Immunohistochemical observations on TSH secreting cells in pituitary glands of goat kids with congenital goitre.

Pituitary glands of normal-termed stillborn goat kids with congenital goitre and normal-termed stillborn goat kids without congenital goitre were examined macroscopically, histopathologically and immunohistochemically. Thyroid glands of these animals were also examined grossly and microscopically. The pituitary glands of kids with goitre were larger than those of normal kids, and on histopathological examination there was hyperplasia of the acidophil cells in the ventral part of the glands. However, it was impossible to distinguish thyroid stimulating hormone (TSH)-secreting cells from other acidophil cells in sections stained with haematoxylin and eosin (HE). Red granules were observed in the cytoplasm of these hyperplastic cells in periodic acid-Schiff (PAS)-stained sections. Sections were also immunostained with an antibody against TSH using the streptavidin-biotin peroxidase technique. Immunohistochemistry revealed TSH-secreting cells to have increased in number in the pituitary glands of kids with congenital goitre because of the extensive proliferation when compared with those of normal kids. The present study indicated that the presence of multiple fetuses (twins or triplets) may be a predisposing factor for congenital goitre.