On the development of the stratification of the inner plexiform layer in the chick retina

Abstract

This study investigated the development of the subdivision of the chick inner plexiform layer (IPL). The approach included an immunohistological analysis of the temporal and spatial expressions of choline acetyltransferase, of the neural-glial-related and neural-glial cell adhesion molecules (NrCAM and NgCAM, respectively) and axonin-1, and of inwardly rectifying potassium (Kir) channels in 5- to 19-day-old (E5-E19) embryos. Ultrastructural investigations evaluated whether synaptogenesis accompanies the onset of differentiation of the IPL. We found that the differentiation of the IPL started at E9. Distinct cholinergic strata appeared, NrCAM immunoreactivity showed a poorly defined stratification, and Kir3.2 was expressed in the IPL and in the inner nuclear layer. From E10 until late E14, NgCAM- and axonin-1-immunoreactive strata emerged in an alternating sequence from the outer to the inner IPL. During this period, the NrCAM pattern sharpened, and eventually five bands of weaker and stronger immunoreactivity were found. Conventional synapses formed at the beginning of E9, and stratification of the IPL also began on the same day at the same location. Synaptogenesis and stratification followed a gradient from the central to the peripheral retina. The topographic course of differentiation of the IPL generally corresponded to the course of maturation of ganglion and amacrine cells. Synaptogenesis and the expression of G-protein-gated Kir3.2 channels accompanied the onset of stratification. These events coincide with the occurrence of robust and rhythmic spontaneous neuronal activity. The subsequent differentiation of the IPL seemed to be orchestrated by several mechanisms.

Transient requirement for ganglion cells during assembly of retinal synaptic layers

“…2C) but over a period of about 10 hours, distinct ON and OFF sublaminae form. Sublamination sweeps across the retina in approximately the same spatiotemporal pattern that characterizes the wave of AC neurogenesis, as has recently been suggested from static images of the chick retina (Drenhaus et al, 2003). This behavior suggests that sublamination may occur at a fixed time after cell specification.…”

Development of Dendritic Form and Function

“…With subsequent waves of neurogenesis, arbor growth, and synapse formation, the neuropil expands and adds new sublayers containing targeted projections of amacrine, bipolar, and RGC neurites (Drenhaus et al 2003, Godinho et al 2005, Kay et al 2004, Mumm et al 2006. Therefore, the process of laminar targeting is tightly coupled to the formation and expansion of the IPL.…”

Random Wiring in the Midget Pathway of Primate Retina

“…The basic mechanisms that govern the precision of connections between distinct populations remain poorly understood. Allegiance to radial clonal identity (Reese et al, 1995) as well as cadherin-mediated cell recognition processes (Drenhaus et al, 2003;Prakash et al, 2005) are likely to play a role in the retina and other brain systems (Sharma and Johnson, 2000;Cramer et al, 2004; for review see Bamji, 2005). Accordingly, in both the visual and olfactory systems of Drosophila, cadherin-mediated developmental sorting serves to identify synaptic target populations, but not individual cells within the population (Hummel and Zipursky, 2004;Prakash et al, 2005).…”