Atlas of the Striatum and Globus Pallidus in the Tree Shrew: Comparison with Rat and Mouse

Abstract

The striatum and globus pallidus are principal nuclei of the basal ganglia. Nissl- and acetylcholinesterase-stained sections of the tree shrew brain showed the neuroanatomical features of the caudate nucleus (Cd), internal capsule (ic), putamen (Pu), accumbens, internal globus pallidus, and external globus pallidus. The ic separated the dorsal striatum into the Cd and Pu in the tree shrew, but not in rats and mice. In addition, computer-based 3D images allowed a better understanding of the position and orientation of these structures. These data provided a large-scale atlas of the striatum and globus pallidus in the coronal, sagittal, and horizontal planes, the first detailed distribution of parvalbumin-immunoreactive cells in the tree shrew, and the differences in morphological characteristics and density of parvalbumin-immunoreactive neurons between tree shrew and rat. Our findings support the tree shrew as a potential model for human striatal disorders.

Keywords: Basal ganglia; Globus pallidus; Parvalbumin; Reconstruction; Rodent; Striatum.

Fig. 1

Coronal sections of the striatum and globus pallidus in the tree shrew, rat, and mouse. AChE-stained sections (A–C) and adjacent Nissl-stained sections (D–F) from rostral to caudal showing distinct subregions of the basal ganglia in the tree shrew. Coronal sections at similar levels show the organization of the basal ganglia in the rat (G–I) and mouse (J–L) in Nissl-stained sections. Dashed lines show the borders of these structures. ac, anterior commissure; Acb, nucleus accumbens; cc, corpus callosum; Cd, caudate nucleus; CPu, caudate putamen (dorsal striatum); d, dorsal; EGP, external globus pallidus; ic, internal capsule; IGP, internal globus pallidus; l, lateral; LV, lateral ventricle; Pu, putamen. Scale bars, 1 mm.

Fig. 2

Schematic drawings showing the general morphology of the striatum and globus pallidus in the coronal plane from rostral to caudal in the tree shrew (A1-A58, referring to The Tree Shrew (Tupaia belangeri chinensis) Brain in Stereotaxic Coordinates [52]). Colors represent distinct subregions of the basal ganglia. ICj, islands of Calleja. Scale bar, 1 cm.

Fig. 3

Rostral view of a 3D reconstruction of the striatum and globus pallidus based on serial histological sections of tree shrew brain (58 sections shown in Fig. 2).

Fig. 4

Sagittal sections of the striatum and globus pallidus of the tree shrew, rat, and mouse. AChE-stained sections (A–C) and adjacent Nissl-stained sections (D–F) from lateral to medial show distinct subregions of the basal ganglia in the tree shrew. Sagittal sections at similar levels show the organization of the basal ganglia of the rat (G–I) and mouse (J–L) in Nissl-stained sections. Dashed lines show the borders of these structures. ac, anterior commissure; Acb, accumbens nucleus; Cd, caudate nucleus; CPu, caudate putamen (dorsal striatum); d, dorsal; EGP, external globus pallidus; ic, internal capsule; ICj, islands of Calleja; LV, lateral ventricle; Pu, putamen; r, rostral. Scale bars, 1 mm.

Fig. 5

Schematic drawings showing the general morphology of the striatum and globus pallidus in the sagittal plane from lateral to medial in the tree shrew (A1–A31, referring to The Tree Shrew (Tupaia belangeri chinensis) Brain in Stereotaxic Coordinates [52]). Colors represent distinct subregions of the basal ganglia. ICj, islands of Calleja. Scale bar, 2 cm.

Fig. 6

Horizontal sections of the striatum and globus pallidus in the tree shrew and rat. AChE-stained sections (A–C) and adjacent Nissl-stained sections (D–F) from ventral to dorsal show distinct subregions of the basal ganglia in the tree shrew. Horizontal sections at similar levels show the organization of the basal ganglia of the rat in Nissl-stained sections (G–I). Dashed lines show the borders of these structures. ac, anterior commissure; Acb, accumbens nucleus; cc, corpus callosum; Cd, caudate nucleus; CPu, caudate putamen (dorsal striatum); D3V, dorsal 3rd ventricle; EGP, external globus pallidus; ic, internal capsule; ICj, islands of Calleja; IGP, internal globus pallidus; l, lateral; LV, lateral ventricle; Pu, putamen; R, rostral. Scale bars, 1 mm.

Fig. 7

Schematic drawings showing the general morphology of the striatum and globus pallidus in the horizontal plane from ventral to dorsal in the tree shrew (A1–A28, referring to The Tree Shrew (Tupaia belangeri chinensis) Brain in Stereotaxic Coordinates [52]). Colors represent distinct subregions of the basal ganglia. ICj, islands of Calleja. Scale bar, 2 cm.

Fig. 8

Camera lucida drawings showing the distribution of parvalbumin-ir cells (dots) in the striatum and globus pallidus of the tree shrew from rostral to caudal (A–I). Representative coronal sections were selected, with reference to bregma. The density of dots represents the relative density of cells in the areas. Each dot represents approximately one parvalbumin-labeled neuron. ac, anterior commissure; Acb, accumbens nucleus; Cd, caudate nucleus; EGP, external globus pallidus; ic, internal capsule; IGP, internal globus pallidus; LV, lateral ventricle; Pu, putamen.

Fig. 9

Photomicrographs of parvalbumin-ir staining in the nucleus accumbens (Acb; A), caudate nucleus (Cd; B), putamen (Pu; C), external globus pallidus (EGP; D), and internal globus pallidus (IGP; E) in the tree shrew. Parvalbumin-ir neurons were also present in the Acb (F), caudate putamen (CPu; G), EGP (H), and entopeduncular nucleus (EP; I) of the rat. Scale bar, 100 μm.

Fig. 10

Quantitative analysis of the density of parvalbumin-ir cells in distinct subregions of the striatum and globus pallidus in the tree shrew (A) and rat (B) (*P < 0.05; **P < 0.01 compared with rat; Mann–Whitney U test and unpaired t-test). Acb, accumbens nucleus; Cd, caudate nucleus; CPu, caudate putamen; EGP, external globus pallidus; EP, entopeduncular nucleus; IGP, internal globus pallidus; Pu, putamen.