Mast cells in female mouse lymph nodes

This study was designed to examine the possible role of sex steroid hormones on mast cells localized in uterus draining lymph nodes (UDLN) in mice. Young virgin estrous animals had more mast cells than diestrous animals in both the UDLN and popliteal lymph nodes (PLN). In retired breeders there were no differences in mast cell numbers of estrous and diestrous animals. There were no differences in mast cell numbers among weanling and older animals in diestrous in the UDLN but, in the PLN, mature animals in either diestrous or estrous had more mast cells than the PLN of weanlings. In mature animals, ovariectomy did not alter mast cell number in either node. However, ovariectomy of weanlings increased mast cell numbers in the PLN but not in the UDLN. These results suggest that the UDLN behaves as a nonclassical target organ for the endocrine system, with mast cell number variations related to gonadal steroid levels.