Histochemical Observations on the Cortical Region of the Oocytes of

The cortical cytoplasm of the developing oocyte of Rana pipiens has been investigated by cytochemical means. Particular emphasis is placed on the nature and distribution of polysaccharide protein complexes. With toluidine blue O, both living and fixed mature oocytes were found to possess a distinct metachromatic region just under the developing vitelline membrane. Younger oocytes, at the previtelline-stage, did not exhibit metachromasia in this region. Comparative studies suggested a similarity of oocyte cortical metachromasia to that of mucoitin sulphuric acid. Oxidation by periodic acid and staining with the Schiff reagent or 2,4-dinitrophenylhydrazine or both, demonstrated reactive granules located in the cortex of both young and mature oocytes. The presence of more than one polysaccharide component was suggested. Hydrolysis with trypsin and chymotrypsin indicated that the proteins in the ectoplasmic region were more readily digestible than those in the endoplasm.