Glucosephosphate I somerase Distribution During Oocyte Maturation and Early Embryologic Stages of the Mouse1

Abstract

The enzyme glucosephosphate isomerase (GPI) is of interest because of its role in glycolysis and its use as a cell marker in embryogenesis studies utilizing chimeras. The distribution of GPI was determined in histologic sections of ovarian follicles and the tissues of early embryonic stages of the mouse. Antibodies of GPI were combined in an immunocytochemical procedure utilizing peroxidase-antiperoxidase to localize GPI in tissue sections. During follicular maturation, GPI is 1st detected in small follicle oocytes and then in the granulosa cells of slightly larger follicles. The relative concentrations of GPI remain high in the granulosa cells adjacent to the oocyte as the follicles mature. GPI in the granulosa cells may play a role in providing the growing oocyte with low MW energy sources. Within the conceptus, differences in GPI concentrations among tissues become apparent during the egg cylinder formation. The highest GPI concentrations are in the embryonic ectoderm, the amniotic folds, the extraembryonic ectoderm and the ectoplacental cone. These are areas of intense mitotic activity. The energy required for cell divisions during embryogenesis is derived from glycolysis, thus the high concentrations of GPI in these tissues correlates well with the cellular function.