophase. Then the intensity decreases gradually (cf. Figs. 7, 9, 10) and finally the reaction disappears in the telophase. The nuclear substances give a very weak PAS reaction in prophase. In meta- and early anaphase the chromosomes are PAS-positive; conversely they are PAS-negative in late ana- and in telophase. The Hale reaction is occasionally faintly positive in prophase but always distinctly positive in meta- and anaphase (cf. Figs. 10 and 11). The telophase chromosomes are Hale-negative.