We investigated microwave-stimulated fixation of tissues for transmission electron microscopy using a domestic microwave oven operating at a frequency of 2.45 GHz with an output power of 500W. Microwave-stimulated fixation, in 4% glutaraldehyde, of fresh rat kidney, liver, heart and brain tissues was compared to conventional fixation. Human renal biopsies were similarly studied. Electron microscopy showed excellent ultrastructural preservation comparable to that obtained by conventional fixation. The optimal temperature range for microwave-stimulated fixation was found to lie between 50 degrees C and 55 degrees C. Our results indicate that microwave-stimulated fixation is a rapid and reproducible technique and can be effectively applied to routine diagnostic pathology.
1853 thyroid lesions subjected to cytological sampling (either by the fine needle aspiration or fine needle capillary sampling technique) from January 1992 to December 1997 at the University Hospital, Kuala Lumpur, were reviewed. Nodular goitre was the most common thyroid lesion needled (67.35%). Among the neoplastic lesions, follicular neoplasms predominated (64%), followed by papillary carcinoma (29.4%). In 325 cases, partial or total thyroidectomy had been done, providing material for histological review and cyto-histological correlation. Cytological diagnosis was found to have high sensitivity and specificity rates of over 75%. Besides, most non-neoplastic thyroid lesions could be diagnosed on cytology. The scope of cytology in the diagnosis of lymphomas, anaplastic and metastatic tumours rendered diagnostic biopsies (or thyroidectomy) unnecessary in these cases. Being a cost-effective technique and having the capacity to provide exact morphological diagnosis in a large variety of thyroid lesions, cytology is obviously the method of choice in the assessment of thyroid nodules.
The use of the colloidal-gold technique in electron microscopy immunocytochemistry has provided important information on the in situ localisation of intracellular antigens. We have developed a post-embedding technique for prolactin localisation on resin-embedded human pituitary tissue sections by the use of the protein-A gold conjugate. Human pituitary tissue obtained at autopsy was processed for electron microscopical study without post-osmication and then embedded in Epon. The indirect immunoperoxidase method was used for light microscopical targetting of lactotroph cells for subsequent electron microscopical antigen localisation. Ultra-thin sections were labelled with human anti-human prolactin followed by protein-A gold conjugate. Specific labelling was observed over secretory granules with a density of 15-30 particles per granule, as determined by the Quantimet 570 image analysis system. This technique provides a means of studying the pathophysiology of hormonal secretion at ultrastructural level and can be a useful tool in diagnostic and research investigations.