Identification of connective tissue components in healing rat gingiva

The aim of the study was to examine connective tissue fiber organization during healing of an incisional wound in rat molar gingiva. Forty rats 50 days old were divided into 10 experimental groups each comprising four animals. Following interdental incisions, healing periods of 11-20 days, and then 3H-proline injection, the animals were sacrificed and specimens prepared for light microscopy, autoradiography, and transmission electron microscopy. Isotope labeling with 3H-proline occurred over newly formed collagen in the path of incision, while preexisting tissue was unlabeled. Ultrastructurally, preexisting and new tissue were identified by measurement of collagen fibril thickness. The spatial relationship between new and remaining fibrous tissue in the transitional zone suggests that reunion is established by side-by-side alignment of new and severed fibrils.