Olfactory ensheathing cells are the main phagocytic cells that remove axon debris during early development of the olfactory system

Nazareth, Lynnmaria, Lineburg, Katie E., Chuah, Meng Inn, Velasquez, Johana Tello, Chehrehasa, Fatemeh, St John, James A., & Ekberg, Jenny A.K. (2015) Olfactory ensheathing cells are the main phagocytic cells that remove axon debris during early development of the olfactory system. The Journal of Comparative Neurology, 523(3), pp. 479-494.

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Abstract

During development of the primary olfactory system, axon targeting is inaccurate and axons inappropriately project within the target layer or overproject into the deeper layers of the olfactory bulb. As a consequence there is considerable apoptosis of primary olfactory neurons during embryonic and postnatal development and axons of the degraded neurons need to be removed. Olfactory ensheathing cells (OECs) are the glia of the primary olfactory nerve and are known to phagocytose axon debris in the adult and postnatal animal. However, it is unclear when phagocytosis by OECs first commences. We investigated the onset of phagocytosis by OECs in the developing mouse olfactory system by utilizing two transgenic reporter lines: OMP-ZsGreen mice which express bright green fluorescent protein in primary olfactory neurons, and S100β-DsRed mice which express red fluorescent protein in OECs. In crosses of these mice, the fate of the degraded axon debris is easily visualized. We found evidence of axon degradation at embryonic day (E)13.5. Phagocytosis of the primary olfactory axon debris by OECs was first detected at E14.5. Phagocytosis of axon debris continued into the postnatal animal during the period when there was extensive mistargeting of olfactory axons. Macrophages were often present in close proximity to OECs but they contributed only a minor role to clearing the axon debris, even after widespread degeneration of olfactory neurons by unilateral bulbectomy and methimazole treatment. These results demonstrate that from early in embryonic development OECs are the primary phagocytic cells of the primary olfactory nerve.

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12 citations in Scopus
11 citations in Web of Science®
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ID Code: 83695
Item Type: Journal Article
Refereed: Yes
Keywords: olfactory nerve; neuron; apoptosis; bulbectomy; degeneratio
DOI: 10.1002/cne.23694
ISSN: 1096-9861
Divisions: Current > Schools > School of Biomedical Sciences
Current > QUT Faculties and Divisions > Faculty of Health
Current > Institutes > Institute of Health and Biomedical Innovation
Funding:
Deposited On: 20 Apr 2015 23:39
Last Modified: 15 Sep 2016 00:57

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