title: Observation on the ultrastructure of the nucleolus of Paracentrotus lividus in relation to morphological events during development.
mesh_terms: D000818:Animals; D002454:Cell Differentiation; D002466:Cell Nucleolus / Q000187:drug effects; D002467:Cell Nucleus / Q000648:ultrastructure*; D003609:Dactinomycin / Q000031:analogs & derivatives / Q000494:pharmacology; D012617:Sea Urchins / Q000196:embryology*
chemical_list: D003609:Dactinomycin