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Micro-magnetic resonance imaging study of live quail embryos during embryonic development.

ABSTRACT: Eggs containing live Japanese quail embryos were imaged using micro-magnetic resonance imaging (?MRI) at 24-h intervals from Day 0 to 8, the period during which the main body axis is being laid down and organogenesis is taking place. Considerable detail of non-embryonic structures such as the latebra was revealed at early stages but the embryo could only be visualized around Day 3. Three-dimensional (3D) changes in embryo length and volume were quantified and also changes in volume in the extra- and non-embryonic components. The embryo increased in length by 43% and nearly trebled in volume between Day 4 and Day 5. Although the amount of yolk remained fairly constant over the first 5 days, the amount of albumen decreases significantly and was replaced by extra-embryonic fluid (EEF). ¹H longitudinal (T?) and transverse (T?) relaxation times of different regions within the eggs were determined over the first 6 days of development. The T? measurements mirrored the changes in image intensity observed, which can be related to the aqueous protein concentrations. In addition, a comparison of the development of Day 0 to 3 quail embryos exposed to radiofrequency (rf) pulses, 7 T static magnetic fields and magnetic field gradients for an average of 7 h with the development of control embryos did not reveal any gross changes, thus confirming that ?MRI is a suitable tool for following the development of live avian embryos over time from the earliest stages.

SUBMITTER: Duce S

PROVIDER: S-EPMC3006493 | biostudies-literature | 2011 Jan

REPOSITORIES: biostudies-literature

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Micro-magnetic resonance imaging study of live quail embryos during embryonic development.

Duce Suzanne S Morrison Fiona F Welten Monique M Baggott Glenn G Tickle Cheryll C

Magnetic resonance imaging 20100921 1

Eggs containing live Japanese quail embryos were imaged using micro-magnetic resonance imaging (μMRI) at 24-h intervals from Day 0 to 8, the period during which the main body axis is being laid down and organogenesis is taking place. Considerable detail of non-embryonic structures such as the latebra was revealed at early stages but the embryo could only be visualized around Day 3. Three-dimensional (3D) changes in embryo length and volume were quantified and also changes in volume in the extra- ...[more]

PMID: 20863641

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Project description:The cholangiopathies are a diverse group of biliary tract disorders, many of which lack effective treatment. Murine models are an important tool for studying their pathogenesis, but existing noninvasive methods for assessing biliary disease in vivo are not optimal. Here we report our experience with using micro-computed tomography (microCT) and nuclear magnetic resonance (MR) imaging to develop a technique for live-mouse cholangiography. Using mdr2 knockout (mdr2KO, a model for primary sclerosing cholangitis (PSC)), bile duct-ligated (BDL), and normal mice, we performed in vivo: (1) microCT on a Siemens Inveon PET/CT scanner and (2) MR on a Bruker Avance 16.4?T spectrometer, using Turbo Rapid Acquisition with Relaxation Enhancement, IntraGate Fast Low Angle Shot, and Half-Fourier Acquisition Single-shot Turbo Spin Echo methods. Anesthesia was with 1.5-2.5% isoflurane. Scans were performed with and without contrast agents (iodipamide meglumine (microCT), gadoxetate disodium (MR)). Dissection and liver histology were performed for validation. With microCT, only the gallbladder and extrahepatic bile ducts were visualized despite attempts to optimize timing, route, and dose of contrast. With MR, the gallbladder, extra-, and intrahepatic bile ducts were well-visualized in mdr2KO mice; the cholangiographic appearance was similar to that of PSC (eg, multifocal strictures) and could be improved with contrast administration. In BDL mice, MR revealed cholangiographically distinct progressive dilation of the biliary tree without ductal irregularity. In normal mice, MR allowed visualization of the gallbladder and extrahepatic ducts, but only marginal visualization of the diminutive intrahepatic ducts. One mouse died during microCT and MR imaging, respectively. Both microCT and MR scans could be obtained in ?20?min. We, therefore, demonstrate that MR cholangiography can be a useful tool for longitudinal studies of the biliary tree in live mice, whereas microCT yields suboptimal duct visualization despite requiring contrast administration. These findings support further development and application of MR cholangiography to the study of mouse models of PSC and other cholangiopathies.

Project description:Driven by a global trend of applying replace-reduce-refine or 3Rs’ guidance for experimental animals in life sciences, chick embryo and particularly allantois with its chorioallantoic membrane have been increasingly utilized to substitute laboratory animals, which call for more extensive and updated knowledge about this novel experimental setup. In this study, being noninvasive, nonionizing, and super-contrasting with high spatiotemporal resolutions, magnetic resonance imaging (MRI) was chosen as an imaging modality for in ovo monitoring morphologic evolution of the chick embryo, allantois, and chorioallantoic membrane longitudinally throughout embryonic day (ED) 1 until ED20. Cooled in 0°C ice bath for 60 min to reduce MRI motion artifacts, 3 chick embryos (n = 60 in total) on each ED were scanned by a clinical 3.0T MRI scanner to demonstrate 3D images of both T2- and T1-weighted imaging (T2WI, T1WI) sequences at axial, sagittal, and coronal slices. The volumes of both the entire chick embryo and allantois were semi-automatically segmented based on intensity-based thresholding and region-growing algorithms. The morphometries or quantified 3D structures were achieved by refined segmentation, and confirmed by histological analyses (one for each ED). After MRI, the rest of chick embryos (n = 40) continued for incubation. The images from ED2 to ED4 could demonstrate the structural changes of latebra, suggesting its transition into a nutrient supplying channel of yolk sac. The allantois could be recognized by MRI, and its relative volumes on each ED revealed an evolving profile peaked on ED12, with a statistically significant difference from those of earlier and later EDs (P < 0.01). The hypointensity of the yolk due to the susceptibility effect of its enriched iron content overshadowed the otherwise hyperintensity of its lipid components. The chick embryos survived prior cooling and MRI till hatching on ED21. The results could be further developed into a 3D MRI atlas of chick embryo. Clinical 3.0T MRI proved effective as a noninvasive approach to study in ovo 3D embryonic development across the full period (ED1–ED20), which can complement the present knowhow for poultry industry and biomedical science.

Dataset Information

Micro-magnetic resonance imaging study of live quail embryos during embryonic development.

Publications

Micro-magnetic resonance imaging study of live quail embryos during embryonic development.

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