Mass transit: Epithelial morphogenesis in the Drosophila egg chamber

Abstract

Epithelial cells use a striking array of morphogenetic behaviors to sculpt organs and body plans during development. Although it is clear that epithelial morphogenesis is largely driven by cytoskeletal rearrangements and changes in cell adhesion, little is known about how these processes are coordinated to construct complex biological structures from simple sheets of cells. The follicle cell epithelium of the Drosophila egg chamber exhibits a diverse range of epithelial movements in a genetically accessible tissue, making it an outstanding system for the study of epithelial morphogenesis. In this review, we move chronologically through the process of oogenesis, highlighting the dynamic movements of the follicle cells. We discuss the cellular architecture and patterning events that set the stage for morphogenesis, detail individual cellular movements, and focus on current knowledge of the cellular processes that drive follicle cell behavior. Developmental Dynamics 232:559 -574, 2005.

Cell death duringDrosophila melanogasterearly oogenesis is mediated through autophagy

“…As they gradually develop, they move posteriorly towards the exit of the ovariole, forming an array of developmentally ordered egg chambers. 8,9 Stem cells for both the germline and soma reside in the germarium. At the anterior of the germarium, overlying somatic cells create a niche to maintain the germline stem cells.…”

Building up the Drosophila eggshell: First of all the eggshell genes must be transcribed

“…Nearby, somatic stem cells give rise to precursor follicle cells and about 16 of them invade between adjoining cysts, cease division, and become pre-polar cells, which ultimately become polar cells and stalk cells. Inward migration of polar, stalk, and epithelial cells separate individual germline cysts into discrete egg chambers (Horne-Badovinac and Bilder, 2005). As the cyst exits the germarium, the other somatic cells covering each chamber, the epithelial follicle cells, remain undifferentiated.…”

“…Follicle cells that surround the egg chamber undergo mitotic divisions to follow the increase in size of the germline cells. By stage 7, the epithelial follicle cells cease proliferation and enter endocycles, a change in cell cycle triggered by Notch signalling (Shcherbata et al, 2004;Horne-Badovinac and Bilder, 2005). Afterwards, these cells begin to show morphological and molecular signs of differentiation into the five main epithelial fates: border, stretched, centripetal, posterior, and main body follicle cells (Fig.…”

Expression of 18‐wheeler in the follicle cell epithelium affects cell migration and egg morphology in Drosophila

“…How are these processes regulated at the molecular level? The somatic follicle cells in the Drosophila ovary are a wellcharacterized polarized epithelium in which these questions can be successfully addressed (Montell, 2003;Berg, 2005;Horne-Badovinac and Bilder, 2005). The viability, morphogenesis, and polarity of the egg chamber rely on the integrity of the polarized epithelium and extensive signaling among follicle cells and between follicle and germ line cells.…”

“…Mutations causing defects in the integrity or epithelial polarity of the follicle cells frequently lead to over-proliferation, as well as disorganized, multilayered growth and subsequent degeneration of the egg chamber during mid-oogenesis (reviewed by Mü ller, 2000;Tepass et al, 2001;Bilder, 2004;Horne-Badovinac and Bilder, 2005). …”