histologies

Histology is the branch of biology and medicine that focuses on the microscopic structure of tissues. It examines how cells interact within tissues to form organs, and it is essential for understanding normal anatomy as well as the changes that occur in disease. Histology traditionally uses light microscopy on fixed, thin sections of tissue, but advances include electron microscopy and various imaging methods. When studying disease, histology is closely linked to histopathology, the practice of diagnosing disease by evaluating tissue architecture and cellular detail after processing and staining.

Typical workflows involve tissue collection by biopsy or surgical specimen, fixation to preserve structure, dehydration and embedding in paraffin, thin sectioning with microtomy, and staining with dyes such as hematoxylin and eosin (H&E). Special stains and immunohistochemical techniques highlight specific components like connective tissue, basement membranes, or proteins, aiding interpretation. Observations are made with light microscopes, and for ultrastructural detail, electron microscopy is used. Modern histology often integrates molecular and digital imaging to quantify features and assess biomarker expression.

Tissues are organized into four basic tissue types: epithelial, connective, muscle, and nervous tissue. Organs consist of parenchyma, which carries out the organ’s specific functions, supported by stroma, including supportive connective tissue and vasculature. Histology also covers development, regeneration, and normal variation among tissues in health.

In medicine, histology underpins cancer diagnosis, transplant assessment, and many diagnostic and research applications. It informs pathology, affects treatment decisions, and supports basic science inquiry into tissue structure and function.

Historically, early microscopists such as Marcello Malpighi and Jan Evangelista Purkinje contributed to tissue-level visualization, laying the groundwork for modern histology. The modern discipline encompasses light microscopy, histopathology, immunohistochemistry, and molecular histology.