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Premigratory Changes in the Hypothalamo‐Hypophysial Neurosecretory System in the Red‐winged Blackbird ( Agelaius phoeniceus) *
Author(s) -
Hawkes Michael P. G.,
George J. C.
Publication year - 1975
Publication title -
acta zoologica
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.414
H-Index - 37
eISSN - 1463-6395
pISSN - 0001-7272
DOI - 10.1111/j.1463-6395.1975.tb00082.x
Subject(s) - median eminence , neurosecretion , biology , hypothalamus , period (music) , anatomy , medicine , endocrinology , physics , acoustics
1 The hypothalamo‐hypophysial neurosecretory system in the Red‐winged Blackbird ( Agelaius phoeniceus ) has been studied with special reference to changes during the period prior to fall migration. 2 In September the supraoptic and paraventricular cells were found to be considerably larger with substantial amounts of aldehyde fuchsin positive neurosecretory material (NSM) accumulating in the perikaryon. Large amounts of the NSM were found also in the anterior median eminence and pars nervosa. 3 Towards migration time (November), the cells in the hypothalamic nuclei contained very little NSM. A marked decline in the amount of NSM was also seen in the anterior median eminence and probably in the pars nervosa too. 4 The release of NSM toward migration time has been discussed as an important event in the sequence of events that control and regulate migratory activity.