Age-related changes in two- and three-dimensional morphology of type-identified endplates in the rat diaphragm

Toshimi Suzuki, Akio Maruyama, Takao Sugiura, Shuichi MacHida, Hirofumi Miyata

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16 Citations (Scopus)


To examine the age-related morphological changes in the motor endplate of type-identified muscle fibers, 20 male Wister rats were divided into 2-month-, 10-month-, 24-month- and 30-month-old groups (n = 5 in each group). Three segments of mid-costal diaphragm muscle were removed, and then a fluorescent double-labeling technique was used to visualize the endplates on type-identified muscle fibers. Endplates were labeled with α-bungarotoxin- tetramethylrhodamine. Muscle segments were first incubated in antibodies to MHC isoforms (I and/or IIa) and then labeled by a second antibody with FITC. The endplates were imaged using 3D confocal microscopy with two lasers. In each age group, the planar area and volume of endplates on type-IIx/b muscle fibers were larger than those on type-I and -IIa muscle fibers, while the normalized planar areas of the endplate (endplate area/muscle fiber diameter) and the mean thickness of the endplate (volume/endplate area) were identical on all fiber types within the same age group. Decreased endplate density (endplate area/surrounding area) in the old diaphragm indicated fragmentation of the endplate, especially on type IIx/b fibers. These morphological changes may lead to functional deficiency and selective denervation of type-IIx/b muscle fiber with aging.

Original languageEnglish
Pages (from-to)57-62
Number of pages6
JournalJournal of Physiological Sciences
Issue number1
Publication statusPublished - 2009 Jan
Externally publishedYes


  • 3D analysis
  • Aging
  • Diaphragm
  • Endplate area

ASJC Scopus subject areas

  • Physiology


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