Synthesis of XXXX and @entity1919 by cultured @entity2419 mesenchyme at various population densities.

@entity268 @entity2918 @entity1426 @entity3009 @entity3044 @entity3900 @entity5015 @entity1919 @entity460 @entity3365 @entity3774 @entity2419
During embryonic development, @entity2419 mesenchymal cells exhibit differential growth rates. Normal palatal growth is regulated in part by hormones and growth factors. Because hormonal responsiveness of some cells correlates with their cell density, we have investigated the relationship between @entity2419 mesenchymal cell population density and their ability to synthesize @entity2918 (PGs) and @entity1919 . Primary cultures of palate mesenchymal cells exhibited typical lag, log, and stationary phases of growth with a doubling time of 32-34 hrs. The ability of cells to produce PGE2 in response to a @entity460 ionophore ( @entity3365 ), an activator of @entity3900 (melittin), @entity1426 , or serum was maximal during the period of early exponential growth. @entity3774 alpha synthesis in response to @entity3365 or @entity1426 showed a similar transient increase also corresponding temporally to the period of early exponential growth. The ability to synthesize PGF2 alpha in response to melittin, however, failed to diminish after early exponential growth. The pattern of @entity268 synthesis in response to @entity3044 and @entity5015 was different from that seen for induced prostaglandin synthesis. A transient increase in sensitivity to @entity3044 and @entity5015 was seen that corresponded temporally to the period of late exponential growth just prior to attainment of confluency. Decreased sensitivity to stimulation of either @entity3009 or @entity268 production as the cells became confluent was shown to be a density-dependent phenomenon; confluent cultures that were subcultured to reestablish logarithmic growth exhibited density-dependent hormonal responses identical to those seen in primary cultures. The ability of palate mesenchymal cells to synthesize both @entity2918 and @entity268 , thought to be critical for proper palatal development, might thus be related to local differential craniofacial growth rates.
