LOCALIZATION AND ASYMMETRIC DISTRIBUTION OF GOLGI COMPLEX AND FIBRILLAR ACTIN IN OOCYTES FROM NEWBORN MOUSE OVARIA

The fetal ovarium forms clusters of synchronously dividing germ cells connected by intercellular bridges. Early mammalian oocytes are reported to form a Balbiani body a perinuclear aggregate of membrane organelles. Our study used immunocytochemical detection of Golgi material and actin in oocytes from newborn mice. In oocytes, Golgi complex was detected as a specific perinuclear circular structure and in the cytoplasmic bridges connecting oocytes. Fibrillar actin was detected in the oocyte periphery, in the interconnecting canals between the oocytes and in the circular perinuclear structure associated with the Golgi material. The perinuclear position and the asymmetric ring view of Golgi and actin allowed us to identify this structure as Balbiani body. Our data for specific distribution of fibrillar actin suggest a role of microfilaments in supporting the Balbiani body and mediating the organelle transfer through intercellular bridges during early mammalian oogenesis.