Noninvasive Ultrasound Monitoring of Embryonic and Fetal Development in Chinchilla lanigera to Predict Gestational Age: Preliminary Evaluation of This Species as a Novel Animal Model of Human Pregnancy

Table 2

Ultrasound visible fetal anatomic structure per gestational stage.

Stage	Anatomic embryo/fetal structure	Ultrasound techniques
T1 (E15–E30)	Longitudinal sac diameter	HFUS, US
	Transversal sac diameter	HFUS, US
	Placental diameter	HFUS
	Placental thickness	HFUS
T2 (E31–E46)	Longitudinal sac diameter	HFUS, US
	Transversal sac diameter	HFUS, US
	Placental diameter	HFUS, US
	Placental thickness	HFUS, US
	Head diameter	HFUS, US
	Occipital snout length	HFUS, US
	Heart rate (BPM)	HFUS, US
	Longitudinal body diameter	HFUS, US
	Crown-rump length	HFUS, US
T3 (E47–E70)	Placental diameter	HFUS, US
	Placental thickness	HFUS, US
	Lens	HFUS, US
	Eye	HFUS, US
	Head diameter	HFUS, US
	Occipital snout length	HFUS, US
	Heart rate (BPM)	HFUS, US
	Stomach	HFUS, US
	Longitudinal body diameter	HFUS, US
	Femur	HFUS, US
	Crown-rump length	US
T4 (E71–E115)	Placental diameter	US
	Placental thickness	US
	Lens	US
	Eye	US
	Head diameter	US
	Occipital snout length	US
	Heart rate (BPM)	US
	Stomach	US
	Longitudinal body diameter	US
	Femur	US
	Crown-rump length	US

BPM: beats per minute.