1 Kevin Moses It is now 25 years since the study of the development of the compound eye in Drosophila really began with a classic paper (Ready et al. 1976). In 1864, August Weismann published a monograph on the development of Diptera and included some beautiful drawings of the developing imaginal discs (Weismann 1864). One of these is the first description of the third instar eye disc in which Weismann drew a vertical line separating a posterior domain that included a regular pattern of clustered cells from an anterior domain without such a pattern. Weismann suggested that these clusters were the precursors of the adult ommatidia and that the line marks the anterior edge of the eye. In his first suggestion he was absolutely correct - in his second he was wrong. The vertical line shown was not the anterior edge of the eye, but the anterior edge of a moving wave of patterning and cell type specification that 112 years later (1976) Ready, Hansen and Benzer would name the "morphogenetic furrow". While it is too late to hear from August Weismann, it is a particular pleasure to be able to include a chapter in this Volume from the first author of that 1976 paper: Don Ready! These past 25 years have seen an astonishing explosion in the study of the fly eye (see Fig.

1 Kevin Moses It is now 25 years since the study of the development of the compound eye in Drosophila really began with a classic paper (Ready et al. 1976). In 1864, August Weismann published a monograph on the development of Diptera and included some beautiful drawings of the developing imaginal discs (Weismann 1864). One of these is the first description of the third instar eye disc in which Weismann drew a vertical line separating a posterior domain that included a regular pattern of clustered cells from an anterior domain without such a pattern. Weismann suggested that these clusters were the precursors of the adult ommatidia and that the line marks the anterior edge of the eye. In his first suggestion he was absolutely correct - in his second he was wrong. The vertical line shown was not the anterior edge of the eye, but the anterior edge of a moving wave of patterning and cell type specification that 112 years later (1976) Ready, Hansen and Benzer would name the "morphogenetic furrow". While it is too late to hear from August Weismann, it is a particular pleasure to be able to include a chapter in this Volume from the first author of that 1976 paper: Don Ready! These past 25 years have seen an astonishing explosion in the study of the fly eye (see Fig.

The compound eye of "Drosophila" is used as a model for human disease and homology to eyes in other taxa. This book covers the major discoveries on the development of the compound eye of "Drosophila melanogaster" over the last 25 years. These include aspects of the biological mechanisms of pattern formation in the nervous system, the specification of neuronal cell types, unexpected phylogenetic conservation and many new insights into the function of several signal transduction pathways. All chapters in this book have been written by leading experts in this field who have made significant contributions to our understanding of fly eye development.

The fruit fly Drosophila melanogaster offers the most powerful means of studying embryonic development in eukaryotes. New information from many different organ systems has accumulated rapidly in the past decade. This monograph, written by the most distinguished workers in the field, is the most authoritative and comprehensive synthesis of Drosophila developmental biology available and emphasizes the insights gained by molecular and genetic analysis. In two volumes, it is a lavishly illustrated, elegantly designed reference work illustrating principles of genetic regulation of embryogenesis that may apply to other eukaryotes.

"Who would believe that so small a space could contain the images of all the universe?" Leonardo da Vinci The last years of the 20th century have found the discipline of Developmental Biology returning to its original position at the forefront of biological re search. This progress can be attributed to the burgeoning knowledge base on molecules and gene families, and to the power of the molecular genetic ap proach. Topping the list of organ systems which have provided the most significant advances would have to be the eye. The vertebrate eye was one of the classic embryologic models, used to demonstrate many important prin ciples, including the concepts of inductive tissue interactions first put forth in the early 1900s. Within the last decade of this century, a return to some of the old questions with the new approaches has put eye development back into the limelight. I find this a highly appropriate topic for a book which aims to spark research for the new millennium. We begin with a chapter that discusses the anatomy of eye development, providing the basic reference information for the chapters that follow. A novel aspect of this introduction is the connection made between develop mental strategies and the eye's optical function. What also emerges from this chapter is the number of important eye structures that have barely been touched by the modern developmental biologist. Work on cornea and ante rior chamber development has lagged behind lens and retina.

(Cont.) First, we characterized the eye phenotypes arising from overexpression of nito. Overexpression of nito perturbs eye development and in contrast to spen, which has been shown to act as a positive effector of EGFR signaling, appears to be a negative effector of EGFR signaling during eye development. Further genetic analysis of the relationship between spen and nito in the eye suggests they function antagonistically, possibly by targeting a common set of genes for transcriptional regulation. Further analysis of SPOC family mutants and study of the functions of these proteins at a molecular level will be necessary to understand the relationship of small and large SPOC proteins and the roles of the proteins in development and disease.