Uptakes and uses of oxygen, from gametes to maturity: an overview

How do rates of oxygen uptakes per unit of body weight change with age in mammals? Marked increases occur, starting on the third day after fertilization; small increases occur just after birth. At birth the factor of body size of the species has a small influence. In the old adult the diminished uptake per unit weight resembles that of the newly fertilized zygote. Special roles of RNA and of mitochondria determine the uses to which energy is put. Anaerobic energy is and can be employed temporarily in embryonic stages. Sensitivities to energy demands are revealed in effects of hypoxia, hyperoxia, low temperatures and norepinephrine. Uses of energy for biosyntheses and active transports change during ontogeny; and differ among the tissues. Strategies of development, and their sequences, appear to supply adequate oxygen throughout prenatal stages.