The role of nitric oxide in the apoptosis of neurons in the retina of the human fetal eye

The locations of NADPH-diaphorase (NADPH-d), inducible NO synthase (iNOS), and TUNEL-immunoreactive neurons in the retina of human fetuses collected during the first to third trimesters of pregnancy were studied. High levels of NADPH-d activity were seen in the inner segments of light-sensitive cells, amacrine cells, and ganglion cells. The population of NADPH-d-positive amacrine cells included three types of neuron. Type 1 neurons were large and had sparse dendritic fields occupying the inner nuclear and outer retinal layers. Small type 2 neurons were located in the inner retinal layer. Ectopic amacrine cells, type 3, were located in the outer part of the ganglion layer. A high density of NADPH-d-positive neurons was seen in the central part of the retina, surrounding the central fovea and optic disk area. NADPH-d activity increased progressively during ontogenesis and correlated with the appearance of immunoreactive iNOS in neurons. iNOS labeled a subpopulation of amacrine and ganglion cells, which appeared at 20–21 weeks of development and reached a peak of immunoreactivity by the end of the third trimester. TUNEL-immunopositive neuron nuclei with signs of apoptotic destruction were seen at 30–31 weeks of pregnancy. The greatest apoptotic index was seen in the ganglion and amacrine cell populations. These data identify NO as a factor mediating apoptosis of neurons during the critical period of differentiation of interneuronal connections in the human retina. Director: Doctor of Biological Sciences M. A. Vashchenko Director: Doctor of Biological Sciences S. L. Kondrashov __________ Translated from Morfologiya, Vol. 129, No. 1, pp. 42–49, January–February, 2006.     

Interepithelial cells of the oral mucosa in mice

Summary Non-epithelial mesenchymal and neuroectodermal cells occur between the keratinocytes in the stratified squamous epithelium of the oral mucosa. These cells cannot be classified adequately by light microscopy. In the present study the oral mucosa of the lip, cheek and tongue of 50 mice were studied by light and electron microscopy. 3,025 mononuclear interepithelial cells were documented and analysed.Monocytogenic macrophages, plasma cells and mast cells were not found interepithelially and cannot be regarded as a regular constituent of the epithelium. Only a few neuroectodermal cells — in mice these are exclusively Merkel cells, with no melanocytes — were localized in the epithelium. The majority of the interepithelial cell population is made up of lymphocytes (22.8%) and Langerhans cells (56.8%). They are an integral constituent of the epithelium. Lymphocytes with rounded and indented nuclei can be identified. The larger and dendritic Langerhans cells are a specific cell of squamous epithelium and also occur in the oral mucosa. Not all cells which feature the cytological characteristics of Langerhans cells contain Langerhans or Birbeck granules. Accordingly these granules cannot be considered an exclusive identification characteristic. Two types of Langerhans cells can be differentiated. 80.9% have the more or less typical appearance known from the epidermis and were termed macrophagocytoid Langerhans cells. The nuclei are irregularly indented and moderately heterochromatic. 19.1% possessed conspicuous large, spherical, euchromatic nuclei and an electron-lucent cytoplasm. These were termed reticuloid Langerhans cells. About 20% of the interepithelial cell population could not be identified, neither as typical lymphocytes nor as Langerhans cells. These were small to medium sized cells with deeply indented cerebriform strongly heterochromatic nuclei. They are similar to the Sézary cells or mycosis fungoides cells of epidermotropic human T-cell lymphomas. The lymphocytic nature of these cells has been confirmed. It seems likely that differentiation of lymphocytes to cerebriform cells occurs within the epithelium. It is further discussed whether cerebriform cells are precursors of Langerhans cells, a conclusion suggested morphologically by transitional forms. This would imply that Langerhans cells originate from lymphocytes, and that the cerebriform cell is an intermediate step of differentiation. The microenvironment of the squamous epithelium may play a role in the process of differentiation, which could explain the epitheliotropy of lymphocytes. The possibility is considered that Langerhans cells and interdigitating reticulum cells of the T-cell area of lymph nodes are identical. The close functional cooperation of Langerhans cells, lymphocytes, and interdigitating reticulum cells in immunological defenses against external antigens is discussed.The authors wish to express their sincere appreciation to Miss P. Starck and Miss I. Brandt for invaluable technical assistance in this project.     

Morphology and function of the cecum in experimental escherichiosis

Laboratory of Infectious Pathology, Research Institute of Human Morphology, Russian Academy of Medical Sciences, Moscow. (Presented by Academician of the Russian Academy of Medical Sciences N. K. Permyakov.) Translated from Byulleten' Éksperimental'noi Biologii i Meditsiny, Vol. 114, No. 10, pp. 442–444, October, 1992.     

Distribution of the A3 subunit of the cyclic nucleotide-gated ion channels in the main olfactory bulb of the rat

Previous data suggest that cyclic GMP (cGMP) signaling can play key roles in the circuitry of the olfactory bulb (OB). Therefore, the expression of cGMP-selective subunits of the cyclic nucleotide-gated ion channels (CNGs) can be expected in this brain region. In the present study, we demonstrate a widespread expression of the cGMP-selective A3 subunit of the cyclic nucleotide-gated ion channels (CNGA3) in the rat OB. CNGA3 appears in principal cells, including mitral cells and internal, medium and external tufted cells. Moreover, it appears in two populations of interneurons, including a subset of periglomerular cells and a group of deep short-axon cells. In addition to neurons, CNGA3-immunoreactivity is found in the ensheathing glia of the olfactory nerve. Finally, an abundant population of CNGA3-containing cells with fusiform morphology and radial processes is found in the inframitral layers. These cells express doublecortin and have a morphology similar to that of the undifferentiated cells that leave the rostral migratory stream and migrate radially through the layers of the OB. Altogether, our results suggest that CNGA3 can play important and different roles in the OB. Channels composed of this subunit can be involved in the processing of the olfactory information taking place in the bulbar circuitry. Moreover, they can be involved in the function of the ensheathing glia and in the radial migration of immature cells through the bulbar layers.     

干细胞研究进展

干细胞研究已成为生命科学中的热点,本文综述了近年来的有关研究,从以下五个方面介绍了干细胞研究取得的重要进展:(1)干细胞的基本概念,包括定义和分类;(2)小鼠胚胎干细胞、人胚胎干细胞的分离、培养及其特征;(3)骨髓干细胞的表面标志特征等;(4)干细胞向特异组织细胞(如心肌细胞、肝细胞、神经细胞等)分化诱导研究;(5)干细胞在治疗心脏疾病、肝脏疾病、神经系统疾病、糖尿病、角膜疾病等方面取得的研究成果。     

Changes in the number of antibody-forming and stem cells in the spleen of unilaterally nephrectomized mice

A suspension of spleen cells from intact and unilaterally nephrectomized mice, obtained in the latter case 19–21 h after the operation, was injected into lethally irradiated (CBA×C57BL/6) F₁ mice 24 h after irradiation. On the 8th day after injection of the cells the number of colony-forming and plaque-forming cells in the spleen of the irradiated recipients was determined. To determine the number of plaque-forming cells, a mixture of spleen cells and sheep's red cells was injected into the irradiated recipients. The number of colonies in the recipients' spleen 19–21 h after the operation either was unchanged or was significantly reduced. Stimulation of the production of antibody-forming cells was observed at these same times, and it coincided in time with the period of manifestation of the ability of the splenic lymphoid cells of the unilaterally nephrectomized mice to induce proliferation in the kidney of the intact recipients.Laboratory of Experimental Genetics, Institute of Medical Genetics, Academy of Medical Sciences of the USSR. Laboratory of Growth and Development, Institute of Human Morphology, Academy of Medical Sciences of the USSR, Moscow. (Presented by Academician of the Academy of Medical Sciences of the USSR, N. A. Fedorov.) Translated from Byulleten' Éksperimental'noi Biologii i Meditsiny, Vol. 78, No. 9, pp. 69–72, September, 1974.     

Ultrastructure of the glomus cells in the carotid body of chronically hypoxic rats: With special reference to the similarity of amphibian glomus cells

The ultrastructural characteristics of the glomus cells in the rat carotid body exposed to extremely long-term hypoxia (10–12 weeks) were investigated. The glomus cells could be classified into four distinct types according to the shape of dense-cored vesicles in the glomus cell cytoplasm: (1) small vesicle cells (SVCs, 50 nm in mean diameter), (2) large vesicle cells (LVCs, 80 nm in mean diameter), (3) dilated eccentric vesicle cells (EVCs, 400–800 nm in diameter), and (4) mixed vesicle cells (MVCs, large and eccentric vesicles). Many clusters of glomus cells were found to contain all four categories of cell types. The appearance of EVCs was a unique and common characteristic of glomus cells in this long-term hypoxia model. We also noted other ultrastructural features with chronic hypoxia which are characteristic of the amphibian carotid labyrinth glomus cells: (1) incomplete covering of glomus cells with the supporting cell missing over a wide area, (2) long thin cytoplasmic projections in the intervascular stroma, and (3) intimate apposition of the glomus cells and pericytes (g-p connection), endothelial cells (g-e connection), plasma cells, and fibrocytes. Because arterial PO₂ is generally low in amphibia, these may be general features of hypoxic adaptation and facilitate both uptake of oxygen from blood and release of catecholamine into the blood. The g-p and g-e connections may take part in the regulation of the microcirculation in the enlarged carotid body. © 1993 Wiley-Liss Inc.     

Influences of the pia mater on the precursors of nerve cells

Summary In the developing cerebellum of 8-day old rats surgical lesions were made. During regeneration of the cerebellum the pia mater was found to penetrate inside the neural tissue. Partially differentiated Purkinje cells and granule cells, that were in close contact with the pial cells, were found atrophied. When the profilerative cells of external granular layer came into contact with the pial cells, they were reduced to a primitive type of epitheloid cells. In this instance epithelio-mesenchymal interaction was found deleterious to the precursors of neurons. However, when the epithelioid cells were freed from the contact with the pial cells by intervening basement membrane, they differentiated into ependymal cells. Such ependymal cells gave rise to small as well as large new ventriculer structures, and structures resembling chorioid plexus.This research was supported by NIH Research Grant NS08817-03. Acknowledgements are due to Sheila Anderson for histology and to Donna Whitehurst for photographic work.     

Roles of lymphoid cells in the differentiation of Langerhans dendritic cells in mice

Langerhans dendritic cells are antigen presenting cells (APC) that reside within the epidermis and are capable of stimulating naive T cells. Reciprocally, lymphocytes may play a role in Langerhans cells (LC) differentiation. Our results show that the differentiation of skin LC is unaffected in the absence of lymphocytes and/or signaling through the common cytokine receptor gamma chain (gammac) required for IL-2, IL-4, IL-7, IL-9, IL-15 and IL-21 signaling. Migration of LC and other dendritic cells (DC) from the skin to the draining lymph nodes (LNs) after FITC skin sensitization, is unaffected in the absence of lymphocytes or CD40. FITC+ LC/DC sorted from the LNs of lymphoid deficient or control mice stimulated naive T cells with similar efficiency. However, while the absence of lymphocytes did not appear to affect the phenotype or number of emigrating LN DC/LC, their persistence in the LN appears to depend on alphabeta T cells. Thus, DC are strikingly reduced in numbers in the peripheral LNs of T-cell deficient mice. Finally, CD8alpha expression on skin emigrants was low and dependent on the presence of CD8+ lymphocytes, while spleen CD8+ DC were present in the absence of lymphocytes. We conclude that the presence of T cells is not required for the differentiation and migration of resident skin DC but is critical for the maintenance of DC and LC migrating into the LNs.     

Complexity of dendritic cell subsets and their function in the host immune system

Dendritic cells (DCs) are professional antigen-presenting cells that are critical for induction of adaptive immunity and tolerance. Traditionally DCs have been divided into two discrete subtypes, which comprise conventional and non-conventional DCs. They are distributed across various organs in the body and comprise a heterogeneous population, which has been shown to display differences in terms of surface marker expression, function and origins. Recent studies have shed new light on the process of DC differentiation and distribution of DC subtypes in various organs. Although monocytes, macrophages and DCs share a common macrophage-DC progenitor, a common DC progenitor population has been identified that exclusively gives rise to DCs and not monocytes or macrophages. In this review, we discuss the recent advances in our understanding of DC differentiation and subtypes and provide a comprehensive overview of various DC subtypes with emphasis on their function and origins. Furthermore, in light of recent developments in the field of DC biology, we classify DCs based on the precursor populations from which the various DC subsets originate. We classify DCs derived from common DC progenitor and pre-DC populations as conventional DCs, which includes both migratory and lymphoid-resident DC subsets and classify monocyte-derived DCs and plasmacytoid DCs as non-conventional DCs.     

Role of radial glia in cytogenesis, patterning and boundary formation in the developing spinal cord

Radial glial fibres provide a transient scaffold and impose constraints in the developing central nervous system (CNS) that facilitate cell migration and axon growth. Recent reports have raised doubts about the distinction between radial glia and precursor cells by demonstrating that radial glia are themselves neuronal progenitor cells in the developing cortex, indicating a dual role for radial glia in both neurogenesis and migration guidance. Radial glia shift toward exclusive generation of astrocytes after neurogenesis has ceased. Radial progenitor cell differentiation and lineage relationships in CNS development are complex processes depending on genetic programming, cell-cell interaction and microenvironmental factors. In the spinal cord, radial cells that arise directly from the neuroepithelium have been identified. At least in the spinal cord, these radial cells appear to be the precursors to radial glia. It remains unknown whether radial glial cells or their precursors, the radial cells, or both can give rise to neurons in the spinal cord. Radial glial cells are also important in regulating the axon out-growth and pathfinding processes that occur during white matter patterning of the developing spinal cord.     

Role of normal adherent cells in the regulation of the autologous mixed lymphocyte reactions in humans

The effect of normal adherent suppressor cells on the blastogenesis of human T lymphocytes in the mixed lymphocyte reaction (MLR) was studied in both allogeneic and autologous combinations. Non-T cells and Ia⁺ T lymphocytes were used as stimulator cells in both allogeneic and autologous MLR. The addition of adherent cells to the stimulators inhibited blastogenesis of T lymphocytes in both types of MLR when the stimulator population was made up of non-T lymphocytes but did not interfere with blastogenesis when Ia⁺ T lymphocytes were used as stimulator cells. The present data indicate that the T lymphocytes able to respond to Ia⁺ T cells (in the MLR, autologous or allogeneic) may be different from those which respond to non-T lymphocytes or may be less sensitive to the regulatory function of normal adherent cells.     

脐带血来源的树突细胞增强LAK细胞的增殖和杀伤活性

目的探讨脐带血来源的树突细胞(CBDC)在体外对LAK(lymphokine activated killer)细胞增殖活性和杀伤活性的影响。方法采用GM-CSF和IL-4联合刺激诱导脐带血单个核细胞分化为CBDC,再将CBDC与同源LAK细胞混合培养,用MTT法测定不同细胞密度的CBDC刺激LAK细胞增殖和杀伤的能力。结果体外诱导出形态典型的CBDC,其具有明显刺激LAK细胞增殖的能力。LAK细胞的增殖和杀伤活性在2种细胞混合比为1∶10时最强。结论CBDC能增强LAK的增殖活性和杀伤活性。     

诱导多能干细胞的研究进展

人类组织工程的最终目的 是细胞在体外生长、分化为功能组织和器官以替代、修复、维持或者增强受损组织和器官功能.胚胎干细胞由于具有体外无限扩增的能力以及分化为机体各种类型细胞的潜能而成为组织工程中首选的细胞来源.主要就应用不同转录因子Oct3/4、Sox2、c-myc、Klf4、Nanog和LIN28经逆病毒导入未经遗传修改的成纤维细胞,从而使该类细胞去分化与重编程成具有分化为其它各种类型细胞的多能干细胞的研究进展作一综述.     

孕中期羊水中细胞研究进展

孕中期羊水中细胞培养和核型鉴定广泛应用于产前诊断领域,可以发现一系列胎儿发育异常。近来,许多研究表明羊水中含有胎儿的干细胞,这些细胞能否应用于干细胞和组织工程学领域成为研究热点。综述了羊水中细胞的组成、来源、生物学特性、干细胞特性及组织工程学应用等方面的内容,并对研究前景进行展望。     

Functional implication of autophagy in steroid-secreting cells of the rat

Background: Autophagy, while frequently observed in embryonic cells undergoing differentiation and in pathologically altered cells, appears to occur less commonly in normal, fully differentiated cells. Our previous work revealed that the frequency of autophagic activity was rather high in the Leydig cells of rat testes, but the functional significance of autophagy in Leydig cells remains obscure. The purpose of the present study is to investigate the possible role of autophagy in steroid-secreting cells. Methods: The autophagic activity was investigated in two steroid-secreting cells, e.g., Leydig cells and adrenocortical fasciculata cells of rats. Cytidine monophosphatase (CMPase) cytochemistry was utilized to show the activity of lysosomal enzymes in autophagosomes. Electron microscopic morphometry was employed to analyze the frequencies of autophgy in the cells of the rats intact or treated with related hormones resulting in a hyper- or hypo-secretion of testosterone and corticosterone. Results: Autophagy took place in normal steroid-secreting cells with higher frequencies than in many other cells including the tubular cells of kidney and hepatocytes. The large number of autophagosomes or autophagic vacuoles allowed to outline the autophagic process in these cells. The C-shaped double-membrane profiles tending to demacate a portion of cytoplasm were referred to as pre-autophagosomes. So called early autophagosomes were the vacuoles enclosed completely by double delimiting membranes, containing normal-looking cellular components. The majority of sequestered organelles appeared to be mitochondria and smooth endoplasmic reticulum. The autophagosomes starting digestion were considered as late autophagosomes or autophagic vacuoles, the indications of which were the destruction of their contents or the presence of lysosomal enzymes demonstrated by a positive CMPase reaction. Residual bodies were frequently observed to be exocytosed. The quantitative assay revealed an alteration of autophagic activity in close relation with steroid-secreting states. The number of autophagosomes was one-fold higher in hyposecreting Leydig cells after 2 days testosterone administration, and three-fold higher in hyposecreting adrenocortical fasciculata cells after one dosage of dexamethasone administration. In addition, the autophagosomes showed a four-fold decrease in hypesecreting Leydig cells stimulated by LRH for 2 days. Conclusions: Considering that most of the autophagocytosed organelles were steroid-producing apparatus, we may conclude that, by removing part of steroid-producing organelles, autophagy might play a role in adapting to or even regulating the secretory activity. This hypothesis was strongly supported by the fact that the intensity of autophagy varied in company with the fluctuation of steroid secretion. © 1995 Wiley-Liss, Inc.