Organogenesis of the juxta-oral organ in mice

The juxta-oral organ is a bilateral organ in the mammalian bucca. It consists of epithelial cords with surrounding mesenchyme. It develops from embryonic oral epithelium, but its macroscopic morphology in mice is less studied and seems to be very different from that of humans. The juxta-oral organ in mice extends more widely from the subcutaneous tissue of the mandible near the lateral fascia of the masseter to the submucosa of the soft palate. In this paper, we report that the mutant mouse allele Bmp7^lacZ presented intense lacZ expression in the epithelial component of the juxta-oral organ in its homo- and heterozygous states. The main aims of this study were to show that this mutant mouse allele is suitable for observing macroscopic structure of the juxta-oral organ and to describe the development of this organ during embryonic and postnatal stages. Whole-mount β-gal staining of this strain of mouse showed that the juxta-oral organ in mice appeared at E12.0 from oral epithelium and lost connection with it before E12.5. Then, the juxta-oral organ extended anteriorly to the lateral fascia of the masseter and posteriorly to the submucosal layer of the soft palate via the orbit. The mature juxta-oral organ had no connection to other epithelia such as those of the bucca and parotid duct. It persisted until adulthood and there seemed to be no tendency to regress. Transmission electron microscopy showed that each part of the juxta-oral organ was an epithelial cord surrounded by a basement membrane and mesenchymal tissue.     

Regeneration of the rat spinal cord after thoracic segmentectomy: Growth and restoration of nerve conductors

The results presented in our previous report (Morfologiya, 127, No. 2 (2005)) provided evidence that consolidation of the spinal cord (SC) after thoracic segmentectomy in rats occurs as a result of the formation of a connective tissue scar, which is quicker when the defect is filled with collagen gel. The present report describes analysis of semithin sections and transmission electron microscopy studies demonstrating that regenerating nerve conductors traverse connective tissue in structures whose organization is identical to that of peripheral nerves. In the zone of SC rarefaction caudal to the trauma site, myelination of growing axons is mediated by glial cells without the formation of nerve trunks. Large numbers of fine regenerating conductors were seen at the sites of degenerated myelin fibers in the fasciculi of the white matter in the lumbar segments of the SC. __________ Translated from Morfologiya, Vol. 129, No. 1, pp. 30–38, January–February, 2006.     

基于干细胞的器官再生研究模型-鹿茸

背景：鹿茸是惟一能够周期性再生的复杂哺乳动物器官,其再生过程是基于干细胞的存在。研究鹿茸再生机制,探索干细胞在哺乳动物器官再生中的作用对于再生生物学和再生医学研究具有重要的意义。 目的：综述鹿茸再生研究,干细胞及相关因子在鹿茸再生中的作用。 方法：应用计算机检索1994年1月至2012年10月PubMed 数据库(http://www.ncbi.nlm.nih.gov/ PubMed)。检索词为：deer antler;antler regeneration; stem cell,并限定文章语言种类为English。此外还手动查阅相关专著数部。纳入文章所述内容涉及鹿茸再生的组织学、形态学、鹿茸干细胞与微环境研究、相关细胞因子。排除重复研究和纳入标准无关的文章。 结果与结论：共检索文献87篇,最终纳入文献36篇。决定鹿茸发生及再生的关键组织分别为生茸区骨膜和角柄骨膜,这两种组织中的细胞被定义为鹿茸干细胞。鹿茸干细胞上覆盖的皮肤组织构成了这些干细胞活动所需的特定微环境。多种细胞因子如胰岛素样生长因子、性激素、人表皮生长因子、血管内皮生长因子等参与了鹿茸再生及快速生长调控。探索鹿茸干细胞微环境内各组分间相互作用所需的信号因子、阐明其调控机制,对于揭示解鹿茸再生之谜,对了解干细胞在哺乳动物器官再生的作用具有十分重要的意义。     

Si(3)N(4)-bioglass composites stimulate the proliferation of MG63 osteoblast-like cells and support the osteogenic differentiation of human bone marrow cells

The in vitro osteocompatibility of a novel Si₃N₄-bioglass composite (70–30% weight proportion) with improved mechanical properties (fracture TOUGHNESS=4.4 MPa m^1/2; bending STRENGTH=383±47 MPa) is reported. Immersion of the composite samples in culture medium (30 min to 7 days) resulted in rapid protein adsorption to the surface and, also, dissolution of the intergranular phase of bioglass (time-dependent process) with the formation of different size cavities. “As-received” and pre-treated material samples presented a similar behaviour concerning the proliferation of MG63 osteoblast-like cells, evaluated during a 5-day culture period. Seeded materials showed a higher cell growth rate as compared to cultures performed on the standard plastic culture plates. To assess the osteogenic potential of the composite, “as-received” material samples were seeded with human bone marrow cells and cultured for 35 days in experimental conditions that favour the development of the osteoblastic phenotype. The cell adhesion process was similar to that observed in control cultures. Cells successfully adapted to the irregularities of the surface and were able to grow towards inside the cavities; in addition, osteogenic differentiation occurred with the formation of abundant cell-mediated mineralised deposits. Results suggest that this Si₃N₄-bioglass composite seems to be a promising candidate for high-stress medical applications.     

Correlative Light Optical, Scanning Electron, and Transmission Electron Microscopy of Skeletal Muscle in Muscular Dystrophy and Muscular Atrophy: A Pilot Study

Biopsies of skeletal muscle from three different cases of muscular dystrophy and one case of spinal muscular atrophy that had been fixed with Karnovsky's fluid were either routinely prepared for scanning electron microscopy (SEM) or were frozen to-20°C and sectioned on a steel knife in a cryostat at 5-10 μm. The sections were coverslipped and examined using a light microscope equipped with polarizing optics (Pol). After areas were selected, the sections were prepared for SEM and thereby examined. The tissues on the slides that had been observed with light microscopy (LM) and SEM were prepared further for transmission electron microscopy (TEM) by infiltrating them with Epon and cutting sections at approximately 100 nm on an ultramicrotome. It is shown that the stage of contraction in one pathologic myofiber may vary along its length. The following advantages may be realized by using correlative (Pol → SEM → TEM) microscopy on skeletal muscle biopsies: 1) lesions can be differentiated from “normal” surrounding tissue; 2) doubtful structures can be reexamined with the SEM and TEM; and 3) the SEM image of different states of muscle contraction can be reinterpreted in the light of the Pol or TEM image.     

A method of paraffin impregnation and its use in morphologic studies of organs

The authors present a method of paraffin infiltration applied to heart specimens. They describe the dissection, trimming and fixation of the specimen which is followed by common tissue dehydration and infiltration by paraffin wax. Thus preserved permanent specimen allows both retaining the entire organ and visualizing its particular structures.     

The anatomical basis for a novel classification of osteoarthritis and allied disorders

Osteoarthritis (OA) has historically been classified as ‘primary’ where no discernible cause was evident and ‘secondary’ where a triggering factor was apparent. Irrespective of the triggering events, late‐stage OA is usually characterized by articular cartilage attrition and consequently the anatomical basis for disease has been viewed in terms of cartilage. However, the widespread application of magnetic resonance imaging in early OA has confirmed several different anatomical abnormalities within diseased joints. A key observation has been that several types of primary or idiopathic OA show ligament‐related pathology at the time of clinical presentation, so these categories of disease are no longer idiopathic – at least from the anatomical perspective. There is also ample evidence for OA initiation in other structures including menisci and bones in addition to articular cartilage. Therefore, a new classification for OA is proposed, which is based on the anatomical sites of earliest discernible joint structural involvement. The major proposed subgroups within this classification are ligament‐, cartilage‐, bone‐, meniscal‐ and synovial‐related, in addition to disease that is mixed pattern or multifocal in origin. We show how such a structural classification for OA provides a useful reference framework for staging the magnitude of disease. For late‐stage or end‐stage/whole organ disease, the final common pathway of these different scenarios, joint replacement strategies are likely to remain the only viable option. However, for younger subjects in particular, near the time of clinical disease onset, this scheme has implications for therapy targeted to specific anatomical locations. Thus, in the same way that tumours can be classified and staged according to their tissue of origin and extent of involvement, OA can likewise be anatomically classified and staged. This has implications for therapeutic strategies including regenerative medicine therapy development.     

Morphological Studies of the Pineal Gland in the Common Gull (Larus canus) Reveal Uncommon Features of Pinealocytes

The avian pineal is a directly photosensory organ taking part in the organization of the circadian and seasonal rhythms. It plays an important role in regulation of many behavior and physiological phenomena including migration. The aim of the study was to investigate morphology of the pineal organ in the common gull (Larus canus). The light and electron microscopic studies were performed on the pineals of juvenile birds living in natural conditions of the Baltic Sea coast, which have been untreatably injured during strong storms in autumn and qualified for euthanasia. The investigated pineals consisted of a wide, triangular, superficially localized distal part and a narrow, elongated proximal part, attached via the choroid plexus to the intercommissural region of the diencephalon. The accessory pineal tissue was localized caudally to the choroid plexus. Based on the histological criteria, the organ was classified as the solid‐follicular type. Two types of cells of fotoreceptory line were distinguished: rudimentary–receptor pinealocytes and secretory pinealocytes. Both types of cells were characterized by unusual features, which have been not previously described in avian pinealocytes: the presence of paracrystalline structures in the basal processes and their endings, the storage of glycogen in the form of large accumulations and the arrangement of mitochondria in clusters. Further studies on other species of wild water birds dwelling in condition of cold seas are necessary to explain if the described features of pinealocytes are specific for genus Larus, family Laridae or a larger group of water birds living in similar environmental conditions. Anat Rec, 2012. © 2012 Wiley Periodicals, Inc.     

Partial characterization of serotonin N - acetyltransferases from northern pike (Esox lucius,L. pineal organ and retina: effects of temperature

In vertebrates, the nocturnal rise in pineal organ and retinal melatonin synthesis results from the increase in the activity of the serotonin N-acetyltransferase (NAT), a cAMP-dependent enzyme. In the fish pineal organ in culture, light and temperature act in a similar manner on cAMP content and NAT activity. It is not known whether the effects of temperature are mediated through cAMP or through modifications of NAT kinetics. The present study was designed: (1) to find out whether NAT activity from pineal organ homogenates is similar to NAT activity from pineal organs in culture, with regard to variations in temperature, and (2) to compare NAT activity from the pineal organ and the retina. Pineal organ and retinal NAT activity increased linearly with protein concentrations. Higher activities were obtained with 0.2 mol/l of phosphate buffer, pH 6. Higher molarity or a higher pH induced a decrease in retinal and pineal organ NAT activity: retinal NAT was more sensitive than pineal organ NAT to changes in molarity, whereas the opposite held true as far as pH was concerned. Pineal organ and retinal NAT obeyed the Michaelis-Menten equation with respect to increasing concentrations of acetyl-coenzyme A. With increasing concentrations of tryptamine: (1) pineal organ NAT activity increased in a manner suggesting positive co-operativity, (2) retinal NAT displayed, after an initial increase, inhibition by substrate. The kinetics of the reactions were temperature dependent. Maximal activities were reached at 18/20 °C in the pineal organ and at 37 °C in the retina. The present study is the first to describe the optimum conditions for the assay of NAT activity in homogenates from the retina of fish and from the pineal organ of poikilotherms, and also the first to compare some characteristics of NAT activity from these two analogous organs. Our results suggest that the effects of temperature on melatonin production are mediated, at least in part, through modifications of NAT kinetics. Future studies will aim to clarify whether the activities measured in the pineal organ and retinal homogenates reflect the presence of one or of several enzymes. Received: 11 September 1995/Received after revision: 19 November 1995/Accepted: 17 January 1996     

Recruitment of dendritic cells to pathological niches in inflamed liver

The liver is a specialized organ for host defense and immunity. Recruitment of dendritic cells (DCs) is crucial to host defense in a granulomatous liver disease in mice. In response to danger signals, DC precursors are mobilized de novo into the circulation. Myeloid DC (mDC) precursors are recruited to perisinusoidal spaces and activated to form granulomas. Recruited mDCs subsequently extravasate into Disse’s space and migrate to the portal area to induce portal tract-associated lymphoid tissue (PALT). Some mDCs are remobilized into draining hepatic lymph nodes (LNs) to prime antigen-specific CD4⁺ helper T cells. Kupffer cell-derived CCL3/MIP-1α attracts mDC precursors to the sinusoidal granulomas, whereas PALT composed cell-derived CCL21/SLC attracts activated mDCs to the T-cell zone of PALT. Inflammatory cytokines modulate this sinusoid-portal migration through IL-1R/TLR signaling. Recruited mDCs themselves also produce several chemokines and cytokines that modulate T-cell responses. A unique trafficking of circulating mDC precursors within the inflammation-associated, newly formed compartments (“pathological niches”) is strictly regulated by both homeostatic and inducible chemokines and determines the final efficiency of the immunity in this organ.     

The ependyma on the pineal of the Guinea pig (Cavia cobaya). A scanning electron microscopic investigation

Summary The proximal part of the epiphysis cerebri of the guinea pig is in close contact with the cerebrospinal fluid of the third ventricle. A direct contact is not present as the pineal tissue is covered by a continuous ependymal layer. Two types of ependymal cells with different surface protrusions are discussed as being involved in possible interactions between the neuroendocrine tissue of the pineal organ and the cerebrospinal fluid. In addition, two different types of supraependymal structures are found on the ependymal surface of the habenulae and the wall of the third ventricle. Because of their morphological characteristics, these supraependymal structures are thought to be neural elements.Supported by a grant of the Deutsche Forschungsgemeinschaft (vo 135/4) within the Schwerpunktprogramm Neuroendokrinologie.I am grateful to Frau Untiedt-Roth for technical assistance.     

Diagnostic Electron Microscopy on Reembedded (“Popped Off”) Areas of Large Spun* Epoxy Sections

A technique is described in which areas of large Spurr epoxy thick sections are directly popped off of glass slides by inverted Beem capsules filled with polymerized plastic. This technique allows the survey of large regions of tissue with the maintenance of tissue relationships and the selection of specific areas for electron microscopic studies. Within the context of diagnostic electron microscopy well-preserved and representative portions of tissues can be selected as well as individual diagnostic cells or other difficult to find structures. Many small pieces of minced, optimally fixed and processed tissue can also be surveyed by this technique. Thus, one can screen the equivalent of 20 or more standard thick sections in one step. This “pop-off” technique does not appear to alter the ultra-structure of the tissue in any way.     

Age-dependent covalent DNA alterations (I-compounds) in rodent tissues: species,tissue and sex specificities

I-compounds are non-polar covalent DNA modifications of as yet undetermined structure that tend to accumulate in an age-dependent manner in tissues of untreated animals. They are detectable by ³²-P-postlabeling assay because of their adduct-like properties and chromatographically resemble DNA nucleotides containing bulky/hydrophobic moieties. To determine which factors may be involved in their formation, I-compounds were examined by ³²-P-postlabeling in liver and kidney DNA of female and male Srague-Dawley rats and Syrian hamsters of different ages (1,4 and 10 months and 1, 2.5 and 9.5 months, respectively). The following results were obtained: (i) Every tissue DNA studied contained characteristics I-compounds. (ii) Patterns and amounts of I-compounds were reproducible among animals of the same kind. (iii) There were pronounced organ and species differences. (iv) I-comound patterns were sex-dependent. (v) I-compound levels increased with age in all tissues studied, except in male hamster kidney, a target organ of estrogen-induced carcinogenesis. The highest levels were observed in liver and kidney of 10-month-old female rats. (vi) The rise of I-compound levels was less steep during the late part of the observation period for female but not male animals. (vii) Gonadectomy decreased I-compound levels in female hamster kidney DNA, while causing a slight increase in male animals later in life. These I-compounds after prolonged estrogen treatment. Points, iv, vi and vii strongly implicated sex hormones in I-compound formation. The qualitative effects of species, tissue differentiation, gender and sex hormones on these DNA modifications support the hypothesis that I-compounds are formed by the binding of endogenous electrophiles to DNA. As persistent DNA alterations, they are likely to affect DNA replication and to play a role in spontaneous and chemically induced carcinogenesis and in aging.     

Reforming the coroner and death certification service

The intention of the Home Office is to introduce a new system that combines an independent check on all deaths and a professional oversight of death patterns, with, for the majority of cases, the minimum of bureaucracy. No public consultation is intended, so that reforms are not delayed. However as the proposals are developed in the coming months, the details, practicalities and costs will be discussed “with relevant professionals (not defined) and those with experience of the existing arrangements”. The imperfections of the present system are outlined. It is hoped the medical profession will have an input, since statements such as “ ‘hospital post mortems’, which are for medical research and public health protection purposes” need amendment. There should be a change in perception of the audit value of this procedure to BOTH the family and the treating doctor. Unfortunately it is proposed the new system in total should cost no more than at present. “Professionals” (not defined) will be involved in the financial detail.All deaths, after verification and certification of the medical cause of death (if known) would then be referred to the ‘medical examiner’ based in the coroner's office. He/she would be a qualified doctor employed by the new coroner service and independent of the Health Service. The medical examiner could provide supplementary advice on medical matters required by the coroner. “Retention of tissue should only take place where absolutely necessary and the coroner and his or her other staff should take account of the needs of families and friends carefully throughout the process.” “Coroners could take advice from their medical examiner to ascertain and prescribe the minimum level of invasiveness to establish the cause of death.” This issue is far from resolved, as signified by a recent call from the DoH giving a grant to study the value of MRI versus a full post mortem. No thought is given to systemic diseases, which may present in one organ system or another disease process, other than that causing death. Medical examiners will have to keep abreast of current developments in medicine BUT will be outside the NHS, which could cause problems. Medical examiners will be appointed (with an input from Regional Directors of Public Health) and managed from within the coroner service. They would work closely with the registrar of births and deaths.Deaths from unnatural causes or when the medical cause of death is unknown will result in judicial inquests. The medical examiner will have an input into causes of death and relevant investigations.Details of the proposed structure of the system are given, as well as the investigative and other roles of Coroner's officers.The establishment of medico-legal centres, as “examples of good practice” is advocated. The drawbacks of this system are stressed in this paper. There is at present an on-going review of forensic pathology services and it is hoped thought will be given to the increasing trend for sub-specialisation in medicine.     

State-of-the-Art computed tomography of primate skulls — Comparison of different scan-protocols

To evaluate the image quality of different scanprotocols on 3 different CT-scanners for data acquisition of skulls of apes and monkeys with special respect on imaging the paranasal sinuses, we compared CT image quality in 452 skulls on either the Philips “Mx8000” Multi-Slice CT, the “Aura” Spiral CT or the “TomoscanM” CT scanner. Therefore, we used sequential and volume scanning as well as different slice thickness, table feed, voltage and X-ray current intensity. Representative axial scans of the anonymized studies as well as three-dimensional reconstructions were independently analyzed by an experienced radiologist and an anthropologist, using a study protocol covering relevant anatomical findings. Low-Dose protocols at 40 mAs demonstrated an equal diagnostic value with better CT-performance due to lower overheatening of the X-ray tube in all studies. Resolution, especially in small anatomical structures, was best with multi-slice CT. On both single-slice scanners resolution was significantly better with sequential-protocols (slice 2–5 mm; feed 1:1) than with volume-protocols. Volume scans are required for 3D-reconstruction. Best 3D results were achieved with “Mx8000” due to its better spatial resolution, followed by the “Aura” scanner. Multi-slice CT (MSCT) was found to be the superior method for the radiographic evaluation of small anatomical structures. However, there is no significant loss of information with thin sequential scans in LD technique on a single-slice spiral CT scanner. Volume-data aquisition is required for 3D reconstruction.