Biomedical subjects

C Straznicky

Publications and source records attributed to C Straznicky.

At least 37 records · Page 2Linked to original sources

PubMed1992

Microtubule-associated protein 2 (MAP2)-immunoreactive neurons in the retina of Bufo marinus: colocalisation with tyrosine hydroxylase and serotonin in amacrine cells.

Neuron populations in the retina of the toad, Bufo marinus, were labelled with a monoclonal antibody raised against microtubule-associated protein 2 (MAP2). A subpopulation of cones, probably corresponding to the blue-sensitive small single cones, large diameter amacrine cells in the most proximal row of the inner nuclear layer and some large ganglion cells in the ganglion cell layer were labelled. Double labelling experiments were carried out to establish the colocalisation of MAP2 with known putative transmitter substances of the anuran amacrine cells. MAP2 was colocalised in a subpopulation of serotonin-immunoreactive and in all tyrosine hydroxylase-immunoreactive amacrine cells. The results indicate, that the MAP2 content in the neurons of the anuran retina can be correlated with other well-defined neurochemical and/or physiological properties.

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PubMed1992

Retinal projections in the cane toad, Bufo marinus.

The location and extent of retinorecipient areas in the cane toad, Bufo marinus, were established by anterograde transport of cobaltic-lysine complex from the cut optic nerve. Most of the labeled optic axons travelled in the marginal optic tract, while others were in the axial optic tract, and/or the basal optic tract. Retinal projections terminated in both contralateral and ipsilateral targets. In addition to the optic tectum, the main visual center, retinorecipient areas included the suprachiasmatic nucleus, rostral visual nucleus, neuropil of Bellonci, corpus geniculatum thalamicum, ventrolateral thalamic nucleus (dorsal part), posterior thalamic neuropil, uncinate neuropil, pretectal nucleus lentiformis mesencephali and basal optic nucleus. While all of these retinorecipient areas receive optic fibers from both eyes, the ipsilateral retinal projections were observed to be generally sparser than those from the contralateral retina. A sparse optic fiber projection covers the surface of the ipsilateral optic tectum and is most prominent rostromedially and caudolaterally. The position and the extent of each of the retinorecipient areas were determined in relation to a three-dimensional coordinate system. Morphometric analysis showed that 85.3% of the retinorecipient area is in the contralateral optic tectum, 10.4% in contralateral non-tectal areas, 1.6% in the ipsilateral optic tectum and 2.7% in ipsilateral non-tectal areas. The presence of an ipsilateral tectal projection and the well defined pretectal visual neuropil complex may be related to the highly developed visual behavior and visual acuity of Bufo marinus.

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PubMed1992

The topographic organization of the retinal ganglion cell layer of the lizard Ctenophorus nuchalis.

The numbers of neurons of the ganglion cell layer (GCL) and their distribution in the retina of an Australian lizard Ctenophorus nuchalis were investigated. Retinal wholemounts and sections were prepared for light microscopic and optic nerves for electron microscopic study. Counts of cell numbers in the GCL from wholemounts varied from 200,000 to 380,000. Neurons in the GCL were non-uniformly distributed, forming a high cell density streak along the naso-temporal axis of the retina. Neurons of the GCL formed 2 to 9 layers in the visual streak and a single layer in the rest of the retina. The number of neurons of the GCL in this area was estimated at about 2,100,000. Although the visual streak represented only 16% of the total retinal surface area, it contained about 90% of all neurons of the GCL. Optic axon counts yielded 147,000 myelinated and 2,643,000 unmyelinated fibres. The estimated optic fibre number of 2,790,000 was 18.2% less than the total number of neurons counted from sections in the GCL of the same eye. The unexpected high number of neurons in the area of the visual streak indicates that cell numbers obtained only from wholemount preparations may vastly underestimate the total neuron numbers in the GCL of the lizard retina.

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PubMed1991

Tyrosine hydroxylase-immunoreactive elements in the distal retina of Bufo marinus: a light and electron microscopic study.

Tyrosine hydroxylase-immunoreactive elements in the distal retina of Bufo marinus were investigated using light and electron microscopic immunocytochemistry. At the light microscopic level, immunoreactive somas were seen in the proximal part of the inner nuclear layer, and immunoreactive processes projected both to the inner and outer plexiform layers. In some instances stained axon-like processes traveled from the inner plexiform layer, across the inner nuclear layer to the distal retina. Immunolabeled elements formed basket-like structures around the photoreceptor inner segments. At the ultrastructural level immunostained fibers were observed in close contact with the necks, lateral walls, bases and the outer surfaces of rod outer segments. Synaptic specializations were neither observed at rod contacts nor at other possible contact sites such as bipolar dendrites and horizontal cell somata and processes in the outer plexiform layer. In contrast, synaptic specializations between immunolabeled profiles and amacrine, bipolar and ganglion cells were regularly present in the inner plexiform layer. These findings suggest that a population of dopaminergic interplexiform cells is present in the Bufo retina and sends axon-like processes towards the distal retina. It is assumed that dopamine is probably released non-synaptically from the immunolabeled terminals in the distal retina influencing rods directly, by which the quality of photopic vision is enhanced in the anuran retina.

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PubMed1991

Retinal distribution of ganglion cells which project to the ipsilateral optic tectum in Bufo marinus.

The retinotectal projection in anura is mainly crossed, although a small proportion of optic axons projects to the ipsilateral tectum. Using the fluorescent carbocyanide dye, DiI, we mapped the retinal topography of ganglion cells which project to the ipsilateral tectum in adult Bufo marinus. DiI was injected into particular locations in the right tectum. After 10 days survival both the right and the left retinals were wholemounted and the number and retinal position of retrogradely filled ganglion cells were determined. The contralateral and ipsilateral cells were visuotopically distributed in the retina in the majority of experiments. However, in two cases cells were located in visuotopically disparate parts of the retina. The ipsilateral cells represented 3.7% of contralaterally projecting cells in the temporal retina, 0.1% in the nasal and dorsal retina and 0.6% of the ventral retina. The density of ipsilaterally projecting ganglion cells varied from a top of 25 cells/mm2 in the temporal retina, 9 cells/mm2 in the nasal, 3 cells/mm2 in the dorsal to 11 cells/mm2 in the ventral retina. The diversity of size and shape of retrogradely filled ganglion cells indicated that the ipsilateral population corresponded to a heterogeneous class of ganglion cell types. The functional significance of the direct ipsilateral retinotectal projection of the anuran visual system has yet to be elucidated. However, in light of the involvement of the indirect ipsilateral retinotectal projection in binocular vision, the direct pathway is likely to be associated with a retino-tecto-spinal circuit subserving postural adjustment to visually derived stimulation.

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PubMed1991

The morphology and distribution of photoreceptors in the retina of Bufo marinus.

The number, cell morphology and retinal distribution of rods and cones were determined in the retina of the toad, Bufo marinus. Adult animals were sacrificed, both eyes were removed and prepared for either tangential section across the outer segments of the photoreceptor layer, or transverse section across the whole retina. Cone densities increased from an average of 7000/mm2 in the peripheral to a maximum of 25,000/mm2 in the central retina. The high cone densities extended across the naso-temporal axis of the retina corresponding to the position of the visual streak in the ganglion cell layer. The total number of cones in the retina was estimated to be 1.1 million. Rod density of 21,000/mm2 in the central retina decreased to 17,000/mm2 at 1.5-4 mm eccentricity, and then increased to 29,000/mm2 in the peripheral retina. The total number of rods amounted to about 2 million. The mean of the cross-sectional area of rod outer segments was 11.2 +/- 1.5 microns 2 (mean +/- SD) in the highest and 17.9 +/- 4.7 microns 2 in the lowest density areas of the retina. The length of the rod outer segments extended from 28 microns in the ventral peripheral retina to a maximum of 89 microns in the dorsal retina, dorsal to the visual streak of the ganglion cell layer. The results of the present study showed a differential retinal distribution of photoreceptors, with a peak density in the retinal centre and a higher density along the naso-temporal axis of the eye. We conclude that the area of high photoreceptor density, matched by high neuron densities of the INL and GCL, corresponds to the site of acute vision of the Bufo retina.

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PubMed1991

Morphology and retinal distribution of tyrosine hydroxylase-like immunoreactive amacrine cells in the retina of developing Xenopus laevis.

The development of neurons immunoreactive to tyrosine hydroxylase (TH-IR) in the retina of Xenopus laevis was investigated from stage 53 tadpoles to adult, by using an antibody against tyrosine hydroxylase. At all developmental stages, most of the immunoreactive somata were located in the inner nuclear layer, and a few in the ganglion cell layer. Immunoreactive processes arborized in the scleral and vitreal sublaminae of the inner plexiform layer, indicating that these cells were bistratified amacrine cells. However, occasionally a few immunoreactive processes were observed projecting to the outer plexiform layer, suggesting the presence of TH-IR interplexiform cells. The number of immunoreactive amacrine cells in the inner nuclear layer per retina increased from 204 at stage 53 tadpole to 735 in adult, while the number of immunoreactive amacrine cells in the ganglion cell layer did not change significantly over the same period. Retinal area increased from 1.95 mm2 at stage 53 to 23.40 mm2 in the adult, and correspondingly cell density in the inner nuclear layer decreased from 104/mm2 to 31/mm2. At all stages there was an increasing density towards the ciliary margin, but this gradient decreased with age. The soma size of immunoreactive amacrine cells increased with age, and was consistently larger in the central than in the peripheral retina. Dendritic field size was estimated to increase 13-fold, from stage 53 to adult. This study shows that tyrosine hydroxylase-like immunoreactive amacrine cells are generated continuously throughout life, that after metamorphosis the retina grows more by stretching than by cell generation at the ciliary margin, and that the increase of dendritic field size is proportional to the increase in retinal surface area.

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PubMed1991

NADPH-diaphorase positive neurons in the retina of Bufo marinus: selective staining of bipolar and amacrine cells.

Unfixed retinal tissues of adult Bufo marinus were reacted for NADPH-diaphorase histochemistry that resulted in selective staining of populations of bipolar and amacrine cells. The number of stained bipolar cells in the retina was estimated to be 233,600 +/- 38,900 (mean +/- S.D.). These cells were non-uniformly distributed across the retina with the highest density of 4,308 cells/mm2 along the visual streak decreasing to lowest density of 1,378 cells/mm2 at the dorsal and ventral poles of the retina. The stained bipolar cells represented a morphologically uniform population. The number of labelled amacrine cells in the retina amounted to 3,116 +/- 405 including 251 cells that were displaced into the ganglion cell layer. Labelled amacrine cells were also unevenly distributed; with no stained cells in the retinal centre from where the density increased steadily to 72 cells mm2 in the retinal periphery. NADPH-diaphorase positive amacrine cells were classified on the basis of their dendritic arborization pattern into three morphological types: 1) narrow-field cells both at the periphery and the centre of the retina; 2) wide-field amacrine cells, and 3) amacrines with eccentric medium-sized dendritic field. The results of this study provide evidence for the presence of NADPH-diaphorase containing neurons in the anuran retina. Furthermore, this is the first report on the selective staining of bipolar cells for NADPH-diaphorase in the vertebrate retina.

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PubMed1991

Substance P-immunoreactive neurons in the retina of two lizards.

The dendritic morphology and retinal distribution of substance P(SP)-immunoreactive neurons was determined in two Australian lizard species Pogona vitticeps and Varanus gouldii, by using immunohistochemistry on retinal wholemounts and sectioned materials. In both species, two classes of SP-immunoreactive neurons were described in the inner nuclear layer (INL) and classified as amacrine cells (types A and B). Type A amacrine cells had large somata and wide-field, bistratified dendrites branching in sublaminas 1 and 5 of the inner plexiform layer (IPL). Their morphology and retinal distribution differed between the two species. Type B amacrine cells in both species had small somata and small-field dendritic branching. A population of SP-immunoreactive neurons with classical ganglion cell morphology were identified in the ganglion cell layer (GCL). Immunostained ganglion cells occurred in larger numbers of Varanus gouldii than in Pogona vitticeps. In both species type B SP cells were the most numerous and were estimated to be about 60,000-70,000. They were distributed non-uniformly with a high density band across the horizontal meridian of the retina, from where the density decreased towards the dorsal and ventral retinal margins. In both species type A amacrine cells occurred in small numbers distributed sparsely in the peripheral retina. The faint immunostaining of SP-immunoreactive neurons in the GCL, did not allow us to reliably determine their numbers and retinal distribution. The functional significance of SP-immunoreactive amacrine and ganglion cells in the lizard retina remains to be determined.

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PubMed1990

Neuropeptide Y- and substance P-like immunoreactive amacrine cells in the retina of the developing Xenopus laevis.

The development of neuropeptide Y-like (NPY-LI) and substance P-like (SP-LI) immunoreactive neurons was studied in retinas of Xenopus laevis from young tadpole through to adult animals. In adult retina these neuropeptides are present in wide-field amacrine cells located in the inner nuclear layer and the ganglion cell layer of the retina. Retinal wholemount preparations and sectioned material showed that immunoreactive cells appeared during early larval life and NPY-LI occurred earlier than SP-LI cells. The primary dendritic branching of NPY-LI neurons appeared from early larval life whilst SP-LI was evident in dendrites from mid-larval stages. In postmetamorphic animals the numbers of immunoreactive cells increased in proportion to retinal area growth with a relatively constant cell density of about 35 cells/mm2 for SP-LI and 45 cells/mm2 for NPY-LI. The maturation of dendritic morphology of both NPY- and SP-LI amacrine cells appeared later in larval development than the appearance of immunoreactivity in cell somas. However, the sequence of expression of NPY- or SP-LI and their dendritic maturation was different for the two classes of amacrine cells. It is suggested that the maturation of dendritic fields of amacrine cells is complete just prior to metamorphosis, consistent with the postmetamorphic onset of electrophysiological features of ganglion cells attributed to amacrine cells.

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PubMed1990

The changing distribution of neurons in the inner nuclear layer from metamorphosis to adult: a morphometric analysis of the anuran retina.

The generation and changing distribution of neurons of the inner nuclear layer (INL) in the retina of two anuran species, Bufo marinus and Xenopus laevis, were studied from metamorphosis to adult. Morphometric studies were undertaken at six developmental stages in Bufo and four in Xenopus. The number and thickness of neurons in the INL were established in 29 predetermined retinal locations from serial sections of the eyes cut vertically or horizontally. The total number of neurons in the INL increased from metamorphosis to adult from 826,000 +/- 185 to 18,760,000 +/- 562 (mean +/- SD) in Bufo and from 308,000 +/- 25 to 877,000 +/- 31 in Xenopus. Over the same period the surface area of the INL increased about 50-fold from 2 mm2 to 96 mm2 in Bufo and 5-fold from 2.5 mm2 to 13 mm2 in Xenopus. In Bufo the difference between the highest cell number (central-temporal retina) and the lowest cell number in a sample area (dorsal and ventral peripheral retina) was 2.1:1 at metamorphosis. This ratio increased to 3.4:1 in the adult. Both the cell number and cell density per sample area in the INL was found to be higher along the nasotemporal meridian of the eye overlying the visual streak of the ganglion cell layer (GCL) of the retina. The retinal distribution of neurons in the INL did not change significantly during postmetamorphic growth in Xenopus. At metamorphosis a 1.7:1 difference was found between the highest neuron number (retinal ciliary margin) and lowest neuron number (retinal centre) decreasing to 1.5:1 in the adult. Retinae were labelled with 3H-thymidine in 15 mm Bufos and examined 2, 6, 12 and 18 weeks later. Higher rates of cell addition to the nasal and temporal poles of the INL were found compared with that at the dorsal and ventral poles. The retinal radial growth at the ciliary margin of the dorsal, ventral, nasal and temporal poles between the time of isotope injection and 18 weeks survival was found to be uneven; more radial elongation occurred at the nasal, dorsal and ventral poles and less at the temporal pole. These observations suggest that (a) the neuron distribution of the INL in adult animals approximates that of the GCL and (b) the visual streak-like area of the INL in Bufo develops by a sustained differential cell addition at the temporal and nasal poles of the retina.

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PubMed1990

Dendritic morphology and retinal distribution of tyrosine hydroxylase-like immunoreactive amacrine cells in Bufo marinus.

Tyrosine hydroxylase-like immunoreactive (TH-IR) amacrine cells (ACs) in the retina of metamorphosing and adult Bufo marinus were visualized, and their retinal distribution established, using immunohistochemistry on retinal wholemount and sectioned material. The somata of TH-IR ACs were located in the innermost part of the inner nuclear layer (INL). Their dendrites branched predominantly in the scleral sublamina of the inner plexiform layer (IPL), with sparse branching also in the vitreal sublamina. In the retinae of metamorphosing animals 592 +/- 113 (mean +/- S.D.) immunoreactive cells and in adult 5,670 +/- 528 cells were found. Usually 1, 2 or 3 stem dendrites arose from the somata of TH-IR cells which branched 2 or 3 times. In the adult retinae the dendritic field sizes of immunoreactive cells were in the range of 0.059 +/- 0.012 mm2, which resulted in a considerable dendritic overlap across the retina. TH-IR cells were unevenly distributed over the retina, with 72 cells/mm2 in the central temporal retina, 45-50 cells/mm2 along the naso-temporal axis of the retina and 25 cells/mm2 in the dorsal and ventral peripheral retina. The average density was 36 +/- 6 cells/mm2. A considerable number of TH-IR cells (range 52-133, n = 4) were displaced into the ganglion cell layer (GCL) of the retina. The mean soma sizes of immunoreactive cells were significantly higher in the low density (95 +/- 13 microns 2) than in the high cell density areas (86 +/- 12 microns 2).(ABSTRACT TRUNCATED AT 250 WORDS)

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PubMed1990

Morphological classification and retinal distribution of large ganglion cells in the retina of Bufo marinus.

The retrograde transport of horseradish peroxidase (HRP) and cobaltic-lysine complex (CLC) was used to morphologically characterize large ganglion cells (GCs) and to determine their distribution in retinal wholemounts and in sectioned material in the retina of Bufo marinus. Large GCs, amounting to about 0.5% of total GC population, were defined to be those with very large dendritic field sizes varying between 0.1 mm2 to 0.6 mm2 and cell soma sizes of between 100 microns 2 to 400 microns 2. These cells were subdivided into 3 major groups, Types I, II and III, on the basis of their dendritic field sizes, aborization patterns and the strata of dendritic branching within the inner plexiform layer (IPL). The majority of large neurons (about 90%) were classified as Type I GCs with symmetrical dendritic arbor. These cells had either bistratified branching in the scleral and vitreal sublamina of the IPL (65% of Type I Cells) or unistratified branching in the scleral (26%) or in the vitreal (9%) sublamina. Their dendritic field sizes increased linearly from the retinal centre from 0.13 mm +/- 0.02 mm2 (mean and S.D.) to 0.58 +/- 0.11 mm2 in the retinal periphery. Type II GCs (about 9% of large GC population) were characterized by an asymmetrical dendritic aborization directed towards the ciliary margin with unistratified branching in the scleral sublamina of the IPL. The mean dendritic field sizes of these cells were 0.26 +/- 0.09 mm2. Type III GCs, the least frequent (about 1%) category of large GCs had sparsely branching, elongated dendritic branching aligned approximately parallel with the nasotemporal axis of the retina. The unistratified dendritic branches of these neurons were located in the vitreal sublamina of the IPL with a mean dendritic field size of 0.42 +/- 0.11 mm2. The dendritic field sizes of Types II and III GCs did not increase with retinal eccentricity. Type I GCs were distributed unevenly across the retina, the density being greatest in the visual streak, along the nasotemporal meridian of the retina. The dendritic field sizes of these cells increased towards the retinal periphery, resulting in a constant dendritic field coverage factor across the retina. Each retinal point was covered by the dendritic fields of 4-5 adjacent GCs. In contrast, Types II and III GCs had only discontinuous dendritic coverage. The identification of morphological types of large GCs with previously described functional classes of GCs in the anuran retina is discussed.

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PubMed1990

Morphology and distribution of serotonin-like immunoreactive amacrine cells in the retina of Bufo marinus.

Using an antibody against serotonin (5-hydroxytryptamine, 5-HT), serotonin-like immunoreactive (serotonin-IR) neurons were demonstrated in the retina of adult Bufo marinus. All immunoreactive neurons were identified as amacrine cells (ACs). The dendrites of serotonin-IR ACs branched diffusely and densely throughout all levels of the inner plexiform layer (IPL) of the retina. The great majority of these cell somata were located in the vitread part of the inner nuclear layer (INL) and a few of them (ranging from 9-29 cells) were displaced into the ganglion cell layer (GCL). On the basis of the soma sizes, two populations of serotonin-IR ACs, large (type A) and small (type B), were distinguished. 6-Hydroxydopamine (6-OHDA) injected into the eye abolished immunoreactivity in the recently reported tyrosine hydroxylase (TH)-IR ACs (Zhu & Straznicky, 1990), whereas serotonin-IR ACs remained unaffected. The number of serotonin-IR cells per retina ranged from 23, 750-27, 390, with a ratio of 1:1.6 to 1:1.9 between type A and B cells. Both cell types were distributed nonuniformly across the retina. Cell densities were slightly lower in the peripheral (96 cells/mm2) than in the central (164 cells/mm2) retina. Linear regression analysis confirmed the presence of a decreasing density gradient from the retinal center to the retinal margin for both small and large cell types. The analysis of the nearest neighbor distances showed that the retinal distribution of serotonin-IR ACs was orderly. These results have been taken to indicate that 5-HT-IR cells correspond to a population of serotonin-containing ACs.(ABSTRACT TRUNCATED AT 250 WORDS)

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PubMed1989

Biplexiform ganglion cells in the retina of Xenopus laevis.

A few cells were seen on retinal wholemounts of Xenopus frogs whose dendrites branched in both the inner and the outer plexiform layers after the application of retrograde tracers to the cut optic nerve. The somas of these cells were displaced into the inner nuclear layer of the retina, and occasionally in orthotopic position. These observations provide convincing evidence that previously described biplexiform cells are ganglion cells and that these cells are regular components of the vertebrate retina.

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PubMed1989

Retino-retinal projections in three anuran species.

In juvenile and adult Xenopus laevis, in adult Bufo marinus and Rana esculenta frogs retino-retinal projections were traced by filling the central stump of one optic nerve, cut 2-3 mm from the eye, with horse-radish peroxidase (HRP) or cobaltic-lysine complex (CLC). The presence of retino-retinal projections was confirmed in all 3 species both in the juvenile and the adult. Up to 12 ganglion cells per retina were found to be filled retrogradely with HRP together with optic axons filled anterogradely with CLC. These findings suggest that (1) a small proportion of ganglion cells project, erroneously, to the opposite retina and (2) this erroneous retino-retinal projection persists throughout the whole lifespan of the animals.

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PubMed1989

Neuropeptide Y-like immunoreactive amacrine cells in the retina of Bufo marinus.

Neuropeptide Y-like immunoreactive (NPY-LI) amacrine cells of the Bufo marinus retina were morphologically characterized, and their retinal distribution was established using immunohistochemistry on retinal wholemount preparations and sectioned material. The somas of NPY-LI amacrine cells were situated in the innermost part of the inner nuclear layer and their dendrites branched primarily in the scleral sublamina of the inner plexiform layer. A subgroup of the NPY-LI cells had dendrites in both the scleral and vitreal sublamina. All immunoreactive cells had large dendritic fields (average 0.5 mm2) that resulted in a high dendritic overlap across the retina. NPY-LI amacrine cells were evenly distributed across the retina, with an average density of 30 cells/mm2, although higher densities were observed at regions adjacent to the ciliary margin. The dendritic field size of the NPY-LI cells, together with the previously characterized substance P-like immunoreactive (SP-LI) amacrine cells, indicates that they belong to the class of wide-field amacrine cells. However, unlike the SP-LI neurons whose dendrites branch in the vitreal sublamina of the inner plexiform layer, the dendrites of the majority of the NPY-LI neurons branch in the scleral sublamina.

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PubMed1989

The development and the topographic organization of the retinal ganglion cell layer in Bufo marinus.

The number and distribution of neurons in the retinal ganglion cell layer were studied from the metamorphic climax to adulthood in the toad Bufo marinus. Retinal wholemounts stained with cresyl violet showed that total neuron numbers increased from 55,000 at metamorphic climax to about 950,000 in adult animals. During the same time the entire retinal area increased 46-fold from an average 3.4 mm2 to 157 mm2. The morphological character of the neurons and their density across the retina changed during development. In metamorphosing animals, the neurons of the ganglion cell layer had a uniform appearance and their density increased slightly from the centre to the dorsal ciliary margin. After metamorphosis a high neuron density area, the visual streak, evolved in the retinal centre, resulting in the formation of a 6 to 1 density gradient from the visual streak out to the dorsal and ventral retinal poles in adult animals. Optic fibre numbers in juvenile and adult optic nerves were estimated to be 330,000 and 745,000, respectively, corresponding to similar ganglion cell numbers. One optic nerve was sectioned in a few animals and 4 weeks later the number of intact neurons--assumed to be displaced amacrine cells (DA)--was estimated. They amounted to 80,000 in juvenile and 189,000 in adult animals or about 20% of the total neuron population of the retinal ganglion cell layer, the remaining 80% being GC. A 1.7 to 1 density gradient of DA from the visual streak out to the dorsal and ventral retinal periphery was established.(ABSTRACT TRUNCATED AT 250 WORDS)

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