The development of the respiratory system in the fetus<>begins<>at about 4 weeks
We studied cytochemical localization of ectoadenosine triphosphatase in the rat liver during development from 15-day-old fetus to 4-week-old and adult animal.
The development of the respiratory system in the fetus begins at about 4 weeks.
The development of the respiratory system in the fetus begins at about?