Table 1.
Comparison between numbers of glutamate and VGLUT positive cells per section.
Figure 1.
Lamprey vesicular glutamate transporter (VGLUT) expression in transverse sections of the spinal cord. A:
Schematic drawing showing the distribution of glutamatergic cell types in rostral spinal levels: primary sensory neurons or dorsal cells (black asterisks); dorsal interneurons (black squares); cells of the lateral population (gray circles); cerebrospinal fluid-contacting cells (CSFc) cells (black circles); edge cells (gray squares); cells associated with reticulospinal and Mauthner axons (black stars).B: Schematic drawing showing the distribution of the major VGLUT-positive cell types in middle levels of the larval spinal cord. Cell type symbols as in Figure 1A. C: Schematic drawing showing the VGLUT-positive neuronal populations in the dorsal fin region; same symbols as in Figure 1A. D: Schematic drawing showing the VGLUT-positive neuronal populations in the caudal fin region; same symbols as in Figure 1A. E–P: High magnification photomicrographs of larva and adult showing details of VGLUT-positive cells (arrows) in the spinal gray (E–K) and white matter (L–P). E: Dorsal cell. F: Dorsal interneurons. G: Small and large lateral interneurons. H, I: CSFc cells of a larva (H) and an adult (I), star indicates the central canal. J: VGLUT-positive giant cell. K: Small and large lateral neurons. L: VGLUT-positive edge cells. M: Glutamatergic neuron situated ventrally to the Mauthner axon (star). N: Glutamatergic cell associated with medium-sized axons of the lateral column. O: VGLUT-positive cells situated ventrally to Müller axons. P: VGLUT-positive neurons situated among the Müller axons. Dorsal is at the top. Lateral is on the left except in G, K, L and O, in which lateral is on the right. F, I, J, K and P correspond to adult individuals. E, G, K, M, N and O correspond to the rostral spinal cord; I and P correspond to the middle spinal cord; H, L and J correspond to the dorsal fin level; F correspond to the caudal fin level. Scale bars = 100 µm (A); 50 µm (B, C, D); 10 µm (E, F, G, H, I, J, K, M, N, O, P); 5 µm (L).
Table 2.
Cell sizes of main glutamatergic populations.
Figure 2.
Glutamate immunoreactivity in transverse sections of the sea lamprey spinal cord.
A–R: High magnification photomicrographs of larvae and adults showing details of glutamate-ir cells (arrows) and processes in the spinal gray matter at different rostro-caudal levels. A: Dorsal cells (arrowhead), DC indicate the dorsal column. B, C: Dorsal interneurons. B: Glutamate-ir cell with thick (dendrite) and thin (axon) processes directed to the dorsal column. C: Glutamate-ir bipolar cell showing ventrolateral (barbed arrowhead) and ventromedial (pointed arrowheads) processes. D: Glutamate-ir small (arrow) and large (arrowhead) neurons of the lateral gray. E: Lateral cell with a process surrounding the Mauthner axon (star). F: Glutamate-ir cells (arrows) of the dorsal population showing processes directed to the dorsal column (DC) and a dendrite (arrowheads) that crosses the midline (dashed line) dorsally. G: Detail of a glutamate-ir bipolar ventrolateral cell (arrow) of the caudal region of the cord. H: Cerebrospinal fluid-contacting (CSFc) cells (arrowhead). The star indicates the central canal. I: Glutamate-ir cerebrospinal fluid-contacting (CSFc) cells of an adult. J: Strong glutamate-ir primary sensory dorsal cells. K: Giant glutamate-ir cell. L: Glutamate-ir edge cells (arrows) and edge neuropil (asterisk). M: Glutamate-ir edge cell (arrow) laterally. The white star indicates the Mauthner axon. N: Positive neuron (arrow) situated ventrally to the Mauthner axon (white star). O: Glutamate-ir cell (arrow) associated with medium-sized axons of the lateral column (White star: Mauthner axon). P, Q: Glutamate-ir cells (arrows) situated among (P) and ventrally (Q) to Müller axons. R: Glutamate-ir cells situated in the ventromedial region of the white matter. Note also CSFc cells around the central canal. Note that the giant Müller axons (in C, R) are apparently glutamate-negative. In all figures dorsal is at the top. Lateral is on the left except in B, C, D, G and K, in which lateral is on the right. I, J, K and R correspond to adult individuals. A, B, C, E, H, J, M, N, O, P correspond to the rostral spinal cord; D, I, L, Q, R correspond to the middle spinal cord; K corresponds to the dorsal fin level; F, G correspond to the caudal fin level. Scale bars = 100 µm (I, J, R); 50 µm (K); 20 µm (A, B, C, D, E, L, M, N, O, P Q); 10 µm (F, G, H).
Figure 3.
Glutamate and GABA colocalization in the lamprey spinal cord.
A–E”: Confocal photomicrographs of transversal sections through the rostral, medial and caudal spinal cord of larvae showing double immunolabeled cells (arrowheads) for glutamate and GABA. Arrows point to single immunolabeled cells. A–C”: Rostral spinal cord. D–D”: Medial spinal cord. E–E”: Caudal spinal cord. A–A”: Dorsal glutamate-ir population. B–B”: Lateral glutamate-ir population. C–C”: Cerebrospinal fluid contacting cells. D–D”: Dorsal glutamate-ir population. E–E”: Lateral glutamate-ir population. F–F”: Confocal photomicrograph of a transverse section through the rostral spinal cord of a larva showing the glutamate-ir processes (curved arrow) surrounded by the GABA-ir fibers constituting the marginal neuropil (arrowhead). Dorsal is at the top. Lateral is on the right except for A–A”, in which lateral is on the left. A, B, C, D, E, F: Overlay; A’, B’, C’, D’, E’, F’: Glutamate; A”, B”, C”, D”, E”, F”: GABA. Scale bars = 20 µm (A–B”; F–F”); 10 µm (C–E”).
Figure 4.
Glutamate and glycine colocalization in the lamprey spinal cord.
A–D”: Rostral spinal cord. E–E”: Medial spinal cord. F–F”: Caudal spinal cord. A–A”: Dorsal glutamate-ir interneurons. B–B”: Lateral glutamate-ir population. C–C”: Cerebrospinal fluid contacting cells. D–D”: Edge cell and marginal neuropil. E–E”: Lateral glutamate-ir population. F–F”: Edge cell and marginal neuropil. In E–E” and F–F” note that the glutamate-ir marginal neuropil mostly lacks glycine immunoreactivity (asterisk). Arrowheads point to double immunolabeled cells and arrows point to single glutamate-ir cells. Dorsal is at the top. Lateral is on the left in B–B” and D–E”, and on the right in A–A” and F–F”. Scale bars = 10 µm (A–A’, C–F”), 20 µm (B–B”).
Table 3.
Percentages of glutamate-ir cells showing GABA colocalization.
Table 4.
Percentages of glutamate-ir cells showing glycine colocalization.