TABLE 1.

Summary of GI vagal afferents classification.

Characteristics			Oesophagus	Stomach	Small Intestine	References
Embryonic origins
	Neural crest-derived		+	−	−	Yu et al., 2005; Surdenikova et al., 2012; Trancikova et al., 2018
	Placode-derived		+	+	+
Conductance velocity			Aδ- and C-fibre	C-fibre	C-fibre	Page and Blackshaw, 1998; Yu et al., 2005
Visceral endings
	Muscle layer
		IGLE	+++	+++	++
		IMA	LES	Pyloric sphincter	Scarce	Rodrigo et al., 1970, 1975a,b; Pedrosa et al., 1976; Berthoud and Powley, 1992; Fox et al., 2000; Powley, 2000; Powley and Phillips, 2011; Powley et al., 2011, 2012, 2013, 2014, 2016
	Mucosal afferents		+	+	+
	Mucosal-muscle afferents		+	N/A	N/A
Brainstem endings
	Nucleus tractus solitarius		NTS centralis	NTS medialis, NTS gelatinosus	NTS commisuralis	Travagli and Anselmi, 2016
	Area postrema		N/A	+	+	Han et al., 2018
Primary response to stimuli
	Mechanosensitive		Tension receptor, Mucosal receptor, Tension-mucosal receptor	Tension receptor, Mucosal receptor	Tension receptor	Page and Blackshaw, 1998; Page et al., 2002
	Chemosensitive		Osmolarity, pH	Osmolarity, pH	Nutrient	Powley and Phillips, 2004; Williams et al., 2016
	Thermosensitive		+	+	+	El Ouazzani and Mei, 1982; El Ouazzani, 1984; Lennerz et al., 2007; Jänig, 2018
Genetic markers
	Mucosal afferents		N/A	Sst/Gpr65, Calca	Glpr1R, Vip/Uts2b, Gpr65	Bai et al., 2019
	IGLE		N/A	GLP1R	Oxtr
	IMA		N/A	Calca	N/A
Physiological function			Baroreceptors, Nociceptors	Mechanosensing	Nutrient sensing	Yu et al., 2005; Kollarik et al., 2010b; Williams et al., 2016; Han et al., 2018; Kaelberer et al., 2018