Whitman Mary C, Greer Charles A
Department of Neurobiology, Yale University School of Medicine, New Haven, Connecticut 06520-8082, USA.
Dev Neurobiol. 2007 Jul;67(8):1079-93. doi: 10.1002/dneu.20389.
In mammals, olfactory bulb (OB) interneurons, granule cells and periglomerular (PG) cells, are generated throughout adulthood. PG cells comprise a heterogeneous population in both morphology and molecular phenotypes. It is unknown whether adult genesis of PG cells occurs among all subtypes or is limited to a subpopulation. We show that within 2 weeks after retroviral labeling in the subventricular zone, two morphological populations of PG cells are found in the OB, one with large multi-glomerular dendritic arbors, and one with dendritic arbors limited to one or two glomeruli. On both types, immature dendritic spines are first evident at 4 weeks and mature, pedunculated spines by 6 weeks. To differentiate PG subpopulations we used expression of calcium binding proteins, GAD67 and tyrosine hydroxylase as markers. Among adult-born BrdU labeled cells, all molecular subtypes were represented, although GAD67 and tyrosine hydroxylase expressing cells were overrepresented proportional to their expression in the total PG cell population. During the time when spines are maturing, approximately half the PG cells are lost, in roughly equal proportions to their generation. Our data show the diverse developmental potential of SVZ neuroblasts and suggest that integration into synaptic circuits is necessary for survival.
在哺乳动物中，嗅球（OB）中间神经元、颗粒细胞和球周（PG）细胞在成年期全程生成。PG细胞在形态和分子表型上均构成一个异质性群体。尚不清楚PG细胞的成年期生成是发生在所有亚型中还是仅限于一个亚群。我们发现，在脑室下区进行逆转录病毒标记后的2周内，在嗅球中发现了两种形态的PG细胞群体，一种具有大型多小球状树突分支，另一种的树突分支仅限于一两个小球。在这两种类型的细胞上，未成熟的树突棘在4周时首次明显出现，到6周时变为成熟的有柄树突棘。为了区分PG亚群，我们使用钙结合蛋白、GAD67和酪氨酸羟化酶的表达作为标记。在成年新生的BrdU标记细胞中，所有分子亚型均有代表，尽管表达GAD67和酪氨酸羟化酶的细胞与其在总PG细胞群体中的表达比例相比，占比过高。在树突棘成熟的这段时间里，大约一半的PG细胞丢失，其丢失比例与其生成比例大致相等。我们的数据显示了脑室下区神经母细胞具有多样的发育潜能，并表明融入突触回路对其存活是必要的。
