EFFECT OF CHRONIC HYPOXIA ON THE CHICK EMBRYO OPTIC TECTUM NEUROEPITHELIAL CELLS PROLIFERATION

DUARTE, SANTIAGO; RAPACIOLI, MELINA; RODRÍGUEZ CELÍN, ALEJANDRA; DI NAPOLI, JENNIFER; TERUEL, LUISA; SANCHEZ, VIVIANA; SCICOLONE, GABRIEL; FLORES, VLADIMIR

Santa Cruz

Congreso; 5th International Meeting of the Latin American Society for Developmental Biology; 2010

Latin American Society for Developmental Biology

The present work analyzes hypoxia-induced changes on the neuroepithelial cells proliferation dynamics in the developing chick optic tectum. A 48h-aerogenic hypoxia (23% decrease PO2–32% increase PCO2), starting at E2 and E4 produced 23% and 50% reduction in mitotic density respectively. Clustering analyses of mitotic cells spatial organization reveals a power-law relationship between “number of clusters” vs. “inter-cluster gaps length” and a hierarchical organization (fractality) of mitotic cells. Over short range scales analyses (i.e. 5-16 µm) hypoxia produced a decrease in the slope of the log-log plot of the number of clusters vs. inter-cluster distance at both E4 and E6 (30% and 50% respectively). At larger scales hypoxia produced a shift to the right of the lines indicating an increase in the number of clusters separated by large distances. Interestingly, at each age there was a number of a typical inter-cluster length, i.e. segment occupied by interphasic cells, that remained unchanged under hypoxia. In fact, the number or clusters separated by 5-7 µm in E4 and 10-16 µm in E6 do not change under hypoxia suggesting that at short-range scales the decrease in mitotic cells occurs at the central region of the smaller clusters. The changes observed at long-range scales are due to the decrease in the mitotic density and increase in the number of larger inter-cluster gaps. Immunohistochemistry evaluation of Notch and NeuroD expression suggests that hypoxia alters the temporal shift between proliferation associated to neuroepithelial cell expansion and neuronogenic proliferation.