ENZYME-HISTOCHEMICAL STUDY ON POSTNATAL-DEVELOPMENT OF RAT STOMACH LYMPHATIC VESSELS

Postnatal development of rat gastric lymphatics was studied by an enzy me-histochemical method to elucidate the morphological changes of lymp hatics and their relationship to maturation and function, especially i n the glandular portion. The significant features of 5'-Nase-positive lymphatics in distribution and structure were examined in different st ages (within 24 hr, 4-21 days, and 2 months). Lymphatics in the greate r curvature and anterior wall grew much slower than those in the:Lesse r curvature and posterior wall of the stomach in newborn and infant ra ts. Lymphatic islands isolated from the primary lymphatic networks in the submucosa and subserosa underwent a morphological change during th is early period. This is considered one of the basic steps in lymphati c development. Occurrence of lymphatic networks in the deep lamina pro pria indicates that development in the gastric wall is well characteri zed from Day 10. With further growth and modification of lymphatics, t he networks in the different layers formed an extensive communication network and many lymphatic valves were found in the submucosa and subs erosa. Pinocytotic vesicles, open junctions, and intraendothelial chan nels were frequently detected in the mucosal and submucosal lymphatic networks of the corpus-antrum and antrum-duodenum divisional zones in the adult rats. These findings suggest that developing lymphatics in t he rat stomach may represent rapidly growing tissue not only with high 5'-Nase activity but also with high adaptability for future physiolog ical demands. (C) 1997 Academic Press.