Fig. S1.

Presence and compartmentalization of secretagogin in rat RMS neurons. (A and B) Secretagogin was typically associated with intracellular membranes (open arrowheads in A₁) in the cytoplasm or with mitochondria (open arrowheads in B). (C and D) In the neuropil, secretagogin was present in the postsynaptic compartment of immature synaptic-like structures (open arrowheads). (E) Secretagogin typically appeared in cellular processes. (F and G) Secretagogin⁺ round or oval pearl-like structures surrounded processes that probably were dendrites in the RMS. (H–H₂) Dark, electron-dense glial cells remained immunonegative for secretagogin. (I–I_2′) Secretagogin⁺ cells were invariably immunonegative for the glial marker NG2 (asterisks in I₂ and I_2′) and stathmin-2 (asterisks in I₁ and I_1′). (J–J_4′′) Secretagogin⁺ neurons were randomly positioned with (white arrowheads) or without (black arrowheads) a close association with vessels in P1, P5, and adult rats. s, synapse; SolTub, Solanum Tuberosum agglutinin. (Scale bars: 50 m in J–J₄; 10 µm in I–I_2′ and J_1′– J_4′′; 3 µm in F; 2 µm in A; 1 µm in E; 300 nm in A₁, B–D, F₁, G, and H; and 200 nm in H₁ and H₂.)