Fig. 4. Hemocyte development in the secondary lymph gland lobe of third instar larva. (A) The secondary lobe expresses high levels of DE-cadherin (red). (B-E') Hemocyte formation in larger secondary lobes. Cg-gal4/UAS-GFP (B,E', green), hml-gal4/UAS-GFP (C, green) and Lz (D, green) are seen in patches where DE-cadherin (B-E', red) expression is downregulated. This is particularly apparent in high-magnification images (compare E with E'). To-pro-3 (blue) marks nuclei. (F) Schematic diagram of the 3rd instar lymph gland based on our analysis of morphology and hemocyte markers. The lymph gland flanks the dorsal vessel (DV) and each lobe is separated by pericardial cells (PC). The primary (1°) lobe consists of three distinct zones: (1) the cortical zone (CZ), where maturing hemocytes are found; (2) the medullary zone (MZ), with prohemocytes lacking differentiation markers; and (3) the posterior signaling center (PSC), which is a unique population of specialized hemocytes. Secondary (2°) lobes usually contain immature hemocytes except in random sites of maturation (arrowheads).