Presence of substance P and angiotensin II in corticotropic cells of the lizard Gallotia galloti: immunochemical study in the adult and during ontogenesis.

The hypophysis of the lizard Gallotia galloti showed substance-P-like immunoreactivity in both the adenohypophysis (pars distalis, PD; pars intermedia, PI) and the neurohypophysis (median eminence and pars nervosa), whereas angiotensin-II-like immunoreactivity appeared only in PD and PI. The elution-restaining procedure has allowed us to demonstrate the colocalization of both peptides with adrenocorticotropic hormone (ACTH) in PD and PI cells. Electron microscopic study revealed the presence of substance P immunoreactivity on ACTH secretory granules. The ontogeny of both peptides in corticotropic cells has been studied, revealing that the presence of substance P in ACTH-containing cells of the PI occurs from the embryonic stage 33 (S 33), whereas in the PD it occurs from S 34, coinciding with the appearance of ACTH within the same cells. In both median eminence and pars nervosa of the neurohypophysis, substance P appeared later in development, at S 38. Angiotensin II immunoreactivity in PI cells first appeared at S 38, while in PD it appeared from S 40.