1
Reviews and abstracts 349 remains untreated and the mandible is adjusted to the retarded maxilla. Accel- eration of forward growth of the maxilla at an early age is desirable for this type of malocclusion. An orthopedic appliance for protraction of the entire maxilla was applied to patients during the growth period in the Hokkaido University Dental Clinic. Consequently, acceleration of forward growth of the maxilla and improvement of lateral jaw relationships have been readily obtained following treatment. With the skeletal imbalance improved and all permanent teeth erupted, ortho- dontic appliances were employed to improve dental alignment and to establish intercuspal relations. Cell Proliferation During Closure of Normal Secondary Palate D. Romeo and R. Nanda Department of Orthodontics, Health Center, Uwivereity of Connecticut, Farmington, Conn. The present study was undertaken to explore in detail the part played by cellular kinetics in horizontalization, growth, and fusion of the palatal shelves of fetuses of Wistar albino rats. Sixty-four pregnant rats were divided into eight equal groups. Each rat received one intraperitoneal injection of 250 pci/kg. (of rat weight) tritiated thymidine. Four fetus heads from each preg- nant animal were processed for autoradiographic study. The sections were studied for total number of labeled cells, mitotic indices, and the distribution of labeled as well as unlabeled cells. During the horizontalization process the proliferation activity was found to be approximately the same in the medial and posterior thirds of the palatal shelves. Once horizontalization was complete, the prominent area of cell pro- liferation was the middle third of the shelves. Similarly, the epithelial cells on the nose, mouth, tongue, and at the medial tip of the palatal shelves also showed differential proliferation. A gradual decrease in labeled epithelial cells at the presumptive zone of fusion was observed after the fifteenth day of gestation. The results indicate that differential cellular proliferation in the palatal shelves prior to fusion may play a part in horizontalization and ultimate fusion of palatal shelves.

Cell proliferation during closure of normal secondary palate

  • Upload
    d-romeo

  • View
    213

  • Download
    0

Embed Size (px)

Citation preview

Page 1: Cell proliferation during closure of normal secondary palate

Reviews and abstracts 349

remains untreated and the mandible is adjusted to the retarded maxilla. Accel- eration of forward growth of the maxilla at an early age is desirable for this type of malocclusion.

An orthopedic appliance for protraction of the entire maxilla was applied to patients during the growth period in the Hokkaido University Dental Clinic. Consequently, acceleration of forward growth of the maxilla and improvement of lateral jaw relationships have been readily obtained following treatment. With the skeletal imbalance improved and all permanent teeth erupted, ortho- dontic appliances were employed to improve dental alignment and to establish intercuspal relations.

Cell Proliferation During Closure of Normal Secondary Palate D. Romeo and R. Nanda

Department of Orthodontics, Health Center, Uwivereity of Connecticut, Farmington, Conn.

The present study was undertaken to explore in detail the part played by cellular kinetics in horizontalization, growth, and fusion of the palatal shelves of fetuses of Wistar albino rats. Sixty-four pregnant rats were divided into eight equal groups. Each rat received one intraperitoneal injection of 250 pci/kg. (of rat weight) tritiated thymidine. Four fetus heads from each preg- nant animal were processed for autoradiographic study. The sections were studied for total number of labeled cells, mitotic indices, and the distribution of labeled as well as unlabeled cells.

During the horizontalization process the proliferation activity was found to be approximately the same in the medial and posterior thirds of the palatal shelves. Once horizontalization was complete, the prominent area of cell pro- liferation was the middle third of the shelves. Similarly, the epithelial cells on the nose, mouth, tongue, and at the medial tip of the palatal shelves also showed differential proliferation. A gradual decrease in labeled epithelial cells at the presumptive zone of fusion was observed after the fifteenth day of gestation. The results indicate that differential cellular proliferation in the palatal shelves prior to fusion may play a part in horizontalization and ultimate fusion of palatal shelves.