Cortical granule-specific components are present within oocytes and accessory cells during sea urchin oogenesis.

Abstract

The coordinate expression of cortical granule-specific components in sea urchin oogenesis was studied using antibody probes. The components used to generate the organelle-specific antibodies included the whole cortical granule exudate, fertilization envelopes, hyalin, beta, 1-3,glucanase, and Ig8. Using immunolocalization techniques at both the light and electron microscopic levels, these molecules were found to be specific to cortical granules in three distinct cell types: developing oocytes, eggs, and accessory cells. In early oocytes, each of the cortical granule components are coordinately accumulated in the developing cortical granules dispersed throughout the cytoplasm. No other organelle within the developing oocytes or eggs contained detectable levels of any of these epitopes. In the somatic interstitial tissue of the ovary, cortical granule components also were accumulated specifically within cortical granule structures. Found only in select accessory cells, these cortical granules were indistinguishable in morphology and epitope composition from eggs and were contained within cytoplasmic aggregates termed mosaic globules. The mechanism of cortical granule concentration into mosaic globules is unknown, but this demonstration of common organelle constituents between oocytes and accessory cells may provide insight for such an understanding.