Comparative immunohistochemical study of stellate cells in normal canine and equine adenohypophyses and in pituitary tumours.

The research article presents an immunohistochemical comparative study of stellate cells in normal and tumorous pituitary glands in dogs and horses. The study examined the presence and distribution of several proteins and antigens within these cells and found a significant presence of S100 protein subunits. Results also indicated the stellate cells in these animals are more closely related to epithelial than glial cells, a characteristic not seen in humans or mice.

Objective of the Research

• The main aim of the research was to study the presence and distribution of certain proteins and antigens in stellate cells, both in normal and tumorous pituitary glands of dogs and horses. Proteins and antigens, like the S100 protein (alpha and beta subunits), cytokeratin polypeptides, etc., were examined in the research.

Methodology of the Study

• The study was conducted immunochemically on four normal canine pituitary glands, five canine pituitary adenomas, two canine pituitary carcinomas and two equine pituitary adenomas, along with surrounding normal glandular tissue.
• Its focus was on the stellate cells of the pars distalis and pars intermedia of the adenohypophyses (anterior pituitary gland) of both dogs and horses.

Key Findings of the Research

• The stellate cells showed a strong reaction with antibodies against S100 protein subunits alpha and beta.
• In contrast, the stellate cells did not react with antibodies against intermediate filament proteins, neuroendocrine markers, HLA-class II DR antigen or pituitary hormones.
• Other cell types, i.e., polygonal cells and marginal epithelial cells, also expressed both subunits of the S100 protein.
• An interesting observation was that the distribution of alpha and beta subunits in pituitary tumour cells differed between dogs and horses.

Conclusion and Suggestions of the Study

• The study concluded that stellate cells of the adenohypophysis in dogs and horses are more closely related to epithelial than to glial cells, distinct from the case in humans or mice.
• No subpopulation of cells of bone marrow origin was identified among the canine stellate cells, as they lack MHC class II antigen.
• The researchers noted that the presence of S100-immunoreactive cells was more striking in canine and equine tumours compared to human tumours.