Effets de O-(?-Hydroxyaethyl)-rutosidea (HR) sur les fibroblastes d'embryon de Poulet cultivs in vitro en diffrentes concentrations d'oxygne@@@Effects of O-(?-Hydroxyaethyl)-Rutosidea (HR) on chick embryo fibroblasts cultivated in vitro in different oxygen concentrations: III. Etudes histochimiques topo-optiques au microscope polarisant@@@III. Histochemical topooptic studies with polarized light microscopy