Development of A‐type (axonless) horizontal cells in the rabbit retina

Abstract

The development of A-type horizontal cells (HC) was studied in the rabbit retina between embryonic day (E)24 and adulthood [the day of birth was called postnatal day (P)1 and corresponds to E31-32]. The cells were visualized by several methods 1) by immunolabeling with antibodies to neurofilament 70,000 (NF-70kD), 2) by immunolabeling with antibodies to a calcium binding protein (CaBP-28kD), 3) by two different methods of silver impregnation, and 4) by histochemical demonstration of NADH-diaphorase activity. Most methods labeled A-type HC only in the dorsal retina; thus, our study is restricted to HC of this region. HC densities were determined at each developmental stage. The cells were drawn at scale, and size, quotient of symmetry, and topographical orientation of dendritic trees were studied by image analysis. The growth of HC dendritic fields was correlated with data on the postnatal local retinal expansion, which is known to be driven by the intraocular pressure (after cessation of retinal cell proliferation at P9). This expansion was evaluated in an earlier paper (Reichenbach et al. [1993] Vis. Neurosci. 10:479-498) by using local subpopulations of Müller cells as "markers" of distinct topographic regions of the retinae. After E24, when the final number of HC is established, we can discriminate three distinct developmental stages of A-type HC. During the first stage, between E24 and E27, the young cells are often vertically oriented and may extend their first short dendrites within (the primordia of) both plexiform layers. The irregular HC mosaic at E24 shows a significant difference to all other stages. The second stage begins after birth when the dendritic trees of the cells are already restricted to the outer plexiform layer. Between P3 and P9, their dendritic trees enlarge more than the surrounding retinal tissue expands, and the coverage factor almost doubles from 2.5 to 4.4. The third stage occurs after P9 when the growth rate of dendritic tree areas corresponds to that of the local retinal tissue expansion caused by "passive stretching" of the postmitotic tissue, and the coverage factor remains constant. This is compatible with the view that mature synaptic connections of A-type HC are mostly established after the first week of life and are then maintained.

Quantitative anatomy, synaptic connectivity and physiology of amacrine cells with glucagon-like immunoreactivity in the turtle retina

“…They were more regular in the visual streak region than in the periphery of the retina, that is the same type of distribution as found for horizontal cells in the rabbit retina (Scheibe et al, 1995). This is in agreement with delayed development of peripheral retina compared to the centre (Robinson, 1991).…”

Afferents and Homotypic Neighbors Regulate Horizontal Cell Morphology, Connectivity, and Retinal Coverage

“…Such dispersion can only change the patterning present at the time of fate assignment, established before migration into the neuroblast layer. That such short-distance movements might improve the patterning of the mosaic is supported by the finding that mosaic regularity improves after horizontal cells settle within the neuroblast layer (Scheibe et al, 1995). Consequently, although fate determination events undoubtedly establish a rudimentary patterning within the population of newly generated horizontal cells, interactions with differentiating neighbors appear to refine their intercellular spacing (Reese and Galli-Resta, 2002).…”

“…Differential retinal expansion may then create the variation in cell density, and, through interstitial dendritic growth, the corresponding variation in dendritic field size to which density is inversely related (Lia et al, 1987;Wässle et al, 1989;Rodieck and Marshak, 1992;Scheibe et al, 1995;Cellerino et al, 2000). Alternatively, horizontal cells may interact with neighboring cells during development to produce the correlation between intercellular spacing and dendritic field size, whereas their cone afferents may stimulate the detailed formation of their dendritic morphology.…”

Mosaics of Islet-1-Expressing Amacrine Cells Assembled by Short-Range Cellular Interactions

“…Postmitotic retinal neurons migrate to their final positions from the proliferative neuroepithelium, but known markers for retinal mosaics are expressed only after the cells have attained a regular spatial arrangement (Wässle and Riemann, 1978;Mitrofanis et al, 1988;Vaney, 1990;C asini and Brecha, 1991;Wikler and Rakic, 1991;Hutsler and Chalupa, 1995;Scheibe et al, 1995), making it difficult to understand how such regularity comes about.…”

“…A number of previous studies have analyzed the development of retinal mosaics, but all relied on markers that are expressed by cells only after they have entered their mosaics, making it difficult to understand how regularity comes about (Wässle and Riemann, 1978;Mitrofanis et al, 1988;Vaney, 1990;Casini and Brecha, 1991;Wikler and Rakic, 1991;Hutsler and Chalupa, 1995;Scheibe et al, 1995). Here we could follow the assembly of two mosaics of amacrine cells that express the transcription factor Islet-1 early in development, because Islet-1 expression appears in postmitotic cells before they migrate to their final position.…”