Figure 3

Expression of the ERK MAP kinase gene rolled ( rl ) and distribution of activated ERK MAP kinase during oviparous and viviparous oogenesis. A-D. rl mRNA is detected in the trophocytes of the germaria and in young oocytes during both oviparous (A,B) and viviparous (C,D) oogenesis. E-M. Activated ERK MAP kinase (dpERK) is first found in early oocytes prior to being extruded from germarium during both oviparous (E and M, see inset for close-up) and viviparous (I,J) development. Following extrusion, dpERK is distributed throughout the oocyte in oviparous (F,G) and viviparous (K,L) cases. During late previtellogenesis of oviparous oocytes, however, dpERK becomes restricted to the most posterior region of the oocyte (H, arrowhead). The progressive nature of this restriction occurs as the oocyte increases in size (M, arrow indicates younger to older oocytes). g, germarium; o, oocyte. Scale bars: 100 μm for A,B; 20 μm for C,D; 100 μm in E-H; 20 μm for I-L; 100 μm in M,N (20 μm in inset). Staging according to [8].