Figure 2. Drosophila egg-chambers under the microscope.

A. Different stages of Drosophila oogenesis. The oocyte and its 15 sibling cells (nurse cells) form a syncytium in the germarium through a series of incomplete cell divisions. These 16 cells stay interconnected by cytoplasmic bridges and become encapsulated by a layer of somatic follicle cells forming the egg-chambers. The egg-chambers mature/go through 14 different stages of oogenesis to give rise to a mature egg (for more details, please refer to e.g., [Bastock and St Johnston, 2008]). To visualize the different cell types, wash-free in situ hybridization to oskar mRNA was performed using a mixture of three different FIT probes ( Hovelmann et al., 2013 ). Scale bar is 50 µm. B-D. Different steps of ooplasm extraction from a stage 9 oocyte (stills taken from Video 3). Scale bar is 500 µm (B-D).