Ultrastructural and cytochemical features of SV 40 transformed hypothalamic cell lines

A continuous cell line was previously obtained by Simian Virus (SV) 40 transformation of primary cultures of dissociated mouse fetal hypothalami. One clone from this cell line has been previously shown to possess some of the ultrastructural features, immunological properties and synthesizing capacities of magnocellular hypothalamic neurons which secrete vasopressin and neurophysins. The present paper reports on the morphological characterization of 14 other clones or subclones of the original cell line, using the following criteria: phase contrast microscopy, electron microscopy, Gomori's aldehyde fuchsin staining, cytochemical detection of beta-glucuronidase, immunochemical staining with antisera against bovine neurophysin I, bovine neurophysin II, lys-vasopressin, oxytocin, LH-RH and TRH. The results allowed the conclusion that the clones as well as the subclones can be distributed into two groups: 1) neurosecretory neurons which all possess several of the ultrastructural and cytochemical features of the neurophysin-vasopressin synthesizing clone, and 2) primitive nerve cells which are devoid of such features but display numerous bundles of filaments. In addition some clones were found to display intermediate features between groups 1 and 2. A similar diversity was observed within clones of the original strain and subclones of a neurosecretory clone. It is suggested that the primitive clones could represent precursors of the neurosecretory clones.