{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,4,3]],"date-time":"2026-04-03T16:07:55Z","timestamp":1775232475758,"version":"3.50.1"},"reference-count":18,"publisher":"Wiley","issue":"3","license":[{"start":{"date-parts":[[2005,2,4]],"date-time":"2005-02-04T00:00:00Z","timestamp":1107475200000},"content-version":"vor","delay-in-days":6244,"URL":"http:\/\/onlinelibrary.wiley.com\/termsAndConditions#vor"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Cell Motil. Cytoskeleton"],"published-print":{"date-parts":[[1988,1]]},"abstract":"<jats:title>Abstract<\/jats:title><jats:p>The sequential changes in the distribution of microtubules during germinal vesicle breakdown (GVBD), fertilization, and mitosis were investigated with antitubulin indirect immunofluorescence microscopy in several species of ascidian eggs (<jats:italic>Molgula occidentalis, Ciona savignyi<\/jats:italic>, and <jats:italic>Halocynthia roretzi<\/jats:italic>). These alterations in microtubule patterns were also correlated with observed cytoplasmic movements. A cytoplasmic latticework of microtubules was observed throughout meiosis. The unfertilized egg of <jats:italic>M. occidentalis<\/jats:italic> had a small meiotic spindle with wide poles; the poles became focused after egg activation. The other two species had more typical meiotic spindles before fertilization. At fertilization, a sperm aster first appeared near the cortex close to the vegetal pole. It enlarged into an unusual asymmetric aster associated with the egg cortex. The sperm aster rapidly grew after the formation of the second polar body, and it was displaced as far as the equatorial region, corresponding to the site of the myoplasmic rescent, the posterior half of the egg. The female pronucleus migrated to the male pronucleus at the center of the sperm aster. The microtubule latticework and the sperm aster disappeared towards the end of first interphase with only a small bipolar structure remaining until first mitosis. At mitosis the asters enlarged tremendously, while the mitotic spindle remained remarkably small. The two daughter nuclei remained near the site of cleavage even after division was complete. These results document the changes in microtubule patterns during maturation in Ascidian oocytes, demonstrate that the sperm contributes the active centrosome at fertilization, and reveal the presence of a mitotic apparatus at first division which has an unusually small spindle and huge asters.<\/jats:p>","DOI":"10.1002\/cm.970090304","type":"journal-article","created":{"date-parts":[[2005,2,24]],"date-time":"2005-02-24T03:59:38Z","timestamp":1109217578000},"page":"219-230","source":"Crossref","is-referenced-by-count":69,"title":["Microtubules in ascidian eggs during meiosis, fertilization, and mitosis"],"prefix":"10.1002","volume":"9","author":[{"given":"Tomo\u2010o","family":"Sawada","sequence":"first","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Gerald","family":"Schatten","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"311","published-online":{"date-parts":[[2005,2,4]]},"reference":[{"key":"e_1_2_1_2_1","doi-asserted-by":"publisher","DOI":"10.1002\/cm.970030303"},{"key":"e_1_2_1_3_1","doi-asserted-by":"publisher","DOI":"10.1016\/S0074-7696(08)61757-X"},{"key":"e_1_2_1_4_1","first-page":"1","article-title":"The organization and cell\u2010lineage of the ascidian egg","volume":"13","author":"Conklin E. G.","year":"1905","journal-title":"J. Acad. Natl. Sci. Phila."},{"key":"e_1_2_1_5_1","doi-asserted-by":"publisher","DOI":"10.1073\/pnas.75.8.3863"},{"key":"e_1_2_1_6_1","first-page":"183","article-title":"The early development of Cynthia roretzi.","volume":"4","author":"Hirai E.","year":"1941","journal-title":"Sci. Rep. Tohoku Imp. Univ."},{"key":"e_1_2_1_7_1","doi-asserted-by":"publisher","DOI":"10.2307\/1541217"},{"key":"e_1_2_1_8_1","doi-asserted-by":"publisher","DOI":"10.1016\/0012-1606(83)90317-2"},{"key":"e_1_2_1_9_1","first-page":"260","article-title":"Distribution of the components of normal unfertilized eggs of Ciona intestinalis examined at the electron microscope","volume":"6","author":"Mancuso V.","year":"1963","journal-title":"Acta Embryol. Exp. Morphol."},{"key":"e_1_2_1_10_1","first-page":"71","article-title":"The distribution of the ooplasmic components in the unfertilized, fertilized and 16\u2010cell stage egg of Ciona intestinalis.","volume":"7","author":"Mancuso V.","year":"1964","journal-title":"Acta Embryol. Exp. Morphol."},{"key":"e_1_2_1_11_1","doi-asserted-by":"publisher","DOI":"10.1016\/0012-1606(84)90141-6"},{"key":"e_1_2_1_12_1","first-page":"507","volume-title":"Ascidians in Experimental Embryology of Marine and Fresh\u2010Water Invertebrates","author":"Reverberi G.","year":"1971"},{"key":"e_1_2_1_13_1","first-page":"488","article-title":"Surface and internal movement in fertilizing Phallusia eggs","volume":"171","author":"Sardet C.","year":"1986","journal-title":"Biol. Bull."},{"key":"e_1_2_1_14_1","first-page":"123","article-title":"How ooplasm segregates bipolarly in ascidian eggs","volume":"17","author":"Sawada T.","year":"1983","journal-title":"Bull. Mar. Biol. Stn. Asamushi Tohoku Univ."},{"key":"e_1_2_1_15_1","doi-asserted-by":"publisher","DOI":"10.1007\/BF00848304"},{"key":"e_1_2_1_16_1","doi-asserted-by":"publisher","DOI":"10.1073\/pnas.82.12.4152"},{"key":"e_1_2_1_17_1","doi-asserted-by":"publisher","DOI":"10.1073\/pnas.83.1.105"},{"key":"e_1_2_1_18_1","volume-title":"The Cell in Development and Heredity","author":"Wilson E. 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