Kakuta S, Oda S, Gotoh Y, Kishi K
1st Department of Anatomy, Toho University School of Medicine, Omorinishi 5-21-16, Ota-ku, Tokyo 143-8540, Japan.
Brain Res Dev Brain Res. 2001 Jul 23;129(1):11-25. doi: 10.1016/s0169-328x(01)00111-5.
The distribution, morphological features, and postnatal development of calbindin-D28k (CB) and calretinin (CR) immunoreactive neurons in the main olfactory bulb (MOB) of the musk shrew, Suncus murinus, were studied by immunostaining to determine the degree of colocalization of CB and CR, and the relationship of CB and CR to neuron development in the MOB of animals of the order Insectivora. In adults, CB-positive neurons were identified as periglomerular and perinidal cells in the periglomerular region, as superficial short-axon cells in the external plexiform layer, and as four types of interneurons (Cajal, horizontal, Golgi, and bitufted cells) in the mitral cell, internal plexiform, and granule cell layers. CR-positive neurons were identified as projection neurons (tufted and mitral cells) and interneurons (periglomerular, perinidal, and granule cells). On postnatal days 1 and 3, CB-positive neurons revealed numerous processes finely arborized near the somata, and were morphologically unidentifiable. At the same time, CR-positive neurons were identified as young periglomerular and granule cells, and as migrating bipolar cells extending leading processes with growth cones in each layer of the MOB and the subependymal layer between the anterior lateral ventricle and the center of the MOB. On postnatal day 28, mature CB-positive and CR-positive interneurons were distributed in their corresponding layers, whereas migrating CR-positive bipolar cells were rarely detected. No cells colocalized CB and CR. The results suggest that perinidal cells in the shrew MOB may develop postnatally, together with glomerular and granule cells. We suggest that CB is associated with mechanisms of the outgrowth of neuronal processes, whereas CR is involved in mechanisms of cell migration and outgrowth of neuronal processes, in some types of neurons in the developing stage of the shrew MOB.
通过免疫染色研究了臭鼩（Suncus murinus）主嗅球（MOB）中钙结合蛋白-D28k（CB）和钙视网膜蛋白（CR）免疫反应性神经元的分布、形态特征和出生后发育情况，以确定CB和CR的共定位程度，以及CB和CR与食虫目动物MOB中神经元发育的关系。在成年臭鼩中，CB阳性神经元被鉴定为嗅小球区域的球周细胞和球周巢旁细胞、外丛状层的浅层短轴突细胞，以及二尖瓣细胞层、内丛状层和颗粒细胞层中的四种中间神经元（卡哈尔细胞、水平细胞、高尔基细胞和双簇细胞）。CR阳性神经元被鉴定为投射神经元（簇状细胞和二尖瓣细胞）和中间神经元（球周细胞、球周巢旁细胞和颗粒细胞）。在出生后第1天和第3天，CB阳性神经元在胞体附近有许多精细分支的突起，形态上无法识别。同时，CR阳性神经元被鉴定为年轻的球周细胞和颗粒细胞，以及在MOB各层和前外侧脑室与MOB中心之间的室管膜下层中延伸带有生长锥的领先突起的迁移双极细胞。在出生后第28天，成熟的CB阳性和CR阳性中间神经元分布在它们相应的层中，而迁移的CR阳性双极细胞很少被检测到。没有细胞同时表达CB和CR。结果表明，臭鼩MOB中的球周巢旁细胞可能在出生后与肾小球细胞和颗粒细胞一起发育。我们认为，在臭鼩MOB发育阶段的某些类型神经元中，CB与神经元突起生长机制有关，而CR参与细胞迁移和神经元突起生长机制。
