Morphogenesis of the Middle Ear during Fetal Development as Observed Via Magnetic Resonance Imaging

Recently, our research group has utilized serial histological sections to investigate the morphogenesis of the middle ear, which corresponds to the period of middle ear ossicle (MEO) cartilage formation. However, research regarding middle ear development during the post‐embryonic period has been limited. In the present study, we investigated morphogenesis of the middle ear in human fetuses with a crown‐rump length (CRL) between 37 and 197 mm using high‐resolution magnetic resonance imaging (MRI). Our findings indicated that the morphology of the MEOs is similar during fetal development and adulthood; further, growth of the MEOs nearly ceases once a CRL of 150 mm is attained. In each MEO, ossification spreads from a single center. The malleus and Meckel's cartilage could be discriminated in samples exhibiting a CRL of 145 mm based on differences in MRI signal intensity. In samples with a CRL of 86 mm, the tympanic cavity (TC) appeared as a thin yet distinct structure attached to the external auditory meatus at the convex surface. Only the handle of the malleus was covered by the TC, while the incus and stapes contacted the cavity at the region of articulation between the two ossicles only, even after a CRL of 145 mm had been attained. Thus, although the TC increased in both diameter and thickness, coverage did not extend across all three MEOs during the observation period. These data are expected to provide a useful standard for morphogenesis and may aid researchers in distinguishing between normal and abnormal development. Anat Rec, 301:757–764, 2018. © 2017 Wiley Periodicals Inc.     

Morphogenesis and Three‐Dimensional Movement of the Stomach During the Human Embryonic Period

The stomach develops as the local widening of the foregut after Carnegie stage (CS) 13 that moves in a dramatic and dynamic manner during the embryonic period. Using the magnetic resonance images of 377 human embryos, we present the morphology, morphometry, and three‐dimensional movement of the stomach during CS16 and CS23. The stomach morphology revealed stage‐specific features. The angular incisura and the cardia were formed at CS18. The change in the angular incisura angle was approximately 90° during CS19 and CS20, and was <90° after CS 21. The prominent formations of the fundus and the pylorus differentiate at around CS20. Morphometry of the stomach revealed that the stomach gradually becomes “deflected” during development. The stomach may appear to move to the left laterally and caudally due to its deflection and differential growth. The track of the reference points in the stomach may reflect the visual three‐dimensional movement. The movement of point M, representing the movement of the greater curvature, was different from that of points C (cardia) and P (pyloric antrum). The P and C were located just around the midsagittal plane in all the stages observed. Point M moved in the caudal‐left lateral direction until CS22. Moreover, the vector CP does not rotate around the dorsoventral axis, as widely believed, but around the transverse axis. The plane CPM rotated mainly around the longitudinal axis. The data obtained will be useful for prenatal diagnosis in the near future. Microsc. Res. Tech, 297:791–797, 2014. © 2013 Wiley Periodicals, Inc.     

Morphogenesis of the middle ear ossicles and spatial relationships with the external and inner ears during the embryonic period

We describe the three‐dimensional morphogenesis of the middle ear ossicles (MEOs) according to Carnegie stage (CS) in human embryos. Seventeen samples including 33 MEOs from CS18 to 23 were selected from the Kyoto Collection. The primordia of the MEOs and related structures were histologically observed and three‐dimensionally reconstructed from digital images. The timing of chondrogenesis was variable among structures. The stapes was recognizable as a vague condensation of the mesenchymal cells in all samples from CS18, whereas the malleus and incus were recognizable at CS19. Chondrogenesis of all MEOs was evident in all samples after CS21. The chondrocranium was recognizable in all samples by CS18, and the perichondrium border of the auricular cartilage and otic capsule was distinct in all samples at CS23. At CS19, the MEOs were positioned in the anterior to posterior direction, following the order malleus, incus, stapes, which adjusted gradually during development. The MEOs connected in all samples after CS22. The stapes was located close to the vestibular part of the inner ear, although the basal part was not differentiated into the “footplate” form, even at CS23. The handles of the malleus were close to the tubotympanic recess at CS23, but were distant from the external auditory meatus. Determining the timeline of the formation of MEOs and connection of the external and inner ears can be informative for understanding hearing loss caused by failure of this connection. These data may provide a useful standard for morphogenesis, and will contribute to distinguishing between normal and abnormal MEO development. Anat Rec, 299:1325–1337, 2016. © 2016 Wiley Periodicals, Inc.     

Ontogenetic Variation in the Bony Labyrinth of Monodelphis domestica (Mammalia: Marsupialia) Following Ossification of the Inner Ear Cavities

Ontogeny, or the development of an individual from conception to death, is a major source of variation in vertebrate morphology. All anatomical systems are affected by ontogeny, and knowledge of the ontogenetic history of these systems is important to understand when formulating biological interpretations of evolutionary history and physiology. The present study is focused on how variation affects the bony labyrinth across a growth series of an extant mammal after ossification of the inner ear chambers. Digital endocasts of the bony labyrinth were constructed using CT data across an ontogenetic sequence of Monodelphis domestica, an important experimental animal. Various aspects of the labyrinth were measured, including angles between the semicircular canals, number of turns of the cochlea, volumes of inner ear constituents, as well as linear dimensions of semicircular canals. There is a strong correlation between skull length and age, but from 27 days after birth onward, there is no correlation with age among most of the inner ear measurements. Exceptions are the height of the arc of the lateral semicircular canal, the angular deviation of the lateral canal from planarity, the length of the slender portion of the posterior semicircular canal, and the length of the canaliculus cochleae. Adult dimensions of several of the inner ear structures, such as the arcs of the semicircular canals, are achieved before the inner ear is functional, and the non‐ontogenetic variation in the bony labyrinth serves as an important source for behavioral, physiological, and possibly phylogenetic information. Anat Rec, 2010. © 2010 Wiley‐Liss, Inc.     

Formation of the Periotic Space During the Early Fetal Period in Humans

The inner ear is a very complicated structure, composed of a bony labyrinth (otic capsule; OC), membranous labyrinth, with a space between them, named the periotic labyrinth or periotic space. We investigated how periotic tissue fluid spaces covered the membranous labyrinth three‐dimensionally, leading to formation of the periotic labyrinth encapsulated in the OC during human fetal development. Digital data sets from magnetic resonance images and phase‐contrast X‐ray tomography images of 24 inner ear organs from 24 human fetuses from the Kyoto Collection (fetuses in trimesters 1 and 2; crown—rump length: 14.4–197 mm) were analyzed. The membranous labyrinth was morphologically differentiated in samples at the end of the embryonic period (Carnegie stage 23), and had grown linearly to more than eight times in size during the observation period. The periotic space was first detected at the 35‐mm samples, around the vestibule and basal turn of the cochlea, which elongated rapidly to the tip of the cochlea and semicircular ducts, successively, and almost covered the membranous labyrinth at the 115‐mm CRL stage or later. In those samples, several ossification centers were detected around the space. This article thus demonstrated that formation of the membranous labyrinth, periotic space (labyrinth), and ossification of the OC occurs successively, according to an intricate timetable. Anat Rec, 301:563–570, 2018. © 2018 Wiley Periodicals, Inc.     

Variations of the Circle of Willis at the End of the Human Embryonic Period

Variations of the circle of Willis (CW) influence blood supply to the brain and adjacent structures in adults. We examined the formation of the CW in 20 human embryo samples at the end of the embryonic period using 3‐D reconstructions of serial histological sections. The CW was closed in all samples, and did not form in a single plane, but was composed of multiple stair‐like planes. The artery acutely curved at the caudal part of the CW, namely, at the inlet of the basilar artery and bifurcation of the P1 segment of the posterior cerebral artery (PCA), reflecting flexure of the mesencephalon and diencephalon at this stage. Variations were observed in 17 of 20 samples—only anterior parts (anterior communicating artery [Acom] and anterior cerebral artery [ACA]) in 10 samples, only posterior parts (posterior communicating artery [Pcom]) in one sample, and both anterior and posterior parts in six samples. Variations included the Acom formed as partially duplicated in three samples, duplicated in four, plexiform in three, and no channel as a result of a single azygos ACA in one. The ACA formed as duplicated in two, median ACA in two, and right hypoplasia in one. The Pcom formed in hypoplasia of either side in six samples. Variations observed in this study are similar to those observed in fetuses, neonates, and adults. The P1 segment of PCA was very large in all samples. The present observations indicate that variations in the CW are present from the initiation of CW formation. Anat Rec, 2018. © 2018 Wiley Periodicals, Inc.     

MicroCT for developmental biology: A versatile tool for high‐contrast 3D imaging at histological resolutions

Understanding developmental processes requires accurate visualization and parameterization of three‐dimensional embryos. Tomographic imaging methods offer automatically aligned and calibrated volumetric images, but the usefulness of X‐ray CT imaging for developmental biology has been limited by the low inherent contrast of embryonic tissues. Here, I demonstrate simple staining methods that allow high‐contrast imaging of embryonic tissues at histological resolutions using a commercial microCT system. Quantitative comparisons of images of chick embryos treated with different contrast agents show that three very simple methods using inorganic iodine and phosphotungstic acid produce overall contrast and differential tissue contrast for X‐ray imaging at least as high as that obtained with osmium. The stains can be used after any common fixation and after storage in aqueous or alcoholic media, and on a wide variety of species. These methods establish microCT imaging as a useful tool for comparative developmental studies, embryo phenotyping, and quantitative modeling of development. Developmental Dynamics 238:632–640, 2009. © 2009 Wiley‐Liss, Inc.     

Positional Changes of the Ocular Organs During Craniofacial Development

The present study aimed to describe the positional changes of the ocular organs during craniofacial development; moreover, we examined the relationships among the ocular organs and other internal structures. To do this, we traced the positions of the ocular organs in 56 human early fetal samples at different stages of development using high‐resolution magnetic resonance imaging and phase‐contrast X‐ray computed tomography. The eyes were located on the lateral side in the ventral view at Carnegie stage (CS) 16, and then changed their positions medially during development. The eyes remained in the neurocranium until CS17. However, the eyes changed their positions medially and caudally in the viscerocranium after CS18. The positional relationship between the eyes and pituitary gland changed in the lateral view as development progressed. Specifically, they were close to each other at CS17, but moved apart during the later stages of development. These positional changes were also demonstrated quantitatively with morphometric analyses. Based on the present data, the positional changes of the eyes can be categorized into phases, as follows: Phase 1, dramatic positional changes (early fetal period until CS23); and Phase 2, mild positional changes (stabilized; early fetal period after CS23). Notably, all absolute lengths measured in the present study linearly increased as the crown‐rump length increased irrespective of the phase, while features of the measured angles and ratios differentially changed in Phases 1 and 2. The present data may help improve our understanding of both the normal and abnormal development of the ocular organs and craniofacial area. Anat Rec, 300:2107–2114, 2017. © 2017 Wiley Periodicals, Inc.     

Segmentation and Surface Reconstruction of the Detailed Ear Structures,Identified in Sectioned Images

The structure of the ear, which intervenes between gross anatomy and histology in size, can be best understood by means of three‐dimensional (3D) surface models on a computer. Furthermore, surface models are the source of interactive simulation for clinical trials, such as tympanoplasty. The objective of this research was to elaborate the surface models of detailed ear structures, which contribute to learning anatomy or the practice of otology. We produced sectioned images of a cadaver head (pixel size, 0.1 mm; 48‐bit color). In the sectioned images, the external, middle, and internal ear structures and other related components were delineated on Photoshop to acquire segmented images at 0.5‐mm intervals. Segmented images of each structure were stacked, and the surface was reconstructed to generate a 3D‐surface model on commercial software. Thirty surface models showed fine ear topographic anatomy (e.g., semicircular ducts), as expected. Herein, we present the corresponding sectioned images, segmented images, and surface models of ear structures that will be released together. It is hoped that these image data will stimulate the development of medical simulations. The efficient technique of segmentation and surface reconstruction enables the manufacture of surface models from other serial images (e.g., CTs and MRIs). Anat Rec, 2011. © 2011 Wiley‐Liss, Inc.     

Diffusible iodine‐based contrast‐enhanced computed tomography (diceCT): an emerging tool for rapid,high‐resolution, 3‐D imaging of metazoan soft tissues

Morphologists have historically had to rely on destructive procedures to visualize the three‐dimensional (3‐D) anatomy of animals. More recently, however, non‐destructive techniques have come to the forefront. These include X‐ray computed tomography (CT), which has been used most commonly to examine the mineralized, hard‐tissue anatomy of living and fossil metazoans. One relatively new and potentially transformative aspect of current CT‐based research is the use of chemical agents to render visible, and differentiate between, soft‐tissue structures in X‐ray images. Specifically, iodine has emerged as one of the most widely used of these contrast agents among animal morphologists due to its ease of handling, cost effectiveness, and differential affinities for major types of soft tissues. The rapid adoption of iodine‐based contrast agents has resulted in a proliferation of distinct specimen preparations and scanning parameter choices, as well as an increasing variety of imaging hardware and software preferences. Here we provide a critical review of the recent contributions to iodine‐based, contrast‐enhanced CT research to enable researchers just beginning to employ contrast enhancement to make sense of this complex new landscape of methodologies. We provide a detailed summary of recent case studies, assess factors that govern success at each step of the specimen storage, preparation, and imaging processes, and make recommendations for standardizing both techniques and reporting practices. Finally, we discuss potential cutting‐edge applications of diffusible iodine‐based contrast‐enhanced computed tomography (diceCT) and the issues that must still be overcome to facilitate the broader adoption of diceCT going forward.     

A Novel Strategy to Reveal the Latent Abnormalities in Human Embryonic Stages from a Large Embryo Collection

The cause of spontaneous abortion of normal conceptuses remains unknown in most cases. The study was aimed to reveal the latent abnormalities by using a large collection of embryo images from a magnetic resonance imaging (MRI) database and novel phase‐contrast radiographic computed tomography (PXCT). MRI from 1,156 embryos between Carnegie stage (CS) 14 and CS23 from the Kyoto Collection were screened by using the volume of the liver as the target organ. Embryos with liver volumes ≥2 SD above or below the mean for the stage of development were screened and examined precisely on MRI. Embryos with potentially abnormal livers were further analyzed by using PXCT. Liver abnormality was detected in all 7 embryos in the extra‐small liver group and in 2 of 8 embryos in the extra‐large liver group. The abnormalities in the extra‐small liver group consisted of hepatic agenesis (2 embryos), hepatic hypogenesis (4), and liver lobe defect (1). Among the 7 extra‐small liver group, 2 had only liver abnormalities and 5 exhibited complications in other organs. Of the 2 embryos in the extra‐large liver group, one had only a single liver abnormality and the other had a morphologically abnormal liver with complications in other organs. Most of such liver abnormality cases are not survive, as liver function becomes essential. The prevalence of liver malformations in CS18 and CS21 in the intrauterine population of externally normal embryos is approximately 1.7%. The present study is the first step toward the elucidation of the latent abnormalities resulting in spontaneous abortion in externally normal embryos. Anat Rec, 299:8–24, 2016. © 2015 Wiley Periodicals, Inc.     

Accessible and Informative Sectioned Images,Color‐Coded Images,and Surface Models of the Ear

In our previous research, we created state‐of‐the‐art sectioned images, color‐coded images, and surface models of the human ear. Our ear data would be more beneficial and informative if they were more easily accessible. Therefore, the purpose of this study was to distribute the browsing software and the PDF file in which ear images are to be readily obtainable and freely explored. Another goal was to inform other researchers of our methods for establishing the browsing software and the PDF file. To achieve this, sectioned images and color‐coded images of ear were prepared (voxel size 0.1 mm). In the color‐coded images, structures related to hearing, equilibrium, and structures originated from the first and second pharyngeal arches were segmented supplementarily. The sectioned and color‐coded images of right ear were added to the browsing software, which displayed the images serially along with structure names. The surface models were reconstructed to be combined into the PDF file where they could be freely manipulated. Using the browsing software and PDF file, sectional and three‐dimensional shapes of ear structures could be comprehended in detail. Furthermore, using the PDF file, clinical knowledge could be identified through virtual otoscopy. Therefore, the presented educational tools will be helpful to medical students and otologists by improving their knowledge of ear anatomy. The browsing software and PDF file can be downloaded without charge and registration at our homepage ( http://anatomy.dongguk.ac.kr/ear/ ). Anat Rec, 2013. © 2013 Wiley Periodicals, Inc.     

Intestinal Rotation and Physiological Umbilical Herniation During the Embryonic Period

Drastic changes occur during the formation of the intestinal loop (IL), including elongation, physiological umbilical herniation (PUH), and midgut rotation. Fifty‐four sets of magnetic resonance images of embryos between Carnegie stage (CS) 14 and CS 23 were used to reconstruct embryonic digestive tract in three dimensions in the Amira program. Elongation, PUH, and rotation were quantified in relation to the proximal part of the superior mesenteric artery (SMA), designated as the origin. Up to CS 16, IL rotation was initially observed as a slight deviation of the duodenum and colorectum from the median plane. The PUH was noticeable after CS 17. At CS 18, the IL showed a hairpin‐like structure, with the SMA running parallel to the straight part and the cecum located to the left. After CS 19, the IL began to form a complex structure as a result of the rapid growth of the small intestinal portion. By CS 20, the IL starting point had moved from the right cranial region to an area caudal to the origin, though elongation of the duodenum was not conspicuous—this was a change of almost 180° in position. The end of the IL remained in roughly the same place, to the left of and caudal to the origin. Notably, the IL rotated around the origin only during earlier stages and gradually moved away, running transversely after CS 19. The movements of the IL may be explained as the result of differential growth, suggesting that IL rotation is passive. Anat Rec, 299:197–206, 2016. © 2015 Wiley Periodicals, Inc.     

肺癌肺内肿瘤不同能量三维适形放疗的比较

目的:研究6 MV和15 MV X射线对肺癌肺内肿瘤三维适形放疗肿瘤组织、危及器官及正常组织剂量的影响。方法:选择11例肺癌肺内肿瘤患者,对每例患者分别采用6 MV和15 MV X射线进行三维适形放疗计划设计,同一患者的两个计划均使用相同的布野方案和剂量体积约束。比较两组计划的计划靶区、危及器官及正常组织的剂量分布。结果:6MV和15 MV两种能量X线三维适形放疗计划计划靶区的剂量分布、均匀性、适形度的差异无显著性意义(P>0.05),危及器官脊髓、食管、心脏,正常组织肺的剂量分布无显著性意义(P>0.05)。结论:肺癌肺内肿瘤6 MV、15 MV三维适形放疗剂量分布无明显差异,三维适形放疗能量用6 MV,不主张用15 MV。     

Quantitative analysis of microscopic X‐ray computed tomography imaging: Japanese quail embryonic soft tissues with iodine staining

Rapid three‐dimensional imaging of embryos to better understand the complex process of morphogenesis has been challenging. Recently introduced iodine staining protocols (I₂KI and alcoholic iodine stains) combined with microscopic X‐ray computed tomography allows visualization of soft tissues in diverse small organisms and tissue specimens. I₂KI protocols have been developed specifically for small animals, with a limited number of quantitative studies of soft tissue contrasts. To take full advantage of the low X‐ray attenuation of ethanol and retain bound iodine while dehydrating the specimen in ethanol, we developed an ethanol I₂KI protocol. We present comparative microscopic X‐ray computed tomography analyses of ethanol I₂KI and I₂KI staining protocols to assess the performance of this new protocol to visualize soft tissue anatomy in late stage Japanese quail embryos using quantitative measurements of soft tissue contrasts and sample shrinkage. Both protocols had only 5% shrinkage compared with the original harvested specimen, supporting the use of whole mounts to minimize tissue shrinkage effects. Discrimination within and among the selected organs with each staining protocol and microscopic X‐ray computed tomography imaging were comparable to those of a gray scale histological section. Tissue discrimination was assessed using calibrated computed tomography values and a new discrimination index to quantify the degree of computed tomography value overlaps between selected soft tissue regions. Tissue contrasts were dependent on the depth of the tissue within the embryos before the embryos were saturated with each stain solution, and optimal stain saturations for the entire embryo were achieved at 14 and 28 days staining for I₂KI and ethanol I₂KI, respectively. Ethanol I₂KI provided superior soft tissue contrasts by reducing overstaining of fluid‐filled spaces and differentially modulating staining of some tissues, such as bronchial and esophageal walls and spinal cord. Delineating the selected soft tissues using optimal threshold ranges derived from the quantitative analyses of the contrast enhancement in optimally stained embryos is possible. The protocols presented here are expected to be applicable to other organisms with modifications to staining time and contribute toward rapid and more efficient segmentation of soft tissues for three‐dimensional visualization.     

Three‐dimensional imaging of palatal muscles in the human embryo and fetus: Development of levator veli palatini and clinical importance of the lesser palatine nerve

Background: After palatoplasty, incomplete velopharyngeal closure in speech articulation sometimes persists, despite restoration of deglutition function. The levator veli palatini (LVP) is believed to be significantly involved with velopharyngeal function in articulation; however, the development and innervation of LVP remain obscure. The development of LVP in human embryos and fetuses has not been systematically analyzed using the Carnegie stage (CS) to standardize documentation of development. Results: The anlage of LVP starts to develop at CS 21 beneath the aperture of the auditory tube (AT) to the pharynx. At CS 23, LVP runs along AT over its full length, as evidenced by three‐dimensional image reconstruction. In the fetal stage, the lesser palatine nerve (LPN) is in contact with LVP. Conclusions: The positional relationship between LVP and AT three‐dimensionally, suggesting that LVP might be derived from the second branchial arch. Based on histological evidence, we hypothesize that motor components from the facial nerve may run along LPN, believed to be purely sensory. The multiple innervation of LVP by LPN and pharyngeal plexus may explain the postpalatoplasty discrepancy between the partial impairment in articulation vs. the functional restoration of deglutition. That is, the contribution of LPN is greater in articulation than in deglutition. Developmental Dynamics 245:123–131, 2016. © 2015 Wiley Periodicals, Inc.     

Computerized three‐dimensional analysis of the heart and great vessels in normal and holoprosencephalic human embryos

The developing heart and great vessels undergo drastic morphogenetic changes during the embryonic period. To analyze the normal and abnormal development of these organs, it is essential to visualize their structures in three and four dimensions, including the changes occurring with time. We have reconstructed the luminal structure of the hearts and great vessels of staged human embryos from serial histological sections to demonstrate their sequential morphological changes in three dimensions. The detailed structures of the embryonic heart and major arteries in normal and holoprosencephalic (HPE) human embryos could be reconstructed and visualized, and anatomical structures were analyzed using 3D images. By 3D analysis, cardiac anomalies such as double‐outlet right ventricle and malrotation of the heart tube were identified in HPE embryos, which were not easily diagnosed by histological observation. Reconstruction and analysis of 3D images are useful for the study of anatomical structures of developing embryos and for identifying their abnormalities. Anat Rec, 2007. © 2007 Wiley‐Liss, Inc.     

Development of the Human Incus With Special Reference to the Detachment From the Chondrocranium to be Transferred into the Middle Ear

The mammalian middle ear represents one of the most fundamental features defining this class of vertebrates. However, the origin and the developmental process of the incus in the human remains controversial. The present study seeks to demonstrate all the steps of development and integration of the incus within the middle ear. We examined histological sections of 55 human embryos and fetuses at 6 to 13 weeks of development. At 6 weeks of development (16 Carnegie Stage), the incus anlage was found at the cranial end of the first pharyngeal arch. At this stage, each of the three anlagen of the ossicles in the middle ear were independent in different locations. At Carnegie Stage 17 a homogeneous interzone clearly defined the incus and malleus anlagen. The cranial end of the incus was located very close to the otic capsule. At 7 and 8 weeks was characterized by the short limb of the incus connecting with the otic capsule. At 9 weeks was characterized by an initial disconnection of the incus from the otic capsule. At 13 weeks, a cavity appeared between the otic capsule and incus. Our results provide significant evidence that the human incus developed from the first pharyngeal arch but independently from Meckel's cartilage. Also, during development, the incus was connected with the otic capsule, and then it was detached definitively. The development of the incus in humans provides evidence that this ossicle is homologous to the quadrate. Anat Rec, 2018. © 2018 Wiley Periodicals, Inc.     

Synchrotron‐Based Micro‐CT Imaging of the Human Lung Acinus

Structural data about the human lung fine structure are mainly based on stereological methods applied to serial sections. As these methods utilize 2D images, which are often not contiguous, they suffer from inaccuracies which are overcome by analysis of 3D micro‐CT images of the never‐sectioned specimen. The purpose of our study was to generate a complete data set of the intact three‐dimensional architecture of the human acinus using high‐resolution synchrotron‐based micro‐CT (synMCT). A human lung was inflation‐fixed by formaldehyde ventilation and then scanned in a 64‐slice CT over its apex to base extent. Lung samples (8‐mm diameter, 10‐mm height, N = 12) were punched out, stained with osmium tetroxide, and scanned using synMCT at (4 μm)³ voxel size. The lung functional unit (acinus, N = 8) was segmented from the 3D tomographic image using an automated tree‐analysis software program. Morphometric data of the lung were analyzed by ANOVA. Intra‐acinar airways branching occurred over 11 generations. The mean acinar volume was 131.3 ± 29.2 mm³ (range, 92.5–171.3 mm³) and the mean acinar surface was calculated with 1012 ± 26 cm². The airway internal diameter (starting from the bronchiolus terminalis) decreases distally from 0.66 ± 0.04 mm to 0.34 ± 0.06 mm (P < 0.001) and remains constant after the seventh generation (P < 0.5). The length of each generation ranges between 0.52 and 0.93 mm and did not show significant differences between the second and eleventh generation. The branching angle between daughter branches varies between 113‐degree and 134‐degree without significant differences between the generations (P < 0.3). This study demonstrates the feasibility of quantitating the 3D structure of the human acinus at the spatial resolution readily achievable using synMCT. Anat Rec 293:1607–1614, 2010. © 2010 Wiley‐Liss, Inc.     

4D MRI of polycystic kidneys from rapamycin‐treated Glis3‐deficient mice

Polycystic kidney disease (PKD) is a life‐threatening disease that leads to a grotesque enlargement of the kidney and significant loss of function. Several imaging studies with MRI have demonstrated that cyst size in polycystic kidneys can determine disease severity and progression. In the present study, we found that, although kidney volume and cyst volume decreased with drug treatment, renal function did not improve with treatment. Here, we applied dynamic contrast‐enhanced MRI to study PKD in a Glis3 (GLI‐similar 3)‐deficient mouse model. Cysts from this model have a wide range of sizes and develop at an early age. To capture this crucial stage and assess cysts in detail, we imaged during early development (3–17 weeks) and applied high spatiotemporal resolution MRI (125 × 125 × 125 cubic microns every 7.7 s). A drug treatment with rapamycin (also known as sirolimus) was applied to determine whether disease progression could be halted. The effect and synergy (interaction) of aging and treatment were evaluated using an analysis of variance (ANOVA). Structural measurements, including kidney volume, cyst volume and cyst‐to‐kidney volume ratio, changed significantly with age. Drug treatment significantly decreased these metrics. Functional measurements of time‐to‐peak (TTP) mean and TTP variance were determined. TTP mean did not change with age, whereas TTP variance increased with age. Treatment with rapamycin generally did not affect these functional metrics. Synergistic effects of treatment and age were not found for any measurements. Together, the size and volume ratio of cysts decreased with drug treatment, whereas renal function remained the same. The quantification of renal structure and function with MRI can comprehensively assess the pathophysiology of PKD and response to treatment. Copyright © 2015 John Wiley & Sons, Ltd.