Meninges comprise three distinct layers, the dura mater, arachnoid, and pia mater that surround the brain, spinal cord and some parts of the nerves. Traditionally the meninges were believed to serve only as protection for tissues that they encase. However recent work shows they have other important functions related to development and regulation of the nervous system. Given the importance of the meninges, it is surprising that we know very little about their development. The embryological origin of the meninges has been debated for over a hundred years. Some studies imply that the meninges develop from the neural crest, while others suggest that they come from the somites. Here, we investigated the temporal development of meninges in birds and mice and found they form at comparable stages. We investigated the origin of avian spinal meninges using chick/quail cell tracing protocols and found they do not develop from the somites as previously thought. We propose that meningeal epithelial blood vessels may have been mistaken as meninges and led to an erroneous conclusion by previous investigators. We present data that show that avian spinal meninges originated from the neural crest supported by data demonstrating that they express the neural crest marker HNK1. Finally using the Wnt1-Cre mouse we show that trunk meninges of mammals also originate from neural crest.

Despite significant advances in tissue engineering such as the use of scaffolds, bioreactors and pluripotent stem cells, effective cardiac tissue engineering for therapeutic purposes has remained a largely intractable challenge. For this area to capitalise on such advances, a novel approach may be to unravel the physiological mechanisms underlying the development of tissues that exhibit rhythmic contraction yet do not originate from the cardiac lineage. Considerable attention has been focused on the physiology of the avian lymph heart, a discrete organ with skeletal muscle origins yet which displays pacemaker properties normally only found in the heart. A functional lymph heart is essential for avian survival and growth in ovo. The histological nature of the lymph heart is similar to skeletal muscle although molecular and bioelectrical characterisation during development to assess mechanisms that contribute towards lymph heart contractile rhythmicity have not been undertaken. A better understanding of these processes may provide exploitable insights for therapeutic rhythmically contractile tissue engineering approaches in this area of significant unmet clinical need. Here, using molecular and electrophysiological approaches, we describe the molecular development of the lymph heart to understand how this skeletal muscle becomes fully functional during discrete in ovo stages of development. Our results show that the lymph heart does not follow the normal transitional programme of myogenesis as documented in most skeletal muscle, but instead develops through a concurrent programme of precursor expansion, commitment to myogenesis and functional differentiation which offers a mechanistic explanation for its rapid development. Extracellular electrophysiological field potential recordings revealed that the peak-to-peak amplitude of electrically evoked local field potentials elicited from isolated lymph heart were significantly reduced by treatment with carbachol; an effect that could be fully reversed by atropine. Moreover, nifedipine and cyclopiazonic acid both significantly reduced peak-to-peak local field potential amplitude. Optical recordings of lymph heart showed that the organ’s rhythmicity can be blocked by the HCN channel blocker, ZD7288; an effect also associated with a significant reduction in peak-to-peak local field potential amplitude. Additionally, we also show that isoforms of HCN channels are expressed in avian lymph heart. These results demonstrate that cholinergic signalling and L-type Ca2+ channels are important in excitation and contraction coupling, while HCN channels contribute to maintenance of lymph heart rhythmicity.

Background: Evaluating the clinical competencies of radiologist and technologist is the primary important factor in all medical imaging areas, and it is a necessary prerequisite for assuring professional standard care in radiography. Aim: to evaluate clinical competences from the views of radiologists and technologists by applying the Radiographers" Competence Scale (RCS). Method: A cross-sectional survey conducted on 185 participants recruited from six hospitals of Asir region of Saudi Arabia. All data were collected using the self-administrative questionnaire of 28 items scale of radiographer competence scale consisting of the two components; initial care scale and technical radiographic process. The level of competencies scale was rated through 10point and frequency of use on 6point scale. Results: The survey completed by 82 (44.3%) radiologist and 103 (55.7%) technologist. Overall mean significant (P < 0.001) differences scores of Initial Care scale observed between radiologist and technologist. However, with reference to technical and radiographic process no mean significant differences were detected between the two groups. The technologist attributed the highest evaluations to such competencies as "Adequately informing the patient" and "Guiding the patient's relatives", while other attributes the lowest evaluations expressed in the competencies. The radiologists attributed the highest evaluations to such competences as "Collaborating with physicians "and "Independent carrying out of the doctor"s prescriptions", while the lowest evaluations to the same competences as the technologists. Conclusion: The significant findings underline the radiologist and high technologist competences in both "Initial Care scale "and "Technical and Radiographic Process". However, the lower rated competences emphasis on continuous professional development in the area of medical radiology.