TABLE 2.

Age-dependent changes in human and rodent NMJs.

	Human	Rodent
Presynaptic changes
Active zone density	Unknown	Decreases (Chen et al., 2012)
Active zone-specific proteins	Unknown	Selective degeneration of bassoon, piccolo and P/Q type VGCC protein level and density per synapse (Chen et al., 2012; Nishimune et al., 2012; Nishimune et al., 2016)
Synaptic vesicle density	Unknown	Decreases (Fahim and Robbins, 1982; Banker et al., 1983)
Nerve terminal branching	Increases (Oda, 1984), no change (Gambino et al., 1990)	Increases (Fahim et al., 1983; Li et al., 2011; Valdez et al., 2012)
Denervation	Increases in intercoastal (Oda, 1984) and VL muscles (Lexell and Downham, 1991; Mosole et al., 2014; Zampieri et al., 2016), no change in the peroneus longus muscle (Jones et al., 2017)	Increases in TA, plantaris, and EDL muscle (Fahim and Robbins, 1982; Deschenes et al., 2010; Valdez et al., 2010; Chai et al., 2011)
Postsynaptic changes
NMJ fragmentation	No change in the peroneus longus muscle (Jones et al., 2017)	Increases in the EDL, diaphragm, soleus, sternomastoid, and TA muscles (Andonian and Fahim, 1988; Valdez et al., 2010; Li et al., 2011; Willadt et al., 2016)
Endplate area	Increases (Oda, 1984) and no change (Wokke et al., 1990) in intercostal muscles. No change in the peroneus longus muscle (Jones et al., 2017)	No change in the EDC, EDL, GM, and soleus muscles (Banker et al., 1983)
Postsynaptic folds number and regularity	Decreases (Arizono et al., 1984; Wokke et al., 1990)	Decreases (Fahim and Robbins, 1982)

The age range for human studies is 4–95 years, and the age range for rodent studies is 21 days to 33 months (mice) and 56 days to 24 months (rats). EDC, extensor digitorum communis; EDL, extensor digitorum longus; GM, gluteus maximus; NMJ, neuromuscular junction; TA, tibialis anterior; VGCC, voltage-gated calcium channel; VL, vastus lateralis.