|
Fig. 5 irx1a is required for neurogenesis of the INL and ONL. (A–J,M,N) Coronal sections of 96 hpf retina. Ventral to the bottom. (A,E) Isl-1 immunostaining of a control retina (A) labeled the RGCs, a subset of amacrine cells in the proximal INL, and a subset of bipolar cells in the distal INL. Only a small patch of Isl-1 positive cells could be detected in the ventral INL of the irx1a morphant retina (E). (B,F) Zn12 (HNK-1) immunostaining labeled the RGCs and amacrine cells in the INL of the control retina (B) but only detected a ventral patch of cells in the irx1a morphant retina (F). IPL, inner plexiform layer. (C,G) GAD 65/67 immunostaining labeled a subset of amacrine cells (C) in the INL but only detected some cells in the ventral side of the irx1a morphant retina (G). (D,H) Glutamine synthetase (GS) immunostaining labeled all Müller cells. In control retinas, Müller glial cells could be found in the INL and the processes are extended through the entire retina (D). In irx1a morphant retinas, Müller glial cells were completely missing (H). (I,M) Zpr1 immunostaining of a control retina (I) labeled a subset of cone photoreceptors in the ONL. In the irx1a morphant retina (M), only a small patch of zpr1 labeled cells (white arrow) could be detected on the ventral side. (J,N) Zpr3 immunostaining of a control retina (J) labeled rod photoreceptors in the ONL. Similar to zpr1 staining, a small patch of zpr3-expressing cells (white arrowhead) could be detected in the ventral aspect of the irx1a morphant retina (N). (K,L,O,P) Schematic representation of the retinal defects of irx1a morphants. Neurogenesis is initiated in a ventronasal patch but does not spread through the retina in the irx1a morphants. (O, P).
Reprinted from Mechanisms of Development, 123(3), Cheng, C.W., Yan, C.H., Hui, C.C., Strähle, U., and Cheng, S.H., The homeobox gene irx1a is required for the propagation of the neurogenic waves in the zebrafish retina, 252-263, Copyright (2006) with permission from Elsevier. Full text @ Mech. Dev.