A light and electron microscopic study of the structure of the nucleus preopticus and nucleus lateral tuberis of the goldfish, Carassius auratus

Abstract

On the basis of fine structure only one cell type could be identified in the nucleus preopticus. The nucleus lateral tuberis (NLT) contains three distinct cell types. Cell type 1, primarily in the NLT pars lateralis, is a large cell with many dense-core granules (DCG) 97.3 nm average diameter. Cell type II, primarily in the NLT pars anterioris, is smaller and contains few DCG, averaging 70.9 nm. Cell type III, found in the NLT pars posterioris, pars inferioris and posteriorly in the pars anterioris, is a small cell with DCG similar to type II cells. Cell type III additionally has large irregular granular bodies (dimensions up to 2 μm) that stain with aldehyde fuchsin and are visible with the light microscope. The possible role of the various cell types in controlling pituitary function is discussed.The juxta-ventricular border of the ependyma in the NPO and NLT regions is lined with cilia and microvilli, each with a regionalized distribution. In addition, there are cells with bleblike cytoplasmic extensions into the third ventricle in the ependyma layer in the NLT pars anterioris and pars posterions regions.