use of microwave accelerated chemical fixation for processing of sample for electron microscopy

A domestic microwave oven was used in this study. Total exposure time to microwave irradiation was 10 seconds. Liver specimens from five albino rats were taken. Specimens were divided into five groups. The first group represented the conventional chemical fixation without the use of microwaves, while fixation in the remaining four groups was done using microwave irradiation alone or assisting different chemical fixatives. The mere use of microwave irradiation for fixation gave disappointing results and caused severe tissue damage. The microwave-glutaraldehyde fixation resulted in good degree of preservation of most of intracytoplasmic constituents, except for ill defined membranes. The use of microwave-osmium fixation gave a very good preservation of liver ultrastructure, but with the disadvantage of faint stained chromatin. The excellent preservation of liver tissue with well demarcated ultrastructural morphological details equivalent to the chemical conventional method was obtained by the sequential use of microwave-glutaraldehyde fixation followed by microwave osmium post-fixation

Ultrastructure of the alveolar-capillary membrane in children with patent ducts arteriosus at different age groups

The ultrastructure of the alveolar-capillary membrane [ACM] was studied in twelve children with patent ductus arteriosus [PDA], divided into three subgroups according to their ages, and in three control children complaining of non cardiac localised chest lesions. Lung biopsies were obtained at the time of thoracotomy. The results revealed definite thickening of the air-blood barrier in the study biopsies. The degree of thickness increased with age. The causal factors for thickening of ACM in children younger than two years, were mainly due to interstitial oedema and mesenchymal cellular deposition. Some degree of elastic and collagen proliferation was noticed as well. In biopsies of old children, the main factor was the massive collagen deposition. The basement membranes of both endothelial and epithelial cells were thin and did not share in membrane thickness. The endothelial cells revealed no changes at age younger than two years, while in old children they exhibited excessive pinocytosis, cytoplasmic bleb formations filled with plasma exudate and abnormal lipid deposition. The alveolar epithelium revealed, in old children, predominance of pneumocyte type II cells to replace the injured type I cells. The findings of the present study constituted a strong motive for early interference to close the ductus whenever its diagnosis becomes certain