Electrical Polarity and Cellular Differentiation in Meroistic Ovaries

Abstract

SYNOPSIS. In the oocyte-nurse cell syncytium of meroistic insect ovaries a gradient in electrical potential is shown to drive a micro-injected basic protein (fluorescein-labeled lysozyme) and its methylcarboxylated, acidic derivative in opposite directions. In the polytrophic Cecropia ovary the electrophoretic effect is greatest in the intercellular bridges, while in the telotrophic <it>Rhodnius</it> ovary it is greatest within the nurse chamber. We speculate that in both systems the potential gradient prevents the free diffusion of cell cycle and differentiative control proteins, while at the same time reinforcing the transport of acidic precursors toward the ooplasm. Because of its apparent ability to affect the distribution of polyions that govern nuclear function, electrical polarity can also be envisioned to have a more general role in the control of differentiation. The possibility is considered that it serves as a relay mechanism for the non-diffusing determinant that is already known to govern the differentiation of oocytes from nurse cells.