Follicle associated epithelium of the gut associated lymphoid tissue of cattle

The morphology of the gut-associated lymphoid tissue of the small and large intestine in three gnotobiotic calves was examined by scanning and transmission electron microscopy, and the distribution of specialized membranous cells present in the follicle associated epithelium was defined. Isolated follicles remaining in the ileum of a cow after involution of the continuous Peyer's patch were examined by scanning electron microscopy. The presence of membrane-bound particles, reported to be exclusively associated with the continuous Peyer's patch, was investigated in other gut-associated tissue of the small and large intestine of the calf. The presence of two types of follicle associated epithelium in the small intestine of the calf was confirmed, and the follicle associated epithelium of the large intestine proved to be a homogeneous population of specialized membranous cells, similar to that of the continuous Peyer's patch of the small intestine. In the discrete Peyer's patches, some specialized membranous cells were completely hidden by adjacent enterocytes and could only be identified by cytoplasmic extensions into the intestinal lumen. In the proximal part of the continuous Peyer's patch, a transitional zone was detected where the follicle associated epithelium of some doomed villi was composed of a homogeneous population of specialized membranous cells, while the epithelium covering other doomed villi consisted of a mixture of absorptive and specialized membranous cells, usually only found in the discrete Peyer's patches. Membrane-bound particles were observed associated with gut-associated lymphoid tissue in the small and large intestine.     

Immunoglobulin containing cells in the tracheobronchial tree of cattle: relationship to age

The cells of the pulmonary immune system of cattle were examined using an immunoperoxidase technique to identify cytoplasmic immunoglobulins. Cells reacting immunohistochemically with bovine IgG1, IgG2, IgA and IgM antisera were quantified in formalin-fixed paraffin embedded tissues from systematically selected sites within the tracheobronchial tree. Non-pneumonic lungs were selected for study from five groups of cattle which ranged in age from neonatal calves to aged adult cattle. Age associated differences were found. Neonatal calves lacked immunoglobulin containing cells (ICC). The numbers of ICC in 18-month-old cattle were significantly greater than in other age groups. The relative frequency of each immunoglobulin class among the cells of the airway mucosa was IgA greater than IgG1 greater than IgG2 greater than IgM for all cattle four months and older (n = 20) with an IgA to IgG1 ratio of 3.46. All airway categories from trachea to bronchiole had similar proportions of cells in each immunoglobulin class although the cell density declined in the distal airways.     

Larynx-associated lymphoid tissue (LALT) in young cattle

This paper describes the presence of lymphoid tissue in the mucosa of the bovine larynx. A total of 15 bovine larynges were examined both macroscopically after tissue fixation in acetic acid and microscopically using histology. It was found that no paraepiglottic tonsil was present in cattle, although a few lymphoid follicles were present in the mucosa at the base of the epiglottis. This result is in accordance with previous reports. In contrast, numerous lymphoid follicles were seen in the mucosa of the epiglottis and the corniculate processes of the arytenoid cartilages. This suggests that larynx-associated lymphoid tissue is present in cattle. Our observation could be of clinical importance, e.g. in the framework of the development of aerosolized vaccines.     

Brain emboli in the lungs of cattle

There is no information whether the BSE agent is introduced into the human food chain through contamination of the lungs of cattle with central nervous system tissue (CNS). Studies in the United Kingdom and in the USA showed that CNS tissue could contaminate the lungs after using pneumatic powered air injection stunners (e.g. "The Knocker") or after pithing. Thus, pithing was forbidden in the European Union since January 2001. In German abattoirs conventional cartridge-fired stunners (e.g. model by Schermer) are usually applied. Pithing was used up to December 2000 in approx. 75% of the German abattoirs. In the present study 323 lungs of cattle were analysed for CNS. The lungs were derived from cattle exclusive stunned by use of the knocker from Schermer. 60% of the lungs contained emboli which were tested with immuno chemistry as well as immuno histochemistry to detect CNS. Two of 108 pooled samples showed a faint immuno reaction in the anti-NSE and anti-GFAP immunoblot. Further two particles showed a faint reaction for NSE and GFAP in immuno histochemistry, thus suggesting the presence of CNS. Even though CNS tissue could not be shown in the histological investigation, we used our findings to estimate the worst case scenario for human BSE exposure risk (HER) by lung contaminated by CNS emboli. The content of CNS in the samples was estimated to be about 0.11% when the respective immuno reactions were calibrated against standards containing known brain concentrations. Under the assumption that only one lung in the pooled samples was contaminated with BSE-infected central nervous tissue, the HER was calculated to reach a maximum of 2.2 x 10(-5) CoID50/consumer after consumption of a sausage with a portion of 10% lung. The results of our study suggest that the contamination of the lung with CNS after using a conventional cartridge-fired stunner cannot be excluded, however, the incidence appears to be very low. In addition, presumed CNS emboli, if at all, are microscopically small. Furthermore the incidence of BSE in Germany is very low and lungs of cattle are usually not consumed. Thus we can judge the potential for human oral exposure after consumption of lungs of cattle which were stunned in Germany to be extremely low. A final assessment, however, is impossible as there is no knowledge about the minimum infectious dose for humans.     

The relationship of maxillary cheek tooth development to age in young Friesian cattle.

Radiographs were taken of both the right and left sets of maxillary teeth in 23 Friesian cattle of known age. The stage of development of each permanent tooth was ascertained and the degree of root resorption in the deciduous premolars was noted. All stages in individuals were later than for those of the mandibular cheek teeth except in the case of the first permanent premolar. As with mandibular cheek tooth development stages of formation occurred within certain age limits.     

M cells and associated lymphoid tissue of the equine nasopharyngeal tonsil

The aim of this study was to characterise the morphological and histochemical features of equine nasopharyngeal tonsillar tissue. Nasal and oropharyngeal tonsillar tissue has been described as the gatekeeper to mucosal immunity because of its strategic location at the entrance to the respiratory and alimentary tracts. A combination of light, scanning and transmission electron microscopy has revealed the presence of follicle-associated epithelium (FAE) overlying lymphoid tissue of the equine nasopharyngeal tonsil caudal to the pharyngeal opening of the guttural pouch. Membranous microvillus (M) cells were identified in the FAE on the basis of short microvilli, an intimate association with lymphocytes, cytoplasmic vimentin filaments and epitopes on the apical surface reactive with lectin GS I-B4 specific for alpha-linked galactose. CD4-positive lymphocytes were scattered throughout the lamina propria mucosae as well as forming dense aggregates in the subepithelial part. The central follicular area was heavily populated with B lymphocytes and the dome and parafollicular areas contained both CD4- and CD8-positive lymphocytes. CD8-positive lymphocytes were also present in the epithelium and, together with B lymphocytes, in small numbers in the lamina propria mucosae. These observations indicate that the nasopharyngeal tonsil is potentially an important mucosal immune induction site in the horse and an appropriate target for intranasally administered vaccines.     

Expression of Toll-like receptor 9 (TLR9) in the lungs and lymphoid tissue of pigs

The pattern of distribution of Toll-like receptor 9 (TLR9) in different tissues varies between species. The aim of the present study was to describe the distribution of TLR9 expression in selected tissues and organs of healthy pigs at 3 weeks and 3 months of age. Representative formalin-fixed samples of lung, thymus and secondary lymphoid tissues were evaluated by immunohistochemistry. TLR9 positive staining was observed in epithelial cells, vascular endothelium and myoepithelial-like cells, as well as in cells of the alveolar septa of the lung. Antigen presenting cells of perifollicular zones (interdigitating, macrophage and dendritic-like cells) of the Peyer's patches, lymph nodes, spleen and thymus were also immunoreactive for TLR9. No differences were seen in TLR9 protein expression in tissues from the two age groups.     

Mandibular cheek tooth development and its relationship to age in young Friesian cattle.

The oral and intra-osseous development of each of the six manidibular cheek teeth found in the permanent dentition of cattle was studied. The animals used were all British Friesians, of varying sex, and slaughtered at different weights at ages between 13 and 22 months. The various stages of development observed in each tooth together with the mean age and age range at which they were seen are recorded. Significant differences were found between the ages at which several of the developmental stages were seen in most of the teeth and indicated that tooth formation in the Friesian cattle studied tended to fall within well defined age limits.     

The relationship of age and stage of gestation to the incidence of embryo death in dairy cattle

Milk progesterone concentrations were measured thrice-weekly in approximately 200 autumn-calving cows of NIRD dairy herds in each of two successive years, about 100 being common to both years. From this, it was concluded that embryo death, later than the 14th day after artificial insemination occurred in about 10% of cows of each year. Most of the deaths occurred around the 35th day after AI, the time when the fetal membranes are becoming attached to the uterine wall. The incidence of embryo death around this time increases with age of cow.     

Characterization of the diffuse mucosal associated lymphoid tissue of feline small intestine

Characterization of the feline intestinal mucosal associated lymphoid tissue (MALT) will facilitate investigation of intestinal disease in the cat and promote the cat as an animal model for a range of human diseases which involve the intestinal lymphoid tissue. This includes inflammatory bowel disease, viral and non-viral associated intestinal lymphomas and immunodeficiency associated syndromes. Morphologic and phenotypic characterization of the normal small intestinal diffuse MALT in 22 SPF cats was performed using flow cytometry and cytology on isolated intestinal leukocytes from the intra-epithelial and lamina proprial compartments, as well as immunohistology on tissues from the feline duodenum, jejunum and ileum. The intra-epithelial compartment (IEC) was dominated by lymphocytes (>85%) which frequently contained intracytoplasmic granules. The most striking findings in the IEC were the elevated percentages of CD8 alpha+ lymphocytes (40%), presumed to express CD8 alpha alpha chains, and CD4-/CD8- (double negative) lymphocytes (44%), and the consistent presence of a minor subpopulation of CD3+/CD11d+ IELs (6%). Small percentages of CD4+ lymphocytes (10%) were observed such that the IEL CD4:CD8 ratio (0.25) was low. The LPC also contained a majority of T cells and few plasma cells. However, this compartment had reduced percentages of CD8 alpha+ lymphocytes (28%) and increased percentages of CD4+ lymphocytes (27%) relative to the IEC. However, the LPL CD4:CD8 ratio (1.0) remained low compared with the ratio in peripheral blood. In feline MALT, MHC class II expression was lower than in other peripheral lymphoid compartments. The results of this study provide important reference values for future investigations involving feline intestinal lymphocytes and demonstrates that the leukocyte distribution and phenotypic characteristics of the feline diffuse MALT appear largely similar to the murine, rat and human counterparts.     

Perinatal development of lymphoid tissue and its associated epithelium in the ovine pharyngeal tonsil: a morphological study

The perinatal development of lymphoid tissue and its associated epithelium in the pharyngeal tonsil of sheep was investigated by light and electron microscopy. The lymphoid cells first appeared in the subepithelium in a scattered form at about 92 days gestation. These cells proliferated rapidly during the last trimester of gestation, and had formed many dense aggregates at the time of parturition. At birth, the epithelium overlying the aggregates was extensively infiltrated with lymphocytes and showed early transformation of follicle-associated epithelium. The lymphoid tissue and its associated epithelium did not, however, fully develop until after birth, when well-differentiated follicle-associated epithelium and lymphoid follicles with vigorous lymphopoiesis were present. In 1-2 week old lambs, these structures were ultrastructurally similar to those seen in adult sheep although their size was smaller. The results of this study suggest that the lymphoid tissue of the ovine pharyngeal tonsil and its associated epithelium are morphologically ready to cope with antigens in the extra-uterine environment at birth, but that their full development and maturation are dependent postnatal antigen stimulation.     

Perinatal development of lymphoid tissue and its associated epithelium in the ovine pharyngeal tonsil: A morphological study

The perinatal development of lymphoid tissue and its associated epithelium in the pharyngeal tonsil of sheep was investigated by light and electron microscopy. The lymphoid cells first appeared in the subepithelium in a scattered form at about 92 days gestation. These cells proliferated rapidly during the last trimester of gestation, and had formed many dense aggregates at the time of parturition. At birth, the epithelium overlying the aggregates was extensively infiltrated with lymphocytes and showed early transformation of follicle-associated epithelium. The lymphoid tissue and its associated epithelium did not, however., fully develop until after birth, when well-differentiated follicle-associated epithelium and lymphoid follicles with vigorous lymphopoiesis were present. In l–2 week old lambs, these structures were ultrastructurally similar to those seen in adult sheep although their size was smaller. The results of this study suggest that the lymphoid tissue of the ovine pharyngeal tonsil and its associated epithelium are morphologically ready to cope with antigens in the extra-uterine environment at birth, but that their full development and maturation are dependent on postnatal antigen stimulation.     

结膜相关淋巴组织和哈氏腺免疫协同关系的研究Ⅰ．结膜相关淋巴组织缺失对哈氏腺点眼免疫应答的影响

采用ＥＬＩＳＡ、免疫组织化学方法、手术切除结膜相关淋巴组织（Ｃｏｎｊｕｎｃｔｉｖａ－ａｓｓｏｃｉａｔｅｄ Ｌｙｍｐｈｏｉｄ Ｔｉｓｓｕｅ，ＣＡＬＴ）法对结膜相关淋巴组织和哈氏腺（Ｈａｒｄｅｒｉａｎ Ｇｌａｎｄ，ＨＧ）在点眼免疫应答过程中的相互协同关系进行了研究。研究发现，采用外科手术于１日龄切除结 膜相关淋巴组织后切除组点眼免疫后泪液中ＮＤＶ－特异性ＩｇＡ、ＩｇＭ型抗体滴度及哈氏腺中ＩｇＡ、ＩｇＭ     

Electron microscopic studies on conjunctiva associated lymphoid tissue (CALT) in Angora goats

The purpose of this study was to investigate the electron microscopic structure of conjunctiva associated lymphoid tissue (CALT) and to determine the uptake of macromolecules from follicle associated epithelium (FAE) of Angora goats. The sample tissues taken from lower and upper eyelids of ten 5-6 month-old healthy Angora goats were used in this study. The conjunctiva associated lymphoid tissue of Angora goats was formed by solitary or aggregate lymphoid follicle and follicle associated epithelium which cover these follicle. FAE was formed by flattened epithelial cells, lymphocytes, monocytes and polymorph nuclear leukocytes but no goblet cells. Ferritin particles were seen on the apical surface, in the invaginations, vesicles, vacuoles of flattened epithelial cells. It was concluded that these epithelial cells were specialized to uptake macromolecules.     

Ultrastructure of nuclear membrane pockets in lymphoid cells in cattle

In comparison with the cells of lymphoreticular tissue in a normal lymph node, the lymphoid cells of a tumorous lymph node in cattle suffering from lymphatic leucaemia show a high occurrence of nuclear pockets. The pockets protrude above the nucleus surface and contain cytoplasmic particles. The wall of a nuclear pocket on the outer side of the nucleus consists of two complete nuclear membranes with an inter-layer of highly condensed heterochromatin. The structure of the nuclear pocket wall documents the origin of the pockets from secondary connection of the plicae of the nuclear membrane and enclosing of part of cytoplasm in the pocket.     

Distribution of the lingual lymphoid tissue in domestic ruminants

The distribution and organisation of the intralingual lymphoid tissue was studied in sheep, goat and cattle. For each species, the tongues of two animals were harvested and divided in sample blocks extending over the total surface of the tongue. With 2.5 mm intervals, ten serial histological sections were made for conventional histological staining (haematoxylin-eosin, Van Gieson, Masson's trichrome) and immunohistochemical staining of lymphoid cells (anti-CD3, anti-CD21, anti-CD45). Lymphocytes were scattered in the subepithelial propria-submucosa and in the connective tissue cores of the lingual papillae. The connective tissue cores of fungiform papillae, including those located on the lingual apex, and vallate papillae showed relatively more lymphocytes than the propria-submucosa. Lymphoid cell aggregations were even more abundant beneath the grooves surrounding the vallate papillae in small ruminants. In cattle, a well-organised lingual tonsil was additionally found at the root of the tongue. CD3-positive lymphocytes were observed in all species examined. CD21-positive lymphocytes were numerous in the lymphoid nodules of the bovine lingual tonsil but very scarce in the ovine and caprine tongues. Therefore, the lymphoid cell aggregations in the tongues of small ruminants should not be referred to by the term 'lingual tonsil'.     

Inverse age resistance to experimental Babesia divergens infection in cattle

Two groups of calves, 1.5-2 and 7-11 months old respectively, and dairy cows were inoculated i.v. with 3 x 10(7) erythrocytes infected with Babesia divergens. High parasitaemia, fever and other clinical signs of babesiosis occurred among adult animals. A very low parasitaemia and a slightly increased body temperature but no other symptoms occurred in calves. these findings substantiate the conclusion that there exists an inverse age resistance against Babesia divergens. The kinetics of B. divergens IgG antibody formation were similar in all age groups. Consequently this antibody response was not the factor determining the development of the primary parasitaemia and thus the inverse age resistance phenomenon. However, age is not necessarily the only factor involved in the clinical expression of babesiosis. The kinetics of antibody formation was not associated with the intensity of the parasitaemia. In fact only about half the animals had a demonstrable parasitaemia although the antibody responses were similar in all age groups.