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Circumferential migration of ameboid microglia in the margin of the developing quail retina
J L Marín-Teva1, R Calvente, M A Cuadros
1Departamento de Biología Celular, Facultad de Ciencias, Universidad de Granada, Granada, Spain.
Abstract:
Central-to-peripheral migration of QH1-positive microglial precursors occurs in the vitrealmost part of the developing quail retina. This study shows that some QH1-positive ameboid cells with morphological features of migrating cells are already present in the margin of the retina before microglial precursors migrating centrally to peripherally arrive in this zone. Because the earlier cells are oriented parallel to the ora serrata, we deduce that some microglial cells migrate circumferentially in the margin of the retina, whereas other microglial precursors migrate from central to peripheral zones. Microglial cells that migrate circumferentially are first seen on embryonic day 6 (E6) and advance in a temporal-to-dorsal-to-nasal direction from the temporoventral quadrant of the retina. When cells migrating centrally to peripherally reach the retinal margin, they meet those migrating circumferentially. From E6 on, some QH1-positive dendritic cells in the ciliary body bear processes that penetrate the retina, where they are oriented circumferentially. These observations suggest that microglial cells that migrate circumferentially in the retinal margin share a common origin with dendritic cells of the ciliary body. Therefore, microglial cells of the quail retina appear to make up a heterogeneous population, with some cells originating from the pecten/optic nerve head area and others from the ciliary body.
Insights
Quail retinal microglia originate from two distinct sources: the pecten/optic nerve head and the ciliary body. This study reveals two migratory pathways for these crucial immune cells during development.
Area of Science:
- Developmental biology
- Neuroscience
- Immunology
Background:
- Microglial precursors migrate within the developing quail retina.
- Previous understanding suggested a single migratory route for retinal microglia.
Purpose of the Study:
- To investigate the origin and migratory patterns of microglial cells in the developing quail retina.
- To determine if retinal microglia represent a heterogeneous population with dual origins.
Main Methods:
- Observation of QH1-positive cell migration in embryonic quail retinas.
- Analysis of cell morphology and orientation relative to retinal structures (ora serrata, ciliary body).
Main Results:
- Two distinct populations of QH1-positive cells identified: centrally-to-peripherally migrating precursors and circumferentially migrating cells in the retinal margin.
- Circumferentially migrating cells appear earlier (E6) and originate from the temporoventral quadrant, moving temporally-to-dorsally-to-nasally.
- QH1-positive dendritic cells in the ciliary body show retinal penetration, suggesting a shared origin with circumferentially migrating microglial cells.
Conclusions:
- Quail retinal microglia are a heterogeneous population originating from both the pecten/optic nerve head and the ciliary body.
- Microglial cells exhibit at least two distinct migratory behaviors: central-to-peripheral and circumferential within the retinal margin.