TABLE 2.

Comparison of inner ear development in different vertebrates.

Event	Pre-placodal region (PPR)	Otic placode	Otic cup	Otic vesicle	Migration of neuroblasts into vestibulocochlear ganglion	Differentiation of ganglion cells/first neurites	Sensory areas begin to separate	First hair cells differentiate	Development of otolith organs and semicircular canals completed
Xenopus	NF 14 (Schlosser and Ahrens, 2004)	NF 21 (Schlosser and Northcutt, 2000)	NF 22/23 (Schlosser and Northcutt, 2000)	NF 28 (Schlosser and Northcutt, 2000)	NF 27–39 This study	NF 29/32 This study	NF 33 This study	NF 31 (Quick and Serrano, 2005)	NF 47 (Quick and Serrano, 2005)
Zebrafish	10 hpf (1 som) (Akimenko et al., 1994; Sahly et al., 1999)	14 hpf (10 som) (Haddon and Lewis, 1996)	−	19.5 hpf (21 som) (Haddon and Lewis, 1996)	17 to 42 hpf (Haddon and Lewis, 1996; Vemaraju et al., 2012)	24/30 hpf (Haddon and Lewis, 1996)	24 hpf (Haddon and Lewis, 1996)	24 hpf (Haddon and Lewis, 1996)	72 hpf (Haddon and Lewis, 1996)
Chick	HH 7 (23–26 h; 1 som) (Esteve and Bovolenta, 1999; McLarren et al., 2003)	HH 10 (33–38 h; 10 som) (Hilfer et al., 1989)	HH 12 (45–49 h; 16 som) (Hilfer et al., 1989; Wu and Oh, 1996)	HH 17 (52–64 h)Wu and Oh, 1996)	HH 16–28 (51 h–6 d) (D’Amico-Martel and Noden, 1983; Hemond and Morest, 1991; Bell et al., 2008	HH 26 (5 d) (Bartolami et al., 1991)	HH 19–24 (3–4.5 d) (Oh et al., 1996; Wu and Oh, 1996)	HH 26 (5 d) (Bartolami et al., 1991; Oh et al., 1996)	HH 30 (6.5–7 d) (Bissonnette and Fekete, 1996)
Mouse	E8 (Sato et al., 2010)	E8.5 (Anniko and Wikstrom, 1984)	E9 (Anniko and Wikstrom, 1984)	E9.5 (Anniko and Wikstrom, 1984)	E9-E11.5 (Carney and Silver, 1983; Wikstrom and Anniko, 1987; Ma et al., 1998; Raft et al., 2004)	E11.5 (Carney and Silver, 1983)	E11.5 (Morsli et al., 1998; Raft et al., 2007)	E11.5 (Shailam et al., 1999)	E13 to E17 (Morsli et al., 1998)