Induction of suppressor T cells of antibody formation under conditions that preferentially stimulate DTH

These studies describe the conditions under which antibody-forming cells and TDTH cells are selectively induced in vitro. TDTH cells are preferentially stimulated when high doses of antigen are included in the culture. Antibody-forming cells, on the other hand, are optimally stimulated with a 100 to 1000-fold less concentration of antigen. The conditions that optimally stimulate TDTH cells also induce a population of suppressor T cells that inhibit the antibody response. However, although their inductive requirements are similar, the suppressor T cells of antibody formation are a distinct subpopulation of cells from the TDTH cells. Whereas the suppressor T cells are LY-1-, 2+, 4-, 6+, and Ia+; the TDTH cells are Ly-1+, 2+/-, 4-, 6+, and Ia-. Furthermore, the DTH cells are sensitive to high doses of irradiation, whereas the suppressor cells are resistant. Based on the Ly phenotype and the kinetics of suppression, the suppressor T cells are not the "feedback suppressors" that have been identified in other systems. The system described in this paper provides a means whereby the cells that regulate humoral and CMI can be studied in vitro.     

Structural and ultrastructural features of boar seminal vesicles

The morphological features of boar seminal vesicles were examined by light and transmission microscopy. Boar seminal vesicles consist of glandular tissue arranged in multiple lobules containing a system of ramified secretory tubules. The secretory tubules are composed of a mucosa formed by an epithelium and an underlying lamina propria and, are surrounded by a muscular layer. The epithelium is made up of columnar cells and occasional basal cells. Mast cells are frequently found among epithelial cells. Three types of columnar cells, considered different stages of the secretory cell cycle, are present: principal cells, clear cells and dense cells. Principal cells are functionally differentiated cells characterised by abundant mitochondria, great development of the rough endoplasmic reticulum and presence of secretory granules in their cytoplasm. The apical surface of many principal cells shows apical blebs filled with PAS-positive material. No acid mucosubstances are detected. Microvilli cover the apical surface except in the apical blebs. Dense cells, arranged between principal cells, are also functional differentiated cells but with signs of cellular degeneration. Clear cells are an initial differentiated stage of columnar cells and are characterised by the presence of a poorly developed rough endoplasmic reticulum and by the absence of secretory granules. Proliferating cells are present among columnar cells. Basal cells contain scarce cytoplasm, few organelles and no secretory granules. The lack of mitotic activity in these cells suggests that they do not act as precursors of columnar cells.     

A morphologic study of the ductus of the epididymis of Sus domesticus

The head, body, and tail regions of the epididymal duct (or caput, corpus, and cauda epididymis) in two healthy and sexually mature Sus domesticus males were examined by light microscopy and by scanning or transmission electron microscopy. The epididymal duct is lined with a pseudostratified epithelium with stereocilia and covered by a muscular-connective tissue sheath that is thickest in the tail region. Diameter of the epididymal duct and height of epididymal epithelium are maximal in the head region. Length of the sterocilia and spermatic density are higher in the head and body regions. Somatic cells are abundant in the tail region. The epididymal epithelium is made up of five cell types: basal cells, principal cells, clear cells, narrow cells, and basophilic cells. Abundant secretory units are observed in the supranuclear cytoplasm of columnar principal cells. Each mature secretory unit is constituted by electron-dense secretion granules covered by more than eight layers of cisternae of reticulum between which the mitochondria are intercalated. In the apical cytoplasm the isolated secretion granules become larger and less electron dense. The apical surface is covered by numerous sterocilia. Basal cells are pyramidal and less high than principal cells. The clear cells, arranged between the principal cells, are characterized by the presence of abundant vesicular elements and electron-lucid secretion granules, and by an apocrine secretory process. The narrow cells are characterized by their highly vacuolized cytoplasm. Intermediate cell typologies can be found among basal, principal, clear, and narrow cells, which could be four developmental stages of the same cell type. The basophilic cells are spheroidal and are found at different levels between the epithelial cells and in the connective tissue underlying the epithelium. © 1993 Wiley-Liss, Inc.     

Ultrastructural aspects of cat submandibular glands

Submandibular glands of five adult female cats were examined by conventional electron microscopic techniques. All gland acini are mucous secreting and each acinus is capped with mucous secreting demilunar cells. Secretory product of demilunar cells is more electron lucent than that of acinar cells. The demilunes show intercellular tissue spaces and intercellular canaliculi whereas similar specializations are absent between acinar cells. Mitochondria and arrays of granular endoplasmic reticulum are more numerous in demilunar cells than in acinar cells. In acinar and demilunar cells secretory droplets first appear as enlarged Golgi saccules which subsequently become closely related to cisternae of the granular endoplasmic reticulum. Filamentous structures, interpreted as mucin molecules, are present in secretory droplets of acinar cells. Intercalated ducts are short, consisting of several junctional cells between acini and striated ducts. Striated ducts are long and tortuous and contain light cells, dark cells and basal cells. Light cells contain numerous membrane bound granules in their distal ends whereas dark cells show electron lucent vesicles in the same position. Basal cells contain a paucity of organelles and membrane plications but exhibit hemidesmosomes along their basal plasma membranes. Myoepithelial cells are abundant in relation to acinar and demilunar cells. Nerve terminals are present in some instances between acinar cells or between acinar and myoepithelial cells.     

Influence of amacrine cells on receptive field organization of ganglion cells of the generalized vertebrate cone retina: Electronic simulation

Two classes of amacrine cells are simulated, small-field and large-field. Small-field amacrine cells are formed by input from a single bipolar cell, while large-field amacrine cell is formed by inputs from same 7 bipolar cells that form the ganglion cell. Only tonic amacrine cells are studied with both chromatic and luminosity types as well as double-and single-opponent receptive fields. Amacrine cells are used in both feedforward to ganglion cells and feedback to bipolar and horizontal cells. Feedback to bipolar cells or feedfoward to ganglion cells affected steady state levels in a predictable fashion. Negative feedback to bipolar cells and positive feedfoward to ganglion cells does not introduce transients to ganglion cells while negative feedback to horizontal cells and negative feedfoward does. Feedback to horizontal cells produces complex effects on bipolar, amacrine and ganglion cells dependent on such factors as center-surround field balance and negative feedback from luminosity type of horizontal cell to cones.     

黑缘烟蟋螽丝腺结构

【目的】蟋螽是直翅目中唯一具有吐丝筑巢行为的类群。本研究旨在探讨蟋螽丝腺的结构特点。【方法】应用解剖学观察、免疫荧光、苏木精-伊红染色、PAS苏木精染色、扫描电镜和透射电镜等方法从细胞水平对黑缘烟蟋螽Capnogryllacris nigromarginata丝腺的显微与超微结构进行了观察。【结果】黑缘烟蟋螽丝腺由导管和腺泡构成。腺泡由鞘细胞延伸形成的结缔组织鞘包围。腺泡的主体有4种细胞,分别为Ⅰ型分泌细胞、Ⅱ型分泌细胞、围细胞和腔细胞。Ⅰ型和Ⅱ型分泌细胞为大的腺细胞,形状不规则。分泌细胞细胞核很大,胞质内有大量的内质网和分泌颗粒。Ⅰ型分泌细胞靠近腺泡中心,PAS-苏木精染色表明Ⅰ型分泌细胞内含糖蛋白,Ⅱ型分泌细胞在腺泡外周,位于Ⅰ型分泌细胞与围细胞或结缔组织鞘之间。腔细胞分散在分泌细胞之间,包围形成胞外运输分泌物的通道。围细胞与鞘细胞接触,具有由细胞膜内陷形成的微绒毛腔,胞质内有大量的线粒体。围细胞微绒毛腔与腔细胞包围的细胞外运输通道相连,分泌细胞分泌的颗粒聚集在分泌细胞和胞外运输通道之间的连接处,并将分泌物排出至胞外运输通道。多个腺泡的胞外运输通道汇集到由单层细胞组成的丝腺导管。单层导管细胞靠近管腔外围具有规则排列的质膜内陷和大量伸长的线粒体;靠近管腔的一侧具连续的细胞膜突起,在导管壁的表皮下紧密排列。【结论】黑缘烟蟋螽丝腺分泌细胞分为Ⅰ型分泌细胞和Ⅱ型分泌细胞。分泌物质产生及分泌过程依次经过分泌细胞、腔细胞包围的胞外通道、分支导管、总导管和唾窦。其中在腺泡细胞之间,分泌物向外运输过程中,围细胞微绒毛腔的微丝束可能对分泌物的外排提供推动力。     

Ultrastructural features of the salt gland of Tamarix aphylla L.

Summary The salt gland in Tamarix is a complex of eight cells composed of two inner, vacuolate, collecting cells and six outer, densely cytoplasmic, secretory cells. The secretory cells are completely enclosed by a cuticular layer except along part of the walls between the collecting cells and the inner secretory cell. This non-cuticularized wall region is termed the transfusion are (Ruhland, 1915) and numerous plasmodesmata connect the inner secretory cells with the collecting cells in this area. Plasmodesmata also connect the collecting cells with the adjacent mesophyll cells.There are numerous mitochondria in the secretory cells and in different glands they show wide variation in form. In some glands wall protuberances extend into the secretory cells forming a labyrinth-like structure; however, in other glands the protuberances are not extensively developed. Numerous small vacuoles are found in some glands and these generally are distributed around the periphery of the secretory cells in association with the wall protuberances. Further, an unusual structure or interfacial apparatus is located along the anticlinal walls of the inner secretory cells. The general structure of the gland including the cuticular encasement, connecting plasmodesmata, interfacial apparatus, and variations in mitochondria, vacuoles, and wall structures are discussed in relation to general glandular function.     

Role of antigen-specific B cells in the induction of SRBC-specific T cell proliferation

In this study, we ask whether antigen presentation can be effected by antigen-activated B cells. Antigen-dependent in vitro proliferation of T cells from mice primed with SRBC or HoRBC occurs in the presence of B cells primed to the relevant antigen. B cells prepared from lymph nodes of mice primed with irrelevant antigens are not effective antigen-presenting cells for RBC-specific T cell proliferation over a wide range of SRBC doses. This is true even when both RBC and the antigen to which the B cells are primed are included in the culture. In contrast, B cells specific for a hapten determinant coupled to SRBC are able to support proliferation of T cells specific for SRBC determinants. We conclude from these data that antigen-specific B cells play a role in the induction of T cell proliferative responses to SRBC and HoRBC antigens. Two models are proposed: either B cells, upon antigen interaction with surface antibody, are able to act as accessory cells to induce Ia-dependent proliferation of immune T cells; or B cells augment the T cell proliferative response by secretion of antibody, leading to opsonization of the antigen for macrophage uptake and presentation.     

Ultrastructure of cell types of the olfactory epithelium in a catfish,Heteropneustesfossilis (Bloch)

Transmission electron microscopical study of olfactory epithelium of a mud-dwelling catfish,Heteropneustes fossilis (Bloch) shows receptor, supporting, goblet and basal cells. The receptor cells are of ciliated and microvillous type. Both ciliated and microvillous receptor cells are provided with olfactory knob. The dendrite of all the receptor cells bears many longitudinally arranged microtubules. Occurrence of the rod cell and its function is quite debatable. Specialized juctional complexes between the receptor and adjacent cells are clearly noted. The supporting cells are both ciliated and nonciliated. The ciliated supporting cells are responsible for water ventilation in the olfactory chamber as well as in the inter-lamellar spaces. This facilitates better perception of odours by the receptor cells. In addition to providing mechanical support to other cells, the nonciliated supporting cells also have a secretory function which is evident from the present study. The different stages of maturity of goblet cells are well documented. The presence of white cells in the olfactory epithelium is a very rare finding.     

长鬣蜥胃肠道5-羟色胺细胞的免疫组织化学定位

研究长鬣蜥消化道内含有的5一羟色胺（5-HT）内分泌细胞的位置和形态,采用ABC（avidin—biotin—peroxidase complex）免疫组织化学法,应用5-HT特异性抗血清,对其消化道内的5-HT细胞进行免疫化学定位。结果：5-HT细胞从胃部到直肠的胃肠道各段均有分布,细胞密度分布以胃部最高,十二指肠次之,回肠最低。5-HT细胞的形态呈圆形、椭圆形和锥体形等,其中胃体部和直肠部以圆形和椭圆形为主,小肠部以锥体形为主;5-HT细胞广泛分布于上皮基部、上皮细胞之间、腺泡上皮及腺泡之间,有时可见于固有膜内。结论：5-HT细胞的密度分布与其食性、食物组成和生活环境有关,5-HT细胞的形态与其内、外分泌是相适应的。     

Role of lymphokine-activated killer cells as mediators of veto and natural suppression

Fresh bone marrow cells have veto activity but little if any NK activity. By contrast, lymphokine-activated bone marrow cells have potent natural suppressor as well as veto activity, and also have cytolytic activity characteristic of lymphokine-activated killer cells. Veto activity of fresh bone marrow cells is eliminated by 9 Gy irradiation and by depletion of cells expressing Qa-2, but is unaffected by removal of cells expressing Thy-1, Qa-5, Ly-5, or asialo GM1. By contrast, the veto and NS activities of lymphokine-activated bone marrow cells are both abrogated by C lysis depletion of cells expressing Qa-2, Qa-5, Thy-1, asialo GM1, NK1, and Ly-11, but are unaffected by depletion of cells expressing Ly-2. Bone marrow cells depleted of Qa2+ cells fail to generate veto or natural suppressor activity when cultured in Con A-conditioned medium, unlike bone marrow cells depleted of mature NK1.1+ NK cells. Cloned NK cell line F8 is able to mediate both natural suppression and veto. These findings indicate that bone marrow veto and natural suppression are not mediated by T or NK cells present de novo in the bone marrow, but are dependent on proliferating cells that phenotypically resemble pre-NK cells. The progeny of these cells have the phenotype and functional activity of lymphokine-activated killer cells, and are capable of directly mediating both veto and natural suppression.     

Fine structure and functions of haemerythrocytes and leucocytes of Sipunculus nudus

The marine sipunculan worm, Sipunculus nudus Linné, possesses a voluminous coelomic cavity filled with a fluid containing different types of free cells. Most of them (more than 90%) are nucleated haemerythrocytes. They arise from free, small haemerythroblastic cells which are described in this report. Different kinds of leucocytes are also found in the coelomic fluid, particularly granulocytes which are phagocytic cells showing some similarities with vertebrate macrophages. These cells seem to arise from small hyalocytes, which are cells having morphological and physiological resemblances with vertebrate lymphocytes. It appears that the older granulocytes are progressively degranulated and give rise to large hyalocytes. Ciliary cells arising from small cells, very similar to small hyalocytes, have also been observed and it is supposed that they give rise to urn cells. Lastly, some of the biological functions of the free coelomic cells of the sipunculan worms are described.     

Vertical motion detectors and their synaptic relations in the third optic lobe of the fly

The synaptic relations of the giant vertical cells in the lobula plate of the fly were investigated using electron microscopical procedures and Lucifer yellow dye backfill and injection techniques. Histological features of the giant vertical cells are described. The giant vertical cells are exclusively postsynaptic in the lobula plate. They function to integrate input from dense arrays of chemical synapses and have a wide spatial input from the lobula plate. The giant vertical cells are postsynaptic to perpendicularly occurring cells. There are two classes of cells presynaptic to the vertical cells, one of which contains large dense-core vesicles. The giant vertical cells are not the only cells postsynaptic to these two classes of perpendicualr cells. A second group of smaller tangential cells, the twin vertical cells, were also found postsynaptic to many of the same cells that synapsed with the giant vertical cells. The twin vertical cells and the giant vertical cells are therefore integrating some of the same information in the lobula plate.     

Calcitonin cells and unusual follicles of the thyroid of the indian grey mongoose, Herpestes edwardsi (Geoffroy).

Histological preparations of thyroid, parathyroid and thymus glands of Herpestes edwardsi were examined for calcitonin cells. They reveal that (1) the thyroid calcitonin cells are oval, rounded and rarely elongated in shape; these cells and their nuclei are distinctly larger than those of the follicular cells and their nuclei; (2) calcitonin cells are unevenly distributed in the thyroid, with the result that certain portions of the thyroid are completely devoid of these cells; (3) on an average, calcitonin cells are in a ratio of 10-15 cells/100 follicular cells; (4) the parathyroid and thymus glands do not display calcitonin cells, and (5) the thyroid gland displays unusual follicles of two categories, (a) follicles with ciliated epithelial cells and (b) follicles with squamous epithelium.     

Presence of cells combining features of two different cell types in the colonic crypts and pyloric glands of the mouse.

A small number of epithelial cells which combine features of two cell types were observed in the descending colon and pyloric stomach of the mouse. In the descending colon, where the base of the crypts is mainly composed of poorly differentiated "vacuolated" cells, a few of these cells contain, besides the characteristic "vacuoles," mucous globules identical to those in mucous cells or, less frequently, dense granules such as are found in entero-endocrine cells. Because there is evidence that the poorly differentiated vacuolated cells give rise to the other cells of the epithelium, those which also contain mucous globules or dense granules are likely to be differentiating into mucous cells or entero-endocrine cells respectively. In the pyloric stomach, where the glands are mainly composed of mucous cells, some of which are poorly differentiated, a few of the latter exhibit, besides the mucous globules, entero-endocrine type granules or features of caveolated cells. It is likely that the poorly differentiated mucous cells give rise to the other gland cells; and, therefore, those mucous-containing cells which also display dense granules or caveolated cell features are taken to be differentiating into entero-endocrine or caveolated cells respectively. Most of the cells containing two kinds of secretory materials are believed to be stem cells which initially contain a few vacuoles (colon) or mucous globules (pylorus) but are differentiating into a cell containing a different type of secretion. Rare observations of two kinds of secretory materials in a mature cell suggest that the transitional period may be prolonged, perhaps indefinitely.     

Angiogenic and invasive properties of neurofibroma Schwann cells

Neurofibromas are benign tumors from patients with von Recklinghausen Neurofibromatosis (NF1) that are comprised primarily of Schwann cells. These Schwann cells are found both in association with axons and in the extracellular matrix that is prevalent in neurofibromas, and in which fibroblasts are also abundant. An unresolved question has been whether cells in neurofibromas are normal cells or are intrinsically abnormal. We have tested the hypothesis that cells in neurofibromas are abnormal and have shown that neurofibroma Schwann cells, unlike normal Schwann cells, promote angiogenesis in the chick chorioallantoic membrane model system, and invade basement membranes in this system. In contrast, neurofibroma fibroblasts neither promote angiogenic reactions nor invade basement membranes. When injected into nude mice, neurofibroma Schwann cells do not form progressive tumors. These results suggest that NF1 Schwann cells differ from normal Schwann cells, that they are preneoplastic, and that genetic and/or epigenetic changes in Schwann cells may be required for development of peripheral nerve tumors in NF1.     

A Unique Expression of Keratin 14 in a Subset of Trophoblast Cells

The placenta, a transient organ in human, is essential for pregnancy maintenance and for fetal growth and development. Trophoblast and stromal cells are the main cell types present in human placenta. Trophoblast cells are present in different subtypes depending on their differentiation state and their temporal and spatial location during pregnancy. The stromal cells are of extraembryonic mesenchymal origin and are important for villous formation and maintenance. Interestingly, many pregnancy–related diseases are associated with defect in trophoblast differentiation and villous integrity. Therefore, it''s crucial to specifically identify each type of placental cells using specific markers. Keratins (CK) are widely used as marker of epithelial cells, cancer origin identification and in some cases as marker of stem/progenitor cells. Vimentin is widely used as marker of mesenchymal cells. The aim of this study is to characterize the presence of different keratins in human trophoblast cells and vimentin in stromal cells. Using immunohistochemistry on term placental sections, our results show that vimentin is solely expressed in stromal-mesenchymal cells while keratins 5, 7, 8, 14 and 19 are expressed in trophoblast cells. Interestingly, all keratins tested, except for keratin 14, were evenly expressed in all trophoblast cells. Keratin 14 was expressed in a subset of CK7 positive cells. Moreover, the same results were obtained when using freshly isolated cytotrophoblast cells or BeWo cells. In conclusion, this study is a crucial step in the advancement of our knowledge in placental cell type identification and characterization.     

Intercoronal cell complex of larvae of the bryozon Watersipora arcuata (cheilostomata: Ascophora)

The coronate larva of the ascophoran bryozoan Watersipora arcuata has a ring of 32 large, multiciliated coronal cells that are used for swimming. Fourteen pairs of small cells are intercalated between the lateral margins of adjacent coronal cells. These intercoronal cells are arranged in a precise pattern and are polymorphic: seven pairs have multiple cilia and seven pairs are mono- or oligociliated. Three pairs of multiciliated intercoronal cells have their cilia arranged as a whorl that is recessed in a pocket formed between the adjacent coronal cells, and they are thought to be photoreceptors that sense general light intensity. Two other pairs of multiciliated cells with cohesive tufts of cilia may be chemo- or mechanoreceptors. Roles of the other intercoronal cells in this species are not evident, but it is proposed that the majority, if not all, of them are sensory. The close proximity of all the intercoronal cells to the equatorial nerve ring is compatible with this interpretation. Analyses of the literature on cleavage patterns, pigment cup ocelli, and flagellar tufts that serve as balancers in coronate larvae lead us to propose that (1) an intercoronal cell is the sensory element of most, if not all, pigment cup ocelli of bryozoan larvae; and (2) intercoronal cells are not modified coronal cells but probably are specialized supra- and/or infracoronal ones that have migrated to an intercoronal position.     

Demonstration of the heterogeneity of the mast cell population on the basis of the mucopolysaccharide content.

From the aspect of its mucopolysaccharide content the mast cell population is not homogeneous. The pulmonary and heart muscle mast cells of the rat are alcian blue positive, the mast cells of the thyroid gland, lymph nodes, subcutaneous connective tissue, mesentery and peripheral nerve are safranin positive, whereas among the mast cells of the peritoneal cavity and the thymus there are both alcian blue and saffranin positive forms. The least acid mucopolysaccharides are in the mast cells of the peritoneal fluid, the mesentery and the lungs, whereas the most acid ones are in the mast cells of the lymph nodes, the subcutaneous connective tissue and the thyroid gland. There is a considerable difference between the two last mentioned organs. The mast cells of the subcutaneous connective tissue are end-product cells without amine or precursor turnover, whereas the mast cells of the thyroid gland incorporate and deliver amines, which may participate in the regulation of the host gland.     

Structural changes in the zonulae occludentes of the chloride cells of young adult lampreys following acclimation to seawater

Summary Thin sections and freeze-fracture replicas have been used to study the structure of the zonulae occludentes of the branchial chloride cells in young adults of the anadromous lamprey Geotria australis, caught during their downstream migration to the sea and after acclimation to full-strength seawater (35). The chloride cells in the epithelium of the gill filaments of both freshwater- and seawater-acclimated animals form extensive multicellular complexes. In freshwater animals, the majority of chloride cells (64%) are covered by pavement cells and are thus not exposed to the external environment. Most of the other chloride cells are separated from each other by pavement cells or their processes. The zonulae occludentes between chloride cells and pavement cells and between adjacent chloride cells are extensive and characterised by a network of 4 (range 3–7) superimposed strands. In seawater-acclimated animals, the pavement cells cover only 30% of the chloride cells and their processes no longer occur between chloride cells. Whereas the zonulae occludentes between chloride cells and pavement cells are still extensive, those between chloride cells are shallow and comprise only a single strand or two parallel strands. The zonulae occludentes between the chloride cells of lampreys acclimated to seawater are similar to those in the gills of teleosts in seawater, and are thus considered to be leaky and to provide a low-resistance paracellular pathway for the passive transepithelial movement of Na⁺.