Fig. 1.

The presence and compartmentalization of secretagogin in rat RMS neurons. (A–A₃) Secretagogin⁺ cells populate the rat RMS. In addition to somatic labeling (open arrowheads in A₁–A₃) a large number of individual processes were identified in the center of the middle domain of the stream (black arrowheads in A₂; also Fig. S1E). Additionally, secretagogin⁺ cells often delineated the border of the RMS with their processes extended bipolarly (open arrowheads in A₁ and A₃). (B) Ultrastructural analysis identified secretagogin⁺ cells in close contact with chain-migrating neurons with secretagogin expression detectable both in the soma (black arrowhead in B₁ and in processes arranged in parallel (open arrowheads in B₁) or transversally (open arrowheads in B₂). Chain-migrating neuronblasts and secretagogin⁺ cells are semitransparently color-coded in green and red, respectively. (C–C′′′) Secretagogin⁺ cells were invariably immunonegative for the gilal marker S100β (black arrowheads in C–C′′′) but were immunopositive for the neuron marker NeuN (white arrowheads in C′–C′′′). ax, axis of RMS; dors, dorsal; m, marginal zone of RMS; rostr, rostral; Scgn, secretagogin. (Scale bars: 500 µm in A, 30 µm in A₁ and A_2′; 20 µm in A₃; 15 µm in C–C′′′; 10 µm in A₂ and A₄; 5 µm in B; 2 µm in B₂; and 1 µm in B₁.)