Increasing evidence implicates the microbiota in the regulation of brain and behaviour. Germ‐free mice (GF; microbiota deficient from birth) exhibit altered stress hormone signalling and anxiety‐like ...behaviours as well as deficits in social cognition. Although the mechanisms underlying the ability of the gut microbiota to influence stress responsivity and behaviour remain unknown, many lines of evidence point to the amygdala and hippocampus as likely targets. Thus, the aim of this study was to determine if the volume and dendritic morphology of the amygdala and hippocampus differ in GF versus conventionally colonized (CC) mice. Volumetric estimates revealed significant amygdalar and hippocampal expansion in GF compared to CC mice. We also studied the effect of GF status on the level of single neurons in the basolateral amygdala (BLA) and ventral hippocampus. In the BLA, the aspiny interneurons and pyramidal neurons of GF mice exhibited dendritic hypertrophy. The BLA pyramidal neurons of GF mice had more thin, stubby and mushroom spines. In contrast, the ventral hippocampal pyramidal neurons of GF mice were shorter, less branched and had less stubby and mushroom spines. When compared to controls, dentate granule cells of GF mice were less branched but did not differ in spine density. These findings suggest that the microbiota is required for the normal gross morphology and ultrastructure of the amygdala and hippocampus and that this neural remodelling may contribute to the maladaptive stress responsivity and behavioural profile observed in GF mice.
Germ‐free mice (GF; microbiota deficient from birth) exhibit alterations in stress responsivity, anxiety‐like behaviour, and sociability, effects influenced by the amygdala and hippocampus. Here, we show that there are alterations in the gross morphology and ultrastructure of the amygdala and hippocampus of GF mice. These findings indicate that the microbiota is required for normal brain structure and that these neuronal changes may contribute to the maladaptive behavioural profile of GF mice.
The article explores how qualitative image analysis impacts the process of image interpretation, particularly in composite microstructure analysis. It highlights the importance of high-quality images ...for accurate computer-based object detection, emphasizing the limitations of rigid pixel-based rules compared to human visual perception. The study underscores the need for optimal imaging conditions to avoid image defects that hinder precise computational analyses in scientific and industrial applications.
The stereology, variant distribution and coarsening behavior of semicoherent α(hcp) precipitates in a β(bcc) matrix of a Ti5553 alloy has been analyzed, and a dominant 3-variant cluster has been ...observed in which the variants are related to each other by an axis-angle pair <112¯ 0 >/ 60°. Shape and spatial distribution independent elastic self and interaction energies for all pairwise and triplet combinations of α have been calculated and it is found that the 3-cluster combination that is experimentally observed most frequently has the lowest energy for the semicoherent state. The coarsening behavior of the delta distribution follows LSW kinetics after an initial transient, and has been modeled by phase field methods.
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Generating numbers has become an almost inevitable task associated with studies of the morphology of the nervous system. Numbers serve a desire for clarity and objectivity in the presentation of ...results and are a prerequisite for the statistical evaluation of experimental outcomes. Clarity, objectivity, and statistics make demands on the quality of the numbers that are not met by many methods. This review provides a refresher of problems associated with generating numbers that describe the nervous system in terms of the volumes, surfaces, lengths, and numbers of its components. An important aim is to provide comprehensible descriptions of the methods that address these problems. Collectively known as design‐based stereology, these methods share two features critical to their application. First, they are firmly based in mathematics and its proofs. Second and critically underemphasized, an understanding of their mathematical background is not necessary for their informed and productive application. Understanding and applying estimators of volume, surface, length or number does not require more of an organizational mastermind than an immunohistochemical protocol. And when it comes to calculations, square roots are the gravest challenges to overcome. Sampling strategies that are combined with stereological probes are efficient and allow a rational assessment if the numbers that have been generated are “good enough.” Much may be unfamiliar, but very little is difficult. These methods can no longer be scapegoats for discrepant results but faithfully produce numbers on the material that is assessed. They also faithfully reflect problems that associated with the histological material and the anatomically informed decisions needed to generate numbers that are not only valid in theory. It is within reach to generate practically useful numbers that must integrate with qualitative knowledge to understand the function of neural systems.
Design‐based stereological methods allow the estimation of basic morphological parameters in representative samples of the sectioned central nervous system. Point probes can be used to estimate volume (illustrated for the Area Fraction Fractionator), line probes can be used to estimate surface area (illustrated for a vertical sections design), area probes can be used to estimate length (illustrated for the Spaceball probe), and volume probes must be used to estimate number (illustrated for the Disector). This review provides an introduction to how these methods solve problems associated with other quantitative approaches, how they are applied to histological material, how a sampling scheme can be designed and evaluated, and which practical problems need to be solved to generate the numbers that we will need to come to an understanding of central nervous system function.
Objective: Cryptorchidism is one of the main causes of infertility and can result in testicular cancer. This study aimed to present quantitative data on the damage caused by cryptorchidism using ...stereological analysis. Methods: Thirty newborn rats were randomly divided into control and experimental groups. The experimental group underwent surgery to induce unilateral cryptorchidism in the left testis, whereas the control group underwent a sham surgical procedure 18 days after birth. The testes were removed at designated time points (40, 63, and 90 days after birth) for stereological evaluation and sperm analysis. Total testicular volume, interstitial tissue volume, seminiferous tubule volume and length, and seminiferous epithelium volume and surface area were measured. Other parameters, such as sperm count, sperm morphology, and sperm tail length, were also examined. Results: Statistically significant differences (p<0.05) were observed between the experimental and the control groups at different ages regarding the volumes of various parameters, including the surface area of the germinal layer, the length of the seminiferous tubules, sperm count, and sperm morphology. However, no significant differences were observed in the epithelial volume and the sperm tail length of the groups. Conclusion: Given the substantial effect of cryptorchidism on different testicular parameters, as well as the irreversible damage it causes in the testes, it is important to take this abnormality seriously to prevent these consequences.
Introduction
Neurogenesis within the dentate gyrus is thought to play an important role in cognitive processes such as reversal learning and pattern separation. The α7 nicotinic acetylcholine ...receptor (α7 nAChR) is expressed early in newly formed granule cells of the dentate gyrus, though its role in neurogenesis and related cognitive function is not fully understood.
Methods
To better characterize relevant function of α7 nAChRs, we performed unbiased stereology to quantify hippocampal granule cells, pyramidal cells, and total volume and used a touchscreen operant spatial discrimination/reversal task to test pattern separation in a global α7 nAChR knockout mouse line.
Results
The knockout resulted in an ≈22% reduction in granule cells and a ≈ 20% reduction in pyramidal cells in both sexes, with no change in total hippocampal volume. However, the knockout impaired performance in the touchscreen task for males only. The sex-dependent difference in behavioral, but not stereological, results suggest a divergence in the structure–function relationship in males versus females. Detailed analyses revealed males were more biased by the initial reversal contingency relative to females indicating a potential source of the sex-specific interaction with the loss of α7 nAChRs.
Discussion
These findings argue that the α7 nAChR plays a critical role in hippocampal development, not just granule cell neurogenesis, and plays a sex-dependent role in cognitive function.
Well-defined particle size distributions are required for good flowability and powder packing properties of additive manufacturing powders. Mounting powders within a polymer and using standard ...metallurgical preparation techniques to cross-section and prepare powder particles for optical analysis allows for simple characterisation processes. However, measured diameters of cross-sectioned particles are typically underestimates of actual particle diameters and hence require stereological correction. The effectiveness of three stereological corrections are investigated in this work, namely the Scheil-Schwartz-Saltykov method, the Goldsmith-Cruz-Orive method and a Finite Difference Method. These methods are investigated against plasma-atomised, gas-atomised and ultrasonically processed Ti-6Al-4V powders. The corrected outputs are compared to laser size diffraction, benchmark data for each powder. Although all three stereological corrections produce improved estimations of the particle size distributions, the Finite Difference Method is recommended producing cumulative mean absolute error values of 2.4%, 3.1% and 7.5% for the plasma-atomised, gas-atomised and ultrasonically processed powders respectively.
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•Feedstock particle sizes impact properties of additively manufactured parts.•Polymer-mounted powders result in significant errors for particle size estimation.•Three stereological corrections identified for improved particle size estimation.•A finite difference method of stereological correction is recommended.
The mouse brain is the most extensively studied brain of all species. We performed an exhaustive review of the literature to establish our current state of knowledge on cell numbers in mouse brain ...regions, arguably the most fundamental property to measure when attempting to understand a brain. The synthesized information, collected in one place, can be used by both theorists and experimentalists. Although for commonly-studied regions cell densities could be obtained for principal cell types, overall we know very little about how many cells are present in most brain regions and even less about cell-type specific densities. There is also substantial variation in cell density values obtained from different sources. This suggests that we need a new approach to obtain cell density datasets for the mouse brain.
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