Chehrehasa Fatemeh, St John James, Key Brian
Brain Growth and Regeneration Lab, Discipline of Anatomy and Developmental Biology, School of Biomedical Sciences, The University of Queensland, Brisbane, Australia.
J Mol Histol. 2005 Sep;36(6-7):427-36. doi: 10.1007/s10735-006-9015-z. Epub 2006 Mar 3.
In order to begin to understand how primary olfactory and vomeronasal organ (VNO) axons target specific regions of the olfactory bulb, we examined the sorting behaviour of these axons following neonatal unilateral olfactory bulbectomy. Bulbectomy induced widespread ipsilateral death of the primary olfactory and VNO neurons. After 4 weeks, many new sensory axons had re-grown into the cranial cavity and established a prominent plexus with evidence of dense tufts that were similar in gross appearance to glomeruli. Axons expressing the cell adhesion molecule OCAM, which normally innervate the ventrolateral and rostral halves of the main and accessory olfactory bulbs, respectively, sorted out and segregated from those axons not expressing this molecule within the plexus. In addition, VNO axons formed large discrete bundles that segregated from main olfactory axons within the plexus. Thus, VNO and primary olfactory axons as well as discrete subpopulations of both are able to sort out and remain segregated in the absence of the olfactory bulb. Sorting and convergence of axons therefore occur independently of the olfactory bulb and are probably attributable either to inherent properties of the axons themselves or to interactions between the axons and accompanying glial ensheathing cells.
为了开始理解初级嗅觉神经和犁鼻器（VNO）轴突如何靶向嗅球的特定区域，我们研究了新生单侧嗅球切除术后这些轴突的分选行为。嗅球切除术导致初级嗅觉神经和犁鼻器神经元广泛的同侧死亡。4周后，许多新的感觉轴突重新长入颅腔，并形成了一个明显的神经丛，有密集的簇状结构，其总体外观与肾小球相似。表达细胞粘附分子OCAM的轴突，通常分别支配主嗅球和副嗅球的腹外侧和 Rostral 半部，在神经丛中与那些不表达该分子的轴突分选并分离。此外，犁鼻器轴突形成大的离散束，在神经丛中与主嗅觉轴突分离。因此，犁鼻器和初级嗅觉轴突以及两者的离散亚群能够在没有嗅球的情况下分选并保持分离。因此，轴突的分选和汇聚独立于嗅球发生，可能归因于轴突本身的固有特性或轴突与伴随的神经胶质包被细胞之间的相互作用。
