High frequency of thymic ectopy in thyroids from autoimmune prone nonobese diabetic female mice.
BACKGROUND
The female nonobese diabetic (NOD) mouse, a well known experimental model to study autoimmune type 1 diabetes, also spontaneously develops thyroiditis. In this study, we report an abnormally high frequency of thymic ectopy in thyroids from NOD mice.


METHODS
Thyroids and thymuses from NOD mice and from control mice of different strains were processed for light and electron microscopy and for immunohistochemistry.


RESULTS
Ectopic thymic tissue was observed in the thyroids of 80% of female NOD mice, whereas it was not found in control age-paired female mice from various other strains. The thymic tissue was present beneath the capsule as a large and unique fragment consisting of both a cortical dark one and a medullary light region. Thymic ectopies, as the thymus itself, contained thymocytes expressing both L3T4 and Lyt2 antigens, specific respectively for T helper and T suppressor/cytotoxic cells. Cortical and medullary epithelial cells were also easily identified by electron microscopy and by immunohistochemical staining using ER-TR4 and ER-TR5 monoclonal antibodies.


CONCLUSIONS
Our observation could be an indication for a relation between abnormal thymus development and autoimmune disorder such as thyroiditis.
Laboratory of Histology, Louvain Medical School, Brussels, Belgium.
M C
MC
Many
H A
HA
Drexhage
J F
JF
Denef
D000818:Animals; D002828:Choristoma / Q000473:pathology*; D003922:Diabetes Mellitus, Type 1 / Q000235:genetics / Q000473:pathology*; D005260:Female; D051379:Mice; D008807:Mice, Inbred BALB C; D008809:Mice, Inbred C3H; D008808:Mice, Inbred CBA; D008813:Mice, Inbred ICR; D016688:Mice, Inbred NOD; D013045:Species Specificity; D013950:Thymus Gland; D013964:Thyroid Neoplasms / Q000473:pathology*