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Eyebrows are the most important facial feature in facial recognition with its shape rated to be more helpful than color or density for facial reconstruction or approximation. However, little extant research has estimated the position and morphological territory of the eyebrow from the orbit. Three-dimensional craniofacial models, produced from CT scans of 180 Koreans autopsied at the National Forensic Service Seoul Institute, were used to conduct metric analyses of subjects (125 males and 55 females) between 19 and 49 (mean 35.1) years. We employed 18 craniofacial landmarks to examine the morphometry of the eyebrow and orbit with 35 pairs of distances per subject measured between landmark and reference planes. Additionally, we used linear regression analyses to predict eyebrow shape from the orbit for every possible combination of variables. The morphology of the orbit has more influence on the position of the superior margin of the eyebrow. In addition, the middle part of the eyebrow was more predictable. The highest point of the eyebrow in female was located more medially than the male. Based on our findings, the equations for estimating the position of the eyebrow from the shape of the orbit is useful information for face reconstruction or approximation. The rest of this paper is structured as follows. We explain the method employed in the next section, after which we explain our findings and results. We then discuss these findings and conclude with the impact of our findings.

Educational technologies in veterinary medicine aim to train veterinarians faster and improve clinical outcomes. COVID-19 pandemic, shifted face-to-face teaching to online, thus, the need to provide effective education remotely was exacerbated. Among recent technology advances for veterinary medical education, extended reality (XR) is a promising teaching tool. This study aimed to develop a case resolution approach for radiographic anatomy studies using XR technology and assess students' achievement of differential diagnostic skills. Learning objectives based on Bloom's taxonomy keywords were used to develop four clinical cases (3 dogs/1 cat) of spinal injuries utilizing CT scans and XR models and presented to 22 third-year veterinary medicine students. Quantitative assessment (ASMT) of 7 questions probing 'memorization', 'understanding and application', 'analysis' and 'evaluation' was given before and after contact with XR technology as well as qualitative feedback via a survey. Mean ASMT scores increased during case resolution (pre 51.6% (±37%)/post 60.1% (± 34%); p 0.01), but without significant difference between cases (Kruskal-Wallis H = 2.18, NS). Learning objectives were examined for six questions (Q1-Q6) across cases (C1-4): Memorization improved sequentially (Q1, 2 8/8), while Understanding and Application (Q3,4) showed the greatest improvement (26.7%-76.9%). Evaluation and Analysis (Q5,6) was somewhat mixed, improving (5/8), no change (3/8) and declining (1/8).Positive student perceptions suggest that case studies' online delivery was well received stimulating learning in diagnostic imaging and anatomy while developing visual-spatial skills that aid understanding cross-sectional images. Therefore, XR technology could be a useful approach to complement radiological instruction in veterinary medicine.

Purpose Extended reality (XR) technology enhances learning in medical education. The purpose of this study was to develop and apply a case-based approach for teaching radiological anatomy utilizing XR technology for improved student exploration and engagement. Methods The workflow consisted of MRI scanning cadavers followed by radiological, pathological, and anatomical assessment, and finally case presentation based on XR visualizations and student interaction. Case information (Subject, History, and Physical Exam) was presented to student groups who generated and recorded hypotheses using Google Forms. Results Use of all components of the system was voluntary and a total of 74 students responded to the survey request (response rate= 95%). Assessment of the experience was conducted through a qualitative survey comprising four Likert scale questions (1-5, 1 lowest), three binary questions, and open-ended comments. Mean, standard deviation, and overall agreement (mean ± SD, OA) showed that students found MRI scans of cadavers to be helpful for dissections (4.14 ± 1.1, 74.3%) and provided an understanding of relevant anatomy (4.32 ± 0.9, 79.7%), while 78.4% of students used the DICOM viewer to visualize scans of cadavers. The difficulty of use was found to be average (2.90 ± 1.0, 23%). zSpace visualizations were used by 40.5% of students, generally agreeing that an understanding of spatial relationships improved as a result (3.60 ± 1.0, 43.2%). More case-based sessions were favored by 97.3% of students. Conclusions Results suggest that cadaveric MRI radiological visualization and XR technology enhance understanding of case-based anatomical dissections and encourage student exploration and engagement.

The neuropathology associated with cognitive decline in military personnel exposed to traumatic brain injury (TBI) and chronic stress is incompletely understood. Few studies have examined clinicopathologic correlations between phosphorylated-tau neurofibrillary tangles, β-amyloid neuritic plaques, neuroinflammation, or white matter (WM) lesions, and neuropsychiatric disorders in veterans. We describe clinicopathologic findings in 4 military veterans with early-onset dementia (EOD) who had varying histories of blunt- and blast-TBI, cognitive decline, behavioral abnormalities, post-traumatic stress disorder, suicidal ideation, and suicide. We found that pathologic lesions in these military-EOD cases could not be categorized as classic Alzheimer’s disease (AD), chronic traumatic encephalopathy, traumatic axonal injury, or other well-characterized clinicopathologic entities. Rather, we observed a mixture of polypathology with unusual patterns compared with pathologies found in AD or other dementias. Also, ultrahigh resolution ex vivo MRI in 2 of these 4 brains revealed unusual patterns of periventricular WM injury. These findings suggest that military-EOD cases are associated with atypical combinations of brain lesions and distribution rarely seen in nonmilitary populations. Future prospective studies that acquire neuropsychiatric data before and after deployments, as well as genetic and environmental exposure data, are needed to further elucidate clinicopathologic correlations in military-EOD.

Keyhole gunshot wounds to the cranium are rare and typically indicative of tangential wounds. The authors present an atypical keyhole gunshot wound to the parietal bone that exhibits a groove that gradually widens and deepens, terminating with an embedded bullet fragment (core). This appears to be the first report describing a groove or “impact platform” indicating the entrance portion of a keyhole injury. This case provides information based on a multidisciplinary approach augmented with 3D photogrammetry that may explain the cranial wound pattern and variability associated with keyhole injuries in partial and complete crania.

Introduction: Systematic identification of anatomical variants and anomalies in large patient populations remains problematic. The purpose of this study is to determine whether anatomical anomalies of the hyoid region can be quantitatively characterized, and corresponding subjects can be identified within a large cohort of cleft lip and palate (CLP) patients Methods: Software was developed (er3d.com) comprising Procrustes transformation (PT) followed by shape state extraction and thin plate spline description. Validation was achieved by simulating specific affine and non-affine geometric changes utilizing a set of 3D printed geometries and assessing expected outcomes. Subsequently, scans derived from cone beam computed tomography (CBCT) of three primary groups were analyzed including control subjects, unilateral CLP, and bilateral CLP patients with each affected group divided into either growing (

Anatomical analysis of conjoined twins provides important information concerning embryological development. Museum specimens provide a unique sample that can be analyzed non-intrusively using advanced biomedical imaging and displayed online which is currently important due to limited in-person learning opportunities as a result of the COVID-19 pandemic. The purpose of this study is to create an extended reality (XR) workflow for visualization of dicephalic parapagus full-term conjoined twins obtained by Dr. Jacob Henle sometime between 1844-1852 for use in anatomy education. The workflow comprised image capture, segmentation, and visualization. The cadaver twins were curated at the University of Heidelberg and were subjected to CT and MR imaging. Relevant bones and soft tissues were manually segmented to create XR models, post-processed for visualization using Unity-based systems. A learning module was created and posted to Rad3d.com for presentation to students including visualization on Z-space computers (zspace.com) and sketchfab.com online. Osteology analysis showed commonality in the upper limb and shared ribs. Two vertebral columns were identified, and a single pelvic girdle was present with a single set of lower limbs. Duplicated supradiaphragmatic structures included two hearts (one with situs inversus) and four lungs, but single subdiaphragmatic visceral organs were observed. In particular, the gut was continuous on the right, but terminated at the distal esophagus on the left. One large liver occupied the abdomen with one large spleen located on the left. These observations suggest zygote fission was blocked near the yolk sac during midgut formation, but with secondary fusion of midline upper extremities and ribs. A radiology report was developed and presented to medical students as an embryology clinical correlation. This application indicates that university based museum specimens are useful as supplemental instructional subjects and, in this case, almost 170 years after arriving in the Department of Anatomy at the University of Heidelberg.

This review about extraoral anatomy depicted in cone beam computed tomography describes the pharyngocervical region. Large (≥ 8 × 8 cm) field of views of the maxilla and/or mandible will inevita-bly depict the pharyngocervical region that com-prises the posterior upper airway, the pharyngeal part of the digestive tract, as well as the cervical segment of the spine. The latter consists of seven cervical vertebrae (C1-C7) with corresponding distinctive features, i.e., the atlas (C1) and the axis (C2). In addition, cervical vertebrae serve as ref-erences for the vertical position of anatomical structures. For instance, C4 is a typical landmark since it generally denotes the level of the chin, of the body of the hyoid bone, of the base of the epiglottis, and of the bifurcation of the common carotid artery, respectively. The pharynx, which is functionally involved in respiration, deglutition, and vocalization, extends from the lower aspect of the skull base to the esophagus. Anatomically, the pharynx is divided into three segments, i.e. the nasopharynx, the oropharynx, and the laryn-gopharynx. All communicate anteriorly with cor-responding cavities, i.e. the nasal cavities, the oral cavity, and the larynx. Although not directly located within the pharyngocervical region, the hyoid bone and the styloid process are also dis-cussed in this review, since both structures are commonly visible on CBCT images of this region.

The Mann-Labrash Osteological Collection of the University of Hawai‘i is the newest collection of contemporary known-identity human skeletal remains in the United States. The collection, consisting of the partial or complete remains of individuals of European, African, Asian, and Pacific Islander ancestry, is an invaluable educational and research resource for medical students and visiting researchers. The collection reflects the population diversity of Hawai‘i. The Mann-Labrash Osteological Collection provides a unique and irreplaceable resource for medical students and scientists interested in anatomy, disease, trauma, developmental defects, and biological diversity, particularly as they pertain to Hawai‘i and the people of Polynesia.

In this review about extraoral anatomy as depicted by cone beam computed tomography, the retromaxillary region is discussed. A medium-sized (6 x 6 cm) or large (≥ 8 x 8 cm) field of view of the maxilla will inevitably depict the retromaxillary region that can be considered a «transition» zone between the viscerocranium and the neurocranium. Major structures of the region include the sphenoid bone and the pterygopalatine fossae. The sphenoid bone is a single but complex bone located between the maxilla and the brain. It is composed of a central body, bilateral greater and lesser wings, and pterygoid processes. Important neurovascular structures pass through the sphenoid bone: the optic nerve and the ophthalmic artery via the optic canal, the maxillary nerve via the foramen rotundum, and the pterygoid nerve via the Vidian canal. The central body of the sphenoid bone also contains the highly variable sphenoid sinus that is the most posteriorly located paranasal sinus. The bilateral pterygopalatine fossae behind the maxillary sinuses contain several important neurovascular structures that supply the maxilla and the midface.

This second article about extraoral anatomy as seen in cone beam computed tomography (CBCT) images presents a literature review of the zygomatico-orbital region. The latter bounds the maxillary sinus superiorly and laterally. Since pathologic changes of the maxillary sinus are a frequent indication for three-dimensional radiography, the contiguous orbital cavity and the zygomatic bone may become visible on CBCT scans. The zygomatic bone forms the cheek prominence and has large contact areas with the maxilla through the zygomaticomaxillary suture in the infraorbital region as well as with the sphenoid bone along the lateral orbital wall. Each of the three surfaces of the zygomatic bone displays foramina that transmit neurovascular structures. The orbital cavity is located immediately above the maxillary sinus from which it is separated only by a thin bony plate simultaneously serving as the orbital floor and the roof of the maxillary sinus. Several openings, such as the superior and inferior orbital fissures, the ethmoidal and cranio-orbital foramina, and the optic and infraorbital canals, connect the orbit to the anterior and middle cranial fossae as well as to the infratemporal and pterygopalatine fossae.

Cone beam computed tomography has become a widely used imaging technique for dental indications. Depending on the selected size of the field of view, anatomical structures outside the dentomaxillary complex become visible. As a consequence, the clinician must be able to interpret also those anatomical regions. In this article, the anatomy of the nasoethmoidal region is presented based on a literature review. The nose is characterized by the nasal septum and the superior, middle, and inferior conchae. The turbinates may be pneumatized (concha bullosa), mainly the middle concha. The ethmoid bone has a complex morphology (ethmoid labyrinths) and contributes with its perpendicular plate to the nasal septum. Other structures of the septum include the vomer and the septal cartilage. The nasal meatuses stabilize the airflow and direct the inhaled air to the nasopharynx via the choanae. The middle nasal meatus, which is also a part of the so called ostiomeatal complex, serves as the major drainage area (semilunar hiatus) of the paranasal sinuses, i.e., maxillary sinus, anterior ethmoid cells, and frontal sinus. Posterior ethmoid cells empty into the superior meatus and the sphenoid sinus drains into the sphenoethmoidal recess, located above the superior concha. The nasolacrimal duct that is running along the middle portion of the lateral nasal wall opens into the inferior nasal meatus.

The face is a unique part of the body with its individual anatomical characteristics. While the dental clinician is usually focused on the oral cavity, the physical examination should involve close attention to the neurosensory status of the facial skin. Furthermore, skin sensitivity should be assessed pre- and postoperatively in conjunction with dental interventions. The face can be divided into several functional units, such as the eyes, nose, mouth/lips, and cheeks. With regard to the neurosensory supply of the skin, various innervation territories of the face can be distinguished representing the three divisions of the trigeminal nerve. In addition, cutaneous branches of the cervical plexus provide sensitivity to the lower and lateral portions of the face. The objective of the present article is to provide the dental clinician with a literature update of the neurosensory innervation of the face.

The male urogenital system represents a morphologically complex region that arises from a common embryological origin. However, it is typically studied separately as the excretory system is dissected with the posterior wall of the abdomen while the reproductive features are exposed with the pelvis and perineum dissection. Additionally, the reproductive structures are typically dissected following pelvic and perineal hemisection obviating a comprehensive and holistic examination. Here, we performed a dissection of the complete male urogenital system utilizing a 70-year-old donor and room temperature silicon plastination. Identification of a direct inguinal hernia during the dissection facilitated a unique opportunity to incorporate a common abdominal wall defect into the plastination requiring a novel approach to retain patency of relevant structures. Results showed that the typical structures identified in medical gross anatomy were retained in addition to the hernia. Thus, the described approach and the resulting specimen provide valuable and versatile teaching tools for male urogenital anatomy.

Objectives: The CL/Fr mouse displays cleft lip and palate (CLP) at a rate of 35%. The clf1 mutation is associated with CLP in related “A” strain mice and affects the gene Wnt9b. The purpose of this study was to determine tissue specific expression of Wnt9b during facial prominence morphogenesis in CL/Fr mice and provide new details concerning gene variants associated with CLP. Methods: Facial prominences from CLP(-) and CLP(+) CL/Fr and 3H1 wild-type (WT) mice at embryonic day 11.5 (E11.5) were collected for expression assays (DNA microarray analysis, qRT-PCR, immunostaining, and in situ hybridization). A modified Chi square test was used to analyze microarray data while a student t-test was used to statistically compare qRT-PCR values (p

BACKGROUND The accessory infraorbital foramen (AIOF) is an anatomical variation associated with the infraorbital foramen (IOF) and nerve (ION). Its occurrence and neural contents have clinical implications regarding failure of loco-regional anesthesia and risk of neural damage during surgical interventions involving the maxillary region. Thus, morphologic characterization of the AIOF and neural contents as well as the spatial relationships to the IOF are potentially useful for optimizing surgical procedures. Additionally, predictive features of the AIOF based on its relationship to IOF morphology could enable the surgeon to anticipate its presence and proceed accordingly. The purpose of this study was to determine whether the presence of an AIOF and its neural contents affected the size, shape, and composition of the IOF and ION. The specific hypothesis tested was that the topography and fascicular composition of the ION and IOF differs between individuals possessing an AIOF and those lacking this anatomical variant. METHODS Gross topographic features of the IOF (42 crania) were compared between specimens possessing (test) or lacking (control) an AIOF. Nerve fascicles of ION (60 cadaveric sides) were examined histologically and compared morphometrically between specimens presenting or lacking an AIOF. An additional sample of 30 crania was subjected to cone-beam computed tomography (CBCT) analysis to determine the course of the canal leading to the AIOF. RESULTS The AIOF incidence was 47.6% (20 crania) and 32.1% of the sides (27 sides). A single AIOF was observed in 24 sides and double AIOF in three sides. The AIOF occurred bilaterally in 7 specimens (16.7%). The majority of AIOF (86.7%) were located superomedial to IOF. A slightly higher frequency of the AIOF was found in left side compared to the right. Using CBCT, a patient sample showed an AIOF incidence in 21 sides of 16 patients (65.6%). A single AIOF was observed in 19 sides. Only 1 double AIOF was found in the scans, whereas 3 were found in the dry skull group. The AIOF occurred bilaterally in 3 scans (10%). The majority of AIOF (90.4%) were located superomedial to the IOF based on the CBCT scans. The AIOF was consistently seen connected to the infraorbital canal and progressed superiorly and medially from the infraorbital canal to the maxillary surface. The size of the ION without an AIOF was not significantly different than the ION in the presence of an AIOF (1.45 × 10/1.32 × 10 μm, P

Fibrous dysplasia is a rare bone disorder characterized by the replacement of normal bone by abnormal fibrous tissue. Here we present a 16-year-old female with a fibrous dysplasia in the maxilla and obliteration of the sinus in the same side. Cone beam computed tomography scan revealed a mixed radiopacity that extended from the alveolar crest of the right posterior teeth to the right orbital floor in the superior-inferior direction. The radiopaque areas had homogenous ground glass appearance. There is a loss of bone trabeculation, thinning of the cortical boundaries but still intact, and a loss of the lamina dura around the right posterior permanent teeth. The radiographical features of the lesion were indicative of fibrous dysplasia in the maxilla.

The individual appearance and facial expression are based on the musculoskeletal system of the face. The bones of the face contribute to the anterior portion of the skull. This region is also referred to as the facial skeleton or viscerocranium. The muscles of the face include all mimetic muscles innervated by the cranial nerve VII (facial nerve). Two masticatory muscles (masseter, temporalis) that are supplied by the motoric portion of the cranial nerve V3 (mandibular nerve) also contribute to the contour of the face. The mimetic muscles (also known as facial muscles or skin muscles) generally originate from underlying bone surfaces and insert to the skin of the face or intermingle with other facial muscles. This complex musculature contributes to the functioning of the orofacial sense organs and the mediation of emotional and affective states (facial expression). Other soft tissue components of the face include the fasciae and fat compartments. The face commonly exhibits a superficial and a deep fascia, and various facial fat compartments are present.

In this study, we report a rare case of osteoma cutis (OC) and tonsillolith, diagnosed using cone beam computed tomography. The dystrophic calcifications in the face and tonsils were incidentally found during examination of the patient's scan with no relation to the main chief complaint. The diagnosis was OC, combined with dystrophic calcification of the tonsils. It is important to mention that OC is a rare soft-tissue ossification of cutaneous tissue, typically on the face and clinically asymptomatic. It may be primary but the majority of cases are secondary. Incidental finding of OC and tonsilloliths on a two-dimensional dental radiograph does not provide sufficient information concerning the location of these calcifications. Thus, cone beam computed tomography (CBCT) provides critical information for the diagnosis of asymptomatic OC lesions not available through any other means of clinical detection.

Vascular supply is key for maintenance of healthy tissue conditions but also with regard to healing following trauma or therapeutic interventions. The face is probably the most exposed part of the body and any changes of vascularity are readily visible (skin blanching, ecchymosis, hematoma, edema). With regard to the arterial supply, all vessels reaching the facial skin originate from the bilateral common carotid arteries. The ophthal­mic artery is considered the major arterial shunt between the internal and external carotid artery systems. Main arterial contributors to the face include the facial, transverse facial, and infraorbital arteries. In general, homonymous veins accompany the arteries, but there are some exceptions (inferior ophthalmic vein, retromandibular vein). Furthermore, the facial vein demonstrates a consistently more posterior course compared to the facial artery. Lymphatic vessels including lymph nodes play an important role for facial drainage.

Radiological anatomy education is an important aspect of the medical curriculum. The purpose of this study was to establish and demonstrate the use of plastinated anatomical specimens, specifically human hearts, for use in radiological anatomy education. Four human hearts were processed with routine plastination procedures at room temperature. Specimens were subjected to cone beam computed tomography and a graphics program (ER3D) was applied to generate 3D cardiac models. A comparison was conducted between plastinated hearts and their corresponding computer models based on a list of morphological cardiac features commonly studied in the gross anatomy laboratory. Results showed significant correspondence between plastinations and CBCT-generated 3D models (98 %; p

Context Plastination techniques have emerged as effective methods for preserving human tissue and enabling human specimens to be utilized in a fashion similar to anatomical models with much greater accuracy. Opportunities to observe and experience human specimens in classroom settings should be beneficial to undergraduate and graduate students in health professions such as athletic training since understanding the spatial orientation of anatomical structures is critical for learning palpation skills and diagnostic tests. Objective To assess the perceived value of a unique series of plastinated specimens depicting common sport injuries in enhancing musculoskeletal injury evaluation education. Design Survey study. Setting We collected data via a questionnaire in the classroom setting. Patients or Other Participants Undergraduate students, graduate students, and certified athletic trainers. Intervention(s) Dissected specimens were plastinated following standard room temperature plastination methods. We used a Likert scale questionnaire to evaluate the usefulness of the plastinated specimens for conveying associated learning issues. Participants completed the questionnaire following a didactic presentation of injury mechanism, symptoms, and diagnostic clinical testing while utilizing the plastinated specimens. Main Outcome Measure(s) Perceived usability and the need for plastinated injury model use by students and certified athletic trainers. Results We found that plastinated injury models were perceived by a majority of the participants as being useful and needed for learning anatomy 3-dimensionally (98.6%), developing palpation skills (94.6%), and enhancing the concept of diagnostic testing used in injury assessment (95.9%). Conclusions Plastination of human specimens is a unique and effective approach that provides students with a learning experience not available through other instructional delivery systems. The ability to practice injury evaluation techniques, especially palpation skills, while using actual anatomical structures provides students with superior learning experiences and should be made more widely available in classroom settings.

Genetic variations affecting neural tube closure along the head result in malformations to the face and brain, posing a significant impact on health care costs and the quality of life. We have established a mouse line from a mutation that arose spontaneously in our wildtype colony that we called tuft. Tuft mice have heritable midline craniofacial defects featuring an anterior lipomatous cephalocele. Whole mount skeletal stains indicated that affected newborns had a broader interfrontal suture where the cephalocele emerged between the frontal bones. Mice with a cephalocele positioned near the rostrum also presented craniofacial malformations such as ocular hypertelorism and midfacial cleft of the nose. Gross and histological examination revealed that the lipomatous cephalocele originated as a fluid filled cyst no earlier than E14.5 while embryos with a midfacial cleft was evident during craniofacial development at E11.5. Histological sections of embryos with a midfacial cleft revealed the cephalic neuroectoderm remained proximal or fused to the frontonasal ectoderm about the closure site of the anterior neuropore, indicating a defect to neural tube closure. We found the neural folds along the rostrum of E9-10.5 embryos curled inward and failed to close as well as embryos with exencephaly and anencephaly at later stages. Whole mount in situ hybridization of anterior markers Fgf8 and Shh indicated closure of the rostral site was compromised in severe cases. We present a model demonstrating how anterior cranial cephaloceles are generated following a defect to neural tube closure and relevance to subsequent craniofacial morphogenesis in the tuft mouse.

Introduction The mental foramen (MF) is an important landmark in dentistry. Knowledge of its position is central to perform block anesthesia of the mental nerve or to avoid nerve damage during surgical procedures in the premolar area of the mandible. The present radiographic study aimed at evaluating the location and dimension of the MF and measuring distances to neighboring structures by using limited cone-beam computed tomography (CBCT). Methods Sagittal, axial, and coronal CBCT images of 142 patients (26 bilateral and 116 unilateral cases) were retrospectively screened to determine the location of the MF with respect to adjacent teeth and to take linear measurements of the size of the MF and its distances to the upper and lower borders of the mandible. In addition, the course and angulation of the mental canal exiting the MF were assessed. Results The majority of MF (56%) were located apically between the 2 premolars, and another 35.7% of MF were positioned below the second premolar. On average, the MF was localized 5.0 mm from the closest root of the adjacent tooth (range, 0.3–9.8 mm). The mean size of the MF showed a height of 3.0 mm and a length of 3.2 mm; however, individual cases showed large differences in height (1.8–5.1 mm) and in length (1.8–5.5 mm). All mental canals exiting the MF demonstrated an upward course in the coronal plane, with 70.1% of the mental canal presenting an anterior loop (AL) in the axial view. The mean extension of AL in cases with an AL was 2.3 mm. Conclusions This study is consistent with previous radiographic studies regarding size and location of MF and distances between MF and adjacent anatomic structures. The assessed bilateral cases showed a high intraindividual concordance for certain features when comparing right and left sides.

The anatomical, radiographic and histological features of accessory mental foramina were assessed in four patients undergoing apical surgery of mandibular premolars or molars. In three cases, the accessory foramina were detected preoperatively, and in one case, the accessory foramen was observed accidentally during surgery. Histologically, the excised soft tissue bundles exiting the accessory foramina contained nerve tissue with fascicles, which contained mainly myelinated nerve fibres, and accompanying small blood vessels and adipocytes. Only one patient reported numbness following surgery. According to the suggested classification of supplementary mandibular buccal foramina, one case was classified as presenting a double mental foramen, two cases as having an accessory mental foramen and one case as displaying a so-called additional buccal foramen.

BACKGROUND Cephalothoracopagus twinning is extremely rare, and it is characterized by fusion of the head and thorax, two separate spines, pelves, and fore- and hindlimbs. CASE: In this case study, we describe cephalothoracopagus twinning in an embryonic mouse displaying a large but exencephalic head, median facial cleft, a single eye, and a second hindbrain rotated roughly 90° from a second spinal cord. There is a bony connection joining the clavicles, resulting in merged asternal thoracic cavities containing two hearts and four lungs. The abdominal cavities contain double caudal digestive tract structures, but a single esophagus and stomach. CONCLUSION There are several proposed theories regarding the mechanism of spontaneous conjoined twinning; however, the specific mechanisms are still largely unknown. In this report, we highlight the morphological features in a murine example of cephalothoracopagus twinning, furthering our understanding of this rare occurrence while also demonstrating developmental morphogenesis consistent with that reported for human conjoined twins. Birth Defects Research (Part A) 97:421–424, 2013. © 2013 Wiley Periodicals, Inc.

Nephron progenitor number determines nephron endowment; a reduced nephron count is linked to the onset of kidney disease. Several transcriptional regulators including Six2, Wt1, Osr1, Sall1, Eya1, Pax2, and Hox11 paralogues are required for specification and/or maintenance of nephron progenitors. However, little is known about the regulatory intersection of these players. Here, we have mapped nephron progenitor-specific transcriptional networks of Six2, Hoxd11, Osr1, and Wt1. We identified 373 multi-factor associated ‘regulatory hotspots’ around genes closely associated with progenitor programs. To examine their functional significance, we deleted ‘hotspot’ enhancer elements for Six2 and Wnt4. Removal of the distal enhancer for Six2 leads to a ~40% reduction in Six2 expression. When combined with a Six2 null allele, progeny display a premature depletion of nephron progenitors. Loss of the Wnt4 enhancer led to a significant reduction of Wnt4 expression in renal vesicles and a mildly hypoplastic kidney, a phenotype also enhanced in combination with a Wnt4 null mutation. To explore the regulatory landscape that supports proper target gene expression, we performed CTCF ChIP-seq to identify insulator-boundary regions. One such putative boundary lies between the Six2 and Six3 loci. Evidence for the functional significance of this boundary was obtained by deep sequencing of the radiation-induced Brachyrrhine (Br) mutant allele. We identified an inversion of the Six2/Six3 locus around the CTCF-bound boundary, removing Six2 from its distal enhancer regulation, but placed next to Six3 enhancer elements which support ectopic Six2 expression in the lens where Six3 is normally expressed. Six3 is now predicted to fall under control of the Six2 distal enhancer. Consistent with this view, we observed ectopic Six3 in nephron progenitors. 4C-seq supports the model for Six2 distal enhancer interactions in wild-type and Br/+ mouse kidneys. Together, these data expand our view of the regulatory genome and regulatory landscape underpinning mammalian nephrogenesis., Author summary Nephrons, the filtering units of the kidney, derive from nephron progenitors. Deficiencies in nephron number increases the risk of kidney disease. An understanding of the regulatory programs governing progenitor actions has important translational potential. Several transcription factors regulate the nephron progenitor population. However, their target interactions are largely unknown. Here, we mapped and intersected the genome-wide binding sites for four such factors in mouse nephron progenitor cells in the developing kidney: Six2, Hoxd11, Osr1, and Wt1. The intersectional data highlight a high-value set of putative enhancer elements linked to genes regulating nephron progenitor properties. We validate the function of two such enhancer elements regulating the levels of Six2, a key transcriptional regulatory factor in nephron progenitor maintenance, and Wnt4, a critical signaling factor controlling the mesenchyme to epithelial transition of induced nephron progenitors. Further characterization of the Six2 regulatory landscape identified higher order regulatory interactions that ensure appropriate enhancer-promoter specificity. CTCF-bound sites between Six2 and the adjacent Six3 locus likely act as boundary elements to define topological interactions domains separating enhancer elements thereby providing distinct tissue specificity to each gene’s expression. An inversion of this region in the Brachyrrhine (Br) mutant mouse reverses Six2 and Six3 expression domains, placing Six3 under control of the Six2 enhancer element above resulting in kidney-specific expression, while Six2 expression shifts to the lens, a normal expression domain for Six3. Together, these data expand our view of the regulatory genome and regulatory landscape underpinning mammalian nephrogenesis.