Ultrasonographic monitoring of fetal eye growth parameters throughout gestation in the common marmoset (Callithrix jacchus)

The common marmoset (Callithrix jacchus) is considered an ideal species for developing genetically modified nonhuman primates (NHP) models of human disease, particularly eye disease. They have been proposed as a suitable bridge between rodents and other NHP models due to their similar ophthalmological features to humans. Prenatal ultrasonography is an accurate and reliable diagnostic tool for monitoring fetal development and congenital malformation. We monitored fetal eye growth and development using noninvasive ultrasonography in 40 heads of clinically normal fetuses during pregnancy to establish the criteria for studying congenital eye anomalies in marmosets. The coronal, sagittal, and transverse planes were useful to identify the facial structures for any associated abnormalities. For orbital measurements, biorbital distance (BOD), ocular diameter (OD), interorbital distance (IOD), and total axial length (TAL) were measured in the transverse plane and carefully identified for intraorbital structures. As a result, high correlations were observed between delivery‐based gestational age (GA) and biparietal diameter (BPD), BOD, OD, and TAL. The correlation assessments based on BOD provide more reliable results for monitoring eye growth and development in normal marmosets than any other parameters since BOD has the highest correlation coefficient according to both delivery‐based GA and BPD among ocular measurements. In conclusion, orbital measurements by prenatal ultrasonography provide reliable indicators of marmoset eye growth, and it could offer early diagnostic criteria to facilitate the development of eye disease models and novel therapies such as genome editing technologies in marmosets. Research highlights Prenatal ultrasound was used to evaluate fetal growth and eye development in 40 clinically normal marmoset fetuses. It identified a high correlation between delivery‐based gestational age (GA) and parietal diameter (BPD), one of the biometrics for assessing fetal size. In addition, high correlations were observed between the delivery‐based GA and the ocular development biometrics, including biorbital distance (BOD), orbital diameter (OD), and total axial length (TAL). Correlation evaluation based on BOD provided more reliable results for monitoring eye development in normal marmosets since BOD has the highest correlation coefficient according to delivery‐based GA and BPD among ocular measurements. Prenatal ultrasonography is an easy and noninvasive m