@entity20135 and @entity413 concentrations (mg/g of tissue) and amounts (mg) were determined in the yolks of fertile eggs on the day of set and in the yolk sac (YS) and liver of broiler @entity1573 embryos between 11 and 21 embryonic days of age (E). On the day of set, the yolk contained 50 mg of @entity413 (0.31% of yolk) but did not contain glycogen. During incubation, the amount of @entity413 in the YS increased from 20 mg on E11 to 60 mg on E19. A parallel increase in YS and liver glycogen concentrations (mg/g) during the last week of incubation implied a similar capacity for glycogen synthesis per gram of tissue. However, due to its larger size, the YS capacity for glycogen storage far exceeded that of the liver, which stored less than 12 mg of glycogen up to E19, as compared with more than 200 mg in the YS. Between E19 and 21, liver and YS glycogen amounts decreased by 10 mg and 100 mg, respectively. These results indicated that the YS is a glycogenic and perhaps gluconeogenic organ. We therefore evaluated the gene expression of glycogen synthase and glycogen phosphorylase as well as gluconeogenic enzymes ( @entity948 1,6-bisphosphatase, @entity7954 carboxykinase, and @entity413 6-phosphatase) in the YS membrane and liver by real-time reverse-transcription PCR. Although the YS membrane and liver displayed different patterns of mRNA abundance, the high abundance of @entity948 1,6-bisphosphatase mRNA in the YS membrane between E11 and 15, and the expression of @entity7954 carboxykinase and @entity413 6-phosphatase, supported the postulated gluconeogenic abilities of the YS membrane and indicated its role in providing @entity413 to the embryo. Thus, @entity413 is probably synthesized in the YS, stored in the form of glycogen, and toward hatch, the YS may have the potential to transfer 10 times more glycogen-derived @entity413 to the embryo as compared with the liver. As such, the YS may play a major role in the synthesis and storage of @entity413 and its supply to the @entity1573 embryo toward hatch.

Yolk sac carbohydrate levels and gene expression of key gluconeogenic and glycogenic enzymes during XXXX embryonic development.

@entity20135 :: ('MESH:D006003', 'Chemical') :: ['Glycogen'] @entity7954 :: ('MESH:D010728', 'Chemical') :: ['phosphoenolpyruvate'] @entity948 :: ('MESH:D005632', 'Chemical') :: ['fructose'] @entity1573 :: ('9031', 'Species') :: ['chick'] @entity413 :: ('MESH:D005947', 'Chemical') :: ['glucose']
@entity1573 :: (9031,Species) :: ['chick']
