Editor’s Choice Articles

Tissue engineering is a powerful tool with which to systematically identify the determinants of biological functions. Applied to the design and fabrication of biomimetic brains, tissue engineering serves to disentangle the complex anatomy of neural circuits and pathways by recapitulating structure-function relationships in simplified model systems. The complex neuroanatomy of the cerebral cortex, with its enigmatic columnar and stratified cytoarchitectonic organization, represents a major challenge toward isolating the minimal set of elements that are required to assemble neural tissues with cognitive functions. Whereas considerable efforts have highlighted important genetic and physical correlates of early cortical tissue patterning, no substantive attempt to identify the determinants of how the cortices acquire their relatively conserved, narrow range of numbered layers is evident in the literature. Similarly, it is not yet clear whether cortical columns and laminae are functionally relevant or epiphenomena of embryonic neurodevelopment. Here, we demonstrate that spatial frequencies (m⁻¹) derived from the width-to-height ratios of cerebral cortical columns predict sinusoids with a narrow range of spatial cycles over the average cortical thickness. The resulting periodicities, denoted by theoretical wavenumbers, reflect the number of observed cortical layers among humans and across several other species as revealed by a comparative anatomy approach. We present a hypothesis that cortical columns and their periodic layers are emergent of the intrinsic spatial dimensions of neurons and their nested, self-similar aggregate structures including minicolumns. Finally, we discuss the implications of periodic tissue patterns in the context of neural tissue engineering. Full article

Computed tomography (CT) angiography is the main method for the initial evaluation of cerebral circulation in acute stroke. A comprehensive CT examination that includes a review of the three-dimensional and maximum-intensity projection images of the main intra and extracranial arteries allows the identification of most abnormalities and normal variants. Anatomical knowledge of the presence of any normal variants, such as fenestration, duplications, and persistent fetal arteries, plays a crucial role in the diagnosis and therapeutic management of acute stroke. However, the opposite is also true. In fact, sometimes it is the clinical picture that allows weighing how relevant or not the alteration found is. Therefore, in this review, a concise representation of the clinical picture attributable to a given arterial vessel will be included. Full article

(1) Background: The anatomical variations of neurovascular canals that are encountered in oral surgery are often overlooked by anatomy textbooks or provided with insufficient information. The aim of this study is to analyze the most common variations, describing their morphology, prevalence and clinical implications. (2) Methods: A review of published literature from the 20th century onwards was performed using the PubMed electronic database as well as anatomical textbooks. The variations being investigated were: retromolar canal (RMC) and foramen (RMF), accessory mental foramen (AMF), midline (MLF) and lateral (MLF) lingual foramina and canalis sinuosus (CS). (3) Results: Anatomical variants of neurovascular canals and foramina have a significant incidence and important clinical implications in the most common oral surgery procedures such as third molar extraction, bone harvesting and implantology. (4) Conclusions: Knowledge of these variables is highly important both for students to have a more accurate anatomical awareness and for professional surgeons to be able to provide better diagnoses and prevent complications during oral surgery techniques. Full article

Although the presence of an arrector pili smooth muscle is documented in many monkey species, its regional peculiarities are hitherto not well documented. We aimed to study this aspect in the face of rhesus monkeys with different areas of hair coat. Eight different regions of six monkeys (male and female) were studied using light microscopy and immunohistochemistry (antibody against smooth muscle alpha actin). We identified two regions (lips and eyelids) with vellus hairs that did not show an arrector pili muscle. In the eyelids, the hairs are rather small and short; in the lips, the vellus hairs were surrounded by striated muscle fibers from the orbicularis oris muscle. In all other regions (frontal region, forehead, cheek, chin), the vellus hairs contained an arrector pili muscle with comparable morphology. Only in the chin region, where additional striated muscles from the face muscles were present, the arrector pili muscles were thinner. All vibrissae showed a close relation to striated muscle fiber bundles of the facial muscles. They never developed smooth muscle bundles assigned as arrector pili equivalent. Full article

Development of effective in vitro human lip models, specific to the vermilion epithelium, has not progressed as much as that of skin and oral mucosa/gingiva models in vitro. Our histologic examination demonstrated that a Japanese macaque (male, 7 years and 9 months old) had vermilion in the lip distinct from adjacent skin and oral mucosa, resembling histological characteristics of the human lip. Therefore, in this study, we examined the gene expression profile of the three distinct epithelia (skin/vermilion/oral mucosa) within the lip of a Japanese macaque to explore a single potential marker of human vermilion epithelium. Six pairwise comparisons in the skin/vermilion/oral mucosa epithelium in vitro and in vivo revealed 69 differentially up-regulated genes in vermilion epithelium in vivo, in which a few unique genes were highly expressed when compared with both skin and oral mucosa epithelium in vivo using clustering analysis. However, we could not detect a single marker specific to vermilion epithelium supported by the gene expression profile of a Japanese macaque. Instead, the pair of keratin 10 and small proline-rich protein 3 resulted in a potential marker of vermilion epithelium in the human lip (female, 53-year-old) via a double-immunostaining technique. Nonetheless, our result may provide further clues leading to other potential markers of the vermilion epithelium. Full article