The marginal zone and marginal sinus in the spleen of the gerbil. A light and electron microscopy study

The spleen of the adult gerbil (M. unguiculatus) is characterized by the absence of venous sinuses and ellipsoid sheaths. The follicle (white pulp) is separated from the surrounding red pulp by a distinct marginal zone. The cell types in the marginal zone are common to both the follicle and red pulp. Separating the marginal zone from the follicle is a vascular channel of capillary dimension, the marginal sinus. A number of terminal segments of the arterial vessels within the follicle were observed to form a direct connection with the marginal sinus. Ultrastructurally, discontinuities were evident within the walls of the marginal sinus that would permit passage of both cellular and plasma components from the marginal sinus to either marginal zone or the follicle.     

Immunocytochemical identification of structures containing putative red pigment-concentrating hormone in two species of decapod crustaceans

Summary By use of an antiserum raised against the Nterminal sequence pGlu-Leu-Asn-Phe..., common to red pigment-concentrating hormone (RPCH) of Pandalus borealis and three structurally similar insect neuropeptides, putative RPCH-immunopositive structures were revealed in the eyestalks of Carcinus maenas and Orconectes limosus and in the brain and thoracic ganglion (TG) of C. maenas. In the eyestalks, complete neurosecretory pathways were demonstrated, consisting of perikarya, axons and terminals in the neurohemal organ, the sinus gland (SG). In C. maenas approximately 20 small RPCH cells are present as a distinct group adjacent to the medulla terminalis ganglionic X-organ (MTGXO, XO). They are morphologically different from the larger XO perikarya, which contain the crustacean hyperglycemic hormone (CHH). The occurrence of both neuropeptides in distinct neurosecretory pathways was ascertained by immunologic double staining (PAP/gold) or by analysis of consecutive sections. In addition, a group of two to four larger RPCH cells is located in the proximal part of the MT. In O. limosus, RPCH cells are found in the XO. Cells corresponding to the proximal MT cells of C. maenas were not found. In both species, a few more weakly staining immunopositive perikarya were observed in clusters of cell somata of the optic ganglia. It is uncertain whether these are connected to the SG.In the brain of C. maenas, several smaller and three larger perikarya were consistently observed in the dorsal lateral cell somata adjacent to the olfactory lobes. In the optic nerve, two axons that project into the eyestalk were stained. Some axons were also observed in the ventral median neuropil of the brain. In the TG, RPCH cells were found in small numbers in median positions, i.e., in clusters of somata between the ganglia of the appendages.HPLC analysis of the red pigment-concentrating activity from the SG of C. maenas revealed that the retention time of the neuropeptide is similar but not identical to that of Pandalus borealis RPCH.     

Freeze-fracture study of the lateral-line canal organ of the Japanese sea eel,Lincozymba nystromi

Summary Specializations of apical surfaces of hair cells, supporting cells and marginal cells in the lateral-line canal organ of Japanese sea eel, Lincozymba nystromi, were examined with a freeze-fracture technique. Apical surfaces of hair cells have a lower density of intramembrane particles (IMP) than those of the surrounding supporting cells. Density of IMP on the streocilia is almost the same as that on the apical surface of hair cells. Junctions between hair and supporting cells were tighter than those between two supporting cells; those between supporting and marginal cells were tighter than those between hair and supporting cells, and those between two marginal cells were the tightest in the lateral-line canal organ.     

Genetic analysis of the position of meiosis in <Emphasis Type="Italic">Porphyra haitanensis</Emphasis> Chang et Zheng (Bangiales,Rhodophyta)

Crossing experiments were carried out between artificial pigmentation mutants and the wild type in Porphyra haitanensis Chang et Zheng to ascertain where meiosis occurs in its life history by confirming whether the color segregation and the color-sectored blades appear in F₁ gametophytic blades developed from conchospores which are released from heterozygous conchocelis. Two red-type pigmentation mutants (R-10 and SPY-1) were used as the female parent. Their blades are red or red orange in color, thinner than the wild type and weak in elasticity, and have no denticles on their margins. The wild type (W) was used as the male parent; its blades are light brown in color, thick and good in elasticity, and have many marginal denticles. The F₁ gametophytic blades developed from conchospores which were released from heterozygous conchocelis produced in the crosses of R-10(♀)×W(♂) and SPY-1(♀)×W(♂) showed two parental colors (R and W) and two new colors (R', lighter in color than R; W', wild-type-like color and redder than W). Linear segregation of colors occurred in the F₁ blades, forming color-sectored blades with 2–4 sectors. In the color-sectored blades, R and R' sectors were thinner than W and W' sectors, and had weak elasticity and no denticles on their margins, whereas W and W' sectors were thick and had good elasticity and many marginal denticles. Of the F₁ gametophytic blades, 95.2–96.7% were color-sectored and only 3.3–4.8% were unsectored. These results indicate that meiosis of P. haitanensis occurs during the first two cell divisions of a germinating conchospore, and thus it is considered that the initial four cells of a developing conchosporeling constitute a linear genetic tetrad leading to the formation of a color-sectored blade. The new colors of R' and W' were recombinant colors due to the chromosome recombination during the first cell division in meiosis. It is considered that color phenotypes of the two mutants used in this paper were result of two (or more) recessive mutations in different genes, and that they also have mutations concerned with blade thickness and formation of marginal denticles, which are linked with the color mutations.     

Demonstration of neural induction using nuclear markers inXenopus

Summary Two nuclear markers were used to investigate the origin of cells in secondary embryos ofXenopus induced by dorsal lip transplants, and to determine the ability of the chordomesoderm to direct cells to change their fates.³H-thymidine was used to label cells transplanted between individualX. laevis embryos, and nuclear quinacrine fluorescence was used to distinguishX. borealis tissues transplanted toX. laevis hosts. In the first set of experiments, dorsal lip tissue (also known as the dorsal marginal zone; DMZ) was transplanted to the ventral marginal zone (VMZ) of host embryos. The marginal zone is the toroid of presumptive mesodermal cells which involutes during gastrulation. Examination of the secondary embryos resulting from these grafts revealed that their notochords were derived almost exclusively from transplanted cells whereas their nervous systems and somites were composed almost entirely of host cells. Next, the nuclear markers were used to show the normal fates of the tissue of the ventral equatorial region immediately above the VMZ by orthotopic grafting. This tissue was found to give rise to structures in the ventral posterior portions of the tailbud embryo. Finally, the same ventral tissue was labeled and transplanted to the dorsal equatorial region above the DMZ. As a result, it was induced to change its fate and become neural. These results lend unequivocal support to Spemann's theory of neural induction which has recently been questioned.     

The marginal sinus in the perifollicular region of the rat spleen

Summary The marginal sinus in the spleen of the Wistar rat surrounds the follicle and has more numerous PAS positive fibers on the inner wall than on the outer wall. India ink- and lead oxide-gelatin were injected into the abdominal aorta. It was found that much of the india ink-gelatin accumulated in the marginal sinus, the marginal zone, and part of the red pulp, while most of the lead oxide-gelatin collected in the marginal sinus.Ultrastructurally, the capillaries of the follicle were found to open into the marginal sinus. Regions not perforated by the marginal sinus lie between the follicle and the marginal zone. The wall of the marginal sinus is discontinuous and the discontinuities are wider on the marginal zone side than on the follicle side. The relationship of these findings is discussed.A part of this study was presented at the 64th Annual Meeting of the Japanese Pathological Society, Takatsuki, April, 1975     

Spatiotemporal metabolic regulation of anthocyanin and related compounds during the development of marginal picotee petals in <Emphasis Type="Italic">Petunia hybrida</Emphasis> (Solanaceae)

Structures and levels of anthocyanin-related compounds were analyzed during the development of marginal picotee petals in white-center and white-marginal cultivars of Petunia hybrida. In the white site of a white-center cultivar, higher concentrations of quercetin derivatives possessing 7-O-glucoside and/or 3′-O-glucoside occurred than in the colored site, suggesting that these two quercetin glycosylation steps are site-specifically regulated. The boundary areas of petal coloration were composed of cells showing various color densities, whose uniformity among adjacent cells varied between these cultivars. These results indicate diversity in spatiotemporal regulation of anthocyanin biosynthesis and flavonol glycosylations between Petunia cultivars during marginal picotee formation. Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

B cells are crucial for both development and maintenance of the splenic marginal zone

The splenic marginal zone is a unique compartment that separates the lymphoid white pulp from the surrounding red pulp. Due to the orchestration of specialized macrophages and B cells flanking a marginal sinus, this compartment plays an important role in uptake of blood-borne Ags and it gives the spleen its specialized function in antibacterial immunity. In this study, we demonstrate that both development and maintenance of this marginal zone is highly dependent on the presence of B cells. Spleens from B cell-deficient mice were found to lack both metallophilic and marginal zone macrophages as well as mucosal addressin cellular adhesion molecule-1+ sinus lining cells. Using an inducible Cre/loxP-driven mouse model in which mature B cells could be partially depleted by removal of the B cell receptor subunit Igalpha, we could show that the integrity and function of an established marginal zone was also dependent on the presence of B cells. This was confirmed in a transgenic model in which all B cells were gradually depleted due to overexpression of the TNF family member CD70. The loss of all cellular subsets from the marginal zone in these CD70 transgenic mice was effectively prevented by crossing these mice on a CD27(-/-) or TCRalpha(-/-) background, because this prohibited the ongoing B cell depletion. Therefore, we conclude that B cells are not only important for the development, but also for maintenance, of the marginal zone. This direct correlation between circulating B cells and the function of the spleen implies an increased risk for B cell lymphopenic patients with bacterial infections.     

Localization of 2-glucuronidase in the marginal sinus of rat spleen

The study demonstrated lysosomal 2-glucuronidase activity localized in the marginal sinus epithelium of rat spleen. Immunologically, the marginal sinus is a key structure of the spleen and its enzymatic apparatus differs from that of the cells of the red pulp venous sinuses. The possible physiological significance of this finding is briefly discussed.     

Simultaneous infection by red rot and chytrid diseases in <Emphasis Type="Italic">Porphyra yezoensis</Emphasis>Ueda

This paper presents the results of a study on the diseases of Porphyra yezoensisUeda along the north coast of China, where red rot (Pythium porphyrae) and the chytrid Olpidiopsis sp. diseases were both found to be present. Infection by the mycelia of Pythium porphyraeand the thallus of Olpidiopsis sp. was studied in detail. At the early stage of infecton the mycelia of Pythium porphyraeand the fungus of chytrid can be found in host cells at the same time. In the middle and late stages of the complication, it mainly appears as red rot disease, toward the end appearing almost completely as red rot disease. The complication even can be found on the cells of fronds from the freeze-storage nori nets. However, the freeze-storage nets can help prevent spread of the infection and improve nori quality.     

枫香变红过程中叶片组织结构、光合特性及色素含量变化研究

枫香(Liquidambar formosana)因其叶片入秋后逐渐变红而极具观赏价值,是优良的景观生态树种。为了解枫香叶片结构变化与叶色的关系,该文通过连续监测枫香叶片变红过程中组织结构、光合特性及色素含量的变化,分析叶片结构与其光合特性和色素的关系。结果表明：(1)叶片变色过程中,表皮细胞均为椭圆形,紧密排列,未观察到明显的细胞变异,表面未附着绒毛和蜡质,且上表皮细胞与栅栏组织细胞间排列紧密,未出现较大的气室。(2)随着叶片逐渐变红,叶片结构变化显著,其中叶片、上表皮、栅栏组织和海绵组织厚度及气孔开度均逐渐减小,而气孔器长和宽、单个气孔器面积则逐渐增大。(3)随着叶片结构的变化,其叶绿素含量逐渐减少,致使净光合速率逐渐减小,在出现光破坏时,叶片通过在栅栏组织细胞液泡内合成花色苷来自我保护,而大量的花色苷致使叶片表面呈现红色。综上认为,叶绿素含量降低,花色素苷大量积累是导致枫香叶片变红的直接原因,而枫香叶色变红则是其一系列生理结构特征综合作用的结果。     

Ultrastructural changes in the spleen of the natterjack,Bufo calamita,after antigenic stimulation

Summary In the present study comparative aspects of the ultrastructure of the spleen were analyzed in non-immunized and T-dependent antigen-challenged natterjacks, Bufo calamita. Special attention is focused on the role of the non-lymphoid components in the splenic immunoreactivity. Ten days after primary immunization with sheep erythrocytes, splenic lymphoid follicles increase considerably in number and size. By that time, lymphoblasts, medium and large lymphocytes abound in the periphery of the white pulp near the marginal zone. Meanwhile, in the red pulp numerous monocytes migrating across the sinusoidal walls apparently transform into giant, dendritic-like cells. Twenty days after immunization the splenic lymphoid follicles decrease in number, although certain reactivity persists and numerous plasma cells occur in the cell cords and sinusoids of the red pulp. These results are discussed comparatively with those reported in other lower vertebrates.     

Development of mantle leaves inPlatycerium bifurcatum (Polypodiaceae)

InPlatycerium bifurcatum the leaf primordia emerge alternately right and left below the shoot apical cell on the dorsal surface of the rhizome. They arise from groups of small cells, a single large cell becoming the initial of the leaf apical cell. The longitudinal axis of the leaf apical cell is at a right angle to the rhizome axis and the leaf primordia are arranged longitudinally in two rows. The leaf apical cell gives rise to marginal initials which are responsible for leaf growth in one plain. Early marginal cells are crescent-shaped while the later ones are wedge-shaped. Hairy marginal cells appear in the very early stages of development. The interpretation of these cells as a promeristem and as initials are discussed.     

Endocochlear potential generation is associated with intercellular communication in the stria vascularis: Structural analysis in the viable dominant spotting mouse mutant

Summary Deafness in the viable dominant spotting mouse mutant is due to a primary defect of the stria vascularis which results in absence of the positive endocochlear potential in scala media. Endocochlear potentials were measured and the structure of stria vascularis of mutants with potentials close to zero was compared with that in normal littermate controls by use of morphometric methods. The stria vascularis was significantly thinner in mutants. Marginal cells were not significantly differnet from controls in terms of volume density or intramembrane particle density but the network density of tight junctions was significantly reduced in the mutants. A virtual absence of gap junctions between basal cells and marginal or intermediate cells was observed, but intramembrane particle density and junctional complexes between adjacent basal cells were not different from controls. The volume density of basal cells was significantly greater in mutants. Intermediate cells accounted for a significantly smaller volume density of the stria vascularis in mutants and had a lower density of intramembrane particles than controls. Melanocytes were not identified in the stria vascularis of mutants. These results suggest that communication between marginal, intermediate and basal cells might be important to the normal function of the stria vascularis.     

Production of interspecific somatic hybrids between tuber mustard (<Emphasis Type="Italic">Brassica</Emphasis><Emphasis Type="Italic">juncea</Emphasis>) and red cabbage (<Emphasis Type="Italic">Brassica oleracea</Emphasis>)

In the present investigation, the interspecific somatic hybridization between tuber mustard and red cabbage was established in order to introduce valuable genes from red cabbage (Brassica oleracea) into Brassica juncea. Prior to fusion treatment, protoplasts of red cabbage were inactivated with 2 mM iodoacetamide to inhibit cell division. Micro-calluses were obtained at a frequency of 10.3% after approximately 5 weeks culture following protoplast fusion. Some of the fusion-derived calluses possessed red pigmented cells after being transferred to proliferation medium, and they were presumably considered to be somatic hybrid cell lines. Plantlets were regenerated from 12 cell lines, of which nine plantlets exhibited characteristics intermediate of both parents in terms of plant morphology. With the exception of common protein bands featured by two parents, there were unique banding patterns produced in the hybrids by using SDS-PAGE analysis. By chromosome countings, it was showed that they ranged approximately from 2n=30 to 42 in chromosome numbers. Their hybridity were further confirmed by RAPD analysis revealing that genes of both parents were partially incorporated into the hybrids. Positively, all these hybrids were capable of seed-setting. The pod-setting was 4.2 in somatic hybrid H₇ when backcrossed with tuber mustard.     

Oxygen as a possible tropic factor in hyphal growth ofCandida albicans

Hyphae ofCandida albicans elongated towards the oxygen-rich direction when exposed to gradients of oxygen concentration in thin-layer and capillary-tube cultures with corn meal (CM) agar. The thin-layer culture was prepared by covering a drop of molten CM agar containingC. albicans cells with a cover slip in Petri dishes. Cells located in the central region of the thin-layered medium neither grew nor produced hyphae. Cells in the marginal regions at first directed their hyphae in arbitrary directions after forming a small colony. Hyphae then gradually changed their direction of elongation and eventually oriented towards the nearest margin. Under anaerobiosis, cells seeded in the thin-layered medium did not grow even in the marginal regions. When exposed to air, the cells in the marginal regions rapidly began to form hyphae which elongated towards the nearest margin. To prepare an oxygen gradient in capillary-tube cultures, CM agar, and dilute and dense cell suspensions in CM agar were introduced sequentially into the capillary tubes, and the end closest to the dense cell suspension was sealed with paraffin. Among cells in the dilute layer, only that located closest to the meniscus grew well and extended hyphae towards the meniscus, where oxygen concentrations were highest. These studies suggest a positive aerotropic response in the hyphal growth ofC. albicans.     

Selective binding of biotinylated albumin to the lymphoid microvasculature

Chemically modified albumin binds to the surface of microvascular endothelia lining the vessel wall in several tissues. In this paper, we report that following their biotinylation, ovalbumin (bioOVA) and bovine serum albumin (BSA) [biotinyated albumin (bioAlb)] showed heterogeneous binding to distinct vascular subsets in different lymphoid tissues. The binding of bioAlb could be demonstrated both by fluorescent and enzymohistochemical techniques. In the spleen, the reaction was restricted to the red pulp sinuses whereas the white pulp vessels (including the central arteriole) and the marginal sinus were negative for bioAlb binding. In lymph nodes, the strongest labeling was observed in the medullary sinuses. In the thymus, the most prominent labeling of capillaries was restricted to the corticomedullary area where it was found to be less intense compared with the splenic reaction. The splenic reactivity of bioAlb in the mouse was defined using antibodies against endothelial cell subsets in distinct vascular beds in the red pulp and marginal zone, respectively. The bioAlb-binding elements of the splenic red pulp sinus architecture corresponded to the display of hyaluronan receptor stabilin-2 and subset-specific marker IBL-9/2 while they differed from the expression pattern of both the complementary red pulp sinus subset and the marginal sinus-lining cells expressing MAdCAM-1 antigen, respectively. Similar red pulp sinus-restricted reactivity could be demonstrated in the human, rat, and guinea pig. The use of bioAlb may thus offer a reliable probe for the histological identification of select microvascular endothelia in lymphoid tissues.     

Autoradiographic localization of 3H-γ-aminobutyric acid uptake in the lamina ganglionaris of Musca and Drosophila

Summary The uptake of ³H-GABA in the visual system of half-head preparations of Musca and Drosophila was studied by means of light and electron microscope autoradiography. Of all three ganglia, only the first synaptic region, the lamina ganglionaris, showed accumulation of radioactive grains, and there a preferential glial uptake could be found. Under normal light conditions at incubation (constant light flux of 100 Lux) the maximum of radio-activity was found in the marginal glia cells. Increasing the time of incubation produced also an increase in the number of grains per surface unit in the marginal glia cells. After changing the light intensity during incubation, quantitative modifications of the distribution of radio-activity were observed: incubating with stroboscopic illumination, the number of grains diminished in the marginal glia cells and remained constant in the epithelial cells; incubated in darkness, the epithelial cells became more intensely labelled whilst the number of grains decreased in the marginal cells.The possibility is discussed that the receptor axons 1–6 are the neurological elements of the lamina which use GABA as a transmitter. This hypothesis is lent some support from results of similar experiments with neurological mutants of Drosophila. In opm 18 there was a delayed uptake of ³H-GABA whereas in opm 3 and ebony the results were comparable to those found in Musca incubated in darkness. Behavioral studies on these mutants have demonstrated a defect, most probably related to the receptor system 1–6.     

Relations between submarginal and marginal sori in ferns IV. The sori of Osmunda and selected Schizaeaceae and their morphological relations

Developmental types of sori in Osmunda and Schizaeaceae are comparatively studied and discussed in a systematic context. (1) The ``simultaneous marginal sorus' is characterized by a minute knob-like receptacle representing the thickened tip of a short costa, simultaneous initiation of massive sporangia, and absence of indusia. (2) The ``acropetal marginal sorus' is characterized as an accessory outgrowth at the end of a costa or at the margin of a sorophore, comprising a minute or elongated bifacial receptacle, acropetal initiation of massive marginal sporangia, and minute or long-extended or hood-shaped upper indusia. The state of superficial singly-arranged massive sporangia such as in Todea may give rise to the Osmunda type of the simultaneous marginal sorus and to the Schizaeaceae types of the acropetal marginal sorus. Phase differentiation in leaf development combined with complete laminar reduction leads to the Osmunda type, while phase differentiation in leaf lamina development and additional processes may give rise to the Mohria, Anemia, and Lygodium types. These morphological results support recent phylogenetic studies by other authors in disclaiming close relationships between Osmundaceae and Gleicheniaceae, and between Marattiaceae and Ophioglossaceae (``Eusporangiatae'). They also potentially support relationships between Osmunda- ceae and Schizaeaceae or between Ophioglossaceae and Schizaeaceae. The high complexity of the sori in Marattiaceae and Ophioglossaceae is surprising if the two families are viewed as basal groups.