Early local reaction and lymph node permeation of rat carcinoma HH9-cl 14 cells. An immunohistological approach.

2 X 10(6) ascites tumor cells of a DMBA-induced rat mammary adenocarcinoma (HH9-cl 14) were injected subcutaneously into tumor-free syngeneic female rats. Investigations were made, in addition to conventional paraffin histology and light microscopy, with immunohistological methods using poly-and monoclonal antisera. From 10 minutes to 2 hrs after inoculation carcinoma cells were seen inert either as single cells or as little clusters between connective and fatty tissue. After 6 hrs the number of tumor cells had decreased, and an increasing quantity of macrophages were found in close contact with them. At this stage some lymphocytes, too, appeared in the inoculation area. 10 minutes after injection, tumor cells were already entering regional lymph nodes and could be observed in the subcapsular sinuses. 2 hours later they had almost traversed the intermediate and medullary sinuses. Up to 6 hours after injection, increasing numbers of macrophages and sinus endothelial cells were seen, and the lymph node's appearance manifested hyperplasia of the paracortical zone. 4 and 6 hrs after injection, the total number of tumor cells in regional nodes decreased again noticeably, and sometimes tumor cells had disappeared. The first lymph node metastases appeared 28 days after inoculation.