Uptake and incorporation of each labeled FA in lipid classes in cultured PHTs after 24 and 30 h of incubation. Absolute concentrations of labeled PA, OA, LA, and DHA in 4 lipid classes in PHT cells isolated from normal-term placentas, expressed as nanomoles of FA per microgram of protein, were determined at 24 and 30 h to measure the FA esterification at the plateau (n = 3, means + sem).