Weitere Aspekte der Lokalisation, Ultrastruktur und Funktion der „Sexualzentren“ des Hypothalamus

Summary

Experiments with stereotaxic lesions of the hypothalamus in several passerine species have shown that photoperiodic induction of testicular growth, observed in intact birds, is prevented by lesions in the region of the infundibular (arcuate) nucleus (Wilson, 1967; Stetson, 1969). Our recent cytoarchitectonic studies of the hypothalamus in fringillid finches have suggested that the main tuberal nuclei (infundibular nucleus, ventromedial nucleus) consist of small cell clusters and layers arranged in a mosaic pattern. Using Falck and Hillarp’s technique, a strong fluorescence has been observed in the tuberal neurons which form the source of the tubero-infundibular tract. It is suggested that the avian hypothalamus contains, besides the classical neurosecretory system (supraoptic nucleus—paraventricular nucleus—pars nervosa) and the aminergic tubero-infundibular system, also peptidergic neuroendocrine centers which may form releasing factors. The existence of rostral and caudal groups of hypophyseal portal vessels suggests that the neuroendocrine tracts in birds have a point-to-point relationship to specialized parts of the pars distalis.

Dem Andenken von Professor Hugo Spatz.

Mit Unterstützung durch die Deutsche Forschungsgemeinschaft. In Zusammenarbeit mit Prof. Dr. D. S. Farner, Department of Zoology, University of Washington, Seattle, USA.