Role of subdermal current shunts in the failure of frogs to regenerate.

Large, uniform, skin-driven currents (20-40 muamp/cm2) leave the ends of limb stumps of post-metamorphic frogs (Rana pipiens) from about the first through the tenth day after amputation. However, right after amputation, while currents of comparable density may leave the periphery of the cut surface, current densities are greatly depressed in the center of this surface. We suggest that this depression is brought about by shunting through the subdermal lymph space (characteristic of anurans but not urodeles); continues in covert form after formation of a wound epithelium; and helps explain the ability of small, imposed currents to initiate frog limb regeneration.     

Immunocytochemical study using semi-thin sections of the phenomena of early differentiation in several cell populations of the human fetal adenohypophysis]

Immunocytological investigations have been performed on semi-thin sections of human fetal pituitaries ranging in fetal age from 6 to 26 weeks. Corticotrophs can be revealed by anti-ACTH (1-24), anti-ACTH (17-39) and anti-beta MSH but not by anti-alpha MSH immunesera from the 8th week. Somatotrophs are revealed with anti-human STH from 9th week. Differentiating cells containing only alpha subunits of glycoproteic hormones are present from 8th to 12th week. At 13th week beta subunits of TSH can be revealed immunocytologically in thyreotrophs. Beta subunits of LH or FSH can be detected in same gonadotrophic cells only from 15th week.     

The fate of cells with chromosome aberrations after total-body irradiation and bone marrow transplantation

Cytogenetic studies were done on bone marrow cells and peripheral lymphocytes of four patients (three with acute nonlymphocytic leukemia, one with aplastic anemia) at various intervals up to 861 days after total-body X irradiation (TBI) at doses between 4.5 and 10 Gy (450-1000 rad) followed by syngeneic or allogeneic bone marrow transplantation. Whereas no radiation-induced aberrations could be found in the bone marrow, apart from a transient finding in the patient with the lowest radiation dose, aberrant metaphases were seen in the peripheral lymphocytes of three patients in the range from 2.5 to 46% even at 861 days after the exposure. There were no demonstrable aberrations related to TBI in the only patient developing graft-versus-host disease. The dicentric yield as determined in the aberrant metaphases with 46 centromeres ranged between 3.4 +/- 1.3 and 4.9 +/- 0.4. In one patient it was demonstrated by BUdR-labeling that after 10 Gy (1000 rad) TBI the surviving and heavily damaged lymphocytes can go into cell cycle and reach at least the third mitosis. The percentage of aberrant cells diminished by about 25% at each mitotic division.