Postnatal development of bronchus-associated lymphoid tissue (BALT) in the rat, Rattus norvegicus.

The pattern of development of bronchus-associated lymphoid tissue (BALT) in specified-pathogen-free and conventional (non-barrier maintained) rats over the initial 4 weeks of life appeared to be similar. BALT first appeared around the 2nd week of life and increased in amount over the following 2 weeks. Overlying large nodules of BALT the bronchial epithelium becomes infiltrated by lymphocytes to form a lymphoepithelium. This transformation occurs earlier in conventional rats, possibly because of the differing antigen levels to which they are exposed.     

Skull growth in the albino rat (Rattus norvegicus)

A longitudinal study of growth in the rat skull, based on serial radiographs, has shown that by the age of one month after birth, the braincase attains some 93% of its adult (fifth-month) size whilst the facial skeleton and mandible attain but 75% of their adult size. By the third month, growth in the braincase has virtually ceased, whereas significant facial growth continues until the age of five months.     

Idiopathic megaesophagus in a rat (Rattus norvegicus)

Necropsy and histopathologic examination of a rat (Rattus norvegicus) revealed megaesophagus and gangrenous bronchopneumonia. The esophageal dilitation, mural atrophy with persistence of neural structures, regurgitation and bronchopneumonia seen in this case were similar to findings in other animals with megaesophagus.     

Autosomal and sex-chromosomal polymorphism in a wild population of the Norway rat,Rattus norvegicus

The karyotypes of 33 specimens of Rattus norvegicus captured in a wild population, were studied by means of conventional Giemsa staining and G- and C-banding methods. A chromosomal polymorphism for the presence or absence of extra segments in autosomes 3 and 12 and the X chromosome was found, beside a polymorphism for centromeric C-bands in pair no. 6.The frequency of different chromosome types found in this population was compared with that found in a wild population in Japan as well as with that found in some inbred strains.     

Polymorphic microsatellite loci of the rat (Rattus norvegicus)

The EMBL and GenBank DNA databases were searched for microsatellite sequences of the rat containing dinucleotide repeats of (CA)_n and (GA)_n. Among those obtained, 23 sequences were analyzed by polymerase chain reaction to examine the size variation of the amplified fragment in inbred rat strains. All of the 23 microsatellite sequences varied in size among the strains tested. The 23 microsatellite loci in a pair of substrains separated from the same progenitor strain were then analyzed. Fragments identical in size were observed in all loci of the two substrains, indicating the stability of the microsatellite over a large number of generations. The microsatellite loci, therefore, should be useful markers for linkage analyses in the rat.     

Ovalbumin-induced immunomorphologic reaction of rat lung with emphasis on bronchus-associated lymphoid tissue (BALT)

Specific pathogen-free albino rats exposed to a series of 5 intratracheal inoculations of pure ovalbumin presented hyperplasia of main bronchi BALT-aggregates, the lymph and plasma cells infiltrated with immunofluorescent elements extending up to the distal end of the bronchial tree. The most intensely reactive alterations, particularly of perivascular proliferations rich in antibody-containing cells were observed in intramuscularly stimulated rats with ovalbumin emulsified in complete Freund's adjuvant. The lung structures of animals subcutaneously stimulated with ovalbumin solution were similar to those of controls.     

The major histocompatibility complex of the rat (Rattus norvegicus)

This review of the RT1 complex, the major histocompatibility complex (MHC) of the rat, focuses on genetic, genomic, evolutionary, and functional aspects at the molecular level. The class I, class II, and framework genes are listed. The physical map of the RT1 complex as revealed by analysis of clonal contigs is compared with the human and mouse MHC, and the degree of orthologous relationship is outlined. Elucidation of the RT1 complex provides important information for using the rat as a model of experimental transplantation and complex diseases.     

Lymphocyte subpopulations in high endothelial venules and lymphatic capillaries of bronchus-associated lymphoid tissue (BALT) in the rat

The subpopulations of lymphocytes and non-lymphoid cells in high endothelial venules (HEV) and in lymphatic capillaries surrounding lymphoid follicles in bronchus-associated lymphoid tissue (BALT) were examined by electron microscopy after preembedding the tissue and staining with an immunoperoxidase technique. The results were compared with those obtained in gut-associated lymphoid tissue (GALT) reported previously. Monoclonal mouse-anti-rat T cell, IgG, IgM, IgA, and Ia antisera were used. Plasma cells that were reactive to anti-IgG, anti-IgM, and anti-IgA were detected as cells in which the 3',3'-diaminobenzidine tetrahydroxychloride reaction product was localized in rough endoplasmic reticulum and perinuclear spaces but not on plasma membranes. These plasma cells did not occur in either lymphatic capillaries or HEV in BALT as they did in GALT. Cells with surface Ig (sIg cells), T-cell antigen (T cells), and Ia antigen (Ia cells) were present in BALT. T cells were located predominantly in the follicular area opposite the bronchial epithelium; IgM- and IgG-reactive cells were found in the follicular area adjacent to the bronchial epithelium; and IgA-positive cells were found in the lateral part of the area where the T cells were localized (T-cell area). Ia cells were abundant throughout BALT and in moderate numbers in the epithelium. A striking observation was the presence of "nurse-cell"-like structures in the periphery of BALT. The percentages of T, sIgG, sIgM, and sIgA cells in the HEV were 54.7%, 2.4%, 28.9%, and 27.3%, respectively, and in the lymphatic capillaries, 41.2%, 3.8%, 38.2%, and 21.2%, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)     

Muscular function and skull growth in the laboratory rat (Rattus norvegicus)

Bilateral masseterectomy in newly-born rats results in a diminution in cranial weight and size. Such reduction affects the facial skeleton to a greater overall extent than the braincase, although in each region it is the dimensions of length that are affected to a greater extent that are those of height or width. Such contrasts are not dependent upon changes in body weight.
Removal of both temporal muscles—a smaller component of the masticatory musculature—results in little change in cranial proportions other than an increase in width of the braincase.
Such findings can be related, first, to contrasts in the timing of growth in the braincase and facial skeleton and, second, to the extent to which muscular function is reduced.     

Low incidence of bronchus-associated lymphoid tissue (BALT) in chronically inflamed human lungs.

The relevance of bronchus-associated lymphoid tissue (BALT) in man is still under discussion. Animal experiments indicate that the development of BALT is dependent on microbial stimulation. Therefore, the incidence of BALT was investigated retrospectively in specimens removed during surgical procedures on patients with chronic pulmonary inflammation. All these patients had severe chronic bronchitis and bronchiectasis, but BALT was found in only 8%. In patients with BALT and a malignant tumor, occlusion of a bronchus with poststenotic pneumonia was always present and BALT was observed exclusively in areas peripheral to the occlusion. In man other compartments of the lung must be responsible for the immune function of BALT found in animals.     

The specificity of the high endothelial venule in bronchus-associated lymphoid tissue (BALT)

By using an in vitro binding assay, the specificity of T and B cell adherence on high endothelial venules (HEV) of bronchus-associated lymphoid tissue (BALT) was studied in the rat and the guinea pig. It was found that the adherence specificity of the BALT HEV is different from that found in Peyer's patches and more closely resembles the specificity of the HEV in mesenteric lymph nodes. The data are discussed in view of a common mucosal immune system.     

Effects of hantaviral infection on survival, growth and fertility in wild rat (Rattus norvegicus) populations of Baltimore, Maryland

Survival, growth rates, body size and fertility of wild caught Norway rats (Rattus norvegicus), infected and uninfected with a Hantavirus (antigenically related to Seoul virus), were compared. No differences were found in the survival of seronegative versus seropositive rats, as measured by mark-recapture experiments. Growth rates, as measured by weight gain but not by increased body length, were slower in seropositive, sexually mature (greater than 200 g) rats, although no differences in the ultimate body size of infected versus uninfected rats were found. No differences in external measures of sexual maturity, or in embryo counts or testes sizes, were found for infected versus uninfected rats. We conclude that hantaviral infections have little or no impact on demographic processes in Norway rat populations.     

Identification, cloning and functional characterization of novel beta-defensins in the rat (Rattus norvegicus)

Background  

beta-defensins are small cationic peptides that exhibit broad spectrum antimicrobial properties. The majority of beta-defensins identified in humans are predominantly expressed in the male reproductive tract and have roles in non-immunological processes such as sperm maturation and capacitation. Characterization of novel defensins in the male reproductive tract can lead to increased understanding of their dual roles in immunity and sperm maturation.     

Electron microscopy and microcalorimetry of the postnatal rat heart (Rattus norvegicus)

The interplay of ultrastructure and tissue metabolism was examined in neonatal, infant and adult rat hearts by electron microscopy and microcalorimetry. Morphometry was used to determine parameters of oxygen diffusion capacity (distance between capillaries and mitochondria, capillary surface density) and oxidative metabolic capacity (mitochondrial volume fraction). Thin slices and large samples of living tissue were examined calorimetrically to quantify aerobic metabolism and ischemia tolerance, respectively. After birth, rat hearts grow in parallel to body mass and show characteristics of cellular hypertrophy. Capillary surface density increases from neonatal to infant rats, and decreases to an intermediate value in adult rats. The distance between capillaries and mitochondria shows no significant changes throughout postnatal development. Mitochondrial volume fraction increases continuously until adulthood. The specific aerobic tissue metabolic rate is higher in the neonatal than in the infant and adult rat. However, the ischemic decline in metabolic rate is much slower in the neonatal rat, reflecting an elevated hypoxia tolerance. In conclusion, the neonatal rat heart exhibits a high metabolic rate despite a low mitochondrial volume fraction. The subsequent structural rearrangements can be interpreted as long-term adaptations to the increased postnatal workload and may contribute to the progressive loss of hypoxia tolerance.