Abstract
Adsorption of vitamin B12, with and without gastric mucosa extract (GME), to intestinal mucosa homogenates from rats was studied at various stages of growth. The development of the activities of producing gastric HCl and pepsinogen was also investigated. The intestine from newborn animals showed extremely high adsorption of vitamin B12 in the absence of GME. The GME-independent vitamin B12 adsorption fell rapidly with time, approaching adult level at about 20 days of age. Stimulation of vitamin B12 adsorption by adult GME and the gastric HCl secretion reached adult levels at about 20 days. On the other hand, intrinsic factor formation and pepsinogen formation did not reach adult levels until about 30 days. Histologic investigations of the gastric gland and ileal villus agreed with the above-mentioned experimental results. The intrinsic factor-dependent vitamin B12 absorption became a predominant system at about 30 days after birth.
