Fujisawa H et al. (1989), An aberrant retinal pathway and visual centers ...

XB-ART-26461

Dev Biol 1989 Oct 01;1352:231-40. doi: 10.1016/0012-1606(89)90175-9.

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An aberrant retinal pathway and visual centers in Xenopus tadpoles share a common cell surface molecule, A5 antigen.

Fujisawa H , Ohtsuki T , Takagi S , Tsuji T .

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A monoclonal antibody A5 (MAb-A5), which was raised against Xenopus tadpole tectal cells, recognizes a cell surface-related protein molecule (A5 antigen) expressed on the visual centers of Xenopus tadpoles (S. Takagi, T. Tsuji, T. Amagai, T. Takamatsu, and H. Fujisawa, 1987, Dev. Biol. 122, 90-100). The present immunohistochemistry using MAb-A5 indicated that, in addition to the visual centers, A5 antigen was expressed on the general somatic sensory tract in the medulla and spinal cord of Xenopus tadpoles. As the general somatic sensory tract has been shown to be a pathway for ectopically transplanted retinal axons (M. Constantine-Paton and R. R. Capranica, 1976, J. Comp. Neurol. 170, 17-32; M. J. Katz and R. J. Lasek, 1979, J. Comp. Neurol. 183, 817-832), we examined whether retinal axons transplanted close to the spinal cord or medulla preferentially grow into the A5 antigen-positive general somatic sensory tract. We performed eye transplantation at embryonic stages and detected precise locations and trajectories of transplanted retinal axons within the medulla and spinal cord in tadpoles after filling retinal axons with horseradish peroxidase (HRP). HRP histochemistry in combination with MAb-A5 immunohistochemistry indicated that almost all HRP-filled transplanted retinal axons joined the A5 antigen-positive general somatic sensory tract. These findings suggest the involvement of A5 antigen in specific cell-cell recognition between retinal axons and their targets.

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Species referenced: Xenopus laevis
Genes referenced: lrch4 nrp1
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	FIG. 1. Binding of MAb-A5 to frozen sections of XWL~JYUS tadpole brains at stage 51. Coronal sections were stained by the ABC method (see text). (A) MAb-A5-binding to the midbrain. The antibody preferentially binds to the superficial eighth and ninth layers of the tectum (tee), but not to the deeper parts of the tectum nor tegmentum (teg). (B-E) MAb-A5 binding to the medulla and spinal cord. Arrows indicate MAb-A5 bindings in the medulla at a level just caudal to the vestibulocochlear nerve root (B), at a level close to the obex (C), and in the spinal cord at the upper cervical level (D) and at the thoracic level (E). Bars, 100 pm
	FIG. 2. Camera lucida drawings of MAb-A5-binding neuropils (arrows) in serial coronal sections of the medulla (l-8) and upper cervical spinal cord (Y-12). Sections 1 and 4 are made at the rostra1 tip of the medulla and at a level of the vestibulocochlear nerve root, respectively. Sections 5, 8, and 12 correspond to B, C, and D in Fig. 1. Dotted lines indicate the boundary between the white matter and the gray matter. Inside of the line in each section is the gray matter. c, cerebellum; R, rostral; C, caudal; D, dorsal; V. ventral. Bar, 400 pm.
	FIG. 3. (A) MAb-A5-binding in the whole-mounted medulla and spinal cord of Xeno~~~s tadpole at stage 51 revealed by the ABC method. MAb-A5-binding neuropil on the left medulla and spinal cord is encircled by a dotted line. The arrow indicates the rostra1 tip of the MAb-A5-binding neuropil at the level of the auricular lobe (al) of the cerebellum. (B) The ascending (at) and descending (dt) tracts of the trigeminal nerve root (nV) filled with HRP in the whole-mounted medulla and spinal cord of Xenopus tadpole at stage 51. An arrow indicates the rostra1 tip of the ascending tract at the level of the auricular lobe (al) of the cerebellum. ob, the obex; lip, the lip of the rhombencephalon. Bars, 500 pm.
	FIG. 4. Outgrowth of retinal axons from ectopically transplanted eyes within the left medulla and spinal cord of Xenopus tadpole at stages 51 (A) and 52 (B, C) demonstrated by whole-mount HRP histochemistry. Dotted lines indicate the ventral perimeter of the left medulla and spinal cord. Asterisks indicate the sites of optic nerve invasion into the spinal cord. Arrow indicate the rostra1 extreme of the retinal axons at the level of the aurieular lobe (al) of the cerebellum. ob, the obex; lip, the lip of the rhombencephalon. Bars, 500 Mm
	FIG. 5. Camera Iucida drawings of trajectories of selected retinal axons from t ransplanted eyes within the whole-mounted left medulla and spinal cord. (A, B) Retinal axons in the specimens shown in Figs. 4A and 4B, respectively. In B, a retinal axon arrived at the tectum (tee) and sprouted after running through the pial surface of the tegmentum (teg). (C) Retinal axons from the eye t ransplanted at the dorsal part of lhe cervical spinal cord. (D) Retinal axons from the eye t ransplanted at the t horacic level of t he spinal cord. Asterisks indicate sites of optic nerve in,•asion. Dotted lines in the medulla indicate the dorsal perimeter of the general somatic sensory tract. ob, the obex; lip, the lip of t he rhombencephalon. Bars, 500 pm.
	FIG. 6. Locations of HRP-filled transplanted retinal axons in coronal sections of a tadpole brain at stage 61. In this specimen, an eye was transplanted at the level of the cervical spinal cord. Transplanted retinal axons (arrows) were detected in superficial parts of the medulla at the level of the trigeminal nerveroot (B), at a level just caudal to the vestibulocochlear nerve root (C), and at a level close to the obex (D), but not at the level of the cerebellum (A). The section shown in A was made at 150 lrn rostra1 to the section shown in B. c, rerehellum. Bars, 100 pm.
	FIG. 7. Camera lucida drawings of the positions of transplanted retinal axons (dotted) in coronal sections of the medulla of the tadpole shown in Fig. 6. Sections 2,3,5, and 8 correspond to A, B, C, and D in Fig. 6. Dotted lines indicate the boundary between the gray matter and the white matter. c, cerebellum; t, tectum; R, rostral; C, caudal; D, dorsal; V, ventral. Bar, 400 pm.
	Frc. 8. Locations and trajectories of retinal axons from the eye transplanted at the left caudal medulla in a tadpole at stage 51. (A) HRP-filled retinal axons (arrows) detected by whole-mount HRP histochemistry of the caudal half of the left medulla. (B) Camera lucida drawings of trajectories of HRP-filled transplanted retinal axons in the specimen shown in A. The left side of each figure is rostral. Asterisks in A and B indicate the sites of optic nerve invasion into the medulla. The region corresponding to the general somatic sensory tract is shown by G. The dorsal perimeter of the tract is indicated by a dotted line. ob, the obex. (C) MAb-A5 immunostaining of a coronal section of the medulla at a level just caudal to the vestibulocochlear nerve root, by the ABC method (see text). Heavily stained HRP-filled transplanted retinal axons (arrow) were detected within a MAb-A5-binding neuropil (asterisk). Bars, 100 gm.