Programa de Neurobiologia, Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil.
PLoS One. 2012;7(6):e39267. doi: 10.1371/journal.pone.0039267. Epub 2012 Jun 19.
The first-generation precursors producing adult-born neurons in the crayfish (Procambarus clarkii) brain reside in a specialized niche located on the ventral surface of the brain. In the present work, we have explored the organization and ultrastructure of this neurogenic niche, using light-level, confocal and electron microscopic approaches. Our goals were to define characteristics of the niche microenvironment, examine the morphological relationships between the niche and the vasculature and observe specializations at the boundary between the vascular cavity located centrally in the niche. Our results show that the niche is almost fully encapsulated by blood vessels, and that cells in the vasculature come into contact with the niche. This analysis also characterizes the ultrastructure of the cell types in the niche. The Type I niche cells are by far the most numerous, and are the only cell type present superficially in the most ventral cell layers of the niche. More dorsally, Type I cells are intermingled with Types II, III and IV cells, which are observed far less frequently. Type I cells have microvilli on their apical cell surfaces facing the vascular cavity, as well as junctional complexes between adjacent cells, suggesting a role in regulating transport from the blood into the niche cells. These studies demonstrate a close relationship between the neurogenic niche and vascular system in P. clarkii. Furthermore, the specializations of niche cells contacting the vascular cavity are also typical of the interface between the blood/cerebrospinal fluid (CSF)-brain barriers of vertebrates, including cells of the subventricular zone (SVZ) producing new olfactory interneurons in mammals. These data indicate that tissues involved in producing adult-born neurons in the crayfish brain use strategies that may reflect fundamental mechanisms preserved in an evolutionarily broad range of species, as proposed previously. The studies described here extend our understanding of neurovascular relationships in the brain of P. clarkii by characterizing the organization and ultrastructure of the neurogenic niche and associated vascular tissues.
第一代产生成年新生神经元的前体细胞位于螯虾（Procambarus clarkii）脑的一个专门的龛位中，位于脑的腹表面。在本工作中，我们使用光水平、共聚焦和电子显微镜方法探索了这个神经发生龛位的组织和超微结构。我们的目标是定义龛位微环境的特征，检查龛位与脉管系统之间的形态关系，并观察位于龛位中心的血管腔的边界处的特化结构。我们的结果表明，龛位几乎完全被血管包裹，血管中的细胞与龛位接触。这项分析还描述了龛位中的细胞类型的超微结构。I 型龛位细胞是迄今为止数量最多的，并且是仅存在于龛位最腹侧细胞层表面的唯一细胞类型。在更背侧，I 型细胞与 II 型、III 型和 IV 型细胞混合存在，这些细胞观察到的频率要低得多。I 型细胞在其朝向血管腔的顶细胞表面具有微绒毛，以及相邻细胞之间的连接复合物，这表明它们在调节从血液到龛位细胞的运输中起作用。这些研究表明，在 P. clarkii 中，神经发生龛位与血管系统之间存在密切关系。此外，与血管腔接触的龛位细胞的特化结构也与脊椎动物的神经血管屏障（包括产生哺乳动物新嗅觉中间神经元的脑室下区（SVZ）细胞）的血液/脑脊液（CSF）-脑界面的特化结构典型。这些数据表明，在螯虾脑中产生成年新生神经元的组织使用的策略可能反映了在广泛的进化物种中保存的基本机制，如先前提出的那样。本研究通过描述神经发生龛位和相关血管组织的组织和超微结构，扩展了我们对 P. clarkii 脑的神经血管关系的理解。
