Relation Between Volume of Vehicle and Chick Comb Response to Androsterone. ∗

Abstract

It was suggested previously (Frank, Klempner and Hollander1) that, in the use of sesame oil as a vehicle in our bioassay method for androgens, a reduction in the volume of vehicle from 0.1 cc to 0.05 cc was one of the factors which contributed to the improvement in response. Subsequently, the possibility presented itself that a further reduction in this volume might effect further improvement, as manifested by increased comb growth for a given dose of andro-gen. Accordingly, we have investigated the response elicited by the application of various dosages of androsterone in 0.05 cc and in 0.02 ccf of oil, applied daily, in paired experiments run simultaneously. In all other respects, the experimental conditions were exactly the same as in our last report (loc. cit.).

The results of such paired experiments are summarized in Table I, using mean comb weight for each group of chicks, regardless of sex, which had been treated in the same way. The dosages ranged from 10 to 50 γ. The response to treatment in any one experiment was measured by the increase in comb growth for that experiment (W) over the comb growth for a control experiment (W_c) run simultaneously, in which the chicks were untreated (columns 5 and 6). This increase (W—W_c), the comb weight corrected for controls, is given in column 7.

It is apparent from the data that the response obtained in any one experiment with the smaller volume of vehicle is in each case greater than the response in the corresponding experiment with the larger volume. Each of these response values has likewise been calculated as per cent of the corresponding control value and is given in column 8. The improvement in response resulting from reduction in volume of sesame oil (IR, column 9) is therefore measured by the difference of these paired percentage values.