Membrane relationships in murine meissner corpuscles: Cytology of freeze-substituted tissue
Article first published online: 22 FEB 2005
Copyright © 1989 Wiley-Liss, Inc.
The Anatomical Record
Volume 223, Issue 4, pages 437–445, April 1989
How to Cite
Yoshida, Y., Ushiki, T., Takashio, M., Munger, B. L. and Ide, C. (1989), Membrane relationships in murine meissner corpuscles: Cytology of freeze-substituted tissue. Anat. Rec., 223: 437–445. doi: 10.1002/ar.1092230414
- Issue published online: 22 FEB 2005
- Article first published online: 22 FEB 2005
- Manuscript Accepted: 14 SEP 1988
- Manuscript Received: 21 AUG 1987
Mechanoreceptive sensory corpuscles (murine Meissner corpuscles) in the toe pad skin of mice, consisting of axon terminals and lamellar cells, were studied following freeze-substitution in order to clarify the plasma membrane relationships between axon terminals and lamellar cells. Tissue preservation of corpuscles was excellent when the corpuscle was located within 10 μm from the contact surface with the precooled metal block.
The axolemmata appeared more electron-opaque than did plasma membranes of lamellar cells. The inner leaflet of the unit membranes was thicker than the outer leaflet in the axolemma, and the contour of cell plasma membranes was relatively smooth and straight. Characteristic focal or regional approximations of plasma membranes were noted between the axon and abutting lamellae. Such membrane appositions resembled gap junctions, although no gap junctions were found between the axon and lamellae in chemically fixed materials. Similar gap junction-like close appositions of plasma membranes also were found between neighboring lamellae. These approximations occurred more frequently than typical gap junctions seen in chemically fixed materials. These findings indicate that there may be a relationship of the plasma membranes in the axon terminals and in abutting lamellae as well as between neighboring lamellae that have not been identified as yet in conventional chemically fixed material.
Another striking finding was that basal laminae on lamellar cells exhibited the same electron opacity as the surrounding connective tissue matrix and thus the two are indistinguishable from one another. Furthermore, the lamina lucida was not evident, and basal lamina material was directly contiguous with the plasma membrane. These findings suggest that freeze-substitution can retain materials that are easily extractable by conventional chemical fixation and dehydration.