Abstract
THE hypotonicity of the fœtal fluids and urine of many mammalian fœtuses is well known1, and attempts have been made to explain it in terms of active transport of water or of sodium2. In certain conditions, the production of osmotically free water may be the physico-chemical consequence of active anabolism. If the anabolism occurs in a medium isotonic with normal extracellular fluid and is accompanied by little or no catabolism, water will be freed. This situation obtains in the mammalian fœtus which, while showing little catabolic activity, is rapidly synthesizing the large molecules of its cell constituents from small molecules passing through the placenta into its circulation. The osmotic freeing of water by this process is sufficiently great to account for the hypotonicity of the fœtal fluids and urine.
Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
