Non‐invasive tracking of avian development in vivo by MRI

Abstract

Conventional microscopic techniques, to study embryonic development, require large numbers of embryos and are invasive, making follow-up impossible. We explored the use of in vivo MRI to study embryonic development, in general, and cardiovascular development in particular, over time. Wild-type quail embryos (n = 11) were imaged at embryonic days 3, 5, 7, 9, and 11, covering the main time course of embryonic heart development. On each imaging day cardiac morphology was evaluated and embryonic length was measured. MRI-embryos as well as control embryos (n = 11) were sacrificed at day 11 and scored for external malformations, while embryonic wet weight and stage were determined. In addition, venous clipped embryos (n = 4), known to develop cardiovascular malformations, were scanned at regular intervals and sacrificed at day 9 for histological analysis ex vivo. We were able to follow heart development of individual quail embryos inside their shell non-invasively over time, with sufficient detail to study cardiac morphology in vivo. We did not find any adverse effect of the repeated MRI examinations on morphology, length, or weight. Prenatally diagnosed malformations, like ventricular septal defects and aortic arch interruptions were confirmed by histology. In conclusion, micro-MRI can be used to evaluate in vivo early embryonic development and to diagnose cardiovascular malformations prenatally.

Developmental stages of the Japanese quail

“…In developmental terms, quail is still an extremely popular animal model, with studies on neural crest, thyroid, heart, pancreas, spleen, intestinal and craniofacial development having been recently published (Chen et al 2008;Eames & Schneider, 2008;Hogers et al 2009;Quinn et al 2009;Rowan-Hull et al 2009). Quail are increasingly being used as a comparator organism in cellbased investigations and are still heavily utilized in chickquail chimeric studies (Binder et al 2008;Costa-Silva et al 2009;Grenier et al 2009;Liem & Aoyama, 2009).…”

“…This is an excellent tool for understanding internal development, which is the main focus of the atlas, but as the embryos were only harvested every 24 h it cannot readily be used for accurate staging of the embryos. Other workers have also started to use non-invasive methods of following avian development (Hogers et al 2009). …”

Quantitative Three‐Dimensional Analysis of Embryonic Chick Morphogenesis Via Microcomputed Tomography

“…High field strength lMRI machines, however, are of limited availability because of their extreme expense (>$3 Million) and require upwards of 30 hr of scan time, which is largely cost prohibitive for routine phenotype screening (Dhenain et al, 2001). Image atlases of whole embryo development have been created for chick Li et al, 2007), quail (Ruffins et al, 2007;Hogers et al, 2009), and mouse (Dhenain et al, 2001;Johnson et al, 2006), but resolution and contrast strength remains challenging for earlier embryos. In the case of the chick, the earliest stage whole embryo 3D image data to date is Day 8, long after many morphogenic processes have occurred (Li et al, 2007).…”

MRI in Developmental Biology and the Construction of Developmental Atlases

“…Several techniques have been used to minimize motion artifacts even at stages where heart rates approach 220 beats per minute (Bogue 1932). In a longitudinal study, quail embryos were imaged over several days to assess whether cardiac defects could be detected by MRI (Hogers et al 2009). Control embryos and embryos that had the vitelline vein clipped were imaged at several stages.…”