3-dimensional imaging modalities for phenotyping genetically engineered mice

Abstract

A variety of 3-dimensional (3D) digital imaging modalities are available for whole-body assessment of genetically engineered mice: magnetic resonance microscopy (MRM), X-ray microcomputed tomography (microCT), optical projection tomography (OPT), episcopic and cryoimaging, and ultrasound biomicroscopy (UBM). Embryo and adult mouse phenotyping can be accomplished at microscopy or near microscopy spatial resolutions using these modalities. MRM and microCT are particularly well-suited for evaluating structural information at the organ level, whereas episcopic and OPT imaging provide structural and functional information from molecular fluorescence imaging at the cellular level. UBM can be used to monitor embryonic development longitudinally in utero. Specimens are not significantly altered during preparation, and structures can be viewed in their native orientations. Technologies for rapid automated data acquisition and high-throughput phenotyping have been developed and continually improve as this exciting field evolves.

Figure 1

Embryo, wild-type mouse. 40-μm spatial resolution, midline sagittal view taken from a 3D magnetic resonance microscopy (MRM) volume image of gadolinium-stained E17.5 wild-type mouse embryo.

Figure 2

Embryo, TEC1KO mouse. 40-μm spatial resolution, midline sagittal view taken from a 3D MRM volume image of gadolinium-stained E17.5 TEC1KO mouse embryo. The white arrows indicate regions in the soft palate and nasal septum of the TEC1KO that are clearly different from those observed in the wild-type littermate shown in Fig. 1.

Figure 3

Cranium, wild-type mouse. Axial view taken through the same E17.5 wild-type mouse embryo presented in Fig. 1.

Figure 4

Cranium, TEC1KO mouse. Axial view taken through the same TEC1KO mouse embryo presented in Fig. 2. The white arrow is pointing to the malformed nasal septum in the TEC1KO embryo.

Figure 5

Cranium, wild-type mouse. Coronal view taken through the same E17.5 wild-type mouse embryo presented in Fig. 1.

Figure 6

Cranium, TEC1KO mouse. Coronal view taken through same TEC1KO mouse embryo presented in Fig. 2. The white arrow is pointing to the thickened secondary palate and collapsed nasopharynx present in the TEC1KO mouse.

Figure 7

Six-day-old, wild-type mouse, 70-μm spatial resolution. Ventral view taken from a 3D microcomputed tomography (microCT) volume image of a 6-day-old wild-type mouse.

Figure 8

Six-day old Pthrp^Δ/Δ mouse, 70-μm spatial resolution. Ventral view taken from a 3D microCT volume image of a 6-day old mouse. An obvious difference in overall size and structure of the Pthrp^Δ/Δ skeleton is observed from that of the wild-type littermate presented in Fig. 7.

Figure 9

Mouse skulls, wild-type and Pthrp^Δ/Δ mouse. An enlarged view of mouse skulls from Figs. 7 and 8 illustrating the gross craniofacial dysplasia and decreased mineralization observed in the mutant mouse.

Figure 10

Adult mouse. Coronal section from a 3D cryoimage volume image of an adult mouse. Twenty separate brightfield image acquisitions collected at 15.6-μm resolution were tiled together to produce the entire whole-body mouse volume with an image size of 5300 × 2100 × 663 pixels.

Figure 11

Adult mouse; 15.6-μm resolution image of the aortic valve taken from the same cryoimage volume presented in Fig. 10. The thoracic muscle (M), iliocostal muscle (I), left ventricle (V), atrium (A), brachiocephalic trunk (B), right common carotid artery (C), and right subclavian artery (S) are clearly observed in this full-resolution section.

Figure 12

Stomach, adult mouse; 15.6-μm resolution image of the stomach and small intestine taken from the same cryoimage volume presented in Fig. 10. The villi of the small intestine (V), stomach (S), and characteristic layers of the stomach lamina propria (LP) and submucosa (arrow), as well as visceral fat (F), are present in this image.

Figure 13

Eye, adult mouse; 15.6-μm resolution image of the eye taken from the same cryoimage volume presented in Fig. 10. The lens (L), choroids (C), retina (R), sclera (S), vitreous (V), and optic nerve (O) are present in this image.

Figure 14

Adult wild-type mouse. Segmented organs from a whole mouse cryoimage volume rendered within a transparent surface of the skin. Organs and organ systems include brain and spinal cord (bsc), lungs (lu), liver (liv), and vasculature (vasc). The inset shows vascular detail in the kidney region. Organ segmentation was performed using an interactive, color-based 3D algorithm. These segmented structures not only are useful for interactive visualization but can be used to calculate morphometric parameters such as organ volume.