S. Kato et al., AFFERENT MIGRATION OF THE KURLOFF CELLS VIA LYMPHATICS INTO THE THYMUS OF ESTRADIOL-TREATED GUINEA-PIGS, Archives of histology and cytology, 60(1), 1997, pp. 101-112
The spatial distribution and migration of Kurloff cells containing PAS
-positive large inclusion bodies in the thymus of estradiol-treated gu
inea pigs were histochemically studied by a combination of light and e
lectron microscopy. Male guinea pigs mere examined at various interval
s from 7 days to 3 months after a single subcutaneous injection of est
radiol. Differentiation of lymphatics from blood capillaries was perfo
rmed by a 5'-nucleotidase (5'-Nase) staining method and the occurrence
of Kurloff cells within 5'-Nase-positive lymphatics was confirmed by
ultrastructural histochemistry. Several Kurloff cells first appeared a
t 7 days within lymphatics in the thymic capsule or interlobular conne
ctive tissues. At 12-15 days after estradiol administration, a lymphat
ic accumulation, a so-called ''lymphatic center'', was seen in the thy
mic septa even though few Kurloff cells were present within the thymic
parenchyma. The ''lymphatic center'' contained many Kurloff cells loc
ated in its periphery and in the surrounding marginal sinus which comm
unicated with the thymic interlobular lymphatics. At 21 days after est
radiol, Kurloff cells were preferentially accumulated along the cortic
omedullary junction extravascularly. Later the distribution was more d
iffuse. The conspicuous accumulation of Kurloff cells in the corticome
dullary region could reflect an inability of Kurloff cells to use bloo
d vessels as a route for migration. These findings strongly suggest th
e afferent migration of Kurloff cells into the thymus via lymphatics.