Estrogen stimulates fetal vascular endothelial growth factor expression and microvascularization.

We recently showed that the ratio of capillaries to myofibers in skeletal muscle, which accounts for 80% of insulin-directed glucose uptake and metabolism, was reduced in baboon fetuses in which estrogen was suppressed by maternal letrozole administration. Since vascular endothelial growth factor (VEGF) promotes angiogenesis, the present study determined the impact of estrogen deprivation on fetal skeletal muscle VEGF expression, capillary development, and long-term vascular and metabolic function in 4- to 8-year-old adult offspring. Maternal baboons were untreated or treated with letrozole or letrozole plus estradiol on days 100-164 of gestation (term = 184 days). Skeletal muscle VEGF protein expression was suppressed by 45% (P < 0.05) and correlated (P = 0.01) with a 47% reduction (P < 0.05) in the number of capillaries per myofiber area in fetuses of baboons in which serum estradiol levels were suppressed 95% (P < 0.01) by letrozole administration. The reduction in fetal skeletal muscle microvascularization was associated with a 52% decline (P = 0.02) in acetylcholine-induced brachial artery dilation and a 23% increase (P = 0.01) in mean arterial blood pressure in adult progeny of letrozole-treated baboons, which was restored to normal by letrozole plus estradiol. The present study indicates that estrogen upregulates skeletal muscle VEGF expression and systemic microvessel development within the fetus as an essential programming event critical for ontogenesis of systemic vascular function and insulin sensitivity/glucose homeostasis after birth in primate offspring.

Retinal Structural and Vascular Changes in Patients with Coronary Artery Disease: A Systematic Review and Meta-Analysis.

BACKGROUND: Retinal microvascular anomalies have been identified in patients with cardiovascular conditions such as arterial hypertension, diabetes mellitus, and carotid artery disease. We conducted a systematic review and meta-analysis (PROSPERO registration number CRD42024506589) to explore the potential of retinal vasculature as a biomarker for diagnosis and monitoring of patients with coronary artery disease (CAD) through optical coherence tomography (OCT) and optical coherence tomography angiography (OCTA). METHODS: We systematically examined original articles in the Pubmed, Embase, and Web of Science databases from their inception up to November 2023, comparing retinal microvascular features between patients with CAD and control groups. Studies were included if they reported sample mean with standard deviation or median with range and/or interquartile range (which were computed into mean and standard deviation). Review Manager 5.4 (The Cochrane Collaboration, 2020) software was used to calculate the pooled effect size with weighted mean difference and 95% confidence intervals (CI) by random-effects inverse variance method. RESULTS: Eleven studies meeting the inclusion criteria were incorporated into the meta-analysis. The findings indicated a significant decrease in the retinal nerve fiber layer (WMD -3.11 [-6.06, -0.16]), subfoveal choroid (WMD -58.79 [-64.65, -52.93]), and overall retinal thickness (WMD -4.61 [-7.05, -2.17]) among patients with CAD compared to controls (p < 0.05). Furthermore, vascular macular density was notably lower in CAD patients, particularly in the superficial capillary plexus (foveal vessel density WMD -2.19 [-3.02, -1.135], p < 0.0001). Additionally, the foveal avascular zone area was statistically larger in CAD patients compared to the control group (WMD 52.73 [8.79, 96.67], p = 0.02). Heterogeneity was significant (I2 > 50%) for most features except for subfoveal choroid thickness, retina thickness, and superficial foveal vessel density. CONCLUSION: The current meta-analysis suggests that retinal vascularization could function as a noninvasive biomarker, providing additional insights beyond standard routine examinations for assessing dysfunction in coronary arteries.

Foveal microvascular features following inverted flap technique for closure of large macular holes.

PURPOSE: To describe the anatomical and functional outcomes following use of the inverted flap technique (IFT) to close idiopathic macular holes (MH) of diameter greater than 400 µm. To compare the changes in the macular microvascularization following surgery in operated and healthy fellow eyes. METHODS: Retrospective study of 24 patients who underwent vitrectomy and IFT for large MH closure. The main variables were closure pattern, best corrected visual acuity (BCVA) and recovery of the external limiting membrane (ELM) and ellipsoid zone (EZ). Foveal avascular zones (FAZ) and vessel and perfusion densities, obtained by OCT angiography scans, were compared with those in healthy fellow eyes. RESULTS: Complete MH closure was achieved in 95.8% (23/24) of patients 6 months after surgery. There was a significant improvement in postoperative BCVA, from 1.0 to 0.4 logMAR (p < 0.001). The most frequent closure pattern was 1a (62.5%, 15/24), followed by 2c (12.5%, 3/24). The closure pattern was not correlated with height, minimum or maximum diameters or macular hole index (MHI) (p > 0.05). ELM and EZ recovery occurred in 87.5% and 83.3% of cases, respectively. FAZ were smaller in operated eyes than in the fellow eyes (p = 0.012). There were no differences in the vessel or perfusion densities between the operated and fellow eyes (p > 0.05). CONCLUSIONS: Use of the inverted flap technique for large MH closure provides a high rate of functional and anatomical recovery. We observed a reduction in the FAZ following surgery, with no differences in the macular microvascularization parameters, suggesting that the technique is safe.

Construction of a novel cell-free tracheal scaffold promoting vascularization for repairing tracheal defects.

Functional vascularization is crucial for maintaining the long-term patency of tissue-engineered trachea and repairing defective trachea. Herein, we report the construction and evaluation of a novel cell-free tissue-engineered tracheal scaffold that effectively promotes vascularization of the graft. Our findings demonstrated that exosomes derived from endothelial progenitor cells (EPC-Exos) enhance the proliferation, migration, and tube formation of endothelial cells. Taking advantage of the angiogenic properties of EPC-Exos, we utilized methacrylate gelatin (GelMA) as a carrier for endothelial progenitor cell exosomes and encapsulated them within a 3D-printed polycaprolactone (PCL) scaffold to fabricate a composite tracheal scaffold. The results demonstrated the excellent angiogenic potential of the methacrylate gelatin/vascular endothelial progenitor cell exosome/polycaprolactone tracheal scaffold. Furthermore, in vivo reconstruction of tracheal defects revealed the capacity of this composite tracheal stent to remodel vasculature. In conclusion, we have successfully developed a novel tracheal stent composed of methacrylate gelatin/vascular endothelial progenitor exosome/polycaprolactone, which effectively promotes angiogenesis for tracheal repair, thereby offering significant prospects for clinical and translational medicine.

Biomimetic in situ tracheal microvascularization for segmental tracheal reconstruction in one-step.

Formation of functional and perfusable vascular network is critical to ensure the long-term survival and functionality of the engineered tissue tracheae after transplantation. However, the greatest challenge in tracheal-replacement therapy is the promotion of tissue regeneration by rapid graft vascularization. Traditional prevascularization methods for tracheal grafts typically utilize omentum or muscle flap wrapping, which requires a second operation; vascularized segment tracheal orthotopic transplantation in one step remains difficult. This study proposes a method to construct a tissue-engineered tracheal graft, which directly forms the microvascular network after orthotopic transplantation in vivo. The focus of this study was the preparation of a hybrid tracheal graft that is non-immunogenic, has good biomechanical properties, supports cell proliferation, and quickly vascularizes. The results showed that vacuum-assisted decellularized trachea-polycaprolactone hybrid scaffold could match most of the above requirements as closely as possible. Furthermore, endothelial progenitor cells (EPCs) were extracted and used as vascularized seed cells and seeded on the surfaces of hybrid grafts before and during the tracheal orthotopic transplantation. The results showed that the microvascularized tracheal grafts formed maintained the survival of the recipient, showing a satisfactory therapeutic outcome. This is the first study to utilize EPCs for microvascular construction of long-segment trachea in one-step; the approach represents a promising method for microvascular tracheal reconstruction.

Acceleration of Wound Healing through Amorphous Calcium Carbonate, Stabilized with High-Energy Polyphosphate.

Amorphous calcium carbonate (ACC), precipitated in the presence of inorganic polyphosphate (polyP), has shown promise as a material for bone regeneration due to its morphogenetic and metabolic energy (ATP)-delivering properties. The latter activity of the polyP-stabilized ACC ("ACC∙PP") particles is associated with the enzymatic degradation of polyP, resulting in the transformation of ACC into crystalline polymorphs. In a novel approach, stimulated by these results, it was examined whether "ACC∙PP" also promotes the healing of skin injuries, especially chronic wounds. In in vitro experiments, "ACC∙PP" significantly stimulated the migration of endothelial cells, both in tube formation and scratch assays (by 2- to 3-fold). Support came from ex vivo experiments showing increased cell outgrowth in human skin explants. The transformation of ACC into insoluble calcite was suppressed by protein/serum being present in wound fluid. The results were confirmed in vivo in studies on normal (C57BL/6) and diabetic (db/db) mice. Topical administration of "ACC∙PP" significantly accelerated the rate of re-epithelialization, particularly in delayed healing wounds in diabetic mice (day 7: 1.5-fold; and day 13: 1.9-fold), in parallel with increased formation/maturation of granulation tissue. The results suggest that administration of "ACC∙PP" opens a new strategy to improve ATP-dependent wound healing, particularly in chronic wounds.

Development of cortical microvascularization in Moyamoya disease using the maximum intensity projection method from three-dimensional rotational angiography.

BACKGROUND: Neurosurgeons often experience increased cortical microvascularization in Moyamoya disease (MMD). However, there are no previous reports that radiologically evaluated preoperative cortical microvascularization. We investigated the development of cortical microvascularization and clinical characteristics of MMD using the maximum intensity projection (MIP) method. METHODS: We enrolled 64 patients at our institution, including patients with MMD (n = 26), intracranial atherosclerotic disease (ICAD; n = 18), and unruptured cerebral aneurysms (n = 20) as the control group. All patients underwent three-dimensional rotational angiography (3D-RA). The 3D-RA images were reconstructed using partial MIP images. Cortical microvascularization was defined as the vessels that branched off from the cerebral arteries and were classified as grade 0-2 depending on their development. RESULTS: Cortical microvascularization observed in patients with MMD was classified into grade 0 (n = 4, 8.9%), grade 1 (n = 17, 37.8%), and grade 2 (n = 24, 53.3%). The development of cortical microvascularization was more common in the MMD group than in the other groups. The inter-rater reliability measured using weighted kappa was 0.68 (95% confidence interval = 0.56-0.80). There were no significant differences in cortical microvascularization according to the onset type and hemispheres. Cortical microvascularization correlated with periventricular anastomosis. Most patients with Suzuki classifications 2-5 developed cortical microvascularization. CONCLUSION: Cortical microvascularization was characteristic of patients with MMD. These findings developed in the early stages of MMD and may act as a bridge to the development of periventricular anastomosis.

Self-gated, dynamic contrast-enhanced magnetic resonance imaging with compressed-sensing reconstruction for evaluating endothelial permeability in the aortic root of atherosclerotic mice.

High-risk atherosclerotic plaques are characterized by active inflammation and abundant leaky microvessels. We present a self-gated, dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) acquisition with compressed sensing reconstruction and apply it to assess longitudinal changes in endothelial permeability in the aortic root of Apoe-/- atherosclerotic mice during natural disease progression. Twenty-four, 8-week-old, female Apoe-/- mice were divided into four groups (n = 6 each) and imaged with self-gated DCE-MRI at 4, 8, 12, and 16 weeks after high-fat diet initiation, and then euthanized for CD68 immunohistochemistry for macrophages. Eight additional mice were kept on a high-fat diet and imaged longitudinally at the same time points. Aortic-root pseudo-concentration curves were analyzed using a validated piecewise linear model. Contrast agent wash-in and washout slopes (b1 and b2 ) were measured as surrogates of aortic root endothelial permeability and compared with macrophage density by immunohistochemistry. b2 , indicating contrast agent washout, was significantly higher in mice kept on an high-fat diet for longer periods of time (p = 0.03). Group comparison revealed significant differences between mice on a high-fat diet for 4 versus 16 weeks (p = 0.03). Macrophage density also significantly increased with diet duration (p = 0.009). Spearman correlation between b2 from DCE-MRI and macrophage density indicated a weak relationship between the two parameters (r = 0.28, p = 0.20). Validated piecewise linear modeling of the DCE-MRI data showed that the aortic root contrast agent washout rate is significantly different during disease progression. Further development of this technique from a single-slice to a 3D acquisition may enable better investigation of the relationship between in vivo imaging of endothelial permeability and atherosclerotic plaques' genetic, molecular, and cellular makeup in this important model of disease.

Intraoperative Evaluation of Brain-Tumor Microvascularization through MicroV IOUS: A Protocol for Image Acquisition and Analysis of Radiomic Features.

Microvascular Doppler (MicroV) is a new-generation Doppler technique developed by Esaote (Esaote s.p.a., Genova, Italy), which is able to visualize small and low-flow vessels through a suppression of interfering signals. MicroV uses advanced filters that are able to differentiate tissue artifacts from low-speed blood flows; by exploiting the space-time coherence information, these filters can selectively suppress tissue components, preserving the signal coming from the microvascular flow. This technique is clinically applied to the study of the vascularization of parenchymatous lesions, often with better diagnostic accuracy than color/power Doppler techniques. The aim of this paper is to develop a reproducible protocol for the recording and collection of MicroV intraoperative ultrasound images by the use of a capable intraoperative ultrasound machine and post-processing aimed at evaluation of brain-tumor microvascularization through the analysis of radiomic features. The proposed protocol has been internally validated on eight patients and will be firstly applied to patients affected by WHO grade IV astrocytoma (glioblastoma-GBM) candidates for craniotomy and lesion removal. In a further stage, it will be generally applied to patients with primary or metastatic brain tumors. IOUS is performed before durotomy. Tumor microvascularization is evaluated using the MicroV Doppler technique and IOUS images are recorded, stored, and post-processed. IOUS images are remotely stored on the BraTIoUS database, which will promote international cooperation and multicentric analysis. Processed images and texture radiomic features are analyzed post-operatively using ImageJ, a free scientific image-analysis software based on the Sun-Java platform. Post-processing protocol is further described in-depth. The study of tumor microvascularization through advanced IOUS techniques such as MicroV could represent, in the future, a non-invasive and real-time method for intraoperative predictive evaluation of the tumor features. This evaluation could finally result in a deeper knowledge of brain-tumor behavior and in the on-going adaptation of the surgery with the improvement of surgical outcomes.

A dZnONPs Enhanced Hybrid Injectable Photocrosslinked Hydrogel for Infected Wounds Treatment.

Chronic wounds caused by related diseases such as ischemia, diabetes, and venous stasis are often hard to manage, mainly because of their susceptibility to infection and the lack of healing-promoting growth factors. Functional hydrogel is a promising material for wound treatment due to its regulable swelling rate and its ability to absorb wound exudate, which can keep the wound isolated from the outside world to prevent infection. In this study, a photocrosslinked physicochemical double-network hydrogel with injectable, antibacterial, and excellent mechanical properties was prepared. The dZnONPs enhanced hybrid injectable photocrosslinked double-network hydrogel (Ebs@dZnONPs/HGT) was synthetized starting from acylated hyaluronic acid and tannic acid via free radical reaction and hydrogen bonding, following doped with ebselen (Ebs) loaded dendritic zinc oxide nanoparticles (dZnONPs) to prepare the Ebs@dZnONPs/HGT hydrogel. The physicochemical characterization confirmed that the Ebs@dZnONPs/HGT hydrogel had excellent mechanical properties, hydrophilicity, and injectable properties, and could fit irregular wounds well. In vitro experiments revealed that the Ebs@dZnONPs/HGT hydrogel presented credible cytocompatibility and prominent antibacterial activity against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus). In vivo experiments further demonstrated that the Ebs@dZnONPs/HGT hydrogel had excellent biosafety and could improve re-epithelialization in the wound area, thus significantly accelerating wound healing.

Effect of synbiotics administered in ovo on microvascularization and histopathological changes in pectoral muscle and the biochemical profile of broiler chicken blood.

The aim of this study was to investigate whether injecting synbiotics to the egg air chamber on d 12 of embryo incubation will affect the processes of angiogenesis, and thus the share of histopathological changes in superficial pectoral muscle, as well as Ca and P in blood of 42-day-old broiler chickens. The eggs containing viable embryos were injected with 0.2 mL suspension of 1/physiological saline, 2/SYN1 composed of galactooligosaccharide (GOS) (trade name: Bi2tos®, Clasado Biosciences Ltd, UK) and L. salivarius or 3/SYN2 composed of RFO and L. plantarum. All birds were fed ad libitum the standard commercial feed mixtures: starter, grower, and finisher, with a constant access to water and feed. Injecting synbiotics in ovo on d 12 of the embryonal development significantly affected the blood supply to superficial breast muscle in broiler chickens. The highest density of capillaries in the muscle area under study and per muscle fiber were identified in the group of birds the egg air chamber of which was provided with synbiotic GOS+L. salivarius. Consequently, for the muscles of the birds injected with the same synbiotic there was found the highest share of normal fibers and least necrosis and splitting, as compared with the control. The conducted research confirms the relationship between the blood supply to the muscle and the occurrence of pathological changes. We have observed a positive effect of synbiotics on the microvascularization and the size of histopathological changes in the chicken muscle, which, from a practical perspective, can affect the health status and the meat quality. Blood biochemical analyses showed that the in ovo injection of synbiotics did not significantly affect the level of parameters, except for Ca and P. A significant increase in the concentration of these minerals in the blood of chickens injected with SYN1 could have a positive effect on the angiogenesis process.

Dynamic Optical Coherence Tomography: A Non-Invasive Imaging Tool for the Distinction of Nevi and Melanomas.

Along with the rising melanoma incidence in recent decades and bad prognoses resulting from late diagnoses, distinguishing between benign and malignant melanocytic lesions has become essential. Unclear cases may require the aid of non-invasive imaging to reduce unnecessary biopsies. This multicentric, case-control study evaluated the potential of dynamic optical coherence tomography (D-OCT) to identify distinguishing microvascular features in nevi. A total of 167 nevi, including dysplastic ones, on 130 participants of all ages and sexes were examined by D-OCT and dermoscopy with a histological reference. Three blinded analyzers evaluated the lesions. Then, we compared the features to those in 159 melanomas of a prior D-OCT study and determined if a differential diagnosis was possible. We identified specific microvascular features in nevi and a differential diagnosis of melanomas and nevi was achieved with excellent predictive values. We conclude that D-OCT overcomes OCT´s inability to distinguish melanocytic lesions based on its focus on microvascularization. To determine if an addition to the gold standard of a clinical-dermoscopic examination improves the diagnosis of unclear lesions, further studies, including a larger sample of dysplastic nevi and artificial intelligence, should be conducted.

Microvascular assessment of fascio-cutaneous flaps by ultrasound: A large animal study.

Objectives: Blood perfusion quality of a flap is the main prognostic factor for success. Microvascular evaluation remains mostly inaccessible. We aimed to evaluate the microflow imaging mode, MV-Flow, in assessing flap microvascularization in a pig model of the fascio-cutaneous flap. Methods: On five pigs, bilateral saphenous fascio-cutaneous flaps were procured on the superficial femoral vessels. A conventional ultrasound evaluation in pulsed Doppler and color Doppler was conducted on the ten flaps allowing for the calculation of the saphenous artery flow rate. The MV-Flow mode was then applied: for qualitative analysis, with identification of saphenous artery collaterals; then quantitative, with repeated measurements of the Vascularity Index (VI), percentage of pixels where flow is detected relative to the total ultrasound view area. The measurements were then repeated after increasing arterial flow by clamping the distal femoral artery. Results: The MV-Flow mode allowed a better follow-up of the saphenous artery's collaterals and detected microflows not seen with the color Doppler. The VI was correlated to the saphenous artery flow rate (Spearman rho of 0.64; p = 0.002) and allowed to monitor the flap perfusion variations. Conclusion: Ultrasound imaging of microvascularization by MV-Flow mode and its quantification by VI provides valuable information in evaluating the microvascularization of flaps.

Correlation Between Retrograde Trans-Synaptic Degeneration of Ganglion Cells and Optical Coherence Tomography Angiography Following Ischemic Stroke.

Objective Following nerve injury, the projection of posterior visual pathway lesions into the macular ganglion cell layer (GCL) region indicates retrograde trans-synaptic degeneration (RTSD) as a mechanism of functional damage. Our purpose is to assess GCL damage and the impacts of ischemic brain lesions affecting the visual pathway on macular microvascularization in patients with stroke. Methods In a case-control study, we examined 15 ischemic stroke patients who showed visual field defects and 50 healthy controls using the high-resolution optical coherence tomography (OCT) techniques such as spectral domain-OCT (SD-OCT) to measure retinal nerve fiber layer (RNFL) and GCL thicknesses, and OCT angiography (OCTA) to assess damage to the macular microvasculature. Results In the cases, the correlation was detected among the site of vascular damage, visual field defect, retinal GCL thinning, and normal RNFL thickness. Further observations were significant reductions in macular thickness, GCL thickness, outer retinal layer vascular density, and vascular area in deeper retinal layers (p < 0.05). Conclusion Our findings suggest that ocular microvasculature abnormalities could serve as diagnostic and/or prognostic markers in patients with stroke and support the described use of GCL thickness as an image marker of visual pathway RTSD after brain injury.

Contrast-enhanced ultrasound perfusion imaging of organs.

In multimodal radiologic imaging, contrast-enhanced ultrasound (CEUS) is increasingly used. One of the advantages of CEUS is the possibility of repeated application of contrast media without decreasing renal function or affecting the thyroid gland. Small solid liver lesions can be diagnosed and detected with high accuracy. Moreover, solid lesions in other abdominal organs can also be characterized. Frequent applications for solid lesions in the near field concern thyroid tumors and lymph nodes. For prostate diagnostics, CEUS can be used with an endorectal probe and perfusion imaging. This review explains how the additional (semi-)quantitative perfusion analysis, especially time-intensity curve (TIC) analyses, and wash-in/wash-out kinetics of integrated or external perfusion software programs facilitate new options in dynamic assessment of microvascularization during tumor follow-up care and even minimally invasive tumor therapy.

Microvascular Tissue Engineering-A Review.

Tissue engineering and regenerative medicine have come a long way in recent decades, but the lack of functioning vasculature is still a major obstacle preventing the development of thicker, physiologically relevant tissue constructs. A large part of this obstacle lies in the development of the vessels on a microscale-the microvasculature-that are crucial for oxygen and nutrient delivery. In this review, we present the state of the art in the field of microvascular tissue engineering and demonstrate the challenges for future research in various sections of the field. Finally, we illustrate the potential strategies for addressing some of those challenges.

Assessment of the retinal and choroidal microvascularization in polycystic ovary syndrome: an optical coherence tomography angiography study.

PURPOSE: To examine the retinal, peripapillary, choroidal microvascularization and the choroid thickness (CT) of the patients with polycystic ovary syndrome (PCOS) using optical coherence tomography angiography (OCT-A) and compare the results to measurements obtained from healthy controls. METHODS: In total, 47 eyes of 47 patients recently diagnosed with PCOS and 47 eyes of 47 age-matched healthy women were included in this study. An RT XR Avanti instrument with AngioVue software was used for the OCT-A imaging using 6 × 6 mm macular and 4.5 × 4.5 mm optic nerve head scans. Quantitative vessel density results of superficial capillary plexus (SCP), deep capillary plexus (DCP) and radial peripapillary capillaries (RPC); flow area and flow density of choriocapillaris; and foveal avascular zone (FAZ) area were analyzed. CT was evaluated by using the measurements obtained from the subfoveolar area. RESULTS: No significant differences were detected between the groups for any of vessel density results for the SCP, DCP, and RPC as well as the FAZ area. The difference in the choriocapillaris flow area and flow density between the groups was not statistically significant. The choroid was significantly thicker in women with PCOS than in the healthy group (p = 0.002). CONCLUSION: Retinal and choroidal microvascularization was comparable between the women who were evaluated early after diagnosed with PCOS and age-matched healthy controls. Choroid was found thicker in patients with PCOS than in healthy women. OCT-A, as a new and noninvasive imaging method, may help in understanding the effect of PCOS on the posterior segment of the eye.

Evaluation of Placental Micro-vascularization by Superb Micro-vascular Imaging Doppler in Cases of Intra-uterine Growth Restriction: A First Step.

Superb micro-vascular imaging (SMI) Doppler has proven to be a valid method to assess normal placental micro-vascularization. In this study, we present the application of SMI Doppler to assess placental micro-vascularization in cases of placental insufficiency. We observed fewer secondary and tertiary villi in cases of intra-uterine growth restriction, as well as a lower pulsatile index of secondary villi. The observations made in our study stress the diagnostic potential of SMI Doppler in placental insufficiency.

Collagen and Microvascularization in Placentas From Young and Older Mares.

In older mares, increasing collagen fibers (fibrosis) in the endometrium and oviduct predisposes to sub-fertility and infertility. In this study, (i) gene transcription of collagen (qPCR: COL1A1, COL1A2, COL3A1, COL5A1); (ii) total collagen protein (hydroxyproline); (iii) collagen distribution (Picrosirius red staining; polarized light microscopy); and (iv) microvascular density (Periodic acid-Schiff staining), were evaluated in mares' placenta, and related to mares age, and placenta and neonate weights. Samples were collected from the gravid horn, non-gravid horn, and body of the placenta from younger (n = 7), and older mares (n = 9) of different breeds. Transcripts of COL1A1, COL3A1 and COL5A1, total collagen protein, chorionic plate connective tissue thickness, and microvascularization increased in the gravid horn of older mares' placentas, compared to the youngest (P < 0.05). Although in other species placenta fibrosis may indicate placental insufficiency and reduced neonate weight, this was not observed here. It appears that older fertile mares, with more parities, may develop a heavier, more vascularized functional placenta with more collagen, throughout a longer gestation, which enables the delivery of heavier foals. Thus, these features might represent morphological and physiological adaptations of older fertile mares' placentas to provide the appropriate nutrition to the equine fetus.

Microvascularization of the human central and peripheral nervous system: A new microcomputed tomography method.

Microcomputed X-ray tomography (microCT), developed since the late 1990s, is a miniaturized version of the tomographs used daily in medical imaging. It produces vascular images that are different from those obtained by microradiography, in particular by facilitating the vision in space, thus understanding microvascularisation. The anatomical specimens, once treated with formalin, are injected with a mixture made of gelatin containing a contrast product (barium) and then analyzed by microCT. The acquisition times that can exceed 24hours and metal sheets used for X-ray filtering vary according to the sample. The projection images are reconstructed to produce 2D sections. These are combined for the reconstruction of 3D models using a volume rendering software. Four examples will allow the imaging of microvascularization: the inferior alveolar nerve, the cerebral cortex and pia-mother, brain stem, central gray nuclei (ganglia at the base of the brain). Small capillaries are highlighted using high-end software for reconstruction. Conventional software or freeware cause a considerable loss of information on small vessels that are not visualized. The VGStudio max high-end software allows the production of videos that are particularly useful for 3D exploration and teaching (four videos are provided with this article).