Figure 2. Representative examples of injections in RSC.
(A) Normalized flatmap (see Figure 1D) of the locations of the injections in RSC, shown in B and E. Injections are located in the rostral A30 (magenta), intermediate rostral A30 (green), intermediate caudal A30 (cyan) and the intermediate rostral quarter of A29 (yellow). (B) Horizontally cut and Nissl stained section at the level of the injections overlaid with a neighboring fluorescent section containing the center of an injection in rostral A30 (magenta) and intermediate-rostral A30 (green) within the same animal. Grey line depicts delineation of A30. (C) The projections after the two injections shown in B were traced and represented in a dorsoventral series of drawings of horizontal sections through the PHR. After injections in rostral A30 (magenta) labeled fibers were mostly observed in the dorsal PrS layers I and III (C1, D1). After injections in intermediate-caudal A30 (green) the densest plexus was located more ventrally in PHR and in addition to labeled fibers in layers I, III and V-VI of PrS, labeled fibers also extended into layers V-VI of PaS, POR and MEC (C2-3 and D3). Numbers above sections indicate the dorsoventral position of the section relative to the total dorsoventral extent of PHR. The yellow boxes in C1 and C3 indicate the position of high power digital images obtained from the actual sections (D1 and D3). Grey lines depict borders between the HF-PHR subdivisions, the border between cortex and white matter and lamina dissecans. (D) High power images of plexus depicted in the sections shown in C and E. Roman numbers indicate cortical layers. Grey lines depict borders between layers. (D1) Labeled fibers in superficial layer III of PrS after injections in rostral A30 (magenta). Additionally a few fibers are seen originating in the intermediate-caudal quarter of RSC (green). (D2) Labeled fibers in proximal PrS deep layer III and layers V-VI after injection in intermediate-rostral A29 (yellow) and labeled fibers in distal PrS deep layer III and layers V-VI after injection in intermediate-caudal A30 (cyan). (D3) Labeled fibers in layers I and III after injection in intermediate-caudal A30 (green). No fibers originating in the rostral A30 were observed. (D4) After injection in intermediate-caudal A30 labeled fibers were observed in medial MEC (cyan), while after injection in intermediate-rostral A29 labeled fibers were observed in lateral MEC (yellow). (E) Top: the projections after two injections (bottom) were traced and represented in a dorsoventral series of drawings of horizontal sections through the PHR. After injections in intermediate-caudal A30 (cyan) labeled fibers were observed in distal PrS dorsally (E1-3). At more ventral levels fibers also extended into deep layers of PaS and medial MEC (E3-4). After injections in intermediate-rostral A29 (yellow) the densest plexus was located in proximal parts of PrS dorsally (E1-2). At more ventral levels the plexus in PrS layers I and III disappeared while in the deep layers the plexus shifted to lateral parts of EC at successively more ventral levels (E3-4). Numbers below sections indicate the dorsoventral position of the section relative to the total dorsoventral extent of PHR. The magenta boxes in E2 and E3 indicate the position of high power digital images obtained from the actual sections (D2 and D4). Grey lines depict borders between the HF-PHR subdivisions, the border between cortex and white matter and lamina dissecans. Bottom: Horizontally cut and Nissl stained sections at the level of the injection overlaid with neighboring fluorescent sections containing the center of an injection in intermediate-caudal A30 (cyan) and intermediate-rostral A29 (yellow) within the same animal. Gray line depicts delineation of A29 and A30. Scale bars equal 100 μm (high power images) and 1000 µm (low power images).