Oxygen consumption in the developing chick cornea

tides are seen in the in vivo experiment than in the in vitro one suggests that synthesis of polyglucose is regulated in the cell even under in vivo histochemical conditions. Another use of the enzyme-synthetic approach in the in vivo cornea has been shown in the present study. The number of synthesized polyglucose particles in the corneal epithelium indicates the amount of glucose-1-phosphate in the medium which permeates the corneal epithelium mainly from the anterior chamber. Such speculation cannot come from conventional histochemistry. Most of the glucose in the cornea has been found to be transported across the endothelium to the epithelium in the cornea from the aqueous humor in the anterior chamber." The concentration of glucose in the stroma is essentially the same as in the aqueous humor, and the corneal endothelium has no significant barrier to glucose penetration at physiological glucose levels. The present study also shows that polyglucose may be synthesized from glucose-1phosphate supplied mainly from the anterior chamber. Glucose-1-phosphate in the medium injected into the bulbar subconjunctiva probably reaches the corneal epithelium mainly through the anterior chamber and partly from the corneal limbus, because as far as the principal metabolites are concerned, the vascular system directly supplies only a very limited peripheral region of the cornea. Such a limited vascular supply of metabolites in the cornea may explain the difference in number of synthesized polyglucose particles between the central and peripheral cornea in the experiment with bulbar subconjunctival injection of the medium. The transportation of metabolites from the corneal limbus may be limited to the superficial layer of the corneal epithelium.