Previous results with thyroid secretory cells in monolayer culture seem contradictory with respect to phenotypic stability of this cell type. On the one hand, in "minimal" medium the cells lose structural and functional specializations which can be returned only by three-dimensional growth in organ culture upon addition of fibroblasts derived from the thyroid capsule. On the other hand, in "ric...

In previous studies, prostaglandins have been applied to organ cultures of dorsal skin from the chick embryo (11, 12) . When prostaglandin-B, (PGB,) is added to the culture medium in which skin pieces are explanted at a time when feather organ loci are present, the latter fail to develop during incubation but the skin continues to grow and mature . Control skins demonstrate normal feather devel...

A possible mechanism for intercellular invasion is that the strength of adhesion between host and invading cells is greater than the average of the strengths of homotypic adhesions. This hypothesis has been examined by a study of the kinetics of aggregation of dispersed populations of an invasive cell type (the rabbit peritoneal neutrophil granulocyte) and a host cell type (the chick embryo hea...

horbar; Ovaries from decapitated, sham-operated and intact 18-day-old chick embryos were cultured in Medium 199 for 6 h, and the amount of 17f3-estradiol released into the culture media was determined by radioimmunoassay. Ovaries from decapitated embryos secreted significantly lower amounts of 17f3-estradiol than those from intact embryos, but there was no difference when they were compared to ...

Antibodies to pure lysyl hydroxylase from whole chick embryos were prepared in rabbits and used for immunological characterization of this enzyme of collagen biosynthesis. In double immunodiffusion a single precipitation line was seen between the antiserum and crude or pure chick-embryo lysyl hydroxylase. The antiserum effectively inhibited chick-embryo lysyl hydroxylase activity, whether measu...

A serum-free organ culture model for chondrocyte maturation, using the Avian sternum, was developed. Day-14 chick embryo sterna were placed in organ culture in the presence of defined medium. The optimal medium for chondrocyte terminal differentiation contained specific concentrations of dexamethasone, insulin, thyroid hormone and ascorbic acid. Three parameters, including sternal growth, cell ...

Nonproducing Rous sarcoma cells of the chicken were capable of transmitting the Rous sarcoma virus genome to neighboring chick embryo fibroblasts. This transfer required close proximity of sarcoma and normal cells and may have been mediated by a subcellular infectious agent which was found to be released from nonproducing cells.

In the developing fetal liver of many animals, the appearance of glycogen in quantities demonstrable by classical chemical methods is a relatively tardy and abrupt event. For example, using Sahyun and Alsberg’s (1) modification of Pfliiger’s technique, Hard et al. (2) have shown in the guinea pig that there is no detectable liver glycogen up to the 56th day of gestation (term 66 days) but that ...

Primary nerve cell cultures contain acetylcholinesterase (AChE: EC 3 .l .1.7) and other special macromolecules associated with cholinergic transmission [l--4 J . Cultured chick nerve cells, like cultured muscle, have been shown to release AChE into their medium [ 5 $1. The experiments presented here examined the levels of activity and release of AChE in nerve cell cultures after treatment with ...

Cultured monolayers of spontaneously contracting chick embryo ventricular cells were perfused with culture medium containing ouabain. Contractile state was monitored by an optical-video system recording amplitude and velocity of cell wall motion. Positive inotropic effects of 2.5 x 10(-7) to 10(-6) M ouabain were manifest within 1.5-2 min, and reached a stable plateau within 5-6 min. The inotro...