Table 1.

Summary of initial oscillation in murine embryos.

Embryonic organs	Initial oscillation at	Circadian genes/proteins	References
Adrenal gland	ED18	Bmal1, Per2, Egr-1, Mt1, and StAR	[35]
Colon	ED20	Bmal1, Per2, and Rev-erb	[36]
Kidney	ED20	CLOCK, Per2, Rev-erb, aENaC, SGK1, NHE3, and AVPR2	[37]
	ED13	Per2	[7]
	ED18	—	[38]
Liver	ED13	Per2	[7]
Heart	ED17	CLOCK, Bmal1, Cry1, Per2, Per3, Nr1d2 (Rev-erbβ), and Dbp	[25]
Pars tuberalis	ED18	Cry1, Cry2, Per1, and Per2	[39]
SCN	ED13	Per2	[7]
	ED14.5	Per2	[40]
	ED18	Per1, Per2, and AVP	[39]

Note: Bmal1, brain-muscle-arnt-like protein 1; Egr-1, early growth response protein 1; Cry1, cryptochrome circadian regulator 1; Cry2, cryptochrome circadian regulator 2; aENaC: epithelial sodium channel; Mt1, melatonin receptor; NHE3, sodium-hydrogen exchanger 3; Per1, circadian period regulator 1; Per2, circadian period regulator 2; Rev-erb, nuclear receptor subfamily 1 group DSGK1, serine/threonine protein kinase 1; StAR, acute regulatory protein.

Abbreviations: AVP, arginine vasopressin; Avpr2, arginine vasopressin receptor 2; CLOCK, circadian locomotor output cycles kaput; ED, embryonic day; SCN, suprachiasmatic nucleus.