C-cell adenoma containing variously sized thyroid follicles in a horse.

This study examines an unusual thyroid gland tumor in a 13-year-old Andalusian horse, looking in-depth at the structure and characteristics of the tumor cells.

Tumor Analysis

• The research focused on a tumor found in the thyroid gland of a horse. The odd characteristics of the tumor made it a subject of interest.
• Under the microscope, scientists noticed the prevalence of a specific type of cell known as a C-cell or parafollicular cell. These cells were made identifiable due to the presence of fine granules within the cell’s cytoplasm.
• The C-cells were not isolated; instead, they surrounded varying sizes of follicles that contained a substance known as colloid. This distribution pattern was diffuse throughout the examined tissue.

Immunohistochemical Observations

• Immunohistochemistry, a technique used to identify cells in tissues by use of antibodies, was utilised to establish the type of cell present in various sections of the tumor.
• The C-cells showed a positive reaction for calcitonin, a hormone produced in the thyroid gland. This coincided with the understanding of normal CELL functions, allowing them to be definitively identified.
• Additionally, the cells forming the follicles also illustrated the presence of thyroglobulin, a protein essential for the production of thyroid hormones, when tested immunohistochemically. This result further added to the understanding of the tumor’s makeup.

Ultrastructural Findings

• For more detailed insights, ultrastructural examination was conducted, which presents the fine detail of tissue and cell structure.
• In the C-cells, secretory granules encapsulated by a membrane and up to 250 nm in diameter were found, giving insights into their possible function and behavior within the tumor.
• The follicular epithelial cells also displayed unique attributes, including the presence of microvilli (small projections that increase the cell’s surface area), junctional complex (structures that connect cells together), and endoplasmic reticulum (an important organization site for cellular activity). These findings further elucidate the intricate structural detailing of the tumor.