Changes of Amniotic Fluid Glucose Concentration in an Isolated Rat Embryos

Park, Hyung Woo

Abstract

In the rat, the neural plate appears at day 9 and the neural tube closes at day 10.3. During neurulation, the neuroepithelium is exposed directly to amniotic fluid and blood circulation begins at day 10.5. Accordingly, amniotic fluid may be an important source of nutrition for normal development of the nervous system. Among many different components of amniotic fluid, glucose is known as common currency of metabolism and the developing embryo is more dependent on this. The purpose of this study is to provide basic data on the capacity of amniotic fluid as a source of glucose for neurulating rat embryos. In the first part of this paper, isolated days 10, 11 and 16 rat embryos with intact amnion were used to pursue the change of the glucose concentratons in the amniotic fluid. The day 10 embryo amniotic fluid glucose disappeared after 20 minutes, and the day 11 amniotic fluid glucose disappeared after 33 minutes. The day 16 amniotic fluid glucose showed no significant changes during 40 minutes. In the second part of this paper, the author determined the time required for glucose concentraton in the day 10 amniotic fluid to be 0 mg% at glucose free Hanks` solution. The day 10 amniotic fluid glucose disappeared afttar 10 minutes. Another embryos were exposed to glucose free Hank`s solution for 10 minutes, and switched immediately to regular Hank`s for measuring the changes of amniotic fluid glucose, that is `charging Phenomena`. During the first 15 minutes amniotic glucose was charged to nearly normal level, and after that it decreased. These changes were similar to the results from the first experiment. These results indicate that neurulating embryo has a potential for restoring its amniotic glucose concentration to the normal level rapidly. So harmful effects of hypoglycemic states may be compensated by this `charging phenomena` of amniotic fluid during neurulation.