[Immunocytochemical study of the development of pepsinogens in the chick embryo]

The appearance and localization of pepsinogens in the chicken proventriculus during the normal development were studied immunocytochemically with use of the antibodies against an embryo-specific and an adult-specific chicken pepsinogens. The embryonic pepsinogen exists mainly in the apical part of the gland cells and in the secreted substances of 10-20 day embryonic proventriculus. The adult pepsinogen appears during hatching, and all gland cells become positive mainly at the basal portion one day after hatching.