M. Itoi et T. Amagai, INDUCTIVE ROLE OF FIBROBLASTIC CELL-LINES IN DEVELOPMENT OF THE MOUSETHYMUS ANLAGE IN ORGAN-CULTURE, Cellular immunology, 183(1), 1998, pp. 32-41
Previously, we have shown that embryonic day 12 thymus anlage cultured
alone cannot develop into the mature organ but degenerates. In the pr
esent study, we investigated the cause of this insufficient organogene
sis of embryonic day 12 thymus anlage in organ culture. We cocultured
embryonic day 12 thymus anlages with various cell lines as pellets for
med by centrifugation. In coculture with fibroblastic cell lines, but
not with thymic epithelial cell lines, embryonic day 12 thymus anlages
developed to support full T cell differentiation, and expressed matur
e stromal cell markers, Ia and K-b. By pellet culture of thymus anlage
s and fibroblastic cell lines transfected with a beta-galactosidase ex
pression vector, we analyzed the distribution of added fibroblastic ce
lls in pellets. The added fibroblastic cells constituted neither thymi
c capsule nor septa but disappeared after about 2 weeks in culture. Mo
reover, immunohistochemical studies indicated that added fibroblastic
cells were adjacent to mesenchymal cells of thymus anlage. Our results
strongly suggest that added fibroblastic cells support the developmen
t of the thymus anlage through interaction with its mesenchymal cells.
(C) 1998 Academic Press.