Ultrastructural changes in the calcium-sensitive (PAS-positive) cells of the pars intermedia of eels kept in deionized water and in normal and concentrated sea water.
The ultrastructure of the calcium-sensitive (Ca-s) (PAS-positive) cells of the pars intermedia was investigated in eels kept in hypo- and hyperosmotic environments. Although the cells were moderately active in fresh water (FW), they were highly stimulated in deionized water (DW) and displayed an enlarged Golgi apparatus, a distinct rough endoplasmic reticulum, few secretory granules, some microtubules and an extended area of contact with the basal lamina that separates nervous and glandular tissues. Some mitosing cells were seen. A similar picture was observed in eels kept in sea water (SW) for 45 days, returned to FW and subsequently to DW for 21 days. In SW (20 and 33%), and particularly in concentrated SW (50, 60 and 63%), the Ca-s cells were inactive. Their granules were significantly smaller than in eels kept in FW, and the area of contact with the basal lamina was greatly reduced. However, signs of granule-release were seen in eels adapted to 50 and 60% SW. Nerve fibers rarely contacted the Ca-s cells and did not synapse with them. The ultrastructural data support the hypothesis that the Ca-s cells of Anguilla, like those of Carassius, are involved in ionic regulation. MSH cells were not greatly affected by the present experiments.
D000818:Animals; D002118:Calcium / Q000502:physiology*; D004524:Eels / Q000502:physiology*; D005618:Fresh Water; D006651:Histocytochemistry; D008297:Male; D009074:Melanocyte-Stimulating Hormones / Q000502:physiology; D008854:Microscopy, Electron; D009412:Nerve Fibers / Q000502:physiology; D009434:Neural Pathways; D010503:Periodic Acid-Schiff Reaction; D010902:Pituitary Gland / Q000166:cytology* / Q000648:ultrastructure; D012623:Seawater; D013997:Time Factors; D014867:Water / Q000494:pharmacology*; D014882:Water-Electrolyte Balance
D014867:Water; D009074:Melanocyte-Stimulating Hormones; D002118:Calcium