PubMed Health⌕ Search

Biomedical subjects

N Quintana

Publications and source records attributed to N Quintana.

29 records · Page 2Linked to original sources
PubMed1971

Golgi apparatus, GERL, and lysosomes of neurons in rat dorsal root ganglia, studied by thick section and thin section cytochemistry.

New insights into the ultrastructure and phosphatase localizations of Golgi apparatus and GERL, and into the probable origin of lysosomes in the neurons of fetal dorsal root ganglia and the small neurons of adult ganglia have come from studying thick (0.5-1.0 micro) as well as thin (up to 500 A) sections by conventional electron microscopy. Tilting the thick specimens, by a goniometer stage, has helped to increase our understanding of the three-dimensional aspects of the Golgi apparatus and GERL. One Golgi element, situated at the inner aspect of the Golgi stack, displays thiamine pyrophosphatase and nucleoside diphosphatase activities. This element exhibits regular geometric arrays (hexagons) of interconnected tubules without evidence of a flattened portion (saccule or cisterna). In contrast, GERL shows acid phosphatase activity and possesses small cisternal portions and anastomosing tubules. Lysosomes appear to bud from GERL. Osmium deposits, following prolonged osmication, are found in the outer Golgi element. Serial 0.5-micro and thin sections of thiamine pyrophosphatase-incubated material demonstrate that, in the neurons studied, the Golgi apparatus is a continuous network coursing through the cytoplasm. Serial thick sections of acid phosphatase-incubated tissue suggest that GERL is also a continuous structure throughout the cytoplasm. Tubules of smooth endoplasmic reticulum, possibly part of GERL, extend into the polygonal compartments of the inner Golgi element. The possible physiological significance of a polygonal arrangement of a phosphatase-rich Golgi element in proximity to smooth ER is considered. A tentative diagram of the Golgi stack and associated endoplasmic reticulum in these neurons has been drawn.

Acid Phosphatase↗
PubMed1966

Nucleoside phosphatase and cholinesterase activities in dorsal root ganglia and peripheral nerve.

IN DORSAL ROOT GANGLIA AND PERIPHERAL NERVE OF THE RAT AND OTHER SPECIES, NUCLEOSIDE PHOSPHATASE AND UNSPECIFIC CHOLINESTERASE REACTION PRODUCTS ARE FOUND IN THE PLASMA MEMBRANES AND SPACES BETWEEN THEM AT TWO SITES: (1) Schwann cell-axon interfaces and mesaxons of unmyelinated fibers, and (2) sheath cell-perikaryon interfaces and interfaces between adjacent sheath cells. Acetylcholinesterase reaction product is found in the perikaryon (within the endoplasmic reticulum) and the axon (axoplasmic surface). Nucleoside phosphatase reaction product is also found in the numerous vacuoles at the surface of perineurium cells, ganglion sheath cells, and cells surrounding some ganglion blood vessels. Nucleoside phosphatase activities in the sections fail to respond, in the manner described for "transport ATPase," to diisopropylphosphofluoridate, sodium and potassium ions, and ouabain. Nucleoside diphosphates are hydrolyzed more slowly than triphosphates in unmyelinated fibers, and are not hydrolyzed at the perikaryon surface. Nucleoside monophosphates are either not hydrolyzed or hydrolyzed very slowly. In contrast to these localizations, which are believed to demonstrate sites of enzyme activity, it is considered likely that diffusion artifacts account for the nucleoside phosphatase reaction product frequently found along the outer surfaces of myelinated fibers and within vacuoles at the Schwann cell surfaces of these fibers. The diffuse reaction product seen in basement membranes of ganglion and nerve may also be artifact.

Adenosine Triphosphatases↗