Ej. Dewaal et al., THE CORTICAL EPITHELIUM OF THE RAT THYMUS AFTER INVIVO EXPOSURE TO BIS(TRI-N-BUTYLTIN)OXIDE (TBTO) - AN (IMMUNO)HISTOLOGICAL AND ULTRASTRUCTURAL-STUDY, Archives of toxicology, 67(3), 1993, pp. 186-192
Bis(tri-n-butyltin)oxide (TBTO) induces cortical atrophy in the rat th
ymus. We studied the potential involvement of the cortical epithelium
in TBTO-induced thymotoxicity by (immuno) histology and electron micro
scopy. Juvenile male Wistar rats were orally intubated once with eithe
r 30 or 90 mg/kg TBTO and sacrificed 4 or 10 days later. A dose-depend
ent thymic atrophy occurred. Anti-keratin labelling showed epithelial
cell aggregation in some animals at 10 days after exposure to 90 mg/kg
TBTO, when recovery of the thymus was apparent. At the ultrastructura
l level, a relative shift was observed from ''pale'' to darker epithel
ial cell subtypes at the 30 mg/kg dose level, both at day 4 and day 10
after intubation. This phenomenon was not observed after exposure to
90 mg/kg TBTO. Both the altered keratin distribution and the increased
electron density of the epithelium probably represent non-specific ph
enomena. The present morphological observations support the concept th
at TBTO affects the thymus via its action on lymphoid cells rather tha
n on the epithelial compartment.