Optimization of Testicular Fixation-Embedding Techniques for Improved Evaluation of Mammalian Spermatogonial Morphology and Function

Numerous methods have been successfully used to evaluate mammalian spermatogonial biology However, the conventional light microscopy assays present a challenge in precisely identifying spermatogonial phenotypes, which can result in discrepancies between molecular and morphological findings. Such precise association could lead to a more robust interpretation of spermatogonial activity in steady-state spermatogenesis, which may facilitate the translation from basic research to clinical applications. In this chapter, we present two histological processing methods that enable a comprehensive analysis of spermatogonial morphology and function, involving fixation of mammalian testicular tissue in glutaraldehyde and embedding in plastic resin. These techniques have proven to be effective in light microscopy studies.

Tissue Processing for Stereological Analyses of Lung Structure in Chronic Obstructive Pulmonary Disease

Quantitative data on lung structure, such as volume, surface area and length, are used for assessment of the functional performance of the lung during normal development and inflammatory-related diseases such as chronic obstructive pulmonary disorder (COPD), and carcinogenesis, in animal models. Stereology is considered as the gold standard to obtain quantitative data on lung structure, with a key advantage being to quantify irregular three-dimensional structures on the basis of measurement made on two-dimensional sections. Therefore, preservation of original tissue dimensions without shrinkage is vital for stereology.Three steps, fixation, sampling and embedding, are essential requirements to minimise tissue shrinkage to obtain theoretically unbiased estimates of stereological parameters of lung structures. Perfusion fixation by intratracheal instillation with 1.5% glutaraldehyde/1.5% formaldehyde at a pressure of 25 cm fluid column is considered as one of the best methods. A systematic uniform random sampling scheme is then applied to the fixed lung to ensure each and every part of the lung is analysed, irrespective of homogeneity or heterogeneity of the structural distribution. The sampled tissue sections are then embedded in glycol methacrylate to minimise further tissue shrinkage. Here we describe the accurate fixation, sampling and embedding for stereological methods to quantify lung structures in mice.