RESUMO
An“agar-island organ culture”technique is described.It consists of both agar substratum and liquid medium in the same culture dish,so that chemicals in different concentrations can be added into the liquid portion of the medium,a convenient method to test their effects on explants.The procedures are as follows: To one gram of agar in a flask,50 ml of aqua distillata is added,and then heated until the agar is completely dissolved.Then add in 50 ml of double-strength 199 solu- tio(?) into the flask.After shaking gently,mixing the media completely,pour it into a dish until it reaches 2/3 of its height.A few minutes later the agar will solidify.Cut off most of the agar substratum and leave enough agar to form“islands”(Eig.A,B).Then add in liguid medium which is composed of 8 vol 199 solution,2 vol calf serum,2 vol extract of 9-day chick embryo diluted into 50% in Hank's solution and a few drops of diluted penicillin and streptomycin.The explants are placed on the agar-islands,the culture dishes covered with glass tops,sealed with paraffin,are put into an incubator.The cul- ture dishes are not sealed they are put into an incubator supplemented with 5%CO_2 Using this technique,we have cultured 80 explanls of 13-day chick embryo meta- tarsal skin for 7～21 days.And the effect of vit.A with different concentrations are tested The results show that the effects of vit,A on the differentiation of the chick embryo metatarsal skin explants are different with the different concentrations.We believe that this technique can be much more convenient as a method to study the eff- ects of chemicals in different concentrations on explants.The other uses of this tech(?)i- que,such as carcinogenesis in culture,the study of embryonic induction,especially the diffuse mechanism of embryo induction are also briefly discussed.
RESUMO
The effects of cytochalasin D (CD), isolated from Engleromyces goetzii found in our country, on cells of established human esophageal cancer line (ECa-109 cell line) were investigated. It was demonstrated that CD was capable of inhibiting the growth of the cells at the concentration of 0.2?g/ml as indicted by growth curve. The action of CD, however, is reversible, and the cells will gradually grow again normally following the withdrawal of CD. The result also indicated that some proportion of the cells became binucleated or multinucleated after CD treatment. And as the duration of exposure time to CD increased. the multinucleated cells increased in number also. At the concentration of 0.5?g/ml of CD, a phenomenon of extrution of nucleus can be seen among the cells. The nucleus is departed from the cell body but still linked by a fine cytoplasm bridge (Fig. 2). The CD-treated cells bacame enucleated when they subjected to centrifugation following CD treatment. The minicells obtained from enucleation appeared to be normal morphologically with nucleoli but retained only a little cytoplasm around the nucleus. Electromicroscopic observation showed that mitochondria and tonofibrils increased after CD treatment, but we failed to find any changes of microfilaments within the cells.