Embryonic Development of Identified Neurons in the Grasshopper

Abstract

Several years ago we began to examine the embryonic development of the grasshopper nervous system. We hope that by someday understanding the cellular and molecular mechanisms underlying the development of this relatively simple and highly accessible nervous system, we will help answer some of the fundamental questions common to the development of all nervous systems. This chapter describes the beginning of such an approach. In particular, the chapter will examine the progeny of two different neuronal precursor cells (called the median neuroblast or MNB, and midline precursor 3 or MP3), and will describe the differentiation from birth to maturation of identified neurons that arise from specific cell divisions of these two precursors. After examining the lineage and differentiation of the progeny of these two precursors in a single segment, the development of these cells in other segments will be examined. Our results demonstrate how segmental specializations in the nervous system can arise by segment-specific differentiation and segment-specific cell death of identified neurons of known lineage.