Transient Morphological Features of Identified Ganglion Cells in Living Fetal and Neonatal Retina

Abstract

The function and morphology of retinal ganglion cells in the adult mammalian visual system has been well studied, but little is known about how the adult state is achieved. To address this question, the morphological changes that retinal ganglion cells undergo during development were studied. Ganglion cells were first identified by retrograde labeling with rhodamine latex microspheres deposited in retinorecipient targets in fetal and early postnatal cats. The structure of ganglion cells was then revealed by intracellular injection of Lucifer yellow in living retinas removed and maintained in vitro. As early as 2 weeks before birth, a morphologically diverse assortment of ganglion cells is present, some of which resemble the alpha, beta, and gamma classes found in the adult. However, in contrast to the adult, developing ganglion cells exhibit several transient features, including excessive axonal and dendritic branching and exuberant somatic and dendritic spines. These morphological features indicate that there is a transient network of connectivity that could play an important role in the final determination of retinal ganglion cell form and function.

The role of protein phosphatase-1 in the modulation of synaptic and structural plasticity

“…Filopodia might therefore not be major players in developmental spinogenesis. Instead, they may have another specific role as they have been detected on neurons that later do not develop spines [45,46]. Now it seems that they are mainly dendritic precursors, as filopodia have been shown to form new dendritic branches in vivo [47].…”

Pseudorabies virus expressing enhanced green fluorescent protein: A tool for in vitro electrophysiological analysis of transsynaptically labeled neurons in identified central nervous system circuits

“…The development of retrogradely transported fluorescent tracers has allowed investigators to examine the physiology of neurons with known projections (13)(14)(15). However, such studies usually require direct and accurate injection of a target region followed by retrograde transport to identify first-order neurons projecting to the target.…”

Retinal ganglion cells of high cytochrome oxidase activity in the rat

“…This population of cytocrome oxidase reactive retinal ganglion cells appeared to have large somata and several primary dendrites, thus resembling the alpha or Y type retinal ganglion cells described in previous reports [1,4,5,19,22]Therefore, this method provides a simple but useful way for studying a population of large retinal ganglior cells with high metabolic activity. The reason why the dendrites of smaller retinal ganglion cells were not stained is not altogether clear, although it is possible that the intensity of staining may reflect the actual amount of the enzyme molecules present in the cells and their processes.…”

“…It has long been recognized that the mitochondrial enzyme cytochrome oxidase can be used not only for revealing neurons or brain regions of high oxidative metabolic activity, but can also be used as an marker enzyme for neurons or anatomical entities of the brain with certain special physiological properties [6-9, 12-14,17,18,24-26] In the retina, it has been demonstrated in a variety of mammalian species that the cytochrome oxidase histochemical technique is useful for staining a population of ganglion cells with relabively large somata [13][14][15] However, in most of the cases reported, the dendrites of the retinal ganglion cells especially their secondary and more distal branches can not be visualized using the cytochrome oxidase histochemistry, In view of the fact that the dendritic morphology has become an important feature for studying or classifying ganglion cells [1,4,5,19,22] it is to our interest to find out that whether the cytochrome oxidase histochemical technique can be modified to such an extent that it can stain not only the somata of neurons but also their dendritic arbors. In this study, our attention is given to a populabion of large or alpha-like retinal ganglion cells which is known to constitute only a small percentage of the ontire population of ganglion cells in the rat robina [13,15,23].…”