Centriolar Behavior and Flagellum Formation in Cell Culture System of Testicular Cells of the Sea Urchin

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Centriolar behavior and flagellum formation during maturation division of male germ cells were studied by using of cultured testicular cells of the sea urchin, Hemicentrotus pulcherrimus.1. Isolated germ cells from the testis were divided by Ficoll density gradient centrifugation into the following 3 cell type fractions : the primary spermatocytes together with spermatogonia, secondary spermatocytes and spermatids. Each cell fraction was then cultured in a culture medium.2. A flagellum was detected in the spermatogonia, the primary and secondary spermatocytes at eary prophase. In this stage, 2 centrioles including a basal body duplicate to form 2 paires of centrioles at the base of the flagellum. At the time of prometaphase, the flagellum was absorbed into the cytoplasm and a pair of centrioles was located at each pole of the first and second division. After the second division, 4 spermatids with a flagellum were formed and developed to spermatozoa.3. When nuclear division was reversibly suppressed by cycloheximide, each of the primary and secondary spermatocytes sprouted frequently 2-4 flagella.4. From above-mentioned results, it was concluded that in spermatogonia and spermatocytes of the sea urchin, duplication of the centriole takes place in association with flagellum growth, and then each paired centriole changes its function to form the cell division centers.