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Figure 4 | EvoDevo

Figure 4

From: Comparative gene expression supports the origin of the incisor and molar process from a single endite in the mandible of the red flour beetle Tribolium castaneum

Figure 4

Expression of Tc-prd in the embryonic mandibular endite relates the inner and outer lobe to the incisor and molar processes. (A-G) The outer lobe/incisor process are indicated with arrows. The inner lobe/molar process are indicated with arrowheads. (A) Ventral view of Tc-prd (red) and Tc-Dll (blue) expression in the developing embryonic mandible of a germ band retracting stage embryo. Anterior is up. (B) Expression of Tc-prd in the mandible endite of a very late stage embryo prior to formation of the cuticle. Anterior is left, dorsal is up. Tc-prd is also expressed in the maxillary ventral branch consisting of fused lacinia and galea (star). (C) Close-up of the right mandible shown in B. Tc-prd e xpression is visible in the pointed distal tip, the presumptive incisor (arrow) and molar (arrowhead) process of the mandibular endite. (D) Mandibles of a first instar larva visualised by fluorescence microscopy. The mandible is unsegmented, with the gnathal edge consisting of an incisor process and molar process. (E, F) Diagrams of Tc-prd expression in the developing mandible. The expression of Tc-prd is in one domain which encompasses the inner and outer lobes. (E) Diagram outlining the shape of both the mandible and maxilla from A with Tc-prd expression (purple). The mandibles will move towards the midline, see red arrows. (F) Diagram outlining the shape of both the mandible and maxilla from B with Tc-prd expression (purple). Mandibles have moved toward the midline. (G) Outline of the larval mandible shown in D with hypothetical expression of Tc-prd (purple) superimposed based upon the expression of Tc-prd in B and C.

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