A light and electron microscopic study of the limb long bones perichondral ossification in the quail embryo (Coturnix coturnix japonica)

The perichondral ossification of the limb long bones in the quail embryo is investigated, in this study, by means of light and electron microscopy. Longitudinal sections of the humerus, radius, ulna, femur, tibia and fibula stained with haematoxylin-eosin were examined by the light microscope. Ultrathin cross sections were selected for the electron microscope as well. Light microscopic analysis showed that the ossification began at the same time in the long bones of the wing and leg. At the embryonic day 6, all the cartilaginous rudiments consisted of three zones. The central zone composed of hypertrophic chondrocytes, a second zone on either side of the central zone, which consisted of flattened cells and a third zone, which represented the epiphyseal region. A thin sheath of osteoid and a bi-layered perichondrium-periosteum surrounded the central zone of the cartilaginous rudiments of the long bones. The perichondrium consisted of a layer of osteoblasts, in contact with the cartilage, and a layer of fibroblasts. At the embryonic day 7, the thickness of the calcified osteoid ring increased and a vasculature appeared between the layer of osteoblasts and the layer of fibroblasts. At the embryonic day 8, a second sheath of periosteal bone began to be formed. Concurrently, vascular and perivascular elements began to invade the cartilage. The ossification spread towards the distal ends of both the diaphysis. At the electron microscopic level, the osteoblasts of the perichondium showed cytoplasmatic characteristics of cells involved in protein synthesis. The perichondral ossification is the first hallmark of the osteogenesis in the long bones. The observations reported above, are in accordance with previous studies in the chick embryo

The amniotic plaques in sheep of the Karagouniko breed

The structure of amniotic plaques and adjacent epithelium of full term ewes of the Karagouniko breed were studied using scanning electron microscopy (SEM) and light microcopy. The amniotic plaques appeared as cauliflower-like structures mainly trifurcate or as single papillae. The wall of their stems possessed numerous foldings and round openings. Of interest to note was the abundant vascularization observed in sections of the amniotic plaques. The adjacent amniotic epithelium to the plaques revealed a heterogenous surface which was composed of cells of various forms. (C) 2007 Elsevier Ltd. All rights reserved

Involvement of a Phe-Arg-b-naphthylamide sensitive efflux mechanism in the intrinsic resistance to erythromycin in Campylobacter jejuni and coli

Poster F-37, supplément CHROInvolvement of a Phe-Arg-b-naphthylamide sensitive efflux mechanism in the intrinsic resistance to erythromycin in Campylobacter jejuni and coli. 12. International Workshop on Campylobacter, Helicobacter and Related Organism

State of the art and future prospects of nanotechnologies in the field of brain-computer interfaces

Neuroprosthetic control by individuals suffering from tetraplegia has already been demonstrated using implanted microelectrode arrays over the patients’ motor cortex. Based on the state of the art of such micro & nano-scale technologies, we review current trends and future prospects for the implementation of nanotechnologies in the field of Brain-Computer Interfaces (BCIs), with brief mention of current clinical applications. Micro- and Nano-Electromechanical Systems (MEMS, NEMS) and micro-Electrocorticography now belong to the mainstay of neurophysiology, producing promising results in BCI applications, neurophysiological recordings and research. The miniaturization of recording and stimulation systems and the improvement of reliability and durability, decrease of neural tissue reactivity to implants, as well as increased fidelity of said systems are the current foci of this technology. Novel concepts have also begun to emerge such as nanoscale integrated circuits that communicate with the macroscopic environment, neuronal pattern nano-promotion, multiple biosensors that have been “wired” with piezoelectric nanomechanical resonators, or even “neural dust” consisting of 10-100μm scale independent floating low-powered sensors. Problems that such technologies have to bypass include a minimum size threshold and the increase in power to maintain a high signal-to-noise-ratio. Physiological matters such as immunological reactions, neurogloia or neuronal population loss should also be taken into consideration. Progress in scaling down of injectable interfaces to the muscles and peripheral nerves is expected to result in less invasive BCI-controlled actuators (neuroprosthetics in the micro and nano scale). The state-of-the-art of current microtechnologies demonstrate a maturing level of clinical relevance and promising results in terms of neural recording and stimulation. New MEMS and NEMS fabrication techniques and novel design and application concepts hold promise to address current problems with these technologies and lead to less invasive, longer lasting and more reliable BCI systems in the near future

3D printing in neurosurgery

Three-dimensional (3D) printing (3DP) has seen spectacular progress in recent years, making it widely available to consumers and researchers, but it has also been steadily expanding its capabilities while becoming more and more affordable. This progress has allowed 3DP technology to be seriously tested in various fields of Medicine and Biomedical Technology. Neurological Surgery is widely considered to be among the most demanding and intricate medical specialties, as it concerns fine and highly critical neural and vascular elements even during standard interventions or the most common pathological conditions. As such, advances in 3DP were quick to be applied to neurosurgical practice (depicting brain aneurysms), research and development (spine and disc models), and neurosurgical education. In the past years, we have seen progress in four main distinct directions for the use of 3DP technologies within the prism of Neurological Surgery, where we also envision future progress: (a)neurovascular physiological anatomy and its associated disorders, (b)complex central nervous system tumors and neuroanatomy, (c)spine instrumentation, deformities, and biomechanical implications, and (d)educational purposes, prototyping of implants, devices, and equipment. In this chapter, we critically review the progress of 3DP technology within each of these described directions and discuss the impact it can possibly have on specific diseases and on the Neurosurgical Specialty as a whole in the years to come. © 2022 Elsevier Inc. All rights reserved