par Geuskens, Maurice
Référence Experimental cell research, 52, 2-3, page (608-620)
Publication Publié, 1968-10
Article révisé par les pairs
Résumé : Paracentrotus lividus eggs were treated with hydroxyurea (1 mg/ml) for 5 h 15 min, immediately after fertilization. This inhibitor of DNA synthesis blocks cleavage at the 4-8 blastomere stage. Both treated and control embryos (morulae) were fixed for an ultrastructural study. The nuclei of the controls contain nucleolar corpuscles (about 0.5 μ in diameter) whose fibrillar component can be condensed into granules. The nuclei of the hydroxyurea treated eggs contain many spherules (about 1.5 μ in diameter) of condensed fibrillar structure. The perivitelline space of the hydroxyurea treated embryos contains polysaccharide granules clumped together or arranged in small chains. At the morula stage, these polysaccharide granules are no longer seen in the perivitelline space, but occur in some of the yolk platelets or in vacuoles localized in a concavity of these platelets. The alterations observed in hydroxyurea treated eggs are consistent with the hypothesis of a direct action of this substance on DNA itself. © 1968.