Macrophages in the hamster parathyroid gland: immunohistochemical and ultrastructural investigations.

The distribution and morphology of the parathyroid macrophages in golden hamsters from neonatal to senile periods were investigated using the monoclonal antibody to ED2 and electron microscopy. The results showed that definite ED2-positive cells were hardly detectable in the parathyroid gland of 1-day-old hamsters. A few ED2-positive cells could be identified in the parathyroid gland of 10-day-old hamsters. The ED2-positive cells were more densely and became conspicuous in 1-, 3-, and 12-month-old hamsters. The number of the cells seems to be increased with aging. Ultrastructurally, we did not find any macrophages in parathyroid glands of 1-day-old hamsters. In the 10-day-old hamster parathyroid gland, a few macrophages existed only in the interstitial tissues. In the parathyroid gland of 1-, 3-, and 12-month-old hamsters, many macrophages were found in the perivascular regions, some cells located among the parenchymal chief cells with no obvious vascular association. These cells showed some physical contacts with chief cells. These results suggest that the parathyroid macrophages exhibit dramatical changes in their distribution and morphology from neonatal to senile periods.