Digital dissection of Xenopus laevis using contrast-enhanced computed tomography

J Anat. August 1, 2017; 231 (2): 169-191.

Digital dissection of the model organism Xenopus laevis using contrast-enhanced computed tomography.

Porro LB , Richards CT.

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     Fig. S1. Interactive 3D PDF of the digitally segmented skeleton of Xenopus laevis.

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     Fig. S2. Interactive 3D PDF of the digitally segmented musculature of Xenopus laevis; with the exception of m. longissimus dorsi, only right side muscles are shown.

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     Fig. S3. Interactive 3D PDF of the digitally segmented nervous system of Xenopus laevis.

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     Fig. S4. Interactive 3D PDF of the digitally segmented digestive, urogenital and respiratory systems of Xenopus laevis.

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Abstract

The African clawed frog, Xenopus laevis, is one of the most widely used model organisms in biological research. However, the most recent anatomical description of X. laevis was produced nearly a century ago. Compared with other anurans, pipid frogs - including X. laevis - exhibit numerous unusual morphological features; thus, anatomical descriptions of more ''typical'' frogs do not detail many aspects of X. laevis skeletal and soft-tissue morphology. The relatively new method of using iodine-based agents to stain soft tissues prior to high-resolution X-ray imaging has several advantages over gross dissection, such as enabling dissection of very small and fragile specimens, and preserving the three-dimensional topology of anatomical structures. Here, we use contrast-enhanced computed tomography to produce a high-resolution three-dimensional digital dissection of a post-metamorphic X. laevis to successfully visualize: skeletal and muscular anatomy; the nervous, respiratory, digestive, excretory and reproductive systems; and the major sense organs. Our digital dissection updates and supplements previous anatomical descriptions of this key model organism, and we present the three-dimensional data as interactive portable document format (PDF) files that are easily accessible and freely available for research and educational purposes. The data presented here hold enormous potential for applications beyond descriptive purposes, particularly for biological researchers using this taxon as a model organism, comparative anatomy and biomechanical modelling.

Fig. 1 Coronal/transverse micro-computed tomography (lCT) sections of Xenopus laevis specimen before (A,C,E) and after staining with I2KI (B,D,F). Position of sections through the head (A,B), abdomen (C,D) and pelvis/hind limb (E,F) are shown in (G).

Fig. 11 Nervous system of Xenopus laevis. Brain in dorsal (A,C) and left lateral (B,D) views, with brain transparent in (C) and (D) to illustrate internal ventricles and pineal body. Cranial nerves in dorsal view (E), with eyes, nasal capsules, brain and spinal cord transparent. Left and right trigeminal nerves (F) in dorsal view. Peripheral nervous system in dorsal view (G), with brain, spinal cord and skeleton transparent (cranial nerves not shown). caq, cerebral aqueduct; cbl, cerebellum; cbh, cerebral hemispheres; CN I– X, cranial nerves 1–10; dch, diencephalon; ft, filum terminale; gg, Gasserian ganglion; hyp, hypothalamus; ifr, infundibular recess; mmt, maxilla-mandibular trunk; mob, medulla oblongata; ncp, nasal capsules; opl, optic lobes; pn, pineal body; pnv, palatine nerve; S 1–10, spinal nerves 1–10; sc, spinal cord; v 1 and 2, first and second ventricles; v3, third ventricle; v4, fourth ventricle; vo, optic ventricles.

Fig. 12 Digestive, urogenital and respiratory systems of Xenopus laevis. Digestive and urogenital organs in ventral (A) and dorsal (B) views. Respiratory system in ventral view (C). bld, bile and cystic ducts; dil, M. dilator laryngis; eso, esophagus; gal, gallbladder; imxg, intermaxillary glands; kid, kidney; liv, liver; lgin, large intestine and rectum; lng, lung; lyx, larynx; pan, pancreas; smin, small intestine; spl, spleen; sto, stomach; thd, thyroid gland; thm, thymus gland; tst, testes; urt, ureter.

Adapted with permission from the Anatomical Society, Journal of Anatomy: Porro & Richards (2017). Digital dissection of the model organism Xenopus laevis using contrast-enhanced computed tomography. J Anat. August 1, 2017; 231 (2): 169-191. DOI: 10.1111/joa.12625. Copyright 2017.

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