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K Pohlhammer

Publications and source records attributed to K Pohlhammer.

14 recordsLinked to original sources
PubMed1990

Immunohistochemical characterization of a widely spread Arg8-vasopressin-like neuroendocrine system in the cricket Teleogryllus commodus Walker (Orthoptera, Insecta).

Two distinct neurons located paramedially within the suboesophageal ganglion of female Australian crickets Teleogryllus commodus were shown to contain Arg8-vasopressin-like immunoreactivity. Immunostained processes project throughout the ganglion. They pass the circumoesophageal connectives, and finally they branch out and enter the neurohemal region of the deuterocerebrum. By means of radioimmunoassay in homogenized cricket brains and suboesophageal ganglia evidence could be found for the presence of a neurohypophyseal-peptide-like substance. Immunofluorescence findings indicate that immunoreactive axonal tracts extend backwards through the ventral nerve cord to the terminal ganglion. Numerous beaded axons with specific immunostaining were also detected within the lateral nerves.

Animals↗
PubMed1986

Skin peptides in Xenopus laevis: morphological requirements for precursor processing in developing and regenerating granular skin glands.

The biosynthesis of the peptides caerulein and PGLa in granular skin glands of Xenopus laevis proceeds through a pathway that involves discrete morphological rearrangements of the entire secretory compartment. Immunocytochemical localization of these peptides during gland development indicates that biosynthetic precursors are synthesized in intact secretory cells, whereas posttranslational processing requires morphological reorganization to a vacuolated stage. The bulk of the processed secretory material is then stored in vacuolae-derived storage granules. In the mature gland, storage granules are still formed at a low level. However, in this case processing takes place in a distinct cytoplasmic structure, the multicored body, which we suggest to be functionally equivalent to vacuolae. When granular glands regenerate after having lost all their storage granules upon strong stimuli, another morphological pathway is used. 2 wk after gland depletion, secretory cells become arranged in a monolayer that covers the luminal surface of the gland. Storage granules are formed continuously within these intact secretory cells. Here, precursor processing does not require a vacuolated stage as in newly generated glands but occurs in multicored bodies. Most storage granules seem to be formed in the third week of regeneration. The high biosynthetic activity is also reflected by the high activity of the putative processing enzyme dipeptidyl aminopeptidase during this period of regeneration.

Animals↗
PubMed1983

Somatostatin-immunoreactive cells in the gastro-entero-pancreatic endocrine system of Xenopus laevis.

Somatostatin-like immunoreactivity has been demonstrated in cells of the gastro-entero-pancreatic endocrine system of Xenopus laevis (Amphibia) using peroxidase-anti-peroxidase immunohistochemistry. The identified cells of the gastro-intestinal tract correspond to the "Open-Paraneurons" of FUJITA (1974). Somatostatin-immunoreactive cells were found in the stomach (fundic and pyloric region), the duodenum and in the anterior ileum, but not in the colon. The dimensions of these 'Somatostatin-Open-Paraneurons' were measured: mean maximum height = 41.31 micron (S.D. = 10.87 micron), mean maximum breadth = 8.73 micron (S.D. = 2.31 micron). Frequency distributions of the maximum height and of the maximum breadth were processed by use of a computer. Somatostatin-immunoreactive cells in the pancreatic islets occupied about 15 to 25% of the total islets volume. These cells are "Closed-Paraneurons" (according to FUJITA 1974) with a mean diameter of 11.68 micron (S.D. = 2.61 micron).

Animals↗
PubMed1978

The paramedial neurosecretory cells of the suboesophageal ganglion of the cricket, Teleogryllus commodus (walk.).

Ovariectomy, performed immediately after the final hatch, caused a reduction of stainable (neurosecretory?) MATERIAL IN THE PARAMEDIAL NEUROSECREtory cells (PNC) (A-type) of the suboesophageal ganglion in 10 day-old females of Teleogryllus commodus (Walk.). A concomitant increase in nuclear volume and in the incorporation of 35S-cysteine indicates increased synthesis of neurosecretory material. From these findings it is concluded that more stainable material is secreted in the cerebral neurohaemal organ after ovariectomy. A functional relationship between the PNC and the ovaries is suggested.

Animals↗
PubMed1978

The paramedial neurosecretory cells of the suboesophageal ganglion in the cricket, Teleogryllus commodus (walk.). II. Electron microscopic studies in normal and ovariectomized females.

The paramedian neurosecretory cells (PNC) (A-type) in the suboesophageal ganglion of the cricket, Teleogryllus commodus (Walk.), have been studied by electron microscopy. In control animals (10 day-old virgin females) three different cell stages could be distinguished: Stage 1 shows a variable content of elementary granules and characteristics of actively synthesising cells. Stage 2 is characterised by the presence of numerous fusion bodies, which are formed by the coalescence of elementary granules, presumably for storage purposes. In stage 3 granules are degraded in lysosomes (?). While the production of material rich in cysteine increases after ovariectomy (Dürnberger et al., 1978), the fine structure of the cells is essentially unchanged. The only noted differences are an increased lysosomal synthetic activity and the existence of stages intermediate between 2 and 3, which were never found in control animals. The functional significance of the different stages is discussed.

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