Radioautographic study of human pulmonary tissues

Abstract

The radioautograms of human lungs were studied after in vitro incubation with tritiated thymidine. Our materials consisted of the lungs of 12 normal foetuses (crown-rump length varied from 7 5 to 16-5 cm.) and of 11 adults (32 to 68 years of age). In the foetal lungs the uptake of tritiated thymidine was highest in the epithelium surrounding small tubular spaces, forerunners of future bronchial epithelium, and in the undifferentiated mesenchyme. The percentage of labelled cells was scarce in the alveolar wall cells of adults (005% to 065%), was unrelated to age, and appeared to be most frequent in phagocytic elements (so-called alveolar cells). There was an uptake of tritiated thymidine in scattered free alveolar macrophages and in a few interstitial cells. The media and adventitia of blood vessels did not show labelling in most cases. The labelling of epithelium of bronchioles and respiratory bronchioles varied from 020% to 070 %. The findings of other investigators in the study of cell turnover in the lungs of laboratory animals are discussed and compared with the data obtained in the present study.

Radiation Biology and Cell Population Kinetics

“…Bresciani (1967) has recently reviewed the available data on cell cycle time in tumours, compared with that in the normal tissue of origin, for both experimental animals and man. His conclusion is that in general the cell cycle time is somewhat less in tumour tissue than in the normal tissue of origin, but that cancer can by no means be considered an ' allout ' growth, since the cell cycle in tumours is generally considerably longer Kury andCart,er (1962) (1965) Titus and Shorter (1965) Cooper, Frank and Wright, (1966) 7 Data from a number of other authors ha,ve also been used in compiling t,his table.…”

6-Alkyl-3,4-dihydro-2H-pyrans: Chemical Secretion Compounds in Neotropical Harvestmen

“…The order Opiliones, popularly known as harvestmen, constitutes the third major group of arachnids, with nearly 6000 known species distributed worldwide . Harvestmen are divided into four suborders (Laniatores, Dyspnoi, Eupnoi, and Cyphophthalmi) that contain 45 recognized families and about 1500 genera.…”