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

Figure 4

Embryonic days 49–60. US B-mode: (a) images of the head at embryonic day 49 with the measurements of the head diameter (HD) (short axis) and occipital to snout length (OSL) (long axis) (9.1 × 5.3 mm); (b) head US aspect at embryonic day 49: skull bones are hyperechoic but still not mineralized; (c) measurement of the occipital to snout length (OSL) at embryonic day 67 (12.6 mm); HFUS B-mode: (d) the eyes (arrow) and the ears are visible at E60.

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