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First published online December 3, 2004
Journal of Experimental Biology 207, 4543-4550 (2004)
Published by The Company of Biologists 2004
doi: 10.1242/jeb.01328

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Anatomy of a live invertebrate revealed by manganese-enhanced Magnetic Resonance Imaging

Jens Herberholz^1,2,*, Christopher J. Mims¹, Xiaodong Zhang^2,3, Xiaoping Hu^2,3 and Donald H. Edwards^1,2

¹ Georgia State University, Department of Biology, Atlanta, GA 30302-4010, USA
² Center for Behavioral Neuroscience, Atlanta, GA 30302-3966, USA
³ Emory University, Department of Biomedical Engineering, Atlanta, GA 30322-4600, USA

View larger version (55K): [in a new window]   Fig. 1. The external and internal morphology of a live crayfish reconstructed from images acquired with conventional MRI. (A) The body surface of an adult female crayfish (mass 28.8 g) reconstructed with digital 3D processing. The animal was imaged in five partitions of 40 slices each to avoid signal drop-off. Scale bar: 2 cm. (B) Internal anatomy of the same animal. Imaging parameters: TR=1.5 s, TE=12.5 ms; matrix dimensions: 256x128, field of view=4 cmx4 cm, number of averages=8, slice thickness, 1000 µm; voxel size, 156x312x1000 µm; acquisition time (total), 2.1 h.

View larger version (100K): [in a new window]   Fig. 2. The effects of systemically administered Mn2+ as a signal and contrast enhancer in crayfish. (A) Single transverse slices through the head of an adult male crayfish (mass 33.5 g) illustrate the difference in contrast before (top) and 32 min after (bottom) injection of 60 µl of a 120 mmol l–1 MnCl2 solution. The brain is undetectable before injection but exhibits the strongest signal and appears below the rostrum (Ro) and between the bases of the bilateral antennae (An) afterwards. Scale bar, 4 mm. (B) Single transverse slices through the thorax of an adult male crayfish (mass 34.0 g), before (top) and 32 min after (bottom) injection of 60 µl of a 120 mmol l–1 MnCl2 solution. Boundaries around the air-filled stomach (St) are more distinct and contrast around and within different areas, e.g. hepatopancreas (He) and gill chamber (GC) is clearly enhanced after injection. The walking legs (WL) are pointing forward and are surrounded by water (Wa) in the tube. Scale bar, 6 mm. Imaging parameters: TR=1.5 s, TE=17.6 ms; matrix dimensions: 256x128, field of view=5.12 cmx5.12 cm, number of averages=2, slice thickness, 1000 µm; voxel size, 200x400x1000 µm; acquisition time (each), 6.4 min. Inset: Red lines indicate the position of the transverse slices through the head and thorax, as shown in A and B, respectively.

View larger version (42K): [in a new window]   Fig. 3. The anatomy of the crayfish brain and its internal subdivisions. (A) 3D model of the crayfish brain (white) shown inside the exoskeleton (made transparent on the right) in a frontal view. Optic nerves (ON) that project into the eyestalks (Est) and the optic ganglia, lamina (La) and medullae (Me; consisting of medulla externa, medulla interna and medulla terminalis) within the eyestalks, are shown. Antennular (AntN) and antennal (AnN) nerves that project into the bases of the antennules (Ant) and antennae (An), respectively, are also displayed. Ro, rostrum. Scale bar, 4 mm. Inset: Red box indicates the area displayed beneath in the enlargement. (B) The brain and nerves shown without the exoskeleton. Scale bar, 3 mm. (C) Enlargement of the deuto- and tritocerebrum. Identified and displayed structures are the olfactory (OL) and accessory (AL) lobes, the antennal neuropils (AnP), a large artery (Ar), several prominent cell clusters (6, 10, 17) and the esophageal connectives (EC). Scale bar, 1 mm. Data in A–C were reconstructed from images acquired from the same crayfish (mass 37.9 g) that had been injected with 100 µl/120 mmol l–1 MnCl2 prior to scanning at TR=1.5 s, TE=17.6 ms; matrix dimensions: 512x512, field of view=3.5 cmx3.5 cm, number of averages=96, slice thickness, 250 µm; voxel size, 68x68x250 µm; acquisition time (total), 20.5 h.

View larger version (90K): [in a new window]   Fig. 4 The anatomy of the thoracic region and stomach of crayfish. (A) Angled view of a 3D model reconstructed from MRI data. The anatomical structures identified and displayed within the thoracic region are the bilateral antennary arteries (AnA), the ventral artery (VA), the antennal glands (AG), the anterior part of both lobes of the hepatopancreas (He) and the foregut, including the stomach (St) and esophagus (Es). The exoskeleton was made transparent for better illustration. (B) A side view of the same model. Cutaway of antennal gland and added transparency to the hepatopancreas reveal internal structures. The bladder (Bl) almost completely encloses the remaining tissue (iAG) of the antennal glands. The hepatopancreatic tubules (HeT) inside the hepatopancreas and the duct that connects them to the stomach can also be seen. Insets in A and B: Red boxes indicate the area displayed beneath in the enlargements. (C) Sagittal section of the stomach. The internal structures identified and displayed within the foregut are the esophagus (Es), the cardiac stomach (CSt), the lateral (LT) and medial tooth (MT), the ventrolateral cardiac filter (VCF), the cardio-pyloric valve (CpV), the pyloric stomach (PSt) and the dorsal valve (DV). (D) Coronal section of the (cardiac) stomach. Identified and displayed structures are the lateral teeth (LT), the esophagus (ES) and the cardio-pyloric valve (CPV). The external tissue surrounding the interior of the stomach is displayed as a uniform structure in bright yellow color. Other organs were removed for means of clarity. Insets in C and D: Dark planes indicate the positions at which the portions of the crayfish displayed beneath in the enlargements were cut open. All scale bars, 1 cm. Data in A–D were reconstructed from images acquired in the same crayfish (mass 31.8 g) that was injected with 60 µl of a 120 mmol l–1 MnCl2 solution and scanned at TR=1.5 s, TE=17.6 ms; matrix dimensions: 256x256, field of view=5.12 cmx5.12 cm, number of averages=20, slice thickness, 200 µm; voxel size, 200x200x200 µm; acquisition time (total), 12.5 h.