Figure 5. CasBurs drives deposition and hardening of cuticle and hemocyte granulation in vitro.

Semi-thin cross-sections (1 µm) through pieces of dorsal carapace cuticle and hemocytes from control crabs (c; A, D, F, G, I) and after treatment with rCasBurs (tr, B, C, E, H). Control cuticle is thin in stage D₂, but grows rapidly to considerable thickness already visible in ecdysis stage E_1% (D) and even more during stage A_{30 min} (F). Treatment (tr) with rCasBurs, however, clearly stimulates cuticle deposition already in the sensitive stage D₂ (B, C) but also in stage E_1% (E). Hemocytes underneath the hypodermis change from virtually inactive as in E_1% and A_{30 min} controls (G, I) to highly active granulated appearance under rCasBurs treatment readily in stage E_1%. (H). Scale bar: A–C = 25 µm, D and E = 50 µm, F = 100 µm G–I = 10 µm. Arrowheads: setae on the cuticle surface; asterisk: laminated layers of exocuticle.