Annual skeletal changes in the little brown bat,Myotis lucifugus lucifugus,with particular reference to pregnancy and lactation

Studies of bone from summer-active little brown bats, Myotis lucifugus lucifugus, have demonstrated sex differences in the renewal of skeletal mineral reserves following spring-arousal from hibernation. Patterns of bone remodeling in both sexes of bats indicate that new bone formation does not occur during hibernation: All new bone formation occurs during the summer-active season. Results show that a short period of time elapses after hibernation before the initial demands of a large fetus and rapidly growing neonate are expressed on maternal skeletal reserves. Bone loss in summer-active females was associated with pregnancy and lactation, whereas summer-active males did not show evidence of bone loss but, instead, uninterrupted bone accretion throughout the summer-active season. Osteoclasts and bone-forming osteoblasts, absent during the hibernation period, reappeared on bone surfaces following spring-arousal from hibernation. There was no apparent increase in osteoclast numbers or activity during lactation but resorption cavities were found in deep cortical lamellae distant from bone surfaces. The increase in bone resorption in lactating bats appeared to be by osteocytic osteolysis, suggesting that it might be a significant mechanism of bone/calcium regulation in this hibernating mammal throughout the year.     

A quantitative study of pituitary colloid in the bat Myotis lucifugus lucifugus in relation to age,sex, and season

Extracellular colloid accumulations were examined in pituitary glands of adult and juvenile, male and female, little brown bats, Myotis lucifugus lucifugus (Chiroptera: Vespertilionidae), collected at various times during the annual reproductive cycle. Round or ovoid periodic acid-Schiffreactive accumulations of colloid were scattered throughout the pars distalis, pars intermedia, and pars tuberalis. These accumulations were surrounded by processes of agranular “follicular” cells. The proportion of the volume of the pars distalis occupied by colloid (volume fraction) exhibited considerable variation among animals, ranging from 0.00 to 3.18% in the total sample of bats. Pituitaries of juvenile males, yearling males, and nonparous females contained significantly less colloid than those of parous females and adult males. The mean volume fraction for each of these groups suggested that colloid content increased progressively from birth through sexual maturity in this animal. In addition, the frequency distribution of colloid content measurements made in parous females and adult males provided indirect evidence that colloid continues to accumulate throughout life. No sexual dimorphism in colloid content was observed before or after sexual maturity, and colloid content did not fluctuate in relation to the annual reproductive cycle of either males or females.     

Pituitary adenoma,primary parathyroid hyperplasia and papillary (non-medullary) thyroid carcinoma

Summary An acidophilic pituitary adenoma associated with primary nodular parathyroid hyperplasia and a small papillary thyroid carcinoma was discovered at the autopsy of a 44 year old female acromegalic. The thyroid carcinoma showed evidence of lymphatic spread. Several etiopathogenetic mechanisms for the non-medullary thyroid carcinomata associated with Multiple Endocrine Neoplasia (MEN) have been postulated, since the follicular epithelium of the thyroid does not belong to the neural ectoderm derivates unlike the C-cells of the thyroid, the adenohypophysis and probably the parathyroid glands. Apart from genetic influence, or coincidence, one has to rule out carcinogenic exposure or hormonal influence. Clinically speaking, one should always consider whether malignant thyroid disease coexists with hyperplastic or neoplastic parathyroid tissue.     

Morphological and ultrastructural characteristics of the epithelial cells of the parathyroid glands]

Histochemical and ultrastructural characteristics of the main, oxyphilic and C-cells of 50 parathyroid glands of man and 105 ones of animals (rats) is presented. Types of the structure of the structure of the parathyroid glands (compact, retiform, lobular) are identified and their morphological changes under conditions of impairment of the phosphorus-calcium metabolism are described.     

Morphologic changes in the parathyroid glands in primary hyperparathyroidism]

On the basis of studies of the histological structure of 7 parathyreoadenomas removed in connection with primary hyperparathyroidism three types of their structure (trabecular, acinose, and solid) were singled out. As to their cellular composition, the adenomas could be divided into clear-cell and dark-cell adenomas (of main cells), oxyphilic adenomas, and adenomas of C-cells. The same cells (predominantly main clear cells) were found in the 9 studied hyperplastic parathyroid glands. Certain differences between the ultrastructure of cells of parathyreoadenomas and that of the hyperplastic parathyroid glands were established.     

Zur Ultrastruktur der Rattenepithelkörperchen bei Normo-, Hyper- und Hypocalcämie

Summary The functionally mediated ultrastructural changes of the parathyroid glands were studied in normocalcemic, hypercalcemic, and hypocalcemic rats. Hypercalcemia was induced by administration of parathyroid hormone or dihydrotachysterol. Hypocalcemia resulted from calcium deficient diet, calcium and phosphate deficient diet, ferric-glycerophosphate injections, and administration of thyrocalcitonin.Suppression of parathyroid gland activity by hypercalcemia is correlated with a relative increase of clear chief cells and straight cell membranes. There is a decrease of ribosomes in general and the ergastoplasmic tubules also lose their attached ribosomes. The endoplasmic reticulum and the Golgi apparatus are reduced in size. Parathyroid glands stimulated by hypocalcemia are morphologically characterized by a predominance of dark chief cells with increased cytoplasmic indentations. There is also an increase of ribosomes, granular endoplasmic reticulum and Golgi apparatus.Inclusion bodies, measuring 150 to 300 mµ in diameter and containing loose granular material, are considered to be prosecretory granules. Inclusion bodies measuring about 600 mµ in diameter, limited by a membrane and containing dense fine granular material, are believed to be hormonal storage granules. It is suggested that the fine granular material of these hormonal storage granules is degraded by lytic enzymes after incorporation of small cytoplasmic vesicles. Based on the analysis of the reported morphological findings and biochemical data from the literature, it is thought that the storage of hormone plays only an unimportant role in parathyroid function. A close functional relationship seems to exist between actual hormonal requirement, hormone synthesis, and cellular hormone secretion without a significant latency period.Stimulation or inactivation of parathyroid glands is regulated merely by the degree of hypocalcemia or hypercalcemia and is unrelated to the different experimental conditions. Apparently there is only an indirect interdependance between the parathyroid gland and the C-cells of the thyroid gland by way of the plasma calcium level. Specific changes in the parathyroid cells after administration of thyrocalcitonin were not observed.

---

---

Mit Unterstützung durch die Deutsche Forschungsgemeinschaft.     

Hypercalcemia in dogs with lymphosarcoma. Biochemical, ultrastructural, and histomorphometric investigations

Dogs with lymphosarcoma and hypercalcemia had decreased trabecular bone volume and increased osteoclastic osteolysis, whereas dogs with lymphosarcoma that were normocalcemic did not have increased bone resorption. Increased osteoclastic resorption was present only in bone from hypercalcemic dogs that contained neoplastic tissue but not in bone free of tumors, suggesting that the factor(s) responsible for stimulating bone resorption were elaborated locally by the tumor tissue. Hypercalcemic dogs with lymphosarcoma had decreased concentrations of plasma immunoreactive parathyroid hormone and serum 1,25-(OH)2D compared with normocalcemic dogs with lymphosarcoma and control dogs with and without other neoplasms. Immunoreactive parathyroid hormone was not detected in lymphosarcoma tissue. The plasma concentration of 13,14-dihydro-15-keto-prostaglandin E2 (PGE2M) was increased approximately 2-fold in hypercalcemic dogs with lymphosarcoma as compared with other groups. Urine excretion of calcium, phosphorus, and hydroxyproline were increased in hypercalcemic dogs with lymphosarcoma. Ultrastructurally, lymphosarcomas were composed of tumor cells with large nuclei and a paucity of cytoplasmic organelles. Light and electron microscopic examination of parathyroid glands revealed inactive or atrophic chief cells in dogs with lymphosarcoma and hypercalcemia. The increased osteoclastic bone resorption in hypercalcemic dogs with lymphosarcoma was not mediated by increased circulating levels of immunoreactive parathyroid hormone and 1,25-(OH)2D but was dependent upon infiltration of bone marrow by neoplastic cells and, presumably, the local production of a bone resorption-stimulating factor.     

The structural reorganization of the calcium-regulating glands in body adaptation to high altitude]

The parathyroid cells and thyroid C-cells were studied morphologically, morphometrically and electron microscopically at the altitude of 3200 m. The increase of functional activity of both parathyroid cells and thyroid cells was observed starting from the 7th day of being at the high altitude. This was manifested in the increase of C-cell number, their size and ultrastructurally in the cell organelles hyperplasia and hypertrophy. As distinct from the normal altitude, high activity of the parathyroid cells was not compensated by an increased function of C-cells, this dysfunction resulting in a high blood level of calcium which may serve as a criterion of this hormonal system adaptivity and as an index of a new level of calcium homeostasis.     

Effect of ethane-1-hydroxy-1,1-diphosphonate (EHDP) on the ultrastructure of parathyroid glands and plasma immunoreactive parathyroid hormone in pregnant cows fed a low calcium diet.

The long term (70 days) effects of administering ethane-1-hydroxy-1,1-diphosphonate (EHDP) (4 mg. per kg. per day) on parathyroid function was investigated in pregnant cows fed a low calcium diet. Serum calcium and phosphorus were significantly lower at parturition and postpartum in EHDP-treated cows compared to pregnant control cows fed the low calcium diet. Plasma immunoreactive parathyroid hormone levels were similar prepartum, at parturition, and postpartum in cows administered EHDP and control cows. Immediately available calcium reserves were greater preparation in control cows than in cows receiving EHDP as indicated by a more rapid rate of return of serum calcium toward normal levels following ethylenediaminetetraacetic acid (EDTA)-induced hypocalcemia approximately 10 days prepartum. EHDP-treated cows responded to the hypocalcemic challenge with similar changes in plasma immunoreactive parathyroid hormone levels as in control cows; however, urinary hydroxyproline excretion increased at certain intervals only in control cows. Ultrastructurally, chief cells in parathyroid glands of both groups of cows were in an active stage of the secretory cycle with well developed organelles concerned with hormonela synthesis. Chief cells in cows administered EHDP were degranulated and contained fewer secretory granules in response to the hypocalcemia than those in control cows. Chief cells in EHDP-treated cows often had prominent perinuclear accumulations of microfilaments, scattered vacuolated mitochondria, and lysosomal bodies in the cytoplasm. Thyroid C-cells were densely granulated and thyroid calcitonin content was similar in both groups of cows. The principal defect in calcium homeostasis of EHDP-treated cows appeared to be an impairment both in bone calcium mobilization and bone matrix catabolism in response to the secretion of parathyroid hormone. In vitro uptake of 45Ca by duodenal mucosa and urinary excretion of cyclic adenosine monophosphate were similar in both groups of cows. The ability of the parathyroid glands to synthesize and secrete parathyroid hormone in response to hypocalcemia induced either by EDTA or associated with parturition was not impaired by the administration of EHDP.     

Changes in leydig cell activity during the annual testicular cycle of the bat Myotis lucifugus lucifugus: Histology and lipid histochemistry

Changes in Leydig cell histology and testicular sudanophilic lipids were examined in relation to spermatogenic activity in the bat Myotis lucifugus lucifugus (Chiroptera: Vespertilionidae) throughout the annual cycle in the northeastern United States. These changes were correlated with annual variations in plasma testosterone concentrations which have recently been described for this species. Gametogenic activity occurred during the months of May-August when bats were metabolically most active. During hibernation (October-April), when sperm are stored in the epididymides, and accessory glands are hypertrophic, the seminiferous tubules were at rest, and the germinal epithelium was reduced to reserve spermatogonia and Sertoli cells. Based on their structure and cyclic pattern of sudanophilic lipids, Leydig cells exhibited a pattern of activity that closely paralleled that of the seminiferous epithelium. On renewal of spermatogenesis in spring, Leydig cells became hypertrophied and accumulated lipid inclusions. These inclusions, seen as vacuoles in plastic sections and sudanophilic droplets in frozen sections, reched maximal accumulations in late June. In late July and during August, when peak testosterone levels occur in blood, lipid droplets were dramatically depleted, and Leydig cells were weakly sudanophilic. In September, when testosterone titers return to low baseline levels, Leydig cells had regressed but exhibited a marked increase in sudanophilic inclusions which appeared to be mostly lipofuscins. During the ensuing mating and hibernation periods, Leydig cells were involuted and filled with lipofuscins. During the periarousal period, however, Leydig cells became weakly Sudan-positive while many large, intensely sudanophilic cells were scattered throughout the interstitium. In electron micrographs these cells were identified as macrophages. They appear to play an important role in the annual testicular cycle by phagocytizing the residues of Leydig cell involution in preparation for a new steroidogenic cycle. Seasonal changes in lipid inclusions were also observed in the seminiferous tubules. In addition, the relationship of the Leydig cell cycle to androgen action and the accessory organs in this bat is discussed.     

Reduced free-radical production and extreme longevity in the little brown bat (Myotis lucifugus) versus two non-flying mammals

The extended longevity of bats, despite their high metabolic rate, may provide insight to patterns and mechanisms of aging. Here I test predictions of the free radical or oxidative stress theory of aging as an explanation for differences in lifespan between the little brown bat, Myotis lucifugus (maximum lifespan potential MLSP=34 years), the short-tailed shrew, Blarina brevicauda (MLSP=2 years), and the white-footed mouse, Peromyscus leucopus (MLSP=8 years) by comparing whole-organism oxygen consumption, hydrogen peroxide production, and superoxide dismutase activity in heart, kidney, and brain tissue. Mitochondria from M. lucifugus produced half to one-third the amount of hydrogen peroxide per unit of oxygen consumed compared to mitochondria from B. brevicauda and P. leucopus, respectively. Superoxide dismutase (SOD) activity did not differ among the three species. These results are similar to those found for birds, which like bats have high metabolic rates and extended longevities, and provide support for the free radical theory of aging as an at least partial explanation for the extreme longevity of bats.     

Developmental change in expression of highly polysialylated neural cell adhesion molecule in C-cells in rat thyroid gland

The expression of the neural cell adhesion molecule (NCAM), highly polysialylated NCAM, and Ecadherin was immunohistochemically studied in the calcitonin-producing cells (C-cells) of developing and adult rat thyroid glands of varying ages. In fetal and neonatal rat thyroids, almost all the C-cells displayed immunoreactivity for highly polysialylated NCAM, whereas most of the follicular cells were negative. The highly polysialylated NCAM-positive C-cells markedly decreased in number between 5 and 14 days after birth. From day 14 onward, immunoreactivity for highly polysialylated NCAM was almost negative in thyroid glands. On the other hand, the expression of immunoreactivity for NCAM peptide persisted in thyroidal C-cells throughout the life span. These results suggest that conversion of the highly polysialylated NCAM into a less sialylated form occurs in the thyroid C-cells between postnatal days 5 and 14. Intense immunoreactivity for E-cadherin was observed in the entire cell surfaces of all the C-cells and follicular cells in the rats of all ages tested. In the course of thyroid organogenesis, C-cells transiently form a cell mass, an ultimobranchial body, which is fated to disappear as the C-cells migrate diffusely into the thyroid. The duration of the polysialic acid expression in the C-cell surfaces appears to coincide with the period of C-cell migration. It is possible that the expression of highly polysialylated NCAM allows the C-cells to migrate into the thyroid by reducing the cell-to-cell adhesion of C-cells with adjacent C-cells and/or with the surrounding follicular cells.     

A longitudinal study of short- and long-term activity levels in male and female spontaneously hypertensive,Wistar-Kyoto,and Sprague-Dawley rats

The pattern of locomotor activity across development was assessed in male and female spontaneously hypertensive (SHR), Wistar-Kyoto (WKY), and Sprague-Dawley (SD) rats. Open field activity did not indicate hyperactivity in the SHR. Instead, the SD strain was generally more active. Strains and sexes did not differ in open-field locomotor response to drug challenges. When short-term (10-12 min) activity in different apparatuses was compared, the SD were most active in the open field, the SHR in the residential figure-eight maze, and the WKY in the running wheel. Long-term tests indicated hyperactivity in the SHR in the residential figure-eight maze and hypoactivity in the SD in the running wheels. Until such strain differences in activity are thoroughly defined, the use of the SHR as a model of attention-deficit/ hyperactivity disorder is limited.     

Effect of low calcium diet on the ultrastructure of the rat parathyroid gland

Young female rats were fed with normal (1.18%) or low (0.05%) calcium diet for 3, 7, 15 or 30 days. The morphology of the parathyroid glands was studied together with serum calcium, parathyroid hormone (PTH), calcitonin and bone mineral density (BMD). As compared to the animals fed with the normal calcium diet, BMD of whole body of the rats fed with the low calcium diet was significantly decreased, whereas the serum PTH level was increased. The parathyroid glands in the rats fed with the low calcium diet were markedly enlarged. In the parathyroid chief cells of the rats fed with the low calcium diet, the Golgi complexes and the cisternae of the granular endoplasmic reticulum were well developed, while the large granules and large vacuolar bodies decreased. Some secretory granules located near the plasma membrane. A proportionally larger increase of the cytoplasm was estimated in the rats fed with the low calcium diet for three and seven days. Enlargement of the cytoplasm and rather frequent mitoses of the chief cells were observed in the rats fed with the low calcium diet for 15 and 30 days. These findings suggest that the rapid bone loss in young rats induced by the low calcium diet is essentially due to stimulated activity of the parathyroid gland. The stimulated gland may be a result of hypertrophy at the early stage and a combination of hypertrophy and hyperplasia at the later stage of calcium deficiency.     

Flow cytometric DNA analysis of benign hyperfunctioning parathyroid glands: significant difference in the S phase fraction and proliferative index between adenomas and hyperplasias

AIMS: Flow cytometric DNA analysis was performed to measure the DNA content of benign parathyroid tumours in patients with primary hyperparathyroidism. METHODS: DNA analysis of paraffin-embedded parathyroid samples was performed on 51 parathyroid glands from 29 patients after parathyroidectomy. Histopathology showed parathyroid adenoma in 25 cases and hyperplasia in four patients. DNA ploidy status, DNA index (DI), percentage of cells in S phase and proliferative index (PI) were determined. RESULTS: Normal cells from normal glands were all diploid. DNA cytometry showed 12 aneuploid and 13 diploid adenomas. There were 12 diploid and four aneuploid hyperplastic glands. Incidence of aneuploid DNA histograms did not show a statistically significant difference between adenomas and hyperplasias (P=0.216). Mean S phase fraction was 3.45% in adenomas and 1.53% in hyperplasias (P= 0.015). Mean PI was 6.48% in adenomas and 2.78% in hyperplastic parathyroid glands. This difference was statistically significant (P=0.006). Diploid cases had a mean PI of 4.78% and aneuploid glands a mean PI of 7.7% (P=0.08). Aneuploid DNA content did not reveal statistically significant correlation with age, gender, pre-operative Ca, alkaline phosphatase, i-PTH levels, and tumour size. The mean S phase fraction and PI were 2.25% and 4.78% in diploid glands, and 4.5% and 7.7% in aneuploid cases. CONCLUSION: Aneuploid DNA content may be present in benign parathyroid diseases, but not in normal parathyroid glands. Aneuploid DNA histograms and higher PI occur more often in adenomas compared with hyperplasias, but the nuclear DNA analysis is unable to make a distinction between adenomas and hyperplasias.     

Regulation of calcitonin and parathyroid hormone secretion by oestrogens

Calcitonin is a peptide hormone secreted by C-cells which, in humans, are found mainly in the thyroid gland. It now seems that a major physiological function of this hormone in man is the long-term maintenance of the skeleton achieved by control of bone resorption. A marked sex difference in circulating calcitonin levels normally exists, with a relative deficiency in women as compared to men.It has now been found that oestrogens regulate calcitonin secretion and it appears likely that the loss of ovarian function at the menopause accelerates the natural decline in calcitonin secretion which occurs with age. Thus, post-menopausal women are more markedly calcitonin-deficient.Levels of the bone-resorbing hormones, parathyroid hormone (PTH) and 1,25 dihydroxyvitamin D are not elevated post-menopausally and it seems likely that the increased bone resorption which leads to post-menopausal bone loss is due mainly to the loss of oestrogen and calcitonin secretion.     

Enzymohistochemical and immunomorphological study of experimental thyroid gland carcinoma]

A total of 8 medullary carcinimas, 134 adenomas of C-cells, 32 solid focal over-growths of C-cells, and 124 normal thyroid glands of rats were investigated by histochemical, immunomorphological and histological methods. Modullary carcinomas were characterized by a high enzymes of hydrolysis of ethers of carboxylic acids, tissue respiration, and by a moderate or low activity of enzymes of the initial link of glycolysis, oxidative deamination, synthesis of amino acids, hydrolysis of monoethers of orthophosphoric acid, pentose and citric acid cycles. In medullary carcinomas, as well as in normal C-cells and adenomas of C-cells, there was revealed the phenomenon of occult metachromasia with the absence of a microsomal tissue-specific antigen and direct reaction to amyloid. The authors consider medullary carcinomas to be analogues of solid carcinoma with amyloidosis of the stroma of the human thyroid gland, differing from the latter by specific metabolic reactions, and therefore, they may serve as an experimental model in studies of these diseases.     

Parathyroid function in rats treated with growth hormone

Summary Male rats weighing 220–250 g were injected i.m. daily with 0.1 mg commercial human growth hormone for 3 days or 12 days. The serum concentration of total calcium, phosphorus and alkaline phosphatase were significantly elevated for some days and returned to normal values at the end of the test period. The parathyroid glands, as studied by light and electron microscopical morphometry showed signs of reduced activity at the 4th day and also at the 13th day: a lowered nucleo-cytoplasmic ratio and a decrease of rough endoplasmic reticulum, of Golgi apparatus and of plasmalemmal tortuosity. The findings suggest a hypercalcemic effect of growth hormone involving peripheral organs of calcium metabolism, especially kidney and bone, and a secondary suppression of parathyroid glands by hypercalcemia.Supported by Deutsche Forschungsgemeinschaft, SPB 34, Endokrinologie, Hamburg     

Seasonal dynamics in the numbers of parasitic bugs (Heteroptera,Cimicidae): a possible cause of roost switching in bats (Chiroptera,Vespertilionidae)

The objective of the present paper is to extend the knowledge of roosting strategies of bats and the interaction of bats with their roost ectoparasites, the bat bugs Cimex pipistrelli. The project was focussed on the potential causality of bat movements and the variation in bug numbers. For 2 years, three model bat boxes with breeding female Pipistrellus pygmaeus were monitored inside floodplain forest. After the arrival of bats in May, adults and first instars of bugs were observed in the boxes. During the lactation period in June, when the bats did not occupy the roosts, the first instar bugs died out followed by the adults. The decrease in bug numbers began only several days after the bats had left the boxes. After a month of the bats’ absence, the abundance of adult bugs decreased by half of their number. Only the eggs survived the period when the roosts were unoccupied in summer. In mid-July, after the arrival of lactating females, an increase in the number of bugs was observed. At the beginning of August, however, no new eggs were found. Although adult C. pipistrelli are able to survive the winter period in the boxes, the bats, by shifting the roosts within the vegetation season, prevent the massive reproduction of these parasites.     

Location, number and morphology of parathyroid glands: results from a large anatomical series

Surgical management of parathyroid gland disease may sometimes be difficult, due mainly to the surgeon's failure to successfully detect parathyroids in unusual locations. The records of 942 cadavers (574 men and 368 women) who underwent autopsy in the Department of Forensic Medicine in Athens during the period 1988-2009 were reviewed. In total, 3,796 parathyroid glands were resected and histologically verified. Parathyroid glands varied in number. In 47 cases (5 %), one supernumerary (fifth) parathyroid was found, while in 19 cases (2 %) three parathyroid glands found. Superior glands were larger than inferior ones. However, there was no significant difference between the genders with respect to gland size. In 324 (8.5 %) out of 3,796, the glands were detected in an ectopic location: 7 (0.2 %) in the thyroid parenchyma, 79 (2 %) in different sites in the neck and 238 (6.3 %) in the mediastinum, 152 (4.1 %) of which were found in the upper and 86 (2.2 %) in the lower mediastinum. Significant anatomical variations of normal parathyroid glands may exist regarding number and location-knowledge that is essential for their successful identification and surgical management.