Seasonal changes in the Thymus gland of Tilapia Nilotica Fish
*Attia, H.F ; I.M.A El-Zoghby; ; Mona N. A. Hussein and **H. H Bakry
*Dept. Histology &Cytology and ** Dept of Forensic medicine. Fac. Vet. Med. Benha University
This study was carried out on 100 thymus gland of apparent
healthy Tilapia Nilotica fish. The thymus was situated on the superior
edge of the gill cover close to the opercular cavity; the thymus was
surrounded by connective tissue capsule which consisted of collagen
fibers and reticular fibers. The thymocytes (T- lymphocytes) form the
main type of cells present in thymus embedded within network of
epithelial reticular cells. The thymus was characterized by presence of
hassall’s body-like structures, myoid cells, mucin secreting cells and
melanomacrophage cells. The thymus showed great involution in winter
in form of decrease number of lymphocytes, proliferation of connective
tissue and adipose tissue. Thymus showed regeneration of tissue during
spring. Sharp increase in lymphocytes number was observed during
summer as the lymphocytic foci became denser and increased in size . In
autumn the parenchyma was divided into cortico-medullary like zones
with increase in connective tissue proliferation especially in the medulla.
The lymphocytic foci become less dense and decreased in size. |
