MIP-immunoreactive innervation of the snail, Helix pomatia, heart. An ultrastructural study.
The ultrastructural characteristics of the innervation established by MIP-(Mytilus inhibitory peptide) immunoreactive neurons was investigated in the heart of the snail, Helix pomatia, applying correlative light- and electron microscopic pre-embedding immunocytochemistry on Vibratome-slices. In both the auricle and ventricle, the muscle fibers receive a rich innervation by MIP-immunoreactive (IR) varicose fibers. However, the innervation is seasonally changing in the two parts of the heart. The varicosities, containing a morphologically uniform population of large (120-150 nm) electron-dense granules, can be found in three different positions in relation to the muscle fibers: (i) close (15-20 nm) but unspecialized membrane connections between MIP-(IR) varicosities and muscle fibers; (ii) MIP-IR varicosities located relatively far (0.5-several microm) from the muscles fibers; (iii) MIP-IR profiles localized freely in the extracellular space among the loosely arranged muscle fibers. A general modulatory role of MIP in regulating the heart activity of Helix is suggested.
Elekes
K
K
Department of Experimental Zoology, Balaton Limnological Research Institute of the Hungarian Academy of Sciences, Tihany.
Nagy
T
T
Fekete
Z N
ZN
D000818:Animals; D006321:Heart / Q000294:innervation*; D006372:Helix, Snails / Q000502:physiology*; D007150:Immunohistochemistry; D008854:Microscopy, Electron; D009842:Oligopeptides / Q000378:metabolism*
C055988:Mytilus inhibitory peptide; D009842:Oligopeptides