PubMed Health⌕ Search

Biomedical subjects

J V Johannessen

Publications and source records attributed to J V Johannessen.

113 records · Page 7Linked to original sources
PubMedDate not supplied

Follicular carcinoma of the human thyroid gland: an ultrastructural study with emphasis on scanning electron microscopy.

Previous ultrastructural studies on follicular thyroid carcinomas present conflicting results, in particular with regard to the surface features of the neoplastic cells. The present study of 9 cases with varying degrees of differentiation is the first comprehensive investigation by concurrent transmission and scanning electron microscopy. In the well-differentiated tumours we found a slightly increased number of microvilli and a decreased number of cilia per cell as compared to the normal thyroid follicles, while moderately differentiated tumours had a smaller number of microvilli and no cilia. The cells in anaplastic foci had unimpressive surfaces with only scattered clusters of short microvilli. Neither scanning nor transmission electron microscopy seem to be of major importance in the diagnostic evaluation of the individual case of follicular thyroid carcinoma or in the assessment of prognosis. Scanning electron microscopy presents a wealth of information on the three dimensional surface arrangement of the neoplastic cells. However, in a tumour where surface alterations may reflect both changes in endocrine function and malignant potential, the interpretation of isolated morphological findings is extremely difficult.

Adenocarcinoma↗
PubMedDate not supplied

Hereditary renal adenomas and adenocarcinomas in rats.

An animal model of renal adenomas and adenocarcinomas is described in rats where tumour development depends on an autosomal dominant gene. This gene seems to have a direct effect on the kidney. Most of the tumours develop from the proximal convoluted tubules. This is the first known animal model where kidney tumours develop on an hereditary basis. The histopathology of the renal tumours not only resembles that of chemically induced rat kidney tumours but also human tumours.

Adenocarcinoma↗
PubMedDate not supplied

Diagnostic ultrastructural pathology--sub-speciality or special stain?

The high resolving power of the electron microscopy gives ultrastructural pathology many of the features of a 'sensitive, multipurpose stain'. But the high resolution gives rise to problems of evaluation since most pathological features of disease are specific in a quantitative rather than in a qualitative way. Thus, pathological changes may be of diagnostic importance when they are severe enough to be seen by light microscopy, but less so when only revealed by electron microscopy. Problems of evaluation and interpretation should not lead to paralysing nihilism but should make us realize that electron microscopy does not represent the ignorant pathologist's key to a diagnostic heaven, no more than do special stains, histochemistry and immunocytochemistry. At present it may be necessary to organize ultrastructural pathology as a kind of sub-speciality of pathology. In the long run, we feel that sub-specialities should be related to the object studied rather than to the instrument used. Thus, the neuropathologist should do ultrastructural neuropathology, the cytologist ultrastructural cytopathology, etc. in the same way as most kidney pathologists already do their own ultrastructural work.

Diagnosis, Differential↗
PubMedDate not supplied

Cellular DNA content in normal human thyroid: a flow cytometric study based on frozen biopsy material.

A method is presented for preparing conventionally frozen biopsy material of thyroid tissue for flow cytometric measurement of DNA content in individual cells. The accuracy of the method was established by measuring cell suspensions of 24 biopsies of normal thyroid tissue from 20 patients. Biopsy material immersed in Histocon preservative solution prior to freezing was found to give better results than material frozen dry. All samples were found to have approximately the same modal DNA value (i.e. diploid), as determined by calibration of the fluorescence measurement with a standard of fluorescent microspheres. It was found that for an unknown sample, a deviation in modal DNA content of more than 13-14 per cent from diploid can be classified as significant by this technique.

Cell Aggregation↗