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Biomedical subjects

G T Bazer

Publications and source records attributed to G T Bazer.

16 recordsLinked to original sources
PubMed1991

Ontogeny of the olfacto-retinalis projection in coho salmon (Oncorhynchus kisutch).

Filling of nucleus olfacto-retinalis neurons by cobaltous lysine injections into one eye of coho salmon of different ages revealed that the terminal nerve projection to the retina is established when the fish leave their freshwater environment. At this time salmons go through a metamorphosis termed "smoltification." FMRF-amide-like immunoreactive neurons in the nucleus olfacto-retinalis already exist in pre-smolts before the retino-petal projection is established. Thus, for the first time in any vertebrate, a projection of the terminal nerve is shown to develop during an advanced ontogenetic state.

Animals↗
PubMed1988

Retinal projections in sockeye salmon smolts (Oncorhynchus nerka).

The retinal projections in 2-year-old salmon smolt (Oncorhynchus nerka) are significantly different from those observed in other teleosts examined to date in that the projections are more extensive. Very noticeable are extensive projections to most of the dorsal thalamus, to all layers of the optic tectum, and into the periaqueductal gray of the torus semicircularis. The salmon smolt has bilateral retinal projections to the diencephalon and pretectum. A small retinal projection to the lateral habenular nucleus has not been described previously. Although these findings suggest striking differences in retinal projections among teleosts, this variation may relate to age differences since the previously studied teleosts were adults.

Animals↗
PubMed1987

Double labeling of neural circuits using horseradish peroxidase and cobalt.

This describes for the first time a non-fluorescent method for studying the connectional interrelationship of two neuronal systems in the same histological sections in which the systems are stained in two different colors (blue and brown). Since HRP and cobaltous-lysine are transported in both anterograde and retrograde directions, it is possible to manipulate the experiments to determine, for example, how the terminal fields of two systems overlap in a given neuropil, or cell aggregate, or how the projections of one system relate to retrogradely stained neurons of another system. The simple staining of HRP and cobalt is accomplished on cryostat sections and involves the combined technology of two previously published methods. The results described here are limited to a comparison of the overlap or lack of overlap of inputs to the thalamus from the two eyes in Xenopus, but the method has also proven useful in similar studies on Ambystoma tigrinum and Esox niger.

Ambystoma↗
PubMed1986

Some primary olfactory axons project to the contralateral olfactory bulb in Xenopus laevis.

Cobaltous lysine and horseradish peroxidase (HRP) were used to trace primary olfactory axons to their terminations. The tracers were taken up in the olfactory mucosa and transported to the olfactory bulb. The results suggest that either HRP or cobaltous-lysine methods are useful and simple tools for studying such connections. In addition to the ipsilateral projection, we report here for the first time a projection to the medial part of the contralateral olfactory bulb. The overlaps of ipsi- and contralateral inputs to the medial bulb provide further evidence that its functions in frogs may be different from the lateral part, because other connections differ as well.

Animals↗
PubMed1985

Axosomatic retinal projection to deep tectal neurons and retinopetal neurons in largemouth bass (Micropterus salmoides lacepede).

Retinal connections were studied in largemouth bass with a cobalt-lysine method. Retinopetal neurons were identified in the area ventralis pars ventralis of the telencephalon. The retinofugal pathways are the same as reported earlier, except for a massive projection to one layer of cells in the striatum griseum periventriculare of the optic tectum. Such a projection has not previously been reported in any vertebrate.

Animals↗
PubMed1984

A simplified cobalt-lysine method for tracing axon trajectories in the central nervous system of vertebrates.

The cobalt-lysine method for tract tracing in the vertebrate CNS has been shortened and simplified to the following steps: (1) the cobalt-lysine is applied to the nerve or tract being studied; (2) the animal is perfused 1-2 days later by the following sequence of solutions: (a) phosphate-buffered ammonium sulfide, (b) phosphate buffer alone and (c) phosphate-buffered glutaraldehyde; (3) the brain is exposed to the fixative overnight and left in 30% sugar another night; (4) the brain is then frozen and cut on a cryostat; the sections being collected directly on slides; (5) the mounted sections are then put in an intensification solution before dehydration, clearing and coverslipping.

Ambystoma↗
PubMed1983

A model of an intraprostatic vas deferens in the rat.

The study of the effect of hormones in seminal fluid upon prostate tissue is hampered by the lack of a suitable model. Such a model is described in this paper, and its possible usefulness is discussed. The vas deferens of the rat is moved from its normal position into a surgical incision into the ventral prostate. Squamous metaplasia of epithelium in prostatic acini at early stages is replaced by cuboidal epithelium. At later stages, normal-appearing glandular epithelium is seen as close as 50 micrometers to the vas deferens. The structure of the vas deferens is not affected.

Animals↗
PubMed1982

Presence of adrenal medullary chromaffin cells in primary adrenal dispersions and their persistence in long-term culture.

Cell suspensions prepared by enzymatic dispersion of whole rat adrenal glands for the purpose of studying adrenocortical cells were found to contain chromaffin cells even though they are commonly thought to not survive in such preparations. These cells fluoresced when treated with methods specific for catecholamines. The fluorescent cells persisted in the cultures of "cortical" cells, took on the morphology of neurons in the cultures, maintained their specific catecholamine fluorescence in long-term cultures, and ultrastructurally were identical to chromaffin cells.

Adrenal Cortex↗
PubMed1980

Mithcondrial glutamine permeability and renal ammonia production in metabolic acidosis.

These experiments were undertaken to determine the correspondence between acidosis-induced in situ motochondrial glutamine uptake and the process by which glutamine moves across the mitochondrial membrane. Feeding rats 1.5% NH4Cl for 2 wk accelerated the in situ uptake rate from 0.12 +/- 0.08 to 1.89 +/- 0.28 mu mol/min or some 16-fold. To determine glutamine uptake independent of its metabolic conversion, D-glutamine was employed. In isolated mitochondria from non-acidotic rat kidneys, D-glutamine diffused into 71 +/- 10% of the mitochondria water volume; in acidotic mitochondria the diffusion volume increased to 127 +/- 16%. The reflection coefficients (sigma) for a series of amides, including glutamine, were determined by gravimetrically following volume decrements in increasing concentrations of solute; D-glutamine's sigma fell from 1.05 +/- 0.08 to 0.50 +/- 0.06 in acidotic rat kidney mitchondria, The permeability coefficients corresponding to the measured sigma were 10(-7) cm/s and 10(-5) cm/s in nonacidosis and acidosis, respectively. When viewed in situ proximal tubule mitochondria undergo dramatic alterations during chronic acidosis. These involved an enlargement in the mitochondria particularly in the basal region of the cell and a reduction in number. Furthermore, numerous autophagic vacuoles, containing mitochondria, appear in the basal region. The findings are consistent availability that becomes activated during acidosis as a consequence of mitochondrial glutamine permeability resulting in increased ammoniagenesis and accelerated organelle turnover.

Acidosis↗
PubMed1980

An inexpensive vibrating microtome for sectioning fixed tissue.

A tissue sectioner which uses a vibrating razor blade and a simple mechanism for the elevation of the tissue can be constructed for less than fifty dollars. The razor blade in fixed to the vibrator of a hair clipper and a nut and bolt serve as the tissue advance mechanism. A metal disc attached to the nut is used for the stage. The tissue advance mechanism is placed inside a machined teflon cylinder which provides a smooth surface upon which the razor assembly is moved. Fixed tissue may be sectioned uniformly at a thickness of 50 micrometer or more. This device has the advantages of portability, rapidity of sectioning, and inexpensive construction.

Microtomy↗
PubMed1980

Basal cell proliferation and differentiation in regeneration of the rat ventral prostate.

To determine the nature of the proliferative response of the rat ventral prostate to partial excision, parts of each lobe were excised and the residual tissue examined by light and electron microscopy. This first evidence of regrowth was the appearance of squamous cells in tubules near the wound surface with concurrent stromal proliferation but no hyperplasia of deeper tissue. A cribriform pattern of alveoli subsequently developed. Transmission electron microscopy revealed transformation of basal cells into squamous cells that contained ribosomes, polyribosomes, numerous mitochondria, tonofibrils, small to moderate amounts of rough endoplasmic reticulum, a prominent Golgi apparatus, and multivesicular bodies. These findings indicate that the regenerative response consists of basal cell hyperplasia and squamous metaplasia that is limited to the wound surface and to those tubules continuous with it.

Animals↗
PubMed1979

Visualization of intrarenal catecholamine-containing elements: fluorescence histochemistry and electron microscopy.

Fluorescence histochemistry and electron microscopy were used to study catecholamine-containing elements in rat and cat kidneys. There were fluorescent nerve plexuses associated with the arterial system of the renal cortex from which nerves extended into the medulla forming dense networks in the vascular bundles of the outer part of the medulla. Also, there were small cells found singly and in clusters which emitted the blue fluorescence characteristic of catecholamine-containing cells. These cells were associated with the periarterial nerve plexuses and were frequently encountered in the cat medullary vascular bundles. Electron microscopy of the cat renal medulla revealed processes with the structure of typical adrenergic terminals and other processes that resemble small intensely fluorescent (SIF) cell processes.

Adrenergic Fibers↗