ABSTRACT
Many embryonic organs have been cultivated in the ‘standard’ medium of E. Wolff and K. Haffen which contains glucose and embryo extract as nutrients. The researches reported in this paper give the first results of experiments designed to find out whether it is possible to replace this extract by definite mixtures of amino-acids and thus to realize the culture of organs in synthetic media.
Several mixtures, containing a greater or lesser number of amino-acids (solutions B, C, and C1, see pp. 58-59), were added to a substrate consisting of agar, saline, and glucose. Vitamins and one stimulating substance (novocaine) were added to the media in some cases. The results of these experiments were compared with those in which the standard medium was used and with those in which organs were explanted on the basic substrate.
Three kinds of organ were explanted: gonad, syrinx, and tibia from chick embryos of from 6 to 10 days’ incubation. The efficiency of the synthetic media was tested by three criteria: survival, differentiation, and growth of the explant.
Gonads explanted in synthetic media either before or after the stage of sex differentiation begin or continue their differentiation. Morphogenesis and histogenesis are similar to those observed in the standard medium. Clear-cut evidence of growth is given by mitoses and by an increase in total N, estimated by an ultra-micro-Kjeldahl method, which indicates an assimilation of amino-acids by the explanted organs.
Syrinxes were explanted both before and after the formation of the first pre-cartilaginous nodules of the tracheo-bronchial arches. They begin, or if already begun they complete, this first differentiation. Four to five pairs of arches are formed in latero-median succession. Growth of the organs was demon-strated by the presence of mitoses and by the increase in total N.
Tibias explanted at the 8th day of incubation as cartilaginous rods continue to differentiate morphologically and histologically in synthetic media to which novocaine had been added as a stimulatory substance. Considerable growth in length and weight occurred, but no increase in total N was associated with it. Nevertheless in the presence of novocaine the catabolism of N is partly compensated for by the assimilation of amino-acids.
Different organs, cultured in synthetic media, do not have the same needs for amino-acids, for vitamins, or for growth-promoting substances.
Growth and differentiation are not necessarily correlated. One or the other of these phenomena may be favoured by certain changes in the medium. From the results reported in this paper it may be concluded that organs isolated in vitro are able to assimilate amino-acids from a synthetic medium for a limited period of growth and development.
D’après les données qui nous ont été obligeamment communiquées par Miss Waymouth, les milieux qui ne contiennent que des acides aminés comme aliments azotés sont incapables d’assurer la croissance. Celle-ci n’apparaît que lorsqu’on ajoute des peptides plus complexes (peptone de Witt).
Les recherches relatées ici ont été effectuées sur l’embryon de poulet à une époque de l’année où l’on ne peut se procurer un nombre suffisant d’œufs de cane. Si les résultats de la différenciation sexuelle sont plus simples et plus nets chez l’embryon de canard, l’embryon de poulet peut aussi bien être utilisé pour les recherches sur la nutrition, la croissance et la différenciation en milieux synthétiques.
La solution employée est dissoute dans une solution de polyvinylpyrrolidone contenant de la novocaïne (solution P).
