Some Considerations of Tracheal Fluid in the Prenatal Calf

Fluid was collected from the tracheas and amniotic sacs of 23 bovine foetuses of estimated age of 125 days to 219 days. In all samples the osmotic pressure of the tracheal fluid was greater than that of the corresponding amniotic fluid. The significance of this finding is discussed in relation to the concept that amniotic fluid is inhaled by the developing foetus and is an essential contributing factor to the expansion of the foetal lung. The author considers that such a concept is no longer tenable. The source of the tracheal fluid is thought to be the active secretory processes of the mucous glands of the tracheo-bronchial tree