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Skeletal myogenesis is precisely regulated by multiple transcription factors. Previously, we demonstrated that enhancer of polycomb 1 (Epc1) induces skeletal muscle differentiation by potentiating serum response factor (SRF)-dependent muscle gene activation. Here, we report that an interacting partner of Epc1, ret finger protein (RFP), blocks skeletal muscle differentiation. Our findings show that RFP was highly expressed in skeletal muscles and was downregulated during myoblast differentiation. Forced expression of RFP delayed myoblast differentiation, whereas knockdown enhanced it. Epc1-induced enhancements of SRF-dependent multinucleation, transactivation of the skeletal α-actin promoter, binding of SRF to the serum response element, and muscle-specific gene induction were blocked by RFP. RFP interfered with the physical interaction between Epc1 and SRF. Muscles from rfp knockout mice (Rfp−/−) mice were bigger than those from wild-type mice, and the expression of SRF-dependent muscle-specific genes was upregulated. Myotube formation and myoblast differentiation were enhanced in Rfp−/− mice. Taken together, our findings highlight RFP as a novel regulator of muscle differentiation that acts by modulating the expression of SRF-dependent skeletal muscle-specific genes. [ABSTRACT FROM AUTHOR]

In the infant the region lateral to the sella turcica which is traditionally termed the 'cavernous sinus' is composed of 3 individual compartments. The aim of this study was to demonstrate a similar compartmentation of the adult cavernous sinus and to identify and quantify the adipose bodies which are located within the compartments. The region of the cavernous sinus in 136 adults was analysed by microdissection and histology. We demonstrate that in 66% of the cavernous sinus in adults is composed of at least 2 compartments and in 22% it is made up of 3. Assimilating the renaming in infants we termed the compartments 'pterygopalatine', 'orbital' and 'lateral sellar'. The pterygopalatine and orbital compartments are connected with extracranial tissue spaces via the superior orbital fissure and contain characteristic adipose bodies. Exact topographic descriptions and measurements of the compartments and their adipose bodies are provided. Our study clearly defines compartmentation of the adult parasellar space in most individuals and thus changes the anatomical view of this space. The direct connection of 2 of these compartments with extracranial tissue spaces and the measurements of their adipose bodies are of interest for surgeons and neuroradiologists.

We have used serial histological sections to document heart formation in Xenopus laevis, from the formation of a linear heart tube to the appearance of morphologically distinct atrial and ventricular chambers. 3D reconstruction techniques have been used to derive accurate models from digital images, revealing the morphological changes that accompany heart differentiation. To demonstrate the utility of this approach in analysing cardiac gene expression, we have reexamined the distribution of Hand1 transcripts in the linear and looped heart tube. Our results demonstrate that prior to looping, an initial asymmetric, left-sided pattern is replaced by more symmetrical localisation of transcripts to the ventral portion of the myocardium. After the onset of looping, Hand1 expression is restricted to the ventral ventricular myocardium and extends along the entire length of the single ventricle., (Copyright 2000 Academic Press.)

Intimal cushions that project into the lumen of arteries are precursors of atherosclerotic plaque formation. The "carotid siphon, " although frequently affected by atherosclerosis, was never analyzed for the occurrence of neonatal intimal hyperplasia. This study provides a topographic and morphometric analysis of intimal cushions in the parasellar internal carotid artery (pICA) of the human infant. A total of 35 specimens were studied in detail, using both standard histological techniques and a new method of computer-aided 3D reconstruction. Intimal hyperplasia occurred at 3 characteristic locations of the pICA: (1) the convex side of the posterior knee (C5 cushion), (2) the bottom of the horizontal segment (C4 cushion), and (3) the concave side of the anterior knee (C3 cushion). The extension of the cushions and the degrees to which they occluded the vessel lumens were measured. The complex shape of the pICA required 3D computer models for exact topographical descriptions and precise measurements. Our results suggest that the occurrence and degree of intimal hyperplasia are related to shape changes of the pICA during postnatal development. We predict that individuals who retain the relatively straight course of the fetal pICA throughout their lives are less prone to develop atherosclerotic lesions at this portion of the carotid artery. A possible contribution of neonatal intimal cushions to the origin of sudden infant death syndrome is discussed.

Object: In this study the authors analyze the peculiarities of the parasellar anatomy and the topography of surgical approaches to the parasellar region (PSR) in human infants., Methods: Forty-nine specimens of the PSR obtained at autopsy were studied using microdissection and histological analysis. Important distances between anatomical landmarks were measured with the aid of a dissecting microscope. One serially sectioned specimen was three-dimensionally reconstructed and analyzed on the computer screen by using the authors' new episcopic reconstruction technique., Conclusions: The anatomy of the infant PSR differs distinctly from that of the adult. The parasellar portion of the internal carotid artery (ICA) does not form a siphon, but takes a straight course, and the venous pathways as well as the cranial and sympathetic nerves have different topographical relationships. Analyses of surgical approaches demonstrate that, in young children, the anterolateral approach can be used to reach the pterygopalatine compartment, the superior ophthalmic vein, and those pathological processes that extend from the orbit into the PSR. The approach via Parkinson's triangle can be used in 45% of cases to access the pathological processes that occur in the voluminous space above and behind the posterior flexure of the parasellar ICA. Taking this route, sympathetic nerve fibers passing through the PSR are not at risk, but some arterial branches that run within the lateral wall of the sinus can complicate this approach. This study presents a guideline that can assist radiologists and neurosurgeons in the planning and performance of interventions within the PSR of neonates and young children.

Background: Computer-based three-dimensional (3D) visualizations reconstructed from sectional images represent a valuable tool in biomedical research and medical diagnosis. Particularly with those imaging techniques that provide virtual sections, such as CT, MRI, and CLSM, 3D reconstructions have become routine. Reconstructions from physical sections, such as those used in histological preparations, have not experienced an equivalent breakthrough, due to inherent shortcomings in sectional preparation that impede automated image-processing and reconstruction. The increased use of molecular techniques in morphological research, however, generates an overwhelming amount of 3D molecular information, stored within series of physical sections. This valuable information can be fully appreciated and interpreted only through an adequate method of 3D visualization., Methods and Results: In this paper we present a new method for a reliable and largely automated 3D reconstruction from physically sectioned material. The 'EMAC' concept (External Marker-based Automatic Congruencing) successfully approaches the three major obstacles to automated 3D reconstruction from serial physical sections: misalignment, distortion, and staining variation. It utilizes the objectivity of external markers for realignment of the sectional images and for geometric correction of distortion. A self-adapting dynamic thresholding technique compensates for artifactual staining variation and automatically selects the desired object contours., Conclusions: Implemented on a low-cost hardware platform, EMAC provides a fast and efficient tool that largely facilitates the use of computer-based 3D visualization for the analysis of complex structural, molecular, and genetic information in morphological research. Due to its conceptual versatility, EMAC can be easily adapted for a broad range of tasks, including all modern molecular-staining techniques, such as immunohistochemistry and in situ hybridization.

The cavernous sinus is traditionally described as a single anatomical compartment that contains cranial nerves, blood vessels, and connective tissue. A detailed analysis of 45 infant and 4 fetal parasellar regions shows that this view must be modified. The spatial arrangement, the topographic relations, and the expansion of the adipose and connective tissue spaces were analysed and reconstructed 3-dimensionally on a computer. It is shown that 3 different anatomical compartments, which are strictly demarcated by connective tissue, compose the parasellar region of infants. Two represent intracranial continuations of extracranial tissue spaces. The 3rd compartment corresponds to the so-called 'cavernous sinus' of the adult. Each of the 3 compartments contains characteristic adipose tissue bodies. Because the cavernous sinus represents only one compartment of the area, we propose to use the term 'parasellar region' to designate the entire anatomical region on either side of the sella turcica.

Sympathetic nerves innervate targets in the orbit and the brain. They issue from the superior cervical ganglion and reach the parasellar region via the internal carotid nerve. Information on their further parasellar course and distribution is scant and contradictory. In this study the parasellar sympathetic pathways of 30 human infants and 6 human fetuses were investigated by microdissection and histologically. A common parasellar sympathetic trunk, which reunites all the nerve fibers emanating from the lateral and medial internal carotid plexus, is described as well as its further divisions. It was found that the posterior knee of the infant carotid siphon is free of large sympathetic nerve bundles. In addition a ganglion is described, which is situated in the parasellar adipose body. It is reached by nerve fibers coming from the parasellar sympathetic pathways. Fibers that issue from this ganglion join the periorbita and the orbital muscle of Müller. These anatomical facts are of immediate importance for preventing nerve damage during cavernous sinus surgery. Furthermore, the study improves the anatomical knowledge of the parasellar region and suggests a new concept for the innervation of the orbital muscle.

This paper reports the development of an objective and time-saving method for the three-dimensional reconstruction of sectioned morphological specimens on the computer. The development of a fiducial marker technique, the design of program extensions for the automatic thresholding and realignment of images, and a technique for the transfer of marker-derived reference points into images of higher magnification are described. The method is based on the use of resin as embedding material and drill holes as fiducials. Images are digitized by a video camera, and NIH-Image is used for image processing. Special macros were written for the automation of a number of operations, such as object and marker segmentation, image reorientation, image scaling, dirt removal, and marker transfer. The so-treated image series were transferred to a workstation and were reconstructed using "Image Volumes". The reconstructs obtained from this largely automated technique exhibit a perfect alignment of the sections. The 3-D representations of the sectioned objects have a much higher degree of objectivity than those obtained by manual image orientation or by semiautomated techniques that do not use fiducials.