Erythropoiesis in the thymus of the spotless starling, Sturnus unicolor

Abstract

Although previously described in other avian species, intrathymic erythropoiesis is a remarkable feature of the thymus of Sturnus unicolor. In discrete stages of the life cycle of this species, erythroblasts and mature erythrocytes occupy large areas of the thymic cortex and cortico-medullary border. Simultaneously, degenerated thymocytes and epithelial-reticular cells occur in the same areas. The relationship between intrathymic erythropoiesis, degeneration of cortical lymphocytes and epithelial-reticular cells, and macrophage activity is discussed and related to a possible functional role of sex hormones in this phenomenon.

Histomorphology of Thymus Gland in Guinea Fowl (Numida meleagris)

“…Erythrocytes were found in the cortex and corticomedullary border of thymus gland as stated by Fonfria et al, (1983) in birds. Macrophages were more in the corticomedullary junction and also in cortex and medulla in all the age groups.…”

Histogenesis of the epithelial component of rat thymus: An ultrastructural and immunohistological analysis

“…These findings support therefore the idea of the thymus as a haemopoietic tissue of non-lymphoid cells. In birds which undergo major cyclic physiological changes, a relationship between intrathymic erythropoiesis and high levels of circulating sex hormones has been pointed out (Fonfria et al, 1983) and the injection of a single dose of estradiol benzoate in adult rats induces intrathymic erythropoiesis, mimicking remarkably the condition of postnatal rats (Martin-Moreno et al, 1994). On this basis, endocrinological changes occurring at birth might at least partially explain our results.…”

Effects of early partial decapitation on the ontogenic development of chicken lymphoid organs. I. Thymus

“…Migration of stem cells into the thymus during chicken ontogeny occurs in receptive periods that alternate with refractory times (Le Douarin et al, 19841, in a process governed probably by chemoattractive substances produced by thymic stroma (Champion et al, 1986). Furthermore, human thymic epithelial cells produce granulocyte and macrophage colony-stimulating factors suggesting that the thymic microenvironment may support myeloid di~erent~ation (Le et al, 19881, whereas avian intrathymic erythropoiesis is associated with profound modifications of cortical epithelia^ components (Fonfria et al, 1983). Similar mechanisms could be operating in the developing thymus of DCx embryos.…”