K. Sakabe et al., ESTABLISHMENT OF CROSSTALK BETWEEN THE THYMUS AND BRAIN AT AN EARLY-STAGE OF FETAL LIFE IN THE RAT, Medical science research, 24(7), 1996, pp. 439-442
The present study was carried out to examine oestrogen receptors (ER),
thymic factor (thymulin) and luteinising hormone releasing hormone (L
HRH) in fetal rats, which would modulate the establishment/development
of an 'hypothalamic-pituitary-gonadal-thymic' axis during pregnancy.
A small amount of ER already appeared both in the thymus and hypothala
mus at the 16th day, and the concentrations in both tissues gradually
increased by the same amplitude until the 21st day. Thymulin in both t
issues also appeared at a small level of concentration, which graduall
y increased with time until delivery. Immunohistochemically, some thym
ulin-positive neurons and LHRH-positive thymic epithelial cell appeare
d in brain and thymus, respectively, and those cells were identical wi
th ER-positive cells, These results may indicate that at the early sta
ge of fetal life circulating E acts through its receptors on the thymu
s and brain to secrete both thymulin and LHRH as local hormones that i
nitiate the development/differentiation of both tissues.