Abstract

The integrity and dynamic reorganization of the cytoskeleton are fundamental to cell division, motility, and morphogenesis, processes that are highly conserved and readily observable in early development models such as the sea urchin embryo. This study investigates the effects of two pharmacologically active compounds, Haloperidol (a dopamine receptor antagonist) and Cyproheptadine (a serotonin and histamine antagonist), on the cytoskeletal architecture and developmental progression of *Strongylocentrotus intermedius* embryos. Our primary objective was to determine if these agents, known to interact with various cellular signaling pathways, induce specific alterations in the actin and microtubule networks that underpin critical developmental stages, including fertilization, cleavage, and gastrulation. Embryos were exposed to varying concentrations of Haloperidol and Cyproheptadine, and their cytoskeletal components were visualized using immunofluorescence microscopy. We found that both compounds significantly disrupted the formation of the mitotic spindle and the contractile ring, leading to abnormal cleavage patterns and developmental arrest. Specifically, Haloperidol exposure resulted in a dose-dependent depolymerization of microtubules, while Cyproheptadine primarily affected actin-based structures, suggesting distinct mechanisms of action. These findings highlight the sensitivity of the embryonic cytoskeleton to pharmacological agents and provide valuable insights into the regulatory mechanisms governing cytoskeletal dynamics, offering a model for studying drug-induced developmental toxicity and the essential role of the cytoskeleton in early embryogenesis.