A microscopic and microanalytical study (Fe, Ca) of the teeth of the larval and juvenile Ambystoma mexicanum (Amphibia: Urodela: Ambystomatidae)*

> Abstract We studied the teeth of larvae and one juvenile of the axolotl Ambystoma mexicanum, a urodele species that undergoes partial metamorphosis, by light microscopy of ground sections, backscattered electron imaging and semi-quantitative microanalysis in the scanning electron microscope. By applying these techniques it was possible to identify enamel, enameloid and dentin in the teeth. Iron was found to be present in enamel and enameloid, the concentrations being highest in the enamel. A staining indicative of the presence of iron was observed in the inner dental epithelium of tooth germs. Dentinal tubules mostly followed a straight course, but some recurved over a short distance distally. In larval teeth and teeth of "larval type" in the juvenile individual the dentinal tubules ended in the basal portion of the enameloid. Our results show that in the axolotl, monocuspid teeth of the "larval type" that developed after partial transformation still possess an enameloid layer beneath a thin enamel cap. The fi ndings of the present study are consistent with the view that enameloid matrix is secreted by odontoblasts, while enameloid maturation is (largely) controlled by ameloblasts. > Zusammenfassun

A microscopic and microanalytical study (Fe, Ca) of the teeth of the larval and juvenile Ambystoma mexicanum (Amphibia: Urodela: Ambystomatidae)*

> Abstract We studied the teeth of larvae and one juvenile of the axolotl Ambystoma mexicanum, a urodele species that undergoes partial metamorphosis, by light microscopy of ground sections, backscattered electron imaging and semi-quantitative microanalysis in the scanning electron microscope. By applying these techniques it was possible to identify enamel, enameloid and dentin in the teeth. Iron was found to be present in enamel and enameloid, the concentrations being highest in the enamel. A staining indicative of the presence of iron was observed in the inner dental epithelium of tooth germs. Dentinal tubules mostly followed a straight course, but some recurved over a short distance distally. In larval teeth and teeth of "larval type" in the juvenile individual the dentinal tubules ended in the basal portion of the enameloid. Our results show that in the axolotl, monocuspid teeth of the "larval type" that developed after partial transformation still possess an enameloid layer beneath a thin enamel cap. The fi ndings of the present study are consistent with the view that enameloid matrix is secreted by odontoblasts, while enameloid maturation is (largely) controlled by ameloblasts. > Zusammenfassun

Localization and Characterization of STRO-1+ Cells in the Deer Pedicle and Regenerating Antler

The annual regeneration of deer antlers is a unique developmental event in mammals, which as a rule possess only a very limited capacity to regenerate lost appendages. Studying antler regeneration can therefore provide a deeper insight into the mechanisms that prevent limb regeneration in humans and other mammals, and, with regard to medical treatments, may possibly even show ways how to overcome these limitations. Traditionally, antler regeneration has been characterized as a process involving the formation of a blastema from de-differentiated cells. More recently it has, however, been hypothesized that antler regeneration is a stem cell-based process. Thus far, direct evidence for the presence of stem cells in primary or regenerating antlers was lacking. Here we demonstrate the presence of cells positive for the mesenchymal stem cell marker STRO-1 in the chondrogenic growth zone and the perivascular tissue of the cartilaginous zone in primary and regenerating antlers as well as in the pedicle of fallow deer (Dama dama). In addition, cells positive for the stem cell/progenitor cell markers STRO-1, CD133 and CD271 (LNGFR) were isolated from the growth zones of regenerating fallow deer antlers as well as the pedicle periosteum and cultivated for extended periods of time. We found evidence that STRO-1+ cells isolated from the different locations are able to differentiate in vitro along the osteogenic and adipogenic lineages. Our results support the view that the annual process of antler regeneration might depend on the periodic activation of mesenchymal progenitor cells located in the pedicle periosteum. The findings of the present study indicate that not only limited tissue regeneration, but also extensive appendage regeneration in a postnatal mammal can occur as a stem cell-based process

Численное моделирование теплофизических условий реализации режима циркулирующего кипящего слоя применительно к топкам котлов

Актуальность проведения исследований, направленных на совершенствование методов численного анализа аэротермохимических процессов в топках с циркулирующим кипящим слоем на основе компьютерного математического моделирования, является весьма высокой для обоснования основных проектно-конструкторских и режимно-эксплуатационных параметров при создании котлов с ЦКС. С помощью наработанных численных расчетов возможно не только правильно осмыслять и понимать физические явления, наблюдаемые, например, на экспериментальных установках, но и в некоторых случаях заменить физический или натуральный эксперимент компьютерным как более дешевым и менее трудоемким.The relevance of research aimed at improving the methods of numerical analysis of aerothermochemical processes in furnaces with a circulating fluidized bed based on computer mathematical modeling is very high for justifying the main design and operational parameters creating boilers with CFB. With the help of accumulated numerical calculations, it is possible not only to correctly comprehend and understand the physical phenomena observed, for example, in experimental installations, but also in some cases to replace a physical or natural experiment with a computer one as cheaper and less time-consuming

Использование микроконтроллера ESP32 совместно с гироприборами MPU-6050 и BNO055 при создании самобалансирующих роботов

Статья посвящена анализу возможностей электронных приборов, таких как гироскоп, акселерометр, магнитометр. Приводятся результаты тестирования и действующие алгоритмы. Анализируются возможности их применения в разных вариантах расчетов. Делаются выводы по развитию возможностей и устранению недостатков полученной комплексной системы позиционирования робота

Teeth of the red fox Vulpes vulpes (L., 1758) as a bioindicator in studies on fluoride pollution

An examination was made of fluoride content in the mandibular first molars of the permanent teeth of the red fox Vulpes vulpes living in north-west (NW) Poland. The teeth were first dried to a constant weight at 105°C and then ashed. Fluorides were determined potentiometrically, and their concentrations were expressed in dry weight (DW) and ash. The results were used to perform an indirect estimation of fluoride pollution in the examined region of Poland. The collected specimens (n = 35) were classified into one of the three age categories: immature (im, 6–12 months), subadult (subad, from 12 to 20 months) and adult (ad, >20 months). The mean concentrations (geometric mean) of fluoride were similar in the im and subad groups (230 and 296 mg/kg DW and 297 and 385 mg/kg ash, respectively), and significantly smaller than in the ad group (504 and 654 mg/kg, respectively, in DW and ash). Basing on other reports that the ∼400 mg/kg DW concentration of fluoride in bones in the long-lived wild mammals generally reflects the geochemical background, it was found that 57% of the foxes in NW Poland exceeded this value by 9% to 170%. This indirectly reflects a moderate fluoride contamination in the tested region

Wild Boar Tissue Levels of Cadmium, Lead and Mercury in Seven Regions of Continental Croatia

Concentrations of cadmium, mercury and lead were analysed by atomic absorption spectrometry in the kidney and muscle of free-living wild boar (n = 169) from hunting grounds in seven counties of continental Croatia. Mean levels of metals (mg/kg) in muscle and kidney of boars ranged as follows: Cd: 0.005–0.016 and 0.866–4.58, Pb: 0.033–0.15 and 0.036–0.441, Hg: 0.004–0.012 and 0.04–0.152. In all seven regions, concentrations exceeded the permitted values (muscle and kidney mg/kg: cadmium 0.05/1; lead 0.1/0.5; mercury 0.03/0.1) in 13.6% and 71.6% of samples (muscle and kidney, respectively) for cadmium; 13.6% and 8.9% for lead; 19.5% and 2.4% for mercury. There were significant differences among the regions. Vukovar-Srijem and Virovitica-Podravina Counties were highly contaminated with cadmium, Sisak-Moslavina and Virovitica-Podravina Counties with lead and Brod-Posavina County had highest mercury concentrations. These results suggest a detailed investigation of physiological and environmental factors contributing to accumulation of metals in boars

Developmental origin and maintenance of distinct testicular macrophage populations

International audienceTesticular macrophages (tM phi) are the principal immune cells of the mammalian testis. Beyond classical immune functions, they have been shown to be important for organogenesis, spermatogenesis, and male hormone production. In the adult testis, two different macrophage populations have been identified based on their distinct tissue localization and morphology, but their developmental origin and mode of homeostatic maintenance are unknown. In this study, we use genetic lineage-tracing models and adoptive transfer protocols to address this question. We show that embryonic progenitors give rise to the interstitial macrophage population, whereas peritubular macrophages are exclusively seeded postnatally in the prepuberty period from bone marrow (BM)-derived progenitors. As the proliferative capacity of interstitial macrophages declines, BM progenitors also contribute to this population. Once established, both the peritubular and interstitial macrophage populations exhibit a long life span and a low turnover in the steady state. Our observations identify distinct developmental pathways for two different tM phi populations that have important implications for the further dissection of their distinct roles in organ homeostasis and testicular function