EFFECTS OF THE SURFACTANTS ON THE CLEAVAGE AND FURTHER DEVELOPMENT OF THE SEA URCHIN EMBRYOS II. DISTURBANCE IN THE ARRANGEMENT OF CORTICAL VESICLES AND CHANGE IN CORTICAL APPEARANCE

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Abstract
After fertilization, 2 types of cortical vesicles were examined using EM (the cortical vesicle I and II) and light microscopy (pigment granules and another kind of vesicles). The cortical vesicle I corresponds to the pigment granule and the cortical vesicle II does to the other vesicle. The unequal division of the sea urchin [Hemicentiotus pulcherrimus and Pseudocentrotus depressus] embryo which occurs at the 4th cleavage was modified to an equal cleavage pattern by the treatment with sodium lauryl sulfate (SLS) or cetyl trimethyl ammonium bromide (CTAB). But other surfactants such as sodium deoxycholate, Tween 80, Lubrol PX did not have such an effect. The cell surface of the embryo which was treated either with SLS or CTAB became rough or smooth. Cortical vesicles and pigment granules disappeared and/or were dislocated from the cortex. Cell organelles were as normal as the control. The cortical appearance of other surfactant-treated embryos showed no disturbance and cell organelles were also more or less normal. The equalization of unequal cleavage may be caused by the disturbance in the cortex and thus the cortex plays a major role on the micromere formation at the 16-cell stage and on the further sea urchin development.