ISSN:
1432-0878
Keywords:
Neurohypophysis
;
Acipenseridae
;
Ultrastructure
;
Quantitative analysis
;
Spawning
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
,
Medicine
Notes:
Summary The percentage of peptidergic (A1 and A2) and adrenergic (B) neurosecretory terminals was studied in the neurohypophysis of sexually mature female sturgeons. Neurosecretory terminals of the A2 type prevail in the neurohypophysis, whereas A1 and B terminals are rare. The activity of these types of terminals was established (1) during upstream migration, (2) shortly after spawning, and (3) three to six weeks after spawning. Terminals of B type are the most active elements during all the periods studied. These elements become strongly activated in sturgeons during upstream migration, i.e., earlier than the peptidergic neurosecretory terminals. Peptidergic terminals, especially elements of type A2, become synchronously and strongly activated in fish shortly after spawning. In the late postspawning period neurosecretory terminals of all three types become synchronously inactive, persisting in a quiescent state in comparison to the two previous periods. The appearance of neurosecretory material discharged into the intercellular clefts by exocytosis correlates on the whole with the activity level of the A1 and A2 terminals in each individual studied. A functional correlation exists between the activity of the peptidergic and adrenergic neurosecretory terminals in the neurohypophysis. The data obtained are discussed with reference to a concept regarding spawning in some fish species as a physiological stress (Polenov et al., 1976). A possible dual control (peptide and monoamine neurohormones) over the function of visceral organs and glandular cells of the intermediate lobe of the hypophysis is also suggested (Polenov, 1970, 1975, 1978; Polenov and Belenky, 1973).
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00237245
