Three-dimensional Digital Reconstruction Research Articles

Three-dimensional analysis of image-free navigation system for total knee arthroplasty

Malalignment causes abnormal forces that may lead to loosening after knee replacement. Whether a computer-assisted technique can improve the precision of implant positioning guaranteeing good long-term results in total knee arthroplasty, this is a matter of discussion. The authors evaluate the alignment accuracy of 20 primary total knee arthroplasties, performed using an image-free computer navigation systems, with standardized CT protocol and three-dimensional digital model reconstruction. The results of this study demonstrate that the image-free navigation system is able to improve accuracy in axial limb alignment and positioning of the components in the majority of cases; moreover, the difference between the mean mechanical axis value of the navigation system (179.7°±1.7°) and the median mean value obtained during the post-operative evaluation (180.3°±1.9°) is not statistically significant (P=0.28).

Selective Beta-1 Receptor Blockade Further Reduces the Mechanically Stabilized Target Coronary Artery Motion during Beating Heart Surgery

Adequate stabilization of anastomosis sites during off-pump coronary artery bypass is essential to obtain excellent graft patency. We examined the effect of beta-1 adrenergic receptor blockade on the target coronary artery motion by three-dimensional (3D) digital motion capture and reconstruction technology. Eight pigs underwent a sternotomy. Reflection markers were attached to the surface coronary arteries, followed by a mechanical stabilizer application. Two high-speed digital cameras captured two-dimensional (2D) motion of the markers from different angles. These 2D data were reconstructed into 3D data points, representing the motion of each coronary artery. Landiolol hydrochloride, a novel selective beta-1 receptor blocker, was infused intravenously after acquisition of control data. Beta-1 receptor blockade decreased heart rate (105 ± 16 vs. 90 ± 9 beat/min; P = 0.007) without decreasing arterial blood pressure. The 3D distance moved (millimeter) during one cardiac cycle was significantly reduced on the left anterior descending (9.6 ± 2.8 vs. 6.6 ± 1.9 mm; P = 0.003), left circumflex (10.5 ± 6.3 vs. 6.4 ± 2.6 mm; P = 0.038), and right coronary (8.3 ± 3.6 vs. 6.5 ± 2.1 mm; P = 0.028) arteries. Reduction in the maximal velocity, maximal acceleration, and maximal deceleration of the anastomosis site in all coronary arteries was also found in a quantitative fashion. Selective beta-1 receptor blockade significantly reduces the 3D motion at anastomosis sites on the beating heart, with stable systemic blood pressure. Further quantitative investigations of pharmacological stabilization are warranted to achieve better outcome of the patients undergoing off-pump coronary artery bypass surgery.

Pannexin 2 Is Expressed by Postnatal Hippocampal Neural Progenitors and Modulates Neuronal Commitment

The pannexins (Panx1, -2, and -3) are a mammalian family of putative single membrane channels discovered through homology to invertebrate gap junction-forming proteins, the innexins. Because connexin gap junction proteins are known regulators of neural stem and progenitor cell proliferation, migration, and specification, we asked whether pannexins, specifically Panx2, play a similar role in the postnatal hippocampus. We show that Panx2 protein is differentially expressed by multipotential progenitor cells and mature neurons. Both in vivo and in vitro, Type I and IIa stem-like neural progenitor cells express an S-palmitoylated Panx2 species localizing to Golgi and endoplasmic reticulum membranes. Protein expression is down-regulated during neurogenesis in neuronally committed Type IIb and III progenitor cells and immature neurons. Panx2 is re-expressed by neurons following maturation. Protein expressed by mature neurons is not palmitoylated and localizes to the plasma membrane. To assess the impact of Panx2 on neuronal differentiation, we used short hairpin RNA to suppress Panx2 expression in Neuro2a cells. Knockdown significantly accelerated the rate of neuronal differentiation. Neuritic extension and the expression of antigenic markers of mature neurons occurred earlier in stable lines expressing Panx2 short hairpin RNA than in controls. Together, these findings describe an endogenous post-translational regulation of Panx2, specific to early neural progenitor cells, and demonstrate that this expression plays a role in modulating the timing of their commitment to a neuronal lineage.

Morphology of the Braincase in the Cretaceous Hybodont Shark Tribodus limae (Chondrichthyes: Elasmobranchii), Based on CT Scanning

The braincase of the Lower Cretaceous hybodont shark Tribodus limae is examined using high-resolution CT scanning, and its internal and external morphology is described based on three-dimensional digital reconstructions. This study represents the first in-depth examination of a hybodont braincase using CT scanning and digital imaging technology. The braincase of an additional Lower Cretaceous hybodont, Egertonodus basanus, is also digitally reconstructed and compared to Tribodus. A reconstruction of cranial nerves and blood vessels in Tribodus is presented on the basis of preserved foramina. The braincase of Tribodus shares many features with those of Egertonodus and neoselachians, providing further support for the sister-group relationship between hybodonts and extant elasmobranchs. CT scans confirm that in both Tribodus and Egertonodus the glossopharyngeal and vagus canals converge and exit from a common foramen (also found in Chlamydoselachus). In both of the hybodonts examined, the trochlear nerve exits the braincase anterior to the optic nerve, a possible hybodont synapomorphy. Separate foramina for the two rami of the octaval nerve are present in both Tribodus and Egertonodus, and may represent an additional hybodont synapomorphy. Also, both taxa have three separate foramina for the trigeminal, facial, and anterodorsal lateral line nerves, apparently including an individual foramen for the superficial ophthalmic complex. However, the basicranial arterial system in Tribodus differs considerably from that of Egertonodus in that in the former the internal carotid arteries enter the braincase much farther posteriorly and through paired foramina rather than a single median foramen. The median ventral basicranial process in Tribodus is similar in structure and position to median ventral processes seen in some extant neoselachians (e.g., Etmopterus) and in embryonic Torpedo (although in the latter this structure disappears during development), and thus may have had a similar ontogenetic origin.

Three-Dimensional Reconstruction of Echinococcus multilocularis Larval Growth in Human Hepatic Tissue Reveals Complex Growth Patterns

In this study we present, for the first time, a three-dimensional digital reconstruction of Echinococcus multilocularis larval growth in human tissue. Formalin-fixed, paraffin-embedded hepatic tissues from patients with alveolar echinococcosis were serially sectioned, stained, and areas of larval growth of the parasite were microphotographed. Parasitic structures were reconstructed from multiple digital planes, revealing a root-like network of interconnected vesicles and tubules extending into the periphery of lesions.

High resolution stereoscopic volume visualization of the mouse arginine vasopressin system

New imaging technologies have increased our capabilities to resolve three-dimensional structures from microscopic samples. Laser-scanning confocal microscopy is particularly amenable to this task because it allows the researcher to optically section biological samples, creating three-dimensional image volumes. However, a number of problems arise when studying neural tissue samples. These include data set size, physical scanning restrictions, volume registration and display. To deal with these issues, we undertook large-scale confocal scanning microscopy in order to visualize neural networks spanning multiple tissue sections. We demonstrate a technique to create and visualize a three-dimensional digital reconstruction of the hypothalamic arginine vasopressin neuroendocrine system in the male mouse. The generated three-dimensional data included a volume of tissue that measures 4.35 mm × 2.6 mm × 1.4 mm with a voxel resolution of 1.2 μm. The dataset matrix included 3508 × 2072 × 700 pixels and was a composite of 19,600 optical sections. Once reconstructed into a single volume, the data is suitable for interactive stereoscopic projection. Stereoscopic imaging provides greater insight and understanding of spatial relationships in neural tissues’ inherently three-dimensional structure. This technique provides a model approach for the development of data sets that can provide new and informative volume rendered views of brain structures. This study affirms the value of stereoscopic volume-based visualization in neuroscience research and education, and the feasibility of creating large-scale high resolution interactive three-dimensional reconstructions of neural tissue from microscopic imagery.

Adenosine-induced ventricular asystole or rapid ventricular pacing to enhance three-dimensional rotational imaging during cardiac ablation procedures

Rotational angiography with digital three-dimensional reconstruction (3DRA) allows per-procedural 3D imaging to facilitate cardiac ablation procedures. We developed a new approach that allows per-procedural 3D imaging of the atria and ventricles with a single C-arm rotation, combining higher 3D image quality with a lower contrast and radiation dose. Forty patients underwent 3DRA of the left atrium (LA, n = 26), right atrium (RA, n = 11), left ventricle (LV, n = 2), or right ventricle (RV, n = 1) during ablation procedures performed under general anaesthesia. Contrast agent (60 +/- 12 mL) was diluted and injected directly in the chamber of interest, during adenosine-induced ventricular asystole (n = 31) or rapid RV pacing (n = 9, atrial imaging only) to reduce cardiac motion artefacts and enhance contrast opacification during rotational imaging. Reconstructed 3D data sets were graded according to predefined quality criteria (n = 40) and quantitatively compared with cardiac computed tomography (CT) (LA, n = 14). Adenosine-induced ventricular asystole and rapid pacing both allowed a sustained and homogeneous contrast opacification of target cardiac chambers, resulting in useful 3D data sets in 39 of 40 (98%) patients. Moreover, it was possible to achieve 'good' or 'optimal' 3D image quality in the majority of patients (adenosine: 61%, pacing 78%, P = 0.69). When compared with rapid pacing, the total elimination of cardiac motion artefacts with adenosine more frequently resulted in 'optimal' 3D image quality (42% vs. 11%, P = 0.01) and added the possibility for single-rotation 3D imaging of the ventricles. Quantitative analysis showed an excellent agreement between pulmonary vein diameters measured on cardiac CT and 3DRA images. Integration of 3DRA-based LA surfaces with real-time fluoroscopy was easy and highly accurate. Adenosine-induced ventricular asystole or rapid ventricular pacing allow acquisition of 3DRA with an excellent direct contrast opacification of any cardiac chamber and a reduction of cardiac motion artefacts, resulting in high-quality per-procedural 3D imaging with a single C-arm rotation.

Three-dimensional geometry of the radial head and its prosthetic design

Objective To obtain anatomic parameters of the normal Chinese radial head through digital three-dimensional reconstruction so as to provide anatomical evidence for design of radial head pros-thesis. Methods Unilateral elbow joints of 45 normal Chinese were scanned by CT. Three-dimensional reconstruction of the radial head was performed using Mimics 10.0 software on the basis of the CT data. The parameters of the radial head were measured by Mimics 10.0 software and compared with the data reported in the existing overseas literature. Results The radial head had obvious individual diversities in shape and size. All morphologic parameters of the radial head approximated a normal distribution. The anteroposterior diameter of the radial head: (22.34±2.46) mm, the anteruposterior canal diameter: (9.04±1.50) mm, the mediolateral diameter of the radial head: (22.63±2.50) mm, the mediolateral canal diameter: (9.34±1.51) mm, the neck shaft angle: 166.80°±2.20°, the length of the radial head and neck: (18.71±2.44) mm. The diameter of the radial head had a strong correlation with the body height. Conclusions Since the anatomical parameters of the Chinese radial head are different from those of other races, it is important to modify the overseas prostheses to enhance the effectiveness of treatment. Three-dimensional digital recon-struction plays a great significance rule in the anatomical measurement for design of a customized prosthesis. Key words: Radius; Anatomy; Prosthesis design; Digitalization; Three-dimensional re-construction

Taxonomía de onicóforos de Santander, Colombia y termogravimetría, calorimetría de barrido diferencial y espectroscopía infrarroja de la secreción adhesiva (Onychophora: Peripatidae)

Onychophoran worms are terrestrial organisms that have changed relatively little since the mid-Cambrian. We collected Macroperipatus geagy in coffee plantations at "Hacienda El Roble", Santander, Colombia, and here redescribe the species based on 15 individuals. A digital three-dimensional reconstruction of the ventral side of the body indicates that the primary and accessory papillae lack a defined distribution pattern. Diagnostic characters: one main tooth and one accessory tooth in the outer jaw, and one main tooth, one accessory tooth and seven denticles in the internal jaw. length (X=45.66 mm; SD=26.10), weight (X=0.95 g; SD=2.21) and number of lobopods (X=28.13 pairs; SD=1.30). We present a taxonomic key for six species of Macroperipatus. The liquid adhesive secretion lost 60% of the initial weight at 70 degrees C (solid: 13% close to 90 degrees C). The stability phase of the liquid secretion was within 90-280 degrees C (100 degrees C - 205 degrees C in the solid secretion). The starting degradation temperature of the sample was 355 degrees C. Heat flow changes in the solid and liquid secretions were confirmed by the sample behavior during thermogravimetric analysis. The percentage of beta sheets calculated by infrared spectrum was 59%. In comparison with Nephila spiders, the onychophoran secretion lost more weight and entered the phase of degradation at lower temperatures. This secondary structure of proteins gives the onychophoran adhesive secretion a tensile strength and extensibility similar to those of the silk produced by spiders for prey-capture.

Preliminary application of digital visualization of anterolateral thigh flaps in clinic

Objective To introduce three-dimensional reconstruction technique used in clinic for wound repair with anterolateral thigh flaps. Methods Eight patients who needed wound repair with the anterolateral thigh flap underwent CT or MRI scanning preoperatively after injection of contrast medium. Their anterolateral thigh flaps were reconstructed three-dimensionally with Amira 4. 1 software. The points, lines and surface of the actual anterolateral thigh flaps were designed and marked according to their digital three-dimensional reconstruction of the flaps. Results In each of the 8 cases, an individualized anterolateral thigh flap was reconstructed three-dimensionally. The three-dimensional reconstruction could show thethree-dimensional relations of blood vessels, skin and adjacent tissues clearly. In 5 cases, the main stalks and perforating branches were displayed clearly in accord with intraoperative findings. In 3 cases, the main stalks were clearly displayed, but perforating branches not. In 2 of them, the diameter of perforating branch wasfound about 0. 5 mm and in the other one less than 0. 3 mm in operation, in this group, 7 flaps survived completely and 1 flap had partial necrosis on the edge. Conclusion The three-dimensional reconstruction of the anterelateral thigh flap on the basis of CT or MR angiography can provide clear visualization of the anatomy and thus can help surgeons in operative design and dissection of the flaps. Key words: Surgical flaps; Three-dimension reconstruction; Angiography; Microsurgery

Three-dimensional digital reconstruction and measurement of posterior condylar angle of distal femur

Objective To explore digital measurement of the posterior condylar angle (PCA) on three-dimensional reconstruction of CT images of the normal adult distal femur, because it may provide rea-sonable parameters for the rotational alignment in the total knee arthroplasty. Methods CT scanning of bilateral knees was conducted for 32 normal adults (18 males and 14 females) . Three-dimensional recon-struction of distal femur was performed using Mimics10.0 software on the basis of the CT data. The bony landmarks determining PCA were made on the three-dimensional images of the normal distal femur. PCA was measured across lateral and medial femoral epicondyli on the three-dimensional images. Results In the 36 male knees, the left side PCA averaged 4.33°± 0. 67° and the right side 4.45°±0.72° (mean, 4.39°±0. 69°). In the 28 female knees, the left side PCA averaged 4.45°± 0. 73° and the right side 4.68°± 0. 37°(mean, 4. 57°±0. 58°) . There was no statistically significant difference in gender or side. Conclusions It is feasible to accurately identify the bony landmarks determining PCA on the three-dimensional recon-struction of the distal femur. Digital measurement of PCA can provide reasonable parameters for rotational alignment in the total knee arthroplasty. It can also be useful in the design of femoral prosthesis. Key words: Digitalization ; Three-dimensional reconstruction; Knee joint

Application of three-dimensional digitalized reconstruction of latissimus dorsi myocutaneous flap

Developments of digital technology and three-dimensional (3D) reconstruction allowed a precise description of anatomic structures. With the introduction of Visible Human Project and Virtual Chinese Human (VCH) techniques, more detailed anatomic images could be obtained. Digitized visible models of these structures can be applied as a useful tool in clinical training. The aim of this study was to reconstruct the normal structures of thoracodorsal artery in 3D images and to establish the digitized visible models of latissimus dorsi myocutaneous (LDM) flap. The cross-sectional images from the four VCH datasets were reviewed to study LDM and thoracodorsal artery structures on a section-by-section basis. Next, two adult fresh cadaver specimens were perfused with lead oxide-gelatine mixture and subject to radiographic CT scanning on their torsos. The cross-sectional images from the CT images were reviewed to study thoracodorsal artery structures. Three-dimensional computerized reconstructions of LDM flap structures were conducted from these datasets by using Amira 3.1 (TGS) software respectively. The 3D reconstructed visible models established from these datasets perfectly displayed the anatomic characteristics of LDM flap.

Lateral Safety Limits during a Facial Transclival Approach to the Cranio-vertebral Junction

Background : Transclival procedures are infrequently performed and carry some dangerous complications. The carotid arteries and the hypoglossal nerves are the most important structures at risk during the subperiostal lateral dissection of the posterior wall of the oropharynx. These lateral landmarks are, however, not easily identified during the surgical dissection.Methods : We measured the location of the foramen lacerum externum and the hypoglossal canal with respect to the midline. These measurements were performed on 76 non-pathological CT-scanned skulls that were converted into accurate three-dimensional digital reconstruction models by the use of 3D image-processing. The same measurements were also taken on 15 non-pathological skulls by the use of a slide calliper.Results : For the foramen lacerum, the distance to the midline was 11 mm ± 1 mm SD (range 8–14 mm) on the right-hand side and 11 mm ± 1 mm SD (range 9–14 mm) on the left-hand side. For the right hypoglossal canal this distance was 17 mm ± 1 mm SD (range 15–22 mm) and for the left hypoglossal canal 17 mm ± 1 mm SD (range 14–20 mm). There was no significant difference between left and right.Conclusion : The posterior wall of the oropharynx can be safely dissected for at least 8 mm from the midline at the level of the foramen lacerum and for at least 14 mm towards the hypoglossal canal from the midline at the level of the anterior border of the foramen magnum. In addition, this technique with the help of 3D software, can be very useful in the pre-operative setting when performing complex skull base procedures.

3-D Histomorphometry of the Normal and Early Glaucomatous Monkey Optic Nerve Head: Lamina Cribrosa and Peripapillary Scleral Position and Thickness

To delineate three-dimensionally the anterior and posterior surfaces of the lamina cribrosa, scleral flange, and peripapillary sclera, to determine the position and thickness of these structures within digital three-dimensional (3-D) reconstructions of the monkey optic nerve head (ONH). The trephinated ONH and peripapillary sclera from both eyes of three monkeys with early glaucoma (EG; one eye normal, one eye given laser-induced EG) were serially sectioned at 3-mum thickness, with the embedded tissue block's face stained and imaged after each cut. Images were aligned and stacked to create 3-D reconstructions, within which Bruch's membrane opening (BMO) and the anterior and posterior surfaces of the lamina cribrosa and peripapillary sclera were delineated in 40 serial radial (4.5 degrees interval) digital sagittal sections. For each eye, a BMO zero reference plane was fit to the 80 BMO points, which served as the reference from which all position measurements were made. Regional laminar, scleral flange, and peripapillary scleral position and thickness were compared between the normal and EG eyes of each monkey and between treatment groups by analysis of variance. Laminar thickness varied substantially within the normal eyes and was profoundly thicker within the three EG eyes. Laminar position was permanently posteriorly deformed in all three EG eyes, with substantial differences in the magnitude and extent of deformation among them. Scleral flange and peripapillary scleral thickness varied regionally within each normal ONH with the scleral flange and peripapillary sclera being thinnest nasally. Overall, the scleral flange and peripapillary sclera immediately surrounding the ONH were posteriorly displaced relative to the more peripheral sclera. Profound fixed posterior deformation and thickening of the lamina are accompanied by mild posterior deformation and thinning of the scleral flange and peripapillary sclera at the onset of confocal scanning laser tomography (CSLT)-detected ONH surface change in young adult monkey eyes with early experimental glaucoma.

Three-Dimensional Histomorphometry of the Normal and Early Glaucomatous Monkey Optic Nerve Head: Neural Canal and Subarachnoid Space Architecture

To delineate three dimensionally the neural canal landmarks-Bruch's membrane opening (BMO), anterior sclera canal opening (ASCO), anterior laminar insertion (ALI), posterior laminar insertion (PLI), and posterior scleral canal opening (PSCO)-and the anterior-most aspect of the subarachnoid space (ASAS), within digital three-dimensional (3-D) reconstructions of the monkey optic nerve head (ONH). The trephinated ONH and peripapillary sclera from both eyes of three early glaucoma (EG) monkeys (one eye normal, one eye with laser-induced EG) were serial sectioned at 3-microm thickness, with the embedded tissue block face stained and imaged after each cut. The images were aligned and stacked in a 3-D volume, within which the BMO, ASCO, ALI, PLI, PSCO, and ASAS were delineated in 40 digital, radial, and sagittal sections. An ellipse was fitted to the 80 BMO points to establish a BMO zero reference plane, on which all other points were projected. The distance from each projected point to the BMO centroid (offset) and BMO zero reference plane (depth) were calculated and compared regionally between normal and EG eyes, both overall and within each monkey, by analysis of variance. BMO was the clinically visible optic disc margin in all six eyes. The neural canal architecture was highly variable in the three normal eyes. Radial expansion of the neural canal was greatest posteriorly in the EG eyes. Axial elongation of the canal was less pronounced overall but was regionally present within all three EG eyes. ASAS was regionally radially expanded and anteriorly displaced within two of the three EG eyes. Profound deformation of the neural canal and ASAS architecture are present in young adult monkey eyes at the onset of ONH surface change in early experimental glaucoma.

Three-dimensional quantification of cardiac surface motion: A newly developed three-dimensional digital motion-capture and reconstruction system for beating heart surgery

This study aimed to evaluate our newly developed 3-dimensional digital motion-capture and reconstruction system in an animal experiment setting and to characterize quantitatively the three regional cardiac surface motions, in the left anterior descending artery, right coronary artery, and left circumflex artery, before and after stabilization using a stabilizer. Six pigs underwent a full sternotomy. Three tiny metallic markers (diameter 2 mm) coated with a reflective material were attached on three regional cardiac surfaces (left anterior descending, right coronary, and left circumflex coronary artery regions). These markers were captured by two high-speed digital video cameras (955 frames per second) as 2-dimensional coordinates and reconstructed to 3-dimensional data points (about 480 xyz-position data per second) by a newly developed computer program. The remaining motion after stabilization ranged from 0.4 to 1.01 mm at the left anterior descending, 0.91 to 1.52 mm at the right coronary artery, and 0.53 to 1.14 mm at the left circumflex regions. Significant differences before and after stabilization were evaluated in maximum moving velocity (left anterior descending 456.7 +/- 178.7 vs 306.5 +/- 207.4 mm/s; right coronary artery 574.9 +/- 161.7 vs 446.9 +/- 170.7 mm/s; left circumflex 578.7 +/- 226.7 vs 398.9 +/- 192.6 mm/s; P < .0001) and maximum acceleration (left anterior descending 238.8 +/- 137.4 vs 169.4 +/- 132.7 m/s2; right coronary artery 315.0 +/- 123.9 vs 242.9 +/- 120.6 m/s2; left circumflex 307.9 +/- 151.0 vs 217.2 +/- 132.3 m/s2; P < .0001). This system is useful for a precise quantification of the heart surface movement. This helps us better understand the complexity of the heart, its motion, and the need for developing a better stabilizer for beating heart surgery.

A stereoscopic method for dihedral angle measurement

A new method is presented for the measurement of equilibrium dihedral angles in intergranular inclusions, and illustrated with pure copper containing 1 wt% lead. The method is based on the selective dissolution of inclusions visible along a polished metallographic section. Scanning electron microscopy stereo image pairs are then taken and processed so as to enable a three-dimensional digital reconstruction of the inclusion/matrix interface along each inclusion. Spherical caps describing the Cu/Pb interface over non-facetted orientations are then fitted to the measured digital inclusion envelope reconstructions. Knowing the center and radius of these spheres, the true dihedral angle of each specific inclusion can then be deduced with good precision.It is found that the true dihedral angle in the Cu/Pb alloy is not a unique function of temperature, reflecting the (known) anisotropy of high-angle grain boundary energy in copper.

BRAINCASE OF THE UPPER DEVONIAN SHARK CLADODOIDES WILDUNGENSIS (CHONDRICHTHYES, ELASMOBRANCHII), WITH OBSERVATIONS ON THE BRAINCASE IN EARLY CHONDRICHTHYANS

The braincase of an Upper Devonian shark (Cladodoides wildungensis) is investigated using high-resolution CT scanning, and its internal and external morphology is described from three-dimensional digital reconstructions. Many features are shared with modern elasmobranchs (neoselachians); these mostly represent conserved elasmobranch, chondrichthyan, or gnathostome characters. C. wildungensis resembles neoselachians in having a closed metotic fissure defining a glossopharyngeal canal, unlike some early chondrichthyans (e.g., Pucapampella, Orthacanthus) in which an open metotic fissure extends a considerable distance beneath the otic capsule. However, the glossopharyngeal canal in C. wildungensis is connected to a persistent dorsal fissure between the occipital arch and otic capsules, whereas this fissure becomes closed during neoselachian ontogeny. The embryonic polar cartilage apparently made a much greater contribution to the basicranium than in neoselachians and gnathostomes generally. This has affected the position of the efferent pseudobranchial foramen and the location of the orbital articulation in Cladodoides (both of which are located anteriorly in the orbit), as well as the size and extent of the dorsum sellae and the hypophyseal chamber inside the braincase. Another unusual feature in Cladodoides is the postorbital position of its trigeminal and facial nerves; instead of being situated in a trigemino-facial fossa of the orbit as in neoselachians, their foramina are located behind the postorbital process, although the pituitary vein and the origin of the external rectus eye muscle (located within the trigemino-facial fossa in neoselachians) both lie in the posterior part of the orbit. The oblique orientation of the postorbital arcade (derived from the embryonic lateral commissure) may be related to the exclusion of the trigeminal and facial nerves from the orbit. A laterally oriented canal through the process probably contained the trigeminal maxillary ramus (perhaps accompanied by the buccal ramus of the anterodorsal lateral line nerve). By contrast, in neoselachians these rami pass directly into the orbit (sometimes forming a buccal-maxillary complex), but they do not pass through the postorbital process. The Cladodoides braincase probably represents a juvenile or submature individual and shows indications of incomplete development (e.g., presence of a wide bucco-hypophyseal fenestra and absence of a precarotid commissure; incomplete enclosure of the internal carotids and orbital arteries by basicranial cartilage; incomplete closure of the braincase roof along the dorsal midline). The braincase also lacks multiple-layered prismatic calcification, possibly representing another juvenile feature. The phylogenetic relationship of Cladodoides wildungensis is discussed. Dental, postcranial, and cranial features lend some support to the old hypothesis that cladodont sharks form a monophyletic group. While such a view is at variance with several recently published phylogenetic analyses, many of the characters noted in the present work have yet to be tested within a rigorous cladistic framework, and their phylogenetic significance is uncertain.

Three-Dimensional Reconstruction of Normal and Early Glaucoma Monkey Optic Nerve Head Connective Tissues

To introduce high-resolution, digital three-dimensional (3-D) reconstruction of the connective tissues of the optic nerve head (ONH). Trephinated ONH and peripapillary sclera from both eyes of three monkeys with early glaucoma (EG; one eye normal, one eye given laser-induced EG) were embedded in paraffin and serial sectioned at 3-mum thickness from the vitreous surface through the orbital optic nerve, with the embedded tissue block face stained and imaged after each cut. Each image was aligned, and then the scleral canal wall, sclera, border tissue of Elschnig, Bruch's membrane, lamina cribrosa, optic nerve septa, pial sheath, and vasculature were delineated as unique objects. Delineated images were stacked, color mapped, and volume rendered and then serial sagittal and transverse digital sections of the resultant voxel geometries were viewed and measured. Substantial differences in the 3-D architecture of the peripapillary sclera, scleral canal wall, and lamina cribrosa were present among the three normal eyes. All three EG eyes displayed permanent posterior deformation of the central lamina cribrosa, as well as expansion of the anterior and posterior neural canal openings in comparison with their respective contralateral normal control eyes. Peripherally, whereas laminar deformation was greatest inferiorly or superiorly in all three EG eyes, statistically significant deformation was present in all four quadrants of all three eyes. High-resolution, digital 3-D reconstructions of the load-bearing connective tissues of the monkey ONH confirm that the ONH connective tissues are profoundly altered at the onset of detectable ONH surface change in experimental glaucoma.

Three-dimensional functional reconstruction of inner medullary thin limbs of Henle's loop.

Digital three-dimensional (3-D) functional reconstructions of inner medullary nephrons were performed. Antibodies against aquaporins (AQP)-1 and -2 and the chloride channel ClC-K1 identified descending thin limbs (DTLs), collecting ducts (CDs), and ascending thin limbs (ATLs), respectively, through indirect immunofluorescence. Tubules were labeled in transverse sections and assembled into 3-D arrays, permitting individual tubule or combined surface representations to depths of 3.3 mm to be viewed in an interactive digital model. Surface representations of 75 tubules positioned near the central region of the inner medulla were reconstructed. In most DTL segments that form loops below 1 mm from the inner medullary base, AQP1 expression begins at the base, becomes intermittent for variable lengths, and continues nearly midway to the loop. The terminal DTL segment exhibiting undetectable AQP1 represents nearly 60% of the distance from the medullary base to the tip of the loop. AQP1 expression was entirely undetectable in shorter long-looped DTLs. ClC-K1 is expressed continuously along the terminal portion of all DTLs reconstructed here, beginning with a prebend region approximately 164 microm before the bend in all tubules and continuing through the entire ascent of the ATLs to the base of the inner medulla. CDs express AQP2 continuously and extensive branching patterns are illustrated. 3-D functional reconstruction of inner medullary nephrons is capable of showing axial distribution of membrane proteins in tubules of the inner medulla and can contribute to further development and refinement of models that attempt to elucidate the concentrating mechanism.