X-Message-Number: 11969 Date: Wed, 16 Jun 1999 21:39:11 -0400 From: Jan Coetzee <> Subject: Directing development Directing development Cells communicate with each other by releasing proteins or other chemical signals that diffuse to their targets. In the case of neurons, they send out a long, thin process called an axon. Tissues in embryonic fruit flies seem to use filaments to carry signals that tell other tissues how and when to develop. In fruit fly larvae, which are segmented, the filaments grow from cells at the border between the front and rear portion of each segment. The filaments, called cytonemes, are also present in embryonic mice, which shows that they are present in vertebrates and invertebrates. Cell, Vol. 97, 599-607, May 28, 1999, Copyright 1999 by Cell Press Cytonemes: Cellular Processes that Project to the Principal Signaling Center in Drosophila Imaginal Discs Felipe-Andr s Ram rez-Weber1, Thomas B. Kornberg1 1 Department of Biochemistry and Biophysics, University of California, San Francisco, California 94143 Corresponding author: Thomas B. Kornberg, 415 476 8821 (phone), 415 476 3892 (fax), Wing imaginal disc cells in Drosophila develop by using information received from a signaling center associated with the anterior/posterior compartment border. We show here that disc cells have thin, actin-based extensions (cytonemes) that project to this signaling center. Cytonemes can be induced when cells from the lateral flanks of a wing disc are cultured next to cells from the A/P border or next to a source of fibroblast growth factor. Mouse limb bud cells also grow projections during a brief culture period, indicating that cytonemes are an attribute of both vertebrate and invertebrate cells. We suggest that cytonemes may be responsible for some forms of long-range cell-cell communication. Rate This Message: http://www.cryonet.org/cgi-bin/rate.cgi?msg=11969