Electron immunocytochemistry of lymphocyte surface immunoglobulins in the bursa of Fabricius in the pre- and early postnatal ontogeny of chickens

The appearance and localization of surface immunoglobulins on B-lymphocytes of the bursa of Fabricius of developing chick embryos and chicks were studied by immuno-electron-cytochemical peroxidase-antiperoxidase (PAP) method. Ultrastructural characteristics of marked and unmarked lymphocytes of the bursa of Fabricius was shown. The increase in the density of reaction product on PAP-complex in the course of lymphocytes differentiation was established.     

Ultrastructure and formation of the bursa mouthpiece of Philocelis cellata (Plathelminthes,Acoela)

Philocelis cellata has a strengthened bursa mouthpiece which is arranged in front of the male copulatory organ. The main components of the bursa mouthpiece are numerous ring-shaped bursa mouthpiece cells whose central parts contain strengthened elements forming a tube around the sperm duct. Each of the peripheral areas of the bursa mouthpiece cells is separated by similarly ring-shaped gap cells. The end of the bursa mouthpiece towards the bursa is formed by a so-called sorting apparatus which consists of different cells; opposite the bursa the sperm duct ends in a globe-shaped sperm vestibule. The bursa mouthpiece is differentiated successively, beginning at the distal part at the bursa and proceeding proximally.     

鸡法氏囊B淋巴细胞中与鸡传染性法氏囊病病毒VP2相互作用蛋白筛选

为了获得鸡法氏囊B淋巴细胞中与鸡传染性法氏囊病病毒 (IBDV) VP2相互作用的蛋白质,利用酵母双杂交系统,用IBDV VP2蛋白为诱饵蛋白,筛选鸡法氏囊B淋巴细胞cDNA表达文库。将表达文库质粒转化含IBDV VP2诱饵质粒的酵母感受态细胞,检测报告基因在相应的营养缺陷型培养基 (SD/-Leu/-Trp/-His) 上表达情况,进一步经β-半乳糖苷酶报告基因检测,筛选到16个阳性克隆。提取阳性克隆质粒,经测序分析获得5个原鸡基因序列,分别是：线粒体DNA、蛋白质O位N-乙酰葡萄糖胺糖基化转移酶、肿瘤     

Sex steroid and glucocorticoid receptors in the bursa of Fabricius of obese strain chickens spontaneously developing autoimmune thyroiditis

The female sex develops autoimmune disease far more often than the male. This is claimed to be due to differences in peripheral sex steroid levels. We have examined in the bursa of Fabricius of Obese strain (OS) chickens, which spontaneously develop autoimmune thyroiditis, as well as in their healthy counterparts androgen(AR)-, estrogen(ER)-, progestin(PR)- and glucocorticoid(GR)-receptors in an attempt to elucidate possible further pathomechanisms, namely at the target site of steroid hormones. The characterization (affinity, specificity, association- and dissociation-rate, sedimentation behaviour) of all four types of receptors revealed no difference between sex or strain. Furthermore, the ontogeny study of the receptor capacity and affinity from the 7th embryonic day (i.e. before lymphocyte settlement) until bursa involution, again showed no difference between OS and healthy chickens of either sex. Thus, it can be concluded that the principal sex dependency of the susceptibility to autoimmune disease results predominantly from differences in sex steroid levels per se, although alterations in mechanisms beyond the cytosolic receptor level can presently not be excluded.     

Light microscopical observation of infraciliary bands of Eodinium posterovesiculatum in comparison with Entodinium bursa and Diplodinium dentatum

Morphological features of the four morphotypes of the rumen ciliate, Eodinium posterovesiculatum, are described from pyridinated silver carbonate-impregnated specimens. Infraciliary bands are compared with those of Entodinium bursa and Diplodinium dentatum. In Entodinium bursa, the adoral polybrachykinety is "C" shaped and the vestibular polybrachykinety extends from the dorsal extremity of the adoral polybrachykinety as in other Entodinium species. In Diplodinium dentatum, the adoral polybrachykinety encircles most of the circumference of the vestibular opening and the vestibular polybrachykinety extends from the inner side of the adoral polybrachykinety as in other Diplodinium species. Infraciliary bands in Eodinium posterovesiculatum encircle the whole circumference of the vestibular opening and are, therefore, distinct from Entodinium, Diplodinium and other ciliates in the family Ophryoscolecidae. In Eodinium posterovesiculatum, the adoral polybrachykinety and the anterior part of the vestibular polybrachykinety encircle the vestibular opening. The wide and long vestibular polybrachykinety extends along the right wall of the tubular vestibulum and is bordered by a kinety. Kinetids in the central part of the vestibular polybrachykinety are randomly disposed. The genus Eodinium is valid because of this characteristic polybrachykinety arrangement in Eodinium posterovesiculatum.     

Studies of testosterone-induced involution of the bursa of Fabricius

The present investigation deals with the effect of testosterone on each of the tissue components of the bursa of Fabricius: the endodermal epithelium, the mesenchyme, and the hemopoietic stem cells. Tissue combination experiments between testosterone-treated endoderm and normal mesenchyme and vice versa have shown that the androgen damages irreversibly the bursal epithelium. The latter is not seeded by hemopoietic stem cells and cannot undergo follicle formation when treated with high doses of testosterone. This occurs even if it is associated with a nontreated bursal mesenchyme. On the contrary, associations of testosterone-treated mesenchyme with normal endoderm result in normal bursa histogenesis. By using an original test of viability for lymphoid cells based on the application of the quail-chick marker system, we demonstrate that disappearance of hemopoietic cells in the endoderm results from their expulsion from the bursa and not from their death in situ. The conspicuous effect of testosterone on the bursa of Fabricius can be related to the levels of androgen receptors found in the organ. Typical cytosol androgen receptors are demonstrated in both bursal endoderm and mesoderm, although the amount in the former is higher. The concentration of binding sites in the bursa is >10 times higher than that in other organs such as lung and small intestine whose development is not affected by testosterone, contrasting with glucocorticosteroid receptor (measured by labeling with dexamethasone) found in the same concentration in all tissues.     

Effect of catecholamines on bursa of fabricius in chicken

Effect of catecholamines are studied on the bursa of fabricius of chicken. It is found that in epinephrine (E) treated chicken, the lymph follicles are slightly decreased in size. Some amount of nuclear pycnosis is visible in E and norepinephrine (NE) treated chicken. There is no change in the bursa weight and histology in NE treated groups. No deviation is observed in the level of DNA, RNA, total protein and sialic acid content of catecholamine treated birds.     

The avian chB6 alloantigen induces apoptosis in DT40 B cells

In avian species, B-lymphocytes develop in the bursa of Fabricius. Cells developing in the bursa are subject to signals regulating their survival, with the majority of cells dying by apoptosis within the bursa. However, the molecules delivering the signals influencing this life and death decision remain enigmatic. We have previously shown that antibodies against the chB6 alloantigen present on avian B-lymphocytes can induce a rapid form of cell death. Here we extend this finding by showing that anti-chB6 antibodies induce true apoptosis in DT40 cells without visible membrane damage. This apoptosis results in DNA degradation and morphologic changes characteristic of apoptosis. Furthermore, this apoptosis is coincident with a loss of mitochondrial membrane potential and is inhibited by either overexpression of bcl-x(L) or the presence of inhibitors of caspase 8, 9, or 3 activity. Collectively these data argue that chB6 may function as a novel death receptor on avian B-lymphocytes and support the use of DT40 as an amenable model to study the signaling involved in chB6-induced apoptosis.     

Defective bursa regeneration after irradiation of young thymectomized chickens

The ability of the bursa of Fabricius to regenerate after gamma-irradiation and bone marrow reconstitution was examined in chickens thymectomized (TX) immediately after hatching. Irradiation (2 X 500 R) 3 weeks after hatching was followed by impaired bursa regeneration, as judged both by bursa/body weight ratios and by bursa follicle development 3-6 weeks later in TX as compared to control birds. Germinal center formation in the spleen was deficient, and immune responses to sheep erythrocytes (SRBC) and B. abortus (BA) were moderately reduced in the TX as compared to control birds irradiated at 3 weeks but not in TX birds irradiated at 5 weeks of age.     

Anatomy and function of the bursa subacromialis.

The ligamentum coracohumerale, as the anterior limit of the bursa subacromialis, runs into the shoulder joint capsule, connecting--broadly based--above the sulcus intertubercularis. It does not, however, originate--as described previously--from the base of the processus coracoideus (viewed frontally), but rather medially from the base, i.e. on the side of the fossa supraspinatus. The sliding mechanism starting at 50 degrees affects the parietal sheet of the bursa subacromialis, whereby the laterally situated section slides under the medially situated section. With an abduction of up to 50 degrees, the lateral section congests in front of the corner of the acromion, sliding from there under the acromion, so that the--hitherto--medial section is located above the section now sliding away beneath it. This sliding mechanism continues on up to 100 degrees. At this point the parietal sheet of the bursa subacromialis lies as follows: The section that had been situated laterally at the beginning of the sliding mechanism now lies caudally to the section that had lain medially at the outset. The bursa subacromialis does not slide fully into the fossa supraspinatus, as in all of the cases observed, it is firmly connected, together with the fascia subdeltoidea, to the corner of the acromion. The visceral sheet does not change in the course of the sliding mechanism as described, as it is connected to the fascia of the supraspinatus muscle--with the exception of a medial stretch of 16 mm. A further finding deals with the course of the muscles of the caput breve of the biceps brachii. Individual muscle fibre components do not connect to the processus coracoideus, but rather run before the tip of the processus coracoideus into the ligamentum coracoacromiale, radiating not only into the ligamentum coracoacromiale, but also--certain components--into the shoulder joint capsule. Through this, the 'aponeurosis tendinis brachii' forms a tendon roof in front of the processus coracoideus that extends to the structures running along the head of the humerus. The muscle fibre components of the caput breve of the m. biceps brachii radiating into the shoulder joint capsule, together with the muscles of the rotator cuff and the ligamentum coracohumerale, keep the shoulder joint capsule tense, thus preventing constriction symptoms.     

The epipharyngeal bursa in the Rhinocerotidae

The mammalian bursa epipharyngea commonly presents as an insignificant mucosal recess, not always recognisable macroscopically. In some mammalian forms, however, it is developed into an obtrusive diverticulum (sacculus epipharyngeus) extending caudally from the epipharynx between the cranial base and the pharynx roof. Among the Rhinocerotidae such an epipharyngeal saccule has been recorded for Ceratotherium simum. Herein it is described for the first time in Rhinoceros unicornis, Diceros bicornis and Didermocerus sumatrensis. Its tonsillar nature is established on morphological and histological grounds.     

豚鼠卵巢囊淋巴孔的发现及卵巢囊超微结构研究

In order to explore its structure and speciality of species, the ovary bursa of guinea pig was studied by using dissecting microscopy and scanning electron microscopy. In this paper, the lymphatic stomata on both internal and external layer of the ovary bursa was frist reported in guinea pig. The results suggested that the stomata in bursa not only provided a pathway to connect the bursal cavity with the lymphatic vessels of bursa and the peritoneal cavity, but also may be involved in the reproduction and local immunity of the ovary. The stomata may play an important role in physiological function of the ovary. At the same time, the structural differences were identified in ovary bursa between guinea pig and golden hamster.     

Dispersal, vaccination and regression of immune defence organs

The thymus in vertebrates and the bursa of Fabricius in birds regress before reproduction, while the immunological information of these organs is maintained as cell memory. Regression at a certain age presupposes that individuals have achieved exposure to a large fraction of parasites in the environment. Here we present a new scenario for regression of immune defence organs, based on optimality reasoning. This scenario links early involution of immune defence organs with (1) effects of exposure to parasites on adaptive immune responses to these parasites, (2) exposure to local parasite communities during natal dispersal and migration as a means of "vaccination" against local parasites, and (3) the function of visits to future breeding sites by juveniles as a means of exposure to local parasites. This scenario provides explanations for why natal dispersal is longer than breeding dispersal, for sex differences in dispersal, and for why the bursa of Fabricius regresses relatively early in life among bird species with delayed start of reproduction.     

Vasculogenesis of the bursa cloacalis (bursa of Fabricius) of the chick embryo

Vasculogenesis of the bursa cloacalis (bursa of Fabricius) was examined in 10- to 21-day chick embryos and in chicks during the first 5 days post-hatching. The entire circulatory system was injected with India ink, and the bursae were then removed and either cleared for examination in toto or sectioned serially. The bursa was supplied by three pairs of extrinsic blood vessels. At 10 and 11 days of incubation, most intrinsic vessels were arranged in a superficial, hexagonal network. In regions of developing plicae, the hexagonal plexus extended into the core of each plica, forming middle plical vessels. The latter were interconnected across interplical areas by cross-connecting vessels. The middle plical vessels gave rise to small capillary offshoots, which soon increased in complexity, forming delicate loops. Branches extended from these loops through the subepithelial lamina propria to incipient epithelial buds by 12 days of incubation. All epithelial buds were supplied by at least one such branch, and similar branches extended to the basal aspect of the epithelium in areas where epithelial buds had not yet formed. This observation is consistent with the hypothesis that blood vessels induce formation of epithelial buds. At about 15 days of incubation, the cortex and medulla of each developing lymphatic follicle were defined clearly, and an intricate, web-like, capillary network coursed throughout the follicular cortex. The medulla appeared to be devoid of capillaries. The diameters of all intrinsic and extrinsic bursal blood vessels gradually increased throughout development. During post-hatching stages, the diameters of the extrinsic vessels continued to increase, whereas those of the intrinsic vessels were markedly decreased from late pre-hatching stages.     

Postembryonale Entwicklung und Involution der Bursa Fabricii beim Haushuhn (Gallus domesticus)

Zusammenfassung Die Bursae Fabricii von Hühnern im Alter von 1 Tag bis zu 1 Jahr werden histologisch untersucht. Dabei sind nach dem histologischen Bild Postembryonal-, Ausreifungs-, Reife-, frühes und spätes Involutions- sowie Reliktstadium zu unterscheiden. Postembryonal-, Ausreifungs- und Reifestadium weichen im wesentlichen hinsichtlich Gesamtgröße, Follikelgröße und Zellzusammensetzung voneinander ab. Die Involution kann im Alter von 14 Wochen bis 5 Monaten beginnen. Während der Involution verschmelzen die Bursafalten, das Lumen verschwindet. Die Bursafollikel verlieren an der Lumenseite zunächst die Rinde, dann das Mark. Die Restfollikel lagern sich zusammen und werden nekrotisch, ein Teil bildet Zysten. Als Reliktstadien finden sich bis zum Alter von 1 Jahr fibrotische, muskel- und gefäßreiche Gebilde, die Bursafollikel, Keimzentren oder Lymphozytenhäufchen enthalten.

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Post-hatching development and involution of the bursa Fabricii in the chicken (Gallus domesticus)

Summary Bursae Fabricii were histologically examined in chickens 1 day to 1 year old. They were divided into 6 stages based on their histological appearance: the post-hatching, maturation, maturity, early involution, late involution, and residual stages. The post-hatching, maturation, and maturity stages differ with regard to bursal size, follicle size, and cellular composition. Involution may begin at 14 weeks to five months of age. During the course of involution, the bursal plicae grow together and the bursal cavity disappears. Near the luminal surface epithelium, the bursal follicles at first lose their cortex and then later their medulla. The remnant follicles join and undergo regressive and cystic changes. Residual stages are present up to 1 year of age; they are composed of fibrous connective tissue with smooth muscle and blood vessels and contain single bursal follicles, germinal centers, or lymphatic nodules.

Für technische Mitarbeit danken wir Fräulein U. Neumann und Frau A. Schick.     

Biochemical characterization of the progesterone receptor in the chick bursa of Fabricius

In a previous work we demonstrated estrogen-inducible progesterone binding sites in the bursa of Fabricius. In the present study these were characterized and compared to the progesterone receptor (PR) in the chick oviduct. When the size of the binding sites was analyzed with sucrose gradient centrifugation, 2 peaks of bound progesterone were obtained. The sedimentation coefficients of the peaks were 8-9 S and 3-4 S. In size exclusion HPLC only 1 peak was seen with a size corresponding to the 8-9 S in the sucrose gradient. The Stokes radius was 7.7 nm. When the ionic strength was elevated or CaCl2 was added, smaller steroid binding forms were detected. The sizes of these progesterone binding molecules at low and high ionic strength and in the presence of CaCl2 were equal in bursa and oviduct when analyzed with HPLC. The Stokes radii of these forms were 5.6 nm in high salt and 2.1 nm with CaCl2. The steroid binding components in the bursa cytosol eluated as 2 peaks from the DEAE column with KCl gradient. The peaks corresponded to the so-called A and B components in the chick oviduct. In the presence of molybdate, bound progesterone eluated as one peak from DEAE in both oviduct and bursa. The progesterone binding capacity was shown to be heat labile with equal half-lives in the bursa and the oviduct. Progesterone and ORG 2058 had a high affinity for the binding site and their binding was specific for progestins. It is concluded that the estrogen-inducible progesterone binding site in the bursa of Fabricius resembles the oviductal progesterone receptor in structural and binding properties.     

Transfer of agammaglobulinemia in the chicken. I. Generation of suppressor activity by injection of bursa cells

Spleen cells from adult agammaglobulinemic (bursectomized) chickens taken 1 to 3 weeks after an injection of histocompatible bursa cells can inhibit the adoptive antibody response to B. abortus of normal spleen or bursa cells in irradiated recipients. Spleen cells from Aγ chickens not injected with bursa cells generally do not. Moreover, bursectomized chickens which have been reconstituted with spleen cells within the first week after hatching do not respond with suppressor cell formation upon bursa cell injection. This apparent “autoimmunization” with bursa cells induces suppressor T cells which are only minimally sensitive to treatment with mitomycin C or to 5000 R γ irradiation. The suppressor activity is neither induced nor potentiated by concanavalin A in vivo. It is much stronger in spleen than in thymus cells and appears to be macrophage independent and to require intact cells. The cell component which stimulates the suppressor activity is more pronounced on bursa than on spleen cells, and is at most present to a very limited extent on bone marrow, thymus, or peritoneal exudate cells. It is better represented in comparable cell numbers of Day 17 than of Day 14 embryonic bursa. The inducing cell component is present in the membrane fraction of disrupted bursa cells. Immunization with bursa cells from B locus histoincompatible chickens leads to suppressor activity against histocompatible bursa cells. Although the removal of Ig-bearing cells from bursa greatly diminishes its immunizing capacity, injection of serum IgM and IgG does not induce suppressor cells. It is suggested that tolerance to a B-cell antigen is lacking in adult Aγ chickens, resulting in an autoimmune response upon exposure to B cells. The B-cell antigen may be a cell surface-specific form of Ig, a complex of Ig and a membrane component, or a differentiation antigen which appears simultaneously with Ig during ontogeny.     

The origin of IgG-containing cells in the bursa of Fabricius

The bursa of Fabricius of the chicken is known as a primary lymphoid organ for B-cell development. Morphologically, the origin of IgG-containing cells in the bursa has not been clear until now, because abundant maternal IgG (MIgG) is transported to the chick embryo and distributed to the bursal tissue around hatching. Thus, it has been difficult to find out whether these cells themselves biosynthesize IgG or if they acquire MIgG via attachment to their surface. Our present study employing in situ hybridization clarified that IgG-containing cells in the medulla of bursal follicles did not biosynthesize IgG. To study the role of MIgG in the development of those IgG-containing cells, MIgG-free chicks were established from surgically bursectomized hen (SBx-hen). We found that, on the one hand, deprivation of MIgG from chicks completely inhibited the development of IgG-containing cells in the medulla after hatching. On the other hand, administration of MIgG to MIgG-free chicks recovered the emergence of those cells. In addition, we observed that those cells did not bear a B-cell marker and possessed dendrites with aggregated IgG. These results demonstrate that IgG-containing cells in the medulla are reticular cells that capture aggregated MIgG. Moreover, we show that the isolation of the bursa from environmental stimuli by bursal duct ligation (BDL) suppressed the development of IgG-containing cells after hatching. Thus, it is implied that environmental stimulations play a key role in MIgG aggregations and dendritic distributions of aggregated MIgG in the medulla after hatching.     

Cell lineage segregation during bursa of Fabricius ontogeny

The population dynamics of myeloid and lymphoid lineages during bursa of Fabricius ontogeny were analyzed by immunofluorescence by using two monoclonal antibodies (mAb). CL-1 mAb reacts with all chicken hemopoietic cells, except mature erythrocytes. L22 mAb reacts with bursa and bursa-derived lymphocytes, with a minor subset of macrophages and with some cells of the thymic medulla. The staining of embryonic bursas by these antibodies helps to distinguish between two different lineages of hemopoietic cells: CL-1+/L22+ cells represent B lymphocytes and a minor subset of macrophages, while CL-1+/L22- cells correspond to most of the macrophages and to the granulocytes, which disappear at the end of the embryonic life. CL-1+/L22- as well as CL-1+/L22+ cells were first observed outside the bursal rudiment. This indicates that there is a pre-bursal segregation between these two hemopoietic lineages and that two different kinds of precursors colonize the bursal rudiment at about the same time (day 9 for CL-1+/L22- cells and days 9 or 10 for CL-1+/L22+ cells). Moreover our data show that the colonization of the bursal epithelium by hemopoietic precursors is a two-step phenomenon. The first cells which enter belong to the CL-1+/L22- lineage, express Ia-like antigens at a high level, are dendritic in morphology, and represent cells of the macrophage/dendritic cell lineage. They are responsible for the formation of the epithelial bud which are then colonized by a small number of lymphoid precursors which belong to the CL-1+/L22+ lineage. Quail-chick bursa grafting experiments were also performed and the grafts were examined for CL-1 (restricted to chicken hemopoietic cells) and L22 reactivity. These observations confirmed our previous findings about the kinetics of the colonization of bursal rudiment by hemopoietic precursors and give support for a pre-bursal segregation between two hemopoietic pathways.     

Ultrastructural Morphology of the Male and Female Genital Tracts of <Emphasis Type="Italic">Psoroptes</Emphasis> spp. (Acari: Astigmata: Psoroptidae)

The structure of the male and female genital systems of the astigmatid mite Psoroptes ovis (Hering) is described. The male genital system is composed of a paired testis, fused at its proximal part, two vasa deferentia, an ejaculatory duct, into which a single accessory gland opens, and a copulatory organ. The testis is characterized by a peripheric syncytial cell surrounding spermatogonia, spermatocytes, spermatids and spermatozoa which are distributed regularly in the gonad according to the sequence of spermatogenesis. The female genital system consists of a copulatory pore (the bursa copulatrix), a seminal receptacle, paired ovaries and oviducts, a glandular uterus and an ovipositor which leads to the oviporus. Ovaries are composed of somatic cells, germ cells and a central cell, with a multilobular nucleus, connected to oocytes by a stalk. Similarities with other astigmatic mites belonging to Psoroptidia and Acaridia are also discussed.