Morphoquantitative Analysis of Cloacal Bursa in Fowls (Gallus gallus domesticus, Linnaeus, 1758) Lineage Master Gris Cou Plumé

Abstract

The functions of the cloacal bursa are not known in great detail; therefore, detailed morphophysiological studies are necessary to elucidate the relationship between this structure and the immunity of birds. A quantitative analysis was performed to determine the volume density of lymphocytes (Vv[lymphocytes]) and connective tissue density arranged along the organ. Cloacal bursa, from male and female Gallus gallus domesticus, aged between one and seven weeks old, were separated in seven groups according to age (G1 to G7). Histological sections were stained with hematoxilin-eosin and Picrosirius red to differentiate lymphocytes and connective tissue, respectively. Vv(lymphocytes) increased up to 4 weeks, decreasing in subsequent weeks. Connective tissue density increased throughout the seven weeks studied. Areas of intense lymphopoiesis were observed from G1 to G4 and areas of distancing between the cells and early tissue necrosis were observed from G5 to G7. Therefore, the increase in the lymphocytes number expected during the development and maturation periods of the cloacal bursa occurred in the first four weeks. From that period, the involution process started, lymphoid depletion was observed while connective tissue density increased. These processes occurred as simultaneous and inversely proportional events during the remodeling process of the organ. A bolsa cloacal apresentou alterações em sua constituição ao longo das sete semanas analisadas. As expected and described in literature, the main alterations observed were the lymphocyte depletion and the increasing in connective tissue density that did not follow a regular pattern, but occurred in simultaneous events and in a inversaly proportional way.