Histochemistry and Cell Biology

, Volume 151, Issue 2, pp 161–173 | Cite as

Distribution and morphology of baroreceptors in the rat carotid sinus as revealed by immunohistochemistry for P2X3 purinoceptors

  • Takuya Yokoyama
  • Kazuya Settai
  • Nobuaki Nakamuta
  • Yoshio YamamotoEmail author
Original Paper


The morphological characteristics of baroreceptors in the rat carotid sinus were reevaluated by whole-mount preparations with immunohistochemistry for P2X3 purinoceptors using confocal scanning laser microscopy. Immunoreactive nerve endings for P2X3 were distributed in the internal carotid artery proximal to the carotid bifurcation, particularly in the region opposite the carotid body. Some pre-terminal axons in nerve endings were ensheathed by myelin sheaths immunoreactive for myelin basic protein. Pre-terminal axons ramified into several branches that extended two-dimensionally in every direction. The axon terminals of P2X3-immunoreactive nerve endings were flat and leaf-like in shape, and extended hederiform- or knob-like protrusions in the adventitial layer. Some axons and axon terminals with P2X3 immunoreactivity were also immunoreactive for P2X2, and axon terminals were closely surrounded by terminal Schwann cells with S100 or S100B immunoreactivity. These results revealed the detailed morphology of P2X3-immunoreactive nerve endings and suggested that these endings respond to a mechanical deformation of the carotid sinus wall with their flat leaf-like terminals.


Carotid sinus Sensory nerve endings P2X purinoreceptor Immunohistochemistry 


Compliance with ethical standards

Conflict of interest

The authors declare no conflicts of interest.

Supplementary material

418_2018_1734_MOESM1_ESM.docx (201 kb)
Supplementary material 1 (DOCX 201 KB)


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© Springer-Verlag GmbH Germany, part of Springer Nature 2018

Authors and Affiliations

  1. 1.Department of Anatomy (Cell Biology)Iwate Medical UniversityYahabaJapan
  2. 2.Laboratory of Veterinary Anatomy and Cell Biology, Faculty of AgricultureIwate UniversityMoriokaJapan

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