Architectonic Subdivisions of Neocortex in the Tree Shrew (Tupaia belangeri)

Abstract

Tree shrews are small mammals that bear some semblance to squirrels, but are actually close relatives of primates. Thus, they have been extensively studied as a model for the early stages of primate evolution. In the present study, subdivisions of cortex were reconstructed from brain sections cut in the coronal, sagittal or horizontal planes, and processed for parvalbumin (PV), SMI-32 immunopositive neurofilament protein epitopes, vesicle glutamate transporter 2 (VGluT2), free ionic zinc, myelin, cytochrome oxidase (CO) and Nissl substance. These different procedures revealed similar boundaries between areas, suggesting the detection of functionally relevant borders and allowed a more precise demarcation of cortical areal boundaries. Primary cortical areas were most clearly revealed by the zinc stain, due to the poor staining of layer 4, as thalamocortical terminations lack free ionic zinc. Area 17 (V1) was especially prominent, as the broad layer 4 was nearly free of zinc stain. However, this feature was less pronounced in primary auditory and somatosensory, cortex. In primary sensory areas, thalamocortical terminations in layer 4 densely express VGluT2. Auditory cortex consists of two architectonically distinct subdivisions, a primary core region (Ac), surrounded by a belt region (Ab) that had a slightly less developed koniocellular appearance. Primary motor cortex (M1) was identified by the absence of VGluT2 staining in the poorly developed granular layer 4 and the presence of SMI-32 labeled pyramidal cells in layers 3 and 5. The presence of well-differentiated cortical areas in tree shrews indicates their usefulness in studies of cortical organization and function.

Cytoarchitecture of the mouse neocortex revealed by the low-molecular-weight neurofilament protein subunit

“…Neurofilament proteins exhibit a specific distribution pattern in the cerebral cortex of many mammalian species, including mouse (Van der Gucht et al 2007), rat (Paxinos et al 1999;Kirkcaldie et al 2002), hamster (Boire et al 2005), squirrel (Wong and Kaas 2008), tree shrew (Wong and Kaas 2009), cat (Kaneko et al 1994; Van der Gucht et al 2001), and several primate species (Campbell and Morrison 1989;Chaudhuri et al 1996;Nimchinsky et al 1997;Preuss et al 1997Preuss et al , 1999Kobayashi and Amaral 2000;Rosa 2003, 2006;Duffy and Livingstone 2003;Sherwood et al 2004;Baldauf 2005; Van der Gucht et al 2006;Duffy et al 2007). These neurochemical studies have used the monoclonal antibody SMI-32 that recognizes the non-phosphorylated epitopes on NF-H and NF-M (Sternberger and Sternberger 1983), as a tool to detect regional and laminar variations in NFP expression patterns.…”

Spatiotemporal Profile of Voltage-Sensitive Dye Responses in the Visual Cortex of Tree Shrews Evoked by Electric Microstimulation of the Dorsal Lateral Geniculate and Pulvinar Nuclei

“…An anterolateral adjacent area (likely area V2; Kaas, 2008) contained a mirrored representation of the V1 retinotopic pattern. Finally, additional cortical areas beyond V2, potentially corresponding to anterior temporal (Ta) and dorsal temporal (Td) areas (Wong and Kaas, 2009) that receive projections from the dorsal pulvinar (Pd) and Pc (Chomsung et al, 2010) were also retinotopically activated. This is the first time, using optical imaging techniques, that the retinotopic organization of cortical visual areas beyond area V1 has been functionally demonstrated in tree shrews.…”

Morphological characteristics and cryodamage of Chinese tree shrew (<I>Tupaia belangeri chinensis</I>) sperm

“…树鼩是一种昼行、树栖的小型哺乳动物, 曾被 定义为攀鼩目、 灵长目 (Liu et al, 2001;Wong & Kaas, 2009), 目前对树鼩的分类地位仍然存在争议。但无 论如何, 树鼩是最接近于灵长类的小型哺乳动物, 具有许多灵长类动物共有的特征 (Poonkhum et al, 2000)。 树鼩在人类医学及生物学研究方面具有重要 地位, 如神经生物学 (Remple et al, 2007)、人类肝炎 病毒感染 (Xu et al, 2007;Li et al, 2008)、视觉系统发 育 (Poveda & Kretz, 2009)及群体阶层应激 (Kozicz et al, 2008;Zambello et al, 2010)等。目前, 有关雄性树 鼩生殖生物学研究的报道较少 (Collins et al, 2007)。 Collins et al 于 1982 年报道了雄性树鼩生殖道的解 剖学特征和生理功能 (Collins et al, 1982); 随后, 有 研究报道了雄性树鼩从出生到性成熟过程的生殖 器官生长与发育 (Collins & Tsang, 1987); 精子细胞 在睾丸内的成熟过程 (Maeda et al, 1998); 雄性树鼩 精子的形成和染色质凝聚 (Suphamungmee et al, 2008) 等结果。然而, 树鼩睾丸、精子形态结构特性的研 究仍然很有限。我们曾报道树鼩精子可以被冷冻保 存 (Ping et al, 2011), 但是精子冷冻后的超微结构变 化尚不清楚。为此, 本研究分析树鼩的睾丸、附睾 精子的形态学结构特征, 以及树鼩精子冷冻复苏后 的结构变化。 1 材料和方法…”