Low noise electron microscopy by merging multiple images digitized from conventional films with reference to the mouse kidney

Telocytes in the interstitium of human exocrine pancreas: ultrastructural evidence

OBJECTIVES

Pancreatic interstitial cells are located among acini, ducts, nerves, and blood vessels. They are essential for pancreas development, physiology, and for oncogenic microenvironment. We identified cells with characteristic ultrastructural features of telocytes in pancreatic interstitium. Telocytes were initially described as interstitial Cajal-like cells, but it gradually became clear that they were a distinct novel cell type not directly related to canonical interstitial Cajal cells.

METHODS

Serial ultrathin sections of human pancreatic tissue were studied by transmission electron microscopy. Computer analysis software was used to obtain 2-dimensional compositions from serial micrographs and to perform morphometry.

RESULTS

Pancreatic telocytes appear as small-body cells with prolongations called telopodes. The ultrastructural features of telopodes are the following: (a) number: 1 to 3; (b) length: tens of micrometers; (c) moniliform aspect: with podoms (thicker portions) and podomers (thin segments, with a mean width of 60 nm, undetectable by light microscopy); (d) dichotomous branching forming a network; (e) establish homocellular and heterocellular junctions; (f) release of microvesicles/multivesicular bodies. Telopodes pass close to blood vessels, nerves, and pancreatic acinar cells and ducts.

CONCLUSIONS

Telocytes are present as distinct interstitial cells in the exocrine pancreatic stroma. They act as important players in intercellular signaling via stromal synapses and shed vesicle transfer.

Supersampling in PET. A concept for improvement of the resolution of positron emission tomography

At present, the maximum spatial resolution of state-of-the-art PET scanners is not better than 5 mm, whereas the maximum resolution obtained in the resulting images is approximately 10 mm. At least some of this difference is a result of an inherent, complex noise component that can be eliminated using "supersampling". The aim of the study was to apply the supersampling technique to PET image recordings to lower the noise and to improve the in-plane resolution of the recorded images. A standardized phantom was investigated with the supersampling technique. In addition to the standard CT and PET series, 14 further PET series were recorded with the phantom at exactly the same position, and 4 further series were recorded with the phantom placed in another well defined position. After merging corresponding images, the image noise index and the image resolution are both substantially improved. The suggested PET image recording and processing technique provides a substantial increase in PET image quality without exposing the patient to any additional radiation, and might therefore become a powerful tool for investigative as well as diagnostic purposes.