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A Hendrickson

Publications and source records attributed to A Hendrickson.

50 records · Page 3Linked to original sources
PubMed1975

Tracing neuronal connections with radioisotopes applied extracellularly.

Methodological and technical problems of the autoradiographic-neuroanatomical tracing (ARNT) technique are discussed. The size of the labeled area after a tritiated amino acid injection varies directly with the volume of isotope, the rate of injection, and the length of exposure of the secretion to the emulsion. Frozen sections can be used for autoradiography if they are mounted on subbed slides, dehydrated in ethanol, defatted for 1 hour in xylene, rehydrated through ethanol and water, and dried before coating with emulsion. Brushes used for mounting frozen sections should be used only for this purpose and dipped in boiling distilled water before use to avoid chemoreduced streaks in the emulsion due to contamination from the brushes. Excessive dilution of Kodak emulsion can leave less than a monolayer of grains over certain types of sections; the emulsion thickness should be checked by exposing coated test sections to a brief flash of light and developing immediately. A high intensity safelight recommended for the ARNT darkroom is the Thomas Duplex Super monochromatic sodium vapor bulb safelight; for Kodak NTB-2, -3 and Ilford L4 emulsions the red-banded and yellow-banded filters are used. A useful stain combination for ARNT is Luxol fast blue stained before coating and cresyl violet stained after developing which demonstrates both neuronal cell bodies and myelinated tracts in the same section.

Amino Acids↗
PubMed1969

Electron microscopic radioautography: identification of origin of synaptic terminals in normal nervous tissue.

A method combining intraocular injection of tritiated leucine and electron microscopic radioautography has been used to study the distribution of optic nerve terminals in the monkey lateral geniculate nucleus. Radioactive label is found in only one type of synaptic terminal, which demonstrates that this terminal is of retinal origin and that this approach can be used to study the origin of synaptic terminals in normal tissue.

Animals↗
PubMedDate not supplied

Shifting relationships between photoreceptors and pigment epithelial cells in monkey retina: implications for the development of retinal topography.

This study examines the spatiotemporal relationships between retinal pigment epithelium (RPE) and photoreceptors (PR) during development of Macaca nemestrina retina. Our aim was to learn more about the developmental dynamics of these two important cell populations, particularly whether development changes in RPE cell densities mimic those of PR at selected retinal points. Twelve eyes ranging in age from 100 fetal days (Fd) to adulthood were flatmounted; the retinal perimeters were traced; and then sample punches were taken of the RPE and neural retina at the fovea, optic disc, mid- and far-nasal periphery, and far temporal, inferior and superior periphery. The two tissues were gently separated and the RPE cells and photoreceptors from the same region of the punch were counted using Nomarski contrast interference optics. We found that the total number of cones remains stable around 4 million between Fd100 and adulthood, but RPE number increases from 1.6 million at Fd100 to 2.56 million in adulthood. At the fovea, the core:RPE ratio increases from 5.4:1 at Fd100 to 28:1 by adulthood. In the temporal periphery by contrast, the cone:RPE ratio declines from 2.2:1 at Fd100-110 to less than 1:1 in the adult. In the vicinity of the optic disc, the ratio of (cones+rods); RPE remains around 35:1 throughout development, but in the retinal periphery it decreases to the adult value of 22:1. These changing ratios indicate that photoreceptors and RPE cells are redistributed independently during development, and that these two cellular sheets slide over one another to achieve their final distribution. This situation suggests that the forces or factors causing foveation are intrinsic to the neural retina.

Aging↗