CYTO-DIFFERENTIATION AND PORTAL VASCULAR DEVELOPMENT IN MOUSE ADENOHYPOPHYSIS

Abstract

The developmental pattern of the hypothalamo-hypophysial vascular system in the mouse was correlated with morphological indications of adenohypophysial function, using light microscopy and EM. Portal vessels 1st extend from the primary plexus to the pars distalis at 17 days post coitum (p.c.), and the number of these increases to reach the adult pattern at 5 days post natal (p.n.). Granulation of secretory cells begins at 16 days p.c.; at 17 days thyrotropes, gonadotropes and corticotropes are recognizable, and these appear actively secretory on days 17-18 p.c. Somatropes are 1st seen at 18 days p.c. Active secretory cells increase in number over the period 2-10 days p.n., and after 11 days p.n. thyrotropes and corticotropes appear progressively less active. Gonadotropes appear progressively less active from day 19, while most somatotropes appear active until 28 days p.n. Hypothalamic control over adenohypophysial function may be present in the mouse from 17 days p.c.