Biol Bull 1990 Oct 01;1792:183-185. doi: 10.2307/1541767.

Occurrence of Partial Nuclei in Eggs of the Sand Dollar, Clypeaster japonicus.

???displayArticle.abstract???
Females of Clypeaster japonicus bearing eggs with multiple nuclei were occasionally found. DAPI (4''-6-diamidino-2-phenylindole) stained all these nuclei. The summed volume of the two nuclei in binucleate eggs was similar to the nuclear volume in mononucleate eggs from the same batch. On fertilization, two partial nuclei migrated to the center of the egg with a time-course similar to that taken by a single nucleus; they then participated in forming the zygote nucleus, which subsequently formed a single mitotic spindle. These multiple nuclei thus appear to function as genuine nuclei. Possibly they result from the failure of a single nucleus to form during oogenesis.

???displayArticle.pubmedLink??? 29314983
???displayArticle.link??? Biol Bull