Dynamic Development

CONTENTS

Main Page Dynamic Development

The Foundations of Developmental Biology

Gametogenesis

From Sperm and Egg to Embryo

Genetic Regulation of Development

Organizing the Multicellular Embryo

Generating Cell Diversity

Dynamic Development at a Glance

Development of Drosophila

by Katherine Plewes, Becky Wong and Leon W. Browder

This exercise is based on The Interactive Fly, which is a resource prepared by Dr. Tom Brody.  The following links are designed to provide you with a basic understanding of Drosophila development.


Introduction

Oogenesis  Execute the "The Process of Oogenesis" link.  This link provides an overview of oogenesis and discusses the genes involved. You are not required to execute the links to each of the genes, but you may do so if you are interested. Note that the genes involved in oogenesis are grouped according to the processes they affect.

Stages of development This module describes gastrulation and morphogenetic movements. Examine the accompanying images. They are taken from a paper by Turner and Mahowald. You are not required to execute the links to each of the genes involved, but you may do so if you are interested. Study (at least) the following images:

  • Cellularization of the blastoderm:  This figure shows the cellular blastoderm stage of the Drosophila embryo.  After the fourteenth nuclear division, cytokinesis of the blastoderm occurs simultaneously over the entire surface of the egg.  The spherical nuclei of the syncytial blastoderm have enlarged and elongated.  This elongation is coupled with a cleavage furrow extending inward from the surface to separate the nuclei into independent cells.  The pole cells (pc) are visible at the posterior end of the embryo (right side).
  • Lateral view of gastrula:  Pole cells have been included in the posterior midgut primordium. This figure shows the beginning of germ band elongation that occurs rapidly.  The amnioproctodeal invagination draws in the epithelium to form the proctodeum, which gives rise to hindgut.  The procephalon and cephalic furrow are also visible at this stage.
  • Germ band elongation:  The germ band expands posteriorly (to the right), wraps around the posterior pole and continues to spread anteriorly along the dorsal surface of the embryo.  At the end of this process, the germ cells are internalized.  The cells in the dorsoposterior region of the embryo move laterally to make room for the expanding germ band.
  • Germ band retraction:  Body segments are readily visible.  As a result of the germ band contraction, the segmented germ band returns to its original position on the ventral surface of the embryo.  The amnioserosa is located over the dorsal region to cover the developing midgut.

Formation of the adult fly:  Read the discussion of fly formation. You are not required to execute any of the links.


Now, for your assignments...

Each Study Group is assigned to obtain information about one of the evolutionarily conserved pathways. Select one of the pathways that interests you and do the following (2.5 points):

    1.  Prepare a short description of a couple of the Drosophila genes, including their roles in development of that organism.
    2.  Compare the role of the homologous genes in the development of Drosophila to the roles of their homologues in other organisms.


Reference

Turner, F.R. and Mahowald, A.P. (1979). Scanning electron microscopy of Drosophila melanogaster embryogenesis. III. Formation of the head and caudal segments. Dev. Biol. 68: 96-109.


Dynamic Development at a Glance
Main Page Dynamic Development

Dynamic Development is a Virtual Embryo learning resource.

This material may be reproduced for educational purposes only provided credit is given to the original source.
Leon Browder & Laurie Iten (Ed.) Dynamic Development
Last revised Wednesday, July 29, 1998