Preparation of an aggregation-promoting supernatant from embryonic chick liver cells

Abstract

1. 1. Liver cells dissociated from chick embryos at ages from 7-day to 20-day were tested for their aggregability in rotation culture. Liver cells dissociated from 7-day formed large aggregates after 24 h of cultivation; liver cells from older embryos showed a gradual decline in average diameter of aggregates formed. Almost complete lack of aggregability was found in liver cells dissociated from 20-day embryo. 2. 2. Mixed suspension of liver cells from both younger and older embryos produced aggregates with an average diameter intermediate between those typical for each of these ages separately. 3. 3. Cell-free supernatants were obtained from short-term flask cultures of embryonic chick liver cells on a reciprocating shaker and tested at 28 °C for their ability to promote aggregation of liver cells. Supernatants prepared from 7-day embryonic liver cells were highly active in enhancing aggregation of 7-day embryonic liver cells, but had no effect on liver cells from 18-day embryos. Supernatants from 18-day embryonic liver cells had no effect on liver cells from either 7- or 18-day embryos. However, at 38 °C supernatant from 7-day embryonic liver cells promoted the aggregation of cells from 18-day embryonic liver after 3 or more days in culture. 4. 4. Chemical analysis of cell-free supernatants from 2-h cultures of 7-day and 18-day embryonic liver cells demonstrated significantly higher amount of protein than in controls and small amounts of DNA or RNA.