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Results for “THYMUS GLAND”

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At least 775 records · Page 43Linked to original sources
PubMed1978

EM changes and other toxic effects of firemaster BP-6 (polybrominated biphenyls) in the mouse.

Groups of Swiss ICR mice were fed 1000 ppm polybrominated biphenyls (FireMaster BP-6) in rodent chow for 4, 8, 11, and 14 days. Control groups were fed standard rodent chow without FireMaster BP-6. Animals were killed at the end of each feeding period and the livers examined by electron microscopy. EM changes noted were progressive increase in size of hepatocytes, a decrease in rough endoplasmic reticulum, a marked increase in smooth endoplasmic reticulum, mitochondrial degeneration, increased lysosomes, and a decrease in glycogen. In addition, there was increasing proliferation of microvilli in bile canaliculi with increasing feeding times. A group of mice fed 1000 ppm FireMaster BP-6 in rodent chow for 11 days had livers with a mean of 13.93% of total body weight as compared with 6.49% for the control group (P=0.02). Tissue distribution following ingestion of 100 ppm FireMaster BP-6 for 14 days was studied. Twelve weeks post-feeding, the tissue concentrations of hexabromobiphenyl in order of highest concentration to lowest were as follows: perithymic fat, perirenal fat, adrenal glands, thymus gland, liver and stomach.

Animal Feed↗
PubMed1999

Cloning of thyrotropin-releasing hormone precursor and receptor in rat thymus, adrenal gland, and testis.

TRH is a hypophysiotropic peptide that acts mainly via the hypothalamic-pituitary-thyroid axis, but TRH immunoreactivity is also detected in several peripheral tissues. PCR with two pairs of primers enabling amplification of three fragments of TRH complementary DNA (cDNA) was used to demonstrate local production of TRH. Products of the expected size were detected in the testis, adrenal gland, lymphoid organs, thymus, and spleen. The amplified cDNA fragments were cloned and sequenced to show that the TRH gene is expressed in the thymus, spleen, and adrenal gland. Competitive RT-PCR showed that the TRH messenger RNA content of the testis was about one third that of the hypothalamus, whereas the adrenal gland contained 2% and the thymus 6%. HPLC analysis of thymus and spleen extracts showed small amounts of TRH, with a particular processing pattern of pro-TRH in lymphoid organs. The expression of the TRH receptor gene in peripheral organs was investigated to determine whether TRH had an autocrine or a paracrine action. cDNA fragments that encompassed the coding region of the receptor were identified in the testis, adrenal gland and thymus. No signal was detected in the spleen. These findings indicate that TRH may have a biological activity in extrapituitary organs and may act locally in the testis, adrenal gland, and thymus.

Adrenal Glands↗
PubMed2004

Noradrenergic responses of peripheral organs to cyclophosphamide in mice.

To determine if the chemotherapeutic drug cyclophosphamide influences the activity of the sympathetic nervous system, the effects of cyclophosphamide on norepinephrine concentration in the heart, adrenal gland, spleen, and thymus gland were evaluated. Male BALB/cByJ mice were administered a single injection of cyclophosphamide (15, 50, or 100 mg/kg, i.p) or saline-vehicle. Organs were collected 72 or 120 h after injection and norepinephrine concentrations were determined by high pressure liquid chromatography with electrochemical detection. Cyclophosphamide reduced spleen, thymus gland, and heart mass while also elevating spleen and thymus gland norepinephrine concentrations (both pmoles/mg tissue and pmoles/mg protein) in a dose- and time-dependent manner. Norepinephrine concentrations in heart and adrenal gland were not altered by cyclophosphamide at any drug dose or time point. Dose- and time-dependent cyclophosphamide-mediated changes in peripheral norepinephrine levels in the spleen and thymus gland are interesting because subjects administered cyclophosphamide may be more susceptible to opportunistic infections, not only because the drug is antineoplastic, but also because the drug alters nervous system-immune system communication and the neurochemical milieu in which surviving cells interact.

Adrenal Glands↗
PubMed2006

[Unusual non-neoplastic lesions in the "surgical pathology" of the thyroid].

This review aims to describe and assist in the categorization of most of the unusual non-neoplastic conditions, encountered in the surgical pathology of the thyroid. The conditions included are: normal intrathyroidal vestigial tissues/structures (i.e. rests of the ultimobranchial body and thyroglossal duct) and their relevant pathological derivatives (ultimobranchial body cyst, intrathyroidal lymphoepithelial cyst, thyroglossal duct cyst); mature intrathyroidal heterologous tissues/organs of either metaplastic or heterotopic origin (adipose tissue, striated skeletal muscle, cartilage, parathyroid glands, thymus, salivary gland tissue) and their relevant pseudotumoural lesions; varieties of metaplastic and non-metaplastic morphologic changes of the thyroid follicular epithelium (oncocytic, clear cell/signet ring cell, darkly pigmented cell, mucinous (myxoid), squamous, spindle cell); amyloid goiter; some reactive and/or degenerative cytologic and nuclear atypicalities (nuclear pseudoclearing and cell pleomorphism) as well as some hyperplastic or peculiar growth patterns (capsular pseudoinvasion; vascular invasion; papillary carcinoma-like and paraganglioma-like patterns) of benign conditions mimicking neoplasia; and finally. some pseudotumoural lesions of the stroma (pseudoangiosarcomatous vascular proliferation, and post-fine-needle aspiration spindle cell nodule). The pathogenetic mechanism, the morphologic interpretation, and the differential diagnosis of each of the above-listed conditions are discussed and pertinent illustrations for many of them are also provided. Lesions of thyroid tissue situated outside of the gland itself are not discussed.

Adipose Tissue↗
PubMed1982

Comparative investigation of keratin-filaments in normal tissues and tumours of skin, oral mucosa, salivary glands and thymus.

Antibodies against different fractions of keratins can be helpful in various fields of special pathology. Antibodies against "small" and "large" keratins permit to evaluate epithelial maturation in skin and oral mucosa. In addition, disturbances of keratinization during inflammatory processes and malignant transformation can be analyzed. The main application of antibodies against the entire fractions of keratins is the detection of the epithelial nature of a neoplasm. By this tool, particular problems in surgical pathology concerning differential diagnosis can be handled in an easier way. Among the different tissues and their neoplasms, examples of the analysis of thymus tumours and salivary gland tumours are presented. Immunoreactivity with keratin antibodies depends crucially on tissue processing. In the normal diagnostic procedure, good results are regularly obtained if cryostat or Bouin-fixed paraffin-embedded sections are used.

Adenoma↗
PubMed1994

Influence of environmental enrichment and sex on predator stress response in rats.

Based on sex, rats were randomly assigned to either an enriched or standard environment for 30 days prior to behavioral testing. The predator stress testing consisted of placing the rat in a cat avoidance apparatus so that the rat's behavioral response to a natural stressor, the cat, could be assessed. The rats were subsequently exposed to a partial predator stimulus (cat urine) that was placed in the home cages for 7 days. Each animal was then sacrificed and the stomach, adrenal glands, and thymus gland were removed and assessed. Results indicated that 1) the enriched rats engaged in less defensive behavior than the standard rats during behavioral testing, 2) female rats demonstrated more defensive behavioral patterns compared to male rats, and 3) the enriched environment affected females more than males, as evidenced by the interaction effects on various recorded behaviors.

Adrenal Glands↗
PubMed2003

[The annual involution and regeneration of the thymus in hibernating animals and perspectives of its studies in gerontology and stem cell proliferation].

Data on a unique phenomenon of annual involution and neogenesis of thymus gland in hibernating animals are reviewed. In accordance with morphological findings, the annual thymus involution in hibernating animals is close to the age-dependent thymus involution occurring in all mammals once in a lifetime. In opposite, thymus involution in hibernating animals is totally different from the accidental involution. During hibernation, the thymus tissue is substituted by the brown fat tissue. In the spring, thymus gland neogenesis stats with intensive growth of epithelial tissue followed by lymphocyte infiltration and exhaustion of brown tissue. Morphological changes in the thymus gland within the annual cycle were compared with seasonal dynamics of structural and functional changes in peripheral lymphoid organs (spleen, lymphoglandular, peritoneal fluid). A general regularity was observed involving a decreased functional activity of immune cells in autumn, its sharp depression during winter hibernation, and obvious increase in summer with the onset of a season of animal activity. It is supposed that a sharp increase in the tumor necrosis factor (TNF) production observed during short-term awakenings in winter may serve an important link in this unique immune adaptation mechanism. The season changes in cellular TNF secretion suggest a mobilization of protective resources in hibernating animals in autumn and winter, i.e. in seasons when the thymus gland activity is depressed. The annual involution of thymus gland cannot be related to droppings in the environmental or body temperatures, as it comes long before their fall. Additionally, it is not related to ageing, as it occurs already in young hibernating animals. The role of hormones, including melatonine and corticosteroids, in mechanisms regulating thymus gland involution in hibernating animals is discussed.

Adaptation, Physiological↗
PubMed1995

Localization of human immunodeficiency virus 1 RNA in thymic tissues from asymptomatic drug addicts.

Thymic tissue was collected from 11 human immunodeficiency virus 1 (HIV-1)-seropositive drug users who died suddenly of drug intoxication or trauma. None of the 11 individuals had symptoms related to HIV-1 infection or were known to be seropositive for HIV-1 before death. Secondary B-cell follicles were present in every thymus, and Warthin-Finckeldey giant cells were noted in three cases. These follicles were enlarged or fragmented and appeared similar to those in lymph nodes excised from the same individuals. Localization of viral RNA by in situ hybridization demonstrated abundant virus in a follicular center cell distribution within hyperplastic follicles and in scattered medullary lymphocytes. In nine thymus glands from seronegative drug addicts and five thymus glands from seronegative trauma victims who were not drug addicts, secondary follicles were absent and no hybridization signal was present. Other than the presence of germinal centers associated with HIV-1 RNA, there were no histologic differences among the thymus glands of seropositive drug addicts, seronegative drug addicts, and seronegative controls without a history of drug abuse. We conclude that the thymus gland in early stages of infection with HIV-1 is characterized by induction of secondary B-cell follicular hyperplasia in medullary tissues, the germinal centers of which contain abundant viral RNA.

Adult↗
PubMed1977

[Changes in adrenal gland and thymus induced by sex steroid administration in newborn rats (author's transl)].

Testosterone, dehydroepiandrosterone (DHEA), progesterone, estradiol-17beta, estrone, estriol, 2-hydroxyestradiol-17beta, 2-hydroxyestriol, deoxyestrone and diethylstilbestrol were injected s.c. in a dose of 0.5 mg each into newborn rats on the first day of life, and changes in the adrenal gland, thymus and spleen were examined 3 days later. Increase in the body weight during the 3 days was less in rats treated with DHEA, 2-hydroxyestriol and deoxyestrone, as compared with that in controls. Development of the thymus was significantly impaired in rats injected with various kinds of sex steroids, except progesterone and diethylstilbestrol. Reduction of the spleen weight by sex steroid treatment was not marked. The weight of adrenal gland decreased in rats injected with DHEA and progesterone, while the weight increased in those given estrone and diethylstilbestrol. Estrogens, particularly estriol, induced a marked increase in adrenal corticosterone content, while 2-hydroxyestriol caused only slight elevation and 2-hydroxyestradiol and deoxyestrone had no influence on the content. Suppressive effect of cortisol on the adrenal gland of newborn rats was slightly, but significantly, lessened by estriol treatment. From the results, physiological role of estriol and DHEA in adrenal secretion was discussed.

Adrenal Glands↗