Micrometer-scale structure in shark vertebral centra.

The vertebral centra of sharks consist of cartilage, and many species' centra contain a bioapatite related to that in bone. Centra microarchitectures at the 0.5-50 µm scale do not appear to have been described previously. This study examines centrum microarchitecture in lamniform and carcharhiniform sharks with synchrotron microComputed Tomography (microCT), scanning electron microscopy and spectroscopy and light microscopy. The analysis centers on the blue shark (carcharhiniform) and shortfin mako (lamniform), species studied with all three modalities. Synchrotron microCT results from seven other species complete the report. The main centrum structures, the corpus calcareum and intermedialia, consist of fine, closely-spaced, mineralized trabeculae whose mean thicknesses and spacings range from 4.5 to 11.2 µm and 4.5 to 15.6 µm, respectively. A significant (p = 0.00001) positive linear relationship between and exists for multiple positions within one mako centrum. Carcharhiniform species' and exhibit an inverse linear relationship (p = 0.005) while in lamniforms these variables tend toward a positive relationship which does not reach statistical significance (p = 0.099). In all species, the trabeculae form an uninterrupted, interconnected network, and the unmineralized volumes are similarly interconnected. Small differences in mineralization level are observed in trabeculae. Centrum growth band pairs are found to consist of locally higher /lower mineral volume fraction. Within the intermedialia, radial canals and radial microrods were characterized, and compacted trabeculae are prominent in the mako intermedialia. The centra's mineralized central zones were non-trabecular and are also described. STATEMENT OF SIGNIFICANCE: This study's novel result is the demonstration that the mineralized cartilage of sharks' vertebral bodies (centra) consists of a fine 3D array of interconnected plates (trabeculae) and an interpenetrating network of unmineralized tissue. This microstructure is radically different from that in tesserae or in teeth, the other main mineralized shark tissues. Using volumetric synchrotron microComputed Tomography, numerical values of mean trabecular thickness and spacing and their relationship were measured for nine species. Scanning electron microscopy added a higher resolution view of the microstructures, and histology provided complementary information on cartilage and cells. The present results suggest centra microstructure helps accommodate the very large in vivo strains and may prevent damage accumulation during millions of cycles of swimming-induced loading.

Antlers - Evolution, development, structure, composition, and biomechanics of an outstanding type of bone.

Antlers are bony appendages of deer that undergo periodic regeneration from the top of permanent outgrowths (the pedicles) of the frontal bones. Of the "less familiar" bone types whose study was advocated by John Currey to gain a better understanding of structure-function relationships of mineralized tissues and organs, antlers were of special interest to him. The present review summarizes our current knowledge about the evolution, development, structure, mineralization, and biomechanics of antlers and how their formation is affected by environmental factors like nutrition. Furthermore, the potential role of antlers as a model in bone biology and several fields of biomedicine as well as their use as a monitoring tool in environmental studies are discussed.

Labeling studies on cortical bone formation in the antlers of red deer (Cervus elaphus).

The formation and mineralization process of antlers, which constitute the fastest growing bones in vertebrates, is still not fully understood. We used oxytetracycline injections to label different stages of bone formation in antlers of 14 red deer between days 28 and 156 of antler growth. Results show that initially a trabecular scaffold of woven bone is formed which largely replaces a pre-existing scaffold of mineralized cartilage. Lamellar bone is then deposited and from about day 70 onwards, primary osteons fill in the longitudinal tubes lined by the scaffold in a proximal to distal sequence. Mineral apposition rate (MAR) in early stages of primary osteon formation is very high (average 2.15 µm/d). Lower MARs were recorded for later stages of primary osteon formation (1.56 µm/d) and for the smaller secondary osteons (0.89 µm/d). Results suggest a peak in mineral demand around day 100 when the extent of mineralizing surfaces is maximal. A few secondary osteons were formed in a process of antler modeling rather than remodeling, as it occurred simultaneously with formation of primary osteons. The degree of cortical porosity reflects a reduction in MAR during later stages of osteonal growth, whereas cortical thickness is determined earlier. Injections given when the antlers were largely or completely clean from velvet produced no labels in antler bone, strongly suggesting that antlers are dead after velvet shedding. The rapidity of antler mineralization and the short lifespan of antlers make them an extraordinary model to assess the effects of chemicals impairing or promoting bone mineralization.

Development of the permanent mandibular cheek teeth in fallow deer (Dama dama).

The study describes crown and root formation of the permanent mandibular cheek teeth of fallow deer from a gestational age of 22-23 weeks up to a post-natal age of 33 months. Tooth development was recorded using a scoring scheme based on morphological criteria ranging from crypt formation to completion of root growth. The morphological appearance of the enamel surface during three different stages (secretory-stage enamel, maturation-stage enamel and mature enamel) was described, and the approximate age at termination of the secretory stage of amelogenesis in the deciduous and permanent mandibular cheek teeth was determined. The data enable an age estimation of fallow deer up to 3 years of age and provide a basis for assessing the timing of stress episodes that affect tooth crown formation. This information is useful for the management of the species as well as in bioarchaeological and bioindication studies.

Enamel hypoplasia in molars of sheep and goats, and its relationship to the pattern of tooth crown growth.

Enamel is the most highly mineralized and durable tissue of the mammalian body. As enamel does not undergo remodeling or repair, disturbances of enamel formation leave a permanent record in the tissue that can be used for life history reconstruction. This study reports light and scanning electron microscope findings on hypoplastic enamel defects, and on the chronology of crown growth in the molars of sheep and goats. A marked reduction of enamel extension rates in cervical compared with more cuspal crown portions of sheep and goat molars was recorded, with formation of the cervical 25% of the crown taking about the same time as that of the upper 75% of the crown. This explains the more frequent occurrence of enamel hypoplasia in cervical compared with upper and middle crown portions. Regarding the identification of hypoplastic enamel defects by external inspection, our results suggest a dependence on the type of defect and the associated presence of smaller or larger amounts of coronal cementum. Defects considered to reflect a slight to moderate impairment of secretory ameloblast function can normally be correctly diagnosed as they are not occluded by thick layers of cementum. In contrast, defects denoting a severe impairment of enamel matrix secretion can typically not be correctly identified because they are occluded by large amounts of cementum, so that neither depth nor extension of the defects can be assessed on external inspection. In these cases, microscopic analysis of tooth sections is required for a correct diagnosis of the hypoplastic enamel defects.

How many mandibles in a mammal? A note on terminology.

This paper briefly reviews the usage of the term 'mandible' in the anatomical literature on mammals, with a focus on human and veterinary anatomy. In all analysed textbooks of human anatomy and physical anthropology as well as in several veterinary anatomy textbooks, the mandible is viewed as a single (unpaired) skeletal element composed of symmetrical (left and right) halves that correspond to the ossa dentalia of comparative anatomical terminology. Other authors, however, maintain that each mammal possesses a left and a right mandible, thus equating the mammalian mandible with the os dentale. The view of the presence of two mandibles per mammal is frequently found in textbooks of comparative vertebrate anatomy. Students of anatomy and workers from neighbouring disciplines need to be aware of the inconsistent use of the term mandible to avoid misunderstandings.

Insights from the inside: histological analysis of abnormal enamel microstructure associated with hypoplastic enamel defects in human teeth.

We studied the abnormalities in enamel microstructure associated with enamel hypoplasia in human teeth from the early medieval (5th-7th century AD) cemetery of Barbing, Germany, using light and scanning electron microscopy. The main aim of the study was to test the hypothesis that by analyzing the microstructure of fully formed enamel it is possible to reconstruct the reaction pattern of secretory ameloblasts to stress events leading to enamel hypoplasia. From the histological findings, a sequence of increasing impairment of secretory ameloblast function involving three thresholds was deduced. Surpassing of each of these thresholds is assumed to result in characteristic changes in enamel microstructure attributable to specific functional/morphological alterations of secretory ameloblasts. Based on our results we propose a model identifying the principal factors influencing the reaction of secretory ameloblasts to stress. The present study demonstrates that by including microscopic analysis in the study of enamel hypoplasia, it is possible to obtain a more complete picture of the formation of these developmental defects than is possible by inspection of crown surface features alone, and to draw more substantiated conclusions about the possible nature of developmental defects of enamel.

Deposition of cellular cementum onto hypoplastic enamel of fluorotic teeth in wild boars (Sus scrofa L.).

The nature of deposits present in hypoplastic defects of fluorotic enamel of wild boar teeth was studied by light microscopy and scanning electron microscopy. The fluorotic enamel showed different developmental abnormalities, denoting a severe disturbance of ameloblast function during the secretory stage of amelogenesis. These abnormalities included the occurrence of grossly accentuated incremental lines with associated zones of aprismatic enamel and the presence of different forms of hypoplastic defects. Two types of deposits were present on the hypoplastic enamel: cellular cementum and posteruptively acquired, presumably partially mineralized dental plaque. Coronal cementum is not normally formed in pig teeth. Presence of this tissue in fluorotic teeth of wild boars is seen as indicative of a premature disintegration of the enamel epithelium prior to the completion of amelogenesis. This was supposed to have resulted in a contact of mesenchymal cells of the dental follicle with the surface of the immature enamel and, in consequence, in a differentiation of these cells into cementoblasts. To our knowledge, this is the first study reporting the formation of coronal cementum as part of the spectrum of pathological changes in fluorotic teeth in a species whose tooth crowns are normally free of cementum.

Fluoride-induced alterations of enamel structure: an experimental study in the miniature pig.

We studied the structural changes in the enamel of mandibular third molars of miniature pigs administered a daily oral dose of 2 mg NaF (approximately 0.9 mg of fluoride) per kg body weight (added to the feed) for 1 year. The treatment period covered most of the secretory stage and the entire post-secretory stage of amelogenesis of the M(3). The enamel of the molars from the fluoride-fed pigs appeared opaque and chalky, and the erupted portions were stained brown. The underlying histopathological change was a pronounced subsurface hypomineralization of the enamel beneath a thin surface rim of higher mineral content. This enamel hypomineralization was attributed to a fluoride-induced impairment of the process of enamel maturation. The most conspicuous finding in the fluorotic enamel was the presence of numerous pit-type hypoplastic defects, denoting a marked fluoride-induced disturbance also of the secretory stage of amelogenesis. Microradiography and scanning electron microscopy revealed an enhanced incremental pattern in the outer enamel of the fluorotic molars. Typically, the bottom of larger hypoplastic defects was underlain by a broad, grossly accentuated incremental line. Occurrence of larger hypoplasias was further associated with the presence of aprismatic enamel, the formation of which was attributed to a loss of the prism-forming (distal) portion of the Tomes' processes of secretory ameloblasts. The findings in the miniature pigs closely parallel earlier observations on fluorotic enamel of free-ranging deer and wild boar from fluoride-polluted areas.

Reconstruction of a decline of ambient lead levels in the Ruhr area (Germany) by studying lead concentrations in antlers of roe deer (Capreolus capreolus).

We determined lead concentrations in antlers (n = 132) of roe bucks > or = 2 years of age, killed between 1951 and 1999 in the northern Ruhr area, Germany. The lead content of the antlers ranged between 0.6 and 19.0 mg/kg dry weight of bone, and overall markedly declined over the study period. As a consequence, mean lead levels in younger samples were always significantly (P<0.001) lower than those in older ones (for the periods: 1951-1969, 1970-1979, 1980-1989 and 1990-1999). Annual mean antler lead concentrations were positively correlated (r(s) = 0.74, P<0.001) with annual mean lead concentrations in airborne particulate matter of the Rhine-Ruhr area during the period 1974-1999. The findings of the present study underscore that roe deer antlers are well suited for a monitoring of temporal trends in environmental lead levels in a cost-effective way.

Assessing regional variation of environmental fluoride concentrations in western Germany by analysis of antler fluoride content in roe deer (Capreolus capreolus).

To assess regional variation in ambient fluoride levels, we analyzed the fluoride content of 188 antlers of roe deer (Capreolus capreolus) killed between 1990 and 1999 in 14 areas of the federal state of North Rhine-Westphalia, Germany. Individual antler fluoride concentrations ranged between 113 and 11,995 mg x F-/kg bone ash, and sample means differed significantly (p < 0.0001) among the study areas. Low average concentrations (geometric means of 262 and 277 mg x F-/kg bone ash, respectively) were found in antler samples from two control areas, located quite remote to major fluoride emission sources. The highest geometric mean fluoride content (1,677 mg x F-/kg bone ash) was recorded for an antler sample from a study area exposed to fluoride emissions from an aluminium smelter and two mineral coal-fired power stations. In eight antlers obtained from roe deer living in the direct vicinity of the aluminium smelter, fluoride values ranged between 2,067 and 11,995 mg x F-/kg bone ash, thereby demonstrating the strong impact of this emission source on its surroundings. The study showed that by analyzing antler fluoride concentrations, large-scale surveys of environmental contamination by fluoride can be performed in a standardized and cost-effective way in areas inhabited by deer. Due to its rather narrow home range, abundance, and high adaptability, the roe deer is particularly suited for such studies.

Fluoride concentrations in antler bone of roe deer (Capreolus capreolus) indicate decreasing fluoride pollution in an industrialized area of western Germany.

In order to reconstruct temporal changes in ambient fluoride levels in the industrialized Ruhr area (western Germany), we analyzed the bone fluoride content of 167 antlers of roe deer (Capreolus capreolus) killed between 1951 and 1999 in the northern part of this region. Individual values ranged between 110 and 8,178 mg F-/kg ash, and there was an overall marked decrease over the sampling period. Average bone fluoride concentrations in antlers from the periods 1980 through 1989 (geometric mean [95% confidence interval]: 1,490 [1,193-1,861] mg/kg ash) and 1990 through 1999 (753 [644-882] mg/kg ash) differed significantly (p < 0.001) and were both significantly (p < 0.001) lower than those from the periods 1951 through 1969 (3,720 [3,227-4,288] mg/kg ash) and 1970 through 1979 (2,573 [2,203-3,006] mg/kg ash). The findings are seen as indicative of a progressively reduced atmospheric fluoride deposition into the study area, caused by effective emission-control measures in Germany and neighboring countries. Because antlers are replaced annually, grow during a fixed period of some months, and are regularly collected and kept as trophies, they are well suited as monitoring units for analyzing temporal trends in environmental pollution by fluoride and other bone-seeking pollutants.

Temporal and geographical variation in skeletal fluoride content of roe deer (Capreolus capreolus) from industrialized areas in Germany.

In order to study temporal and spatial variation of environmental fluoride levels, we analyzed the mandibular bone fluoride content of 157 roe deer (age range: 1-11 years) from two industrialized regions (Ruhr area: n = 76, sampling period 1955-1998; area W of Cologne: n = 81, sampling period 1983 1998) in the federal state of North Rhine-Westphalia, Germany. Bone fluoride values (dry weight basis) ranged between 150 mg F/kg (2 year-old specimen taken in 1997) and 5724 mg F/kg (10 year-old specimen taken in 1957). In both study areas, a pronounced decline in mandibular bone fluoride concentrations occurred over the respective sampling periods. In consequence, bone fluoride content of animals (both study areas pooled) taken during the period 1990-1998 was significantly (P < 0.00001) lower than that of roe deer from the period 1955 1989, while the two animal groups did not significantly differ in age. These findings are regarded as indicative of a considerable reduction of fluoride deposition into the animals' habitats, due to effective emission control measures. Bone fluoride values for the period 1990-1998 in the roe deer from the Ruhr area significantly (P < 0.005) exceeded those of the individuals from the study area W of Cologne, while the difference in age between the two groups was not significant. In both study areas, a significant (P < 0.00001) positive correlation between age and mandibular bone fluoride content (Ruhr area: rs = 0.601; area W of Cologne: rs = 0.725) was found for animals taken during this period. The present study underscores the suitability of analyzing skeletal fluoride concentrations in wild roe deer in order to monitor the magnitude of environmental contamination by fluoride and thereby to assess the efficiency of measures taken to reduce fluoride emissions from industrial sources.

Changes in the structure of dentine from cheek teeth of deer chronically exposed to high levels of environmental fluoride.

The purpose of this study was to examine, using backscattered electron imaging, the changes occurring in the structure of the dentine including giant tubules in the teeth of deer chronically exposed to fluoride. The primary and secondary dentine was characterised by the presence of interglobular dentine and regular bands of hypo- and hypermineralised dentine. Giant tubules in the unworn teeth of animals exposed to low and high levels of fluoride were characterised by a large lumen and hypermineralised rim in which there were calcospherites. With the occlusal wear of the teeth tubules beneath the immediate surface of the exposed dentine in teeth from fluorotic animals became occluded with mineral, but in low fluoride animals some tubules at the surface were not occluded with mineral. It is suggested that mineral which occludes the tubules may come from both intrinsic and extrinsic sources. The presence of some open tubules at the immediate surface in the worn teeth of animals exposed to low fluoride suggests an extrinsic source for this mineral.

Delayed ectopic antler growth and formation of a double-head antler in the metacarpal region of a fallow buck (Dama dama L.) following transplantation of antlerogenic periosteum.

Autologous transplantation of antlerogenic periosteum to the metacarpal region of a fallow buck resulted in the formation of an ectopic pedicle within a few months after transplantation. In the following years the pedicle increased in size, but no ectopic antler development occurred. However, in the ninth year after transplantation a first antler of about 3 cm length grew from the ectopic pedicle. The hard ectopic first antler was not cast, and renewed antler growth, starting in late spring of the following year, led to the formation of a larger subsequent antler of 7.3 cm length. The latter exhibited a distal flattening (palmation) and a rudimentary basal coronet, thereby displaying morphological features typical of the subsequent antlers of fallow bucks. The results of the experiment indicate (1) that transformation from pedicle to antler growth can occur several years after pedicle initiation, when the pedicle has reached a certain threshold size, (2) that species and age specific features of antler morphology tend to be realized even in ectopic locations, and (3) that primary and subsequent antler growth was apparently triggered by cells of the pedicle periosteum, being derived from the transplanted antlerogenic periosteum. The findings thereby emphasize the importance of local factors in the control of pedicle/first antler transformation and antler morphogenesis.

Roe deer antlers as monitoring units for assessing temporal changes in environmental pollution by fluoride and lead in a German forest area over a 67-year period.

Fluoride and lead concentrations were analyzed in antlers of adult roe bucks (Capreolus capreolus) collected between 1932 and 1998 in a forest area of 800 ha, that directly borders on the eastern suburbs of Cologne (Germany). Values ranged between 158 and 3,713 mg/kg dry weight for fluoride and from 0.4 to 12.0 mg/kg dry weight for lead, and varied significantly between periods (1932-49, 1950-59, 1960-69, 1970-79, 1980-89, 1990-98). Antler bone levels of both contaminants decreased markedly during the 1980s and 1990s. As a consequence, mean fluoride and lead concentrations in antlers collected in the 1990s were significantly lower than those from all preceding periods. These findings indicate a pronounced decline in fluoride and lead pollution of the study area, which is attributed to reduced emissions from stationary sources and, in the case of lead, to the introduction of unleaded gasoline and the subsequent phasing out of leaded gasoline in Germany. Because antlers are replaced annually, grow during a seasonally fixed period of some months, and are regularly collected and kept by hunters, they are useful monitoring units for recording past and present environmental pollution by "bone-seeking" pollutants in a cost-effective way. Due to its relative abundance and its rather narrow home range, the roe deer is well suited as a monitoring species for assessing changes in ambient contaminant levels on a local scale.

Disturbed enamel formation in wild boars (Sus scrofa L.) from fluoride polluted areas in Central Europe.

The pathological alterations of enamel structure in the teeth of wild boars from fluoride polluted areas in N-Bohemia (Czech Republic) and S-Saxony (Germany) were studied on a macroscopic and a microscopic level. Mandibular bone fluoride concentration (mg F(-)/kg, dry wt; mean +/-SD, individuals <24 months of age) in the specimens from N-Bohemia (754.3+/-149.6) and S-Saxony (490.8+/-135.1) was significantly higher than that of controls (free of dental fluorosis), originating from the western part of Germany (304.7+/-91.0). Fluoride content in bulk enamel (mg F(-)/kg, ash wt) of fluorotic permanent teeth from N-Bohemia (382.1+/-165.2) and S-Saxony (125.0+/-38.3) was likewise significantly increased over that of non-fluorotic control teeth from W-Germany (33.6+/-26.7). Macroscopically, fluorosed wild boar enamel exhibited opacity and discoloration of varying extent, accentuated perikymata as well as hypoplastic and posteruptive surface defects. Microradiographic and scanning electron microscopic analyses revealed enamel subsurface hypomineralization, accentuated Retzius lines and occurrence of broad, hypomineralized incremental bands of abnormal structure underlying hypoplastic enamel surface defects. The presence of zones of aprismatic enamel was associated with these bands. Incremental bands with altered enamel structure and enamel surface hypoplasias, both denoting a severe disturbance during the secretory stage of amelogenesis, have previously been observed in rodents following acute parenteral fluoride dosing. It is concluded that in the chronically fluoride exposed wild boars periods of especially elevated plasma fluoride levels exerted an acute toxic effect on the secretory ameloblasts. A feature not previously reported from fluorosed enamel was the occurrence of canal-like structures that originated at the broad incremental bands and extended into the external enamel. The presence of these canals presumably results from a delay in the resumption of secretory activity by groups of ameloblasts following a fluoride insult. Based on experimental evidence in domestic pigs and in sheep, the overall subsurface hypomineralization of fluorosed wild boar enamel is attributed to a disturbance of enamel maturation. The distribution of fluorotic enamel changes within the dentition of the wild boars could be related to the developmental sequence of tooth formation in the species. Teeth whose crown formation took place prenatally (deciduous teeth) or largely pre-weaning (permanent first molars) exhibited no or only moderate fluorotic enamel alterations. Based on the extension of enamel surface hypoplasias along the coronoapical axes of the tooth crowns, the timing of excess fluoride exposure that caused a marked disruption of enamel matrix secretion was estimated in specimens with a known date of death. The results indicate that the wild boars had been exposed to a particularly severe fluoride impact during autumn and winter of their first year of life.

Structure and mineralisation density of antler and pedicle bone in red deer (Cervus elaphus L.) exposed to different levels of environmental fluoride: a quantitative backscattered electron imaging study.

The structure and relative degree of mineralisation of antler and pedicle bone of yearling red deer stags exposed either to low or high levels of environmental fluoride were determined by digital quantitative backscattered electron (BSE) imaging. Bone fluoride content (BFC) in antlers (845 +/- 86 mg F-/kg ash, arithmetic mean +/- S.E.M.) and pedicles (1448 +/- 154 mg F-/kg ash) of deer from a highly fluoride polluted area in North Bohemia (Czech Republic) were significantly higher (P < 0.001) than those of controls from uncontaminated regions in West Germany (antlers: 206 +/- 41, pedicles: 322 +/- 52 mg F-/kg ash). Mean (56.5 +/- 4.5%) and maximum (84.9 +/- 2.1%) mineralised bone area of the control antlers significantly (P < 0.05 and P < 0.001, respectively) exceeded the corresponding values for the N. Bohemian deer (43.3 +/- 1.3 and 73.3 +/- 1.9%, respectively), while the pedicles from the 2 groups did not differ significantly. In the pooled antler samples (n = 18), negative correlations existed between BFC and mean (r(s) = -0.62, P < 0.01) as well as maximum (r(s) = -0.69, P < 0.01) mineralised bone area. Morphological imaging revealed a decreased width and an increased porosity of the antler cortex in the N. Bohemian specimens. Mean (148.5 +/- 1.7) and maximum (154.2 +/- 1.7) BSE-signal intensities (= grey levels; range between a monobrominated (grey level 0) and a monoiodinated (grey level 255) dimethacrylate resin standard) of the antlers from the controls were significantly higher than those of the N. Bohemian deer (140.7 +/- 2.1 and 145.7 +/- 2.2, respectively; P < 0.05 for both comparisons). In the pooled antler samples, negative correlations between BFC and mean (r(s) = -0.51, P < 0.05) as well as maximum (r(s) = -0.52, P < 0.05) BSE-signal intensities were observed. No significant differences in mineralisation density parameters were found for the 2 pedicle samples, and BFC and mineralisation density of the pooled pedicles were uncorrelated. Morphological imaging revealed bone mottling (denoting increased remodelling activity) and frequent occurrence of apparently increased osteocyte lacunae in some of the pedicles from the N. Bohemian deer. It is concluded that the reduced amount of mineralised bone in, and the lower mineralisation density of, the N. Bohemian antlers resulted from a fluoride induced disturbance of bone mineralisation. The rapid growth of antlers leads both to a high mineral demand and a high rate of fluoride uptake during antlerogenesis. This, and the limited lifespan of antlers, which does not allow for a compensation of a delay in the onset or progression of the mineralisation process, renders antler bone particularly susceptible to fluoride. Antlers are therefore considered a useful model for studying fluoride effects on bone formation. Furthermore, analysis of cast antlers enables a noninvasive monitoring of environmental pollution by fluorides.

Cyproterone acetate reduced antler growth in surgically castrated fallow deer.

We studied the role of androgens in antler growth. In particular, we investigated whether the onset of antler regrowth is triggered by a short-term pulse of testosterone and if low levels of androgens are required for antler growth. The study was conducted on 12 surgically castrated fallow deer bucks (Dama dama) aged approximately 27 months. Six animals (CA group) were given the antiandrogen, cyproterone acetate (CA, 1000 mg/treatment); the others were given vehicle solution only (control). Before each CA treatment, blood was sampled and analysed for testosterone, androstenedione, IGF-1, cortisol, FSH, and LH. CA treatment and blood sampling were performed 2 days before castration, on the day of castration and afterwards at 2-day intervals until day 22. Subsequently, CA treatment and blood sampling continued at weekly intervals until day 270. All animals cast their antlers, followed by antler regrowth in all control bucks, but in only four of the six CA-treated castrates. Plasma testosterone concentrations were low in all animals (between 0.01 and 0.20 ng/ml), but were significantly (P<0001) greater in the controls. In both groups, a temporary increase in testosterone values was recorded around the time of antler regrowth, the peak being significantly (P<0.01) higher in the controls. Androstenedione showed a similar pattern as testosterone. Plasma IGF-1 concentrations increased sharply during the antler growth spurt and did not differ significantly between the two groups throughout the study period. Cortisol concentrations were greater in controls than in the CA group. However, no link with the antler cycle was apparent. FSH and LH concentrations were higher in the controls for most of the study. Antlers produced by the control bucks were significantly larger than those in the CA group (P<0.03). For antler length, testosterone, androstenedione and IGF-1, areas under the curve (AUC) were calculated over the period of antler growth. For the pooled deer (n=12) significant correlations existed between AUCs of antler length and testosterone, but not for antler length and IGF-1. Also, a trend for a positive correlation between AUCs of antler length and androstenedione was noted. It is concluded that a plasma androgen concentration at least above a minimal threshold level is a necessary prerequisite for normal antler regrowth in fallow deer, and that this androgen effect is not mediated via circulating IGF-1. The biological role of low levels of androgens may be to sensitize antler cells to the stimulating effect of IGF.

The fluoride content of antlers as an indicator of fluoride exposure in red deer (Cervus elaphus): A historical biomonitoring study.

Bone fluoride concentrations were analyzed in 141 red deer antlers grown between the 17th/early 18th century and 1997, that originated from four study areas (Arnsberg, Bad Berleburg, Dämmerwald, Schmidtheim) in the federal state of North Rhine-Westphalia, Germany. Fluoride concentrations in the specimens ranged between 27.7 and 1, 392.1 mg F(-)/kg ash and varied significantly both between samples collected during different time-spans in the same area and between samples taken from different study areas over the same period. For antlers (n = 8) collected prior to 1860 in the study areas Arnsberg and Schmidtheim, values between 27.7 and 78.7 mg F(-)/kg ash were recorded. It is assumed that antler fluoride contents in this range are quite close to baseline levels for these regions, i.e., represent concentrations largely unaffected or only slightly influenced by fluoride from anthropogenic sources. With the onset and expansion of large-scale industrial activities, bone fluoride concentrations in the antler samples markedly increased over these baseline values, indicating fluoride deposition from industrial emissions into the red deer habitats. In the later 1980s and the 1990s, a pronounced decline in antler fluoride content was observed, which is attributed to the reduction of industrial fluoride discharges due to effective emission control programs. However, even the lowest fluoride values recorded for antlers grown in the 1990s (study area Schmidtheim, n = 10, range 158.5-367.3 mg F(-)/kg ash) clearly exceeded the concentrations found in the antlers collected prior to 1860, thereby indicating an additional fluoride burden from anthropogenic sources on the recent populations. The present study has corroborated the view that antlers are good indicators of fluoride exposure in deer. The facts that they grow during a seasonally fixed time-span and thus constitute relatively well "naturally standardized" samples and are often kept over long periods of time make antlers suitable monitoring units for historical biomonitoring studies.