Hilde Levi

Incorporation of 3H-thymidine in stratum germinativum of epidermis in the toad Bufo bufo bufo (L): an autoradiographic study of moulting cycle and diurnal variations.

Abstract 1. In normal toads, the % of stratum germinativum cells that incorporated 3H-thymidine (labelling index) varied considerably, but this variation was not correlated with the phase in the moulting cycle. 2. The labelling index varied less between regions of the epidermis of one animal than between animals. 3. The labelling index did not show a clear diurnal cycle.

Quantitative β-track autoradiography of single cells ☆

Abstract A method of high resolution beta track autoradiography applicable to single cells (such as yeast or algae) is described. The cells are suspended in liquid G-5 emulsion of Ilford and low energy beta tracks from C-14 and S-35 are registered quantitatively.

Some observations on α-track autoradiographs of biological specimens

Abstract The application of α autoradiography in the study of biological specimens containing thorium and its decay products is described. The experimental procedure is outlined, various artefacts and necessary corrections are discussed.

Cell kinetics in the epidermis of the toad Bufo bufo bufo (L.) after partial hypophysectomy followed by corticotrophin treatment (an autoradiographic study).

1. Cell kinetic parameters in the epidermis of partially hypophysectomized, ACTH-treated toads whose moulting frequency was increased threefold were studied using labelled thymidine and the autoradiographic technique. 2. The labelling index, length of S-phase and cycle time of stratum germinativum cells changed slowly as a function of the number of ACTH injections, and so did the migration of cells from stratum germinativum to stratum corneum. 3. A cell production in stratum germinativum of normal toads in excess of cell loss, as demonstrated by Levi & Nielsen (1982) should make it possible to maintain a status quo over a limited period of time following ablation of pars distalis and ACTH treatment.