Ontogeny and immunohistochemical differentiation of the Pars Tuberalis in the lizard Gallotia gallotti.

The development of the pituitary Pars Tuberalis (PT) was studied in the lizard Gallotia galloti using classical, histological and immunohistochemical techniques. As early as stage 32 of development, the Rathke's pouch exhibits 2 lateral extensions that will give rise to the PT. In these extensions, cellular proliferation results in the formation of two cell masses which develop rostro-laterally and contact the basal diencephalon at stage 35. At stage 37, these two cell groups lose their connection with the pars distalis (PD). Until the end of embryonic development, connective tissue separates the nervous tissue from the glandular one. At hatching, the disappearance of this connective tissue results in the incorporation of the two cell groups into the nervous tissue without visible separation. During development, immunoreactivity for anti-betaLH and anti-TSH appears in the cells of the PT respectively at stage 39 and 37. In adults, almost all cells of the PT can be demonstrated using antisera against gonadotrophins.