Limits...
Inhibitory neuron migration and IPL formation in the developing zebrafish retina.

Chow RW, Almeida AD, Randlett O, Norden C, Harris WA - Development (2015)

Bottom Line: Finally, HCs, iACs and dACs each undergo cell type-specific migration.In contrast to current hypotheses, we find that most dACs send processes into the forming inner plexiform layer (IPL) before migrating through it and inverting their polarity.By imaging and quantifying the dynamics of HCs, iACs and dACs from birth to final position, this study thus provides evidence for distinct and new migration patterns during retinal lamination and insights into the initiation of IPL formation.

View Article: PubMed Central - PubMed

Affiliation: Department of Physiology, Development and Neuroscience, University of Cambridge, Cambridge CB2 3DY, UK.

Show MeSH
Early stages of IPL formation. (A) Snapshot of a 55 hpf retina showing different stages of retinal development along the developmental wave. The RIN labelled with the orange asterisk probably represents a misplaced cell. (B) Quantification of the degree of interdigitation along the apical surface of RGCs, drawn as a white line in A. The vertical grey line indicates the angular position of the minimum value, and the corresponding 20° segment is indicated by the yellow line and yellow arrowheads in A. (C) The average line intensity values of the boxed region in A, showing the BC plexus (Crx) located between the RGC (Ath5) dendritic plexus and RINs (Ptf1a) in this region. (D) Selected frames of a movie of an RGC (blue arrowheads) migrating basally past RINs (orange arrowheads) and stratifying at a location basal to the RINs. (E) Selected frames of a movie of a BC axon (blue arrowheads) retracting to the basal side of RINs in the INL before the subsequent migration of a dAC (orange arrowheads) into the GCL. Time is shown as h:min from the start of the imaging sessions, at ∼44 hpf (D) and ∼48 hpf (E).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC4529032&req=5

DEV122473F8: Early stages of IPL formation. (A) Snapshot of a 55 hpf retina showing different stages of retinal development along the developmental wave. The RIN labelled with the orange asterisk probably represents a misplaced cell. (B) Quantification of the degree of interdigitation along the apical surface of RGCs, drawn as a white line in A. The vertical grey line indicates the angular position of the minimum value, and the corresponding 20° segment is indicated by the yellow line and yellow arrowheads in A. (C) The average line intensity values of the boxed region in A, showing the BC plexus (Crx) located between the RGC (Ath5) dendritic plexus and RINs (Ptf1a) in this region. (D) Selected frames of a movie of an RGC (blue arrowheads) migrating basally past RINs (orange arrowheads) and stratifying at a location basal to the RINs. (E) Selected frames of a movie of a BC axon (blue arrowheads) retracting to the basal side of RINs in the INL before the subsequent migration of a dAC (orange arrowheads) into the GCL. Time is shown as h:min from the start of the imaging sessions, at ∼44 hpf (D) and ∼48 hpf (E).

Mentions: Our finding that multipolar dACs migrate basally through a pre-formed proto-IPL (Fig. 4C; supplementary material Fig. S3) does not support current hypotheses on IPL formation (supplementary material Fig. S2). To gain further insights into how the IPL originates, we examined the formation of the IPL across the wave of retinal differentiation in SoFa1 (Almeida et al., 2014) embryos (Fig. 8A). We observed that RINs can first be visualized in the centre of the retina at times when RGCs are still migrating and that RGCs and RINs are initially interdigitated in the GCL. However, consistent with our previous work (Almeida et al., 2014), we find that this interdigitation is lost as development proceeds and the unevenness of the apical side of the RGC layer decreases to a minimum before the first signs of a continuous RGC dendritic plexus (Fig. 8A,B). Shortly after a sharp boundary is formed between RGCs and RINs, a BC (Crx-positive) axonal plexus forms at the interface between RGCs and RINs (Fig. 8A,C), and it is only after the BC plexus begins to form that dACs migrate to their positions within the GCL (Fig. 8A,C). Our analysis also shows that late-arriving RGCs can migrate basally past ACs to take up residence in the GCL (n=4 RGCs; Fig. 8D), arguing against the idea that ACs arrive at a pre-formed GCL (Godinho et al., 2005).Fig. 8.


Inhibitory neuron migration and IPL formation in the developing zebrafish retina.

Chow RW, Almeida AD, Randlett O, Norden C, Harris WA - Development (2015)

Early stages of IPL formation. (A) Snapshot of a 55 hpf retina showing different stages of retinal development along the developmental wave. The RIN labelled with the orange asterisk probably represents a misplaced cell. (B) Quantification of the degree of interdigitation along the apical surface of RGCs, drawn as a white line in A. The vertical grey line indicates the angular position of the minimum value, and the corresponding 20° segment is indicated by the yellow line and yellow arrowheads in A. (C) The average line intensity values of the boxed region in A, showing the BC plexus (Crx) located between the RGC (Ath5) dendritic plexus and RINs (Ptf1a) in this region. (D) Selected frames of a movie of an RGC (blue arrowheads) migrating basally past RINs (orange arrowheads) and stratifying at a location basal to the RINs. (E) Selected frames of a movie of a BC axon (blue arrowheads) retracting to the basal side of RINs in the INL before the subsequent migration of a dAC (orange arrowheads) into the GCL. Time is shown as h:min from the start of the imaging sessions, at ∼44 hpf (D) and ∼48 hpf (E).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4529032&req=5

DEV122473F8: Early stages of IPL formation. (A) Snapshot of a 55 hpf retina showing different stages of retinal development along the developmental wave. The RIN labelled with the orange asterisk probably represents a misplaced cell. (B) Quantification of the degree of interdigitation along the apical surface of RGCs, drawn as a white line in A. The vertical grey line indicates the angular position of the minimum value, and the corresponding 20° segment is indicated by the yellow line and yellow arrowheads in A. (C) The average line intensity values of the boxed region in A, showing the BC plexus (Crx) located between the RGC (Ath5) dendritic plexus and RINs (Ptf1a) in this region. (D) Selected frames of a movie of an RGC (blue arrowheads) migrating basally past RINs (orange arrowheads) and stratifying at a location basal to the RINs. (E) Selected frames of a movie of a BC axon (blue arrowheads) retracting to the basal side of RINs in the INL before the subsequent migration of a dAC (orange arrowheads) into the GCL. Time is shown as h:min from the start of the imaging sessions, at ∼44 hpf (D) and ∼48 hpf (E).
Mentions: Our finding that multipolar dACs migrate basally through a pre-formed proto-IPL (Fig. 4C; supplementary material Fig. S3) does not support current hypotheses on IPL formation (supplementary material Fig. S2). To gain further insights into how the IPL originates, we examined the formation of the IPL across the wave of retinal differentiation in SoFa1 (Almeida et al., 2014) embryos (Fig. 8A). We observed that RINs can first be visualized in the centre of the retina at times when RGCs are still migrating and that RGCs and RINs are initially interdigitated in the GCL. However, consistent with our previous work (Almeida et al., 2014), we find that this interdigitation is lost as development proceeds and the unevenness of the apical side of the RGC layer decreases to a minimum before the first signs of a continuous RGC dendritic plexus (Fig. 8A,B). Shortly after a sharp boundary is formed between RGCs and RINs, a BC (Crx-positive) axonal plexus forms at the interface between RGCs and RINs (Fig. 8A,C), and it is only after the BC plexus begins to form that dACs migrate to their positions within the GCL (Fig. 8A,C). Our analysis also shows that late-arriving RGCs can migrate basally past ACs to take up residence in the GCL (n=4 RGCs; Fig. 8D), arguing against the idea that ACs arrive at a pre-formed GCL (Godinho et al., 2005).Fig. 8.

Bottom Line: Finally, HCs, iACs and dACs each undergo cell type-specific migration.In contrast to current hypotheses, we find that most dACs send processes into the forming inner plexiform layer (IPL) before migrating through it and inverting their polarity.By imaging and quantifying the dynamics of HCs, iACs and dACs from birth to final position, this study thus provides evidence for distinct and new migration patterns during retinal lamination and insights into the initiation of IPL formation.

View Article: PubMed Central - PubMed

Affiliation: Department of Physiology, Development and Neuroscience, University of Cambridge, Cambridge CB2 3DY, UK.

Show MeSH