• Applied Microscopy
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• v.33 no.2
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• pp.105-116
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• 2003

In Vitro fertilization of U. unicinctus eggs observed by immunofluorescence and electron microscopes revealed an overview of the meiotic pattern of the tide animals. The eggs have been fertilized early at germinal vesicle stage, followed by germinal vesicle break down (GVBD), but pre-mitotic aster like structure could not be resolved by the methods employed in this work. The meiotic features, such as rotation-shift movement of spindle fibers, behavior of spermatozoonmonaster in the egg cytoplasm and active spindle fiber of the 1st polar body, have been observed. The antitubulin-FITC fluorescence show the 2nd meiotic apparatus appeared firstly parallel to the tangential line of the oolemma, proceeding the meiosis, its bipolarity is rotated and shifted towards the oolemma. The polar bodysite of the oolemma was not amorphous, but active in a sense of anti-tubulin-FITC reactions during the extrusions of the polar bodies. The immunofluorescence reactions of the spermatozoon centriole appeared at a later stage of the 2nd meiosis. During the time periods, the fertilized spermatozoon resided in the egg cytoplasm. Activating the centrioles, spermatozoon approaches towards the chromosomal materials of the 2nd oocyte. This suggests that spermatozoon centrioles initiate and play a roll to fuse male and female pronuclei.