Kinetics of cell replication of the uterine cervix. V. Behavior of DNA-replicating tumor cells in invasive squamous carcinomas in mice.

The intratumoral migration of tritiated thymidine ([3H]dThd)-labeled cells was recorded at various intervals (from 1 to 240 hr) in squamous invasive carcinomas of the cervix in 25 inbred C57Bl mice. Carcinomas were induced by local application of benzo[a]pyrene for 5 months. This treatment was discontinued 7 days before the animals were killed. Cells were labeled by a single ip injection of 6 muCi [3H]dThd/g body weight. The tumors were divided by the aid of an ocular scale into three equal compartments: a peripheral zone, an intermediate zone, and a central zone. Many densely (initially) labeled cells were present in the peripheral and intermediate zones 1-48 hours after the injection of isotope, but these cells decreased in number in the intermediate zone and had disappeared from the peripheral zone by 96 hours. Conversely, densely labeled cells were absent in the center of the tumor during the first 24 hours, but they were recorded in large numbers at 48 hours. It was concluded that in addition to already known mechanisms of cell migration in solid tumors (e.g., invasion of the surrounding normal tissue, intravascular migration, migration toward the center of individual tumor nests, and cell exfoliation), there is intratumoral migration of cells toward the center in cervical carcinomas in mice.