Morphological Changes In Blood Vessels Research Articles

Width measurement of retinal vessels using cubic spline fitting and extended edge‐searching mode

AbstractAbnormal changes in the retinal vessel width usually indicate the presence of certain diseases. This paper presents a novel model to measure the width of retinal vessels. This method firstly employs cubic spline fitting to determine the vessel cross‐sectional direction at the center point of a vessel profile, then uses the extended edge‐searching mode to detect vessel edge points along the vessel cross‐sectional direction, and finally obtains the width value by calculating the distance between the edge point and the center point. The method can accurately locate vessel edge points and successfully solve the problem of central light reflex in blood vessels. Experimental analyses on a publicly available database show that the proposed approach has excellent performance in accuracy with other existing measurement techniques. It provides an effective idea for analyzing morphological changes in blood vessels and can be extended to obtain the shape features of other objects.

Morphological and molecular genetic diagnosis of CADASIL: a rare clinical case

Background: Cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL) is a hereditary autosomal dominant vascular injury of the brain. Currently, the clinical diagnosis of CADASIL is based on the following criteria: the onset of the condition at a relatively young age (4050 years), recurrent lacunar infarcts, gradual progression of encephalopathy with the development of pseudobulbar syndrome and dementia, various emotional disorders, and autosomal dominant inheritance. Having a family history of relatives with similar symptoms. The diagnosis is verified on the basis of the results of the following studies: neuroimaging, instrumental, morphological, and laboratory. The presence of leukoaraiosis and multiple small bilateral infarctions in such anatomical structures as the basal ganglia and white matter of the cerebral hemispheres, visual tubercles and the pons, and brain stem during MRI diagnostics. Histologically, transmission electron microscopy reveals granular osmiophilic inclusions in the adventitial membrane of the blood vessels of the brain, and on the periphery in the adventitia of the vessels of skeletal muscles and somatic nerves and in vascular biopsies of skin flaps. A mutation in the Notch3 gene determines the clinic of the disease and morphological changes in blood vessels and is detected by a molecular genetic method. The article presents a clinical case, which was a manifestation of this rare hereditary microangiopathy. Clinical case description: A 43-year-old patient was admitted to the Department of Neurology of the Republican Clinical Hospital in Simferopol for ischemic stroke in the basin of the left middle cerebral artery. According to the anamnesis, the patient suffered from migraine without aura from a young age and lacunar strokes; examination revealed a decrease in cognitive function, and MRI showed signs of microangiopathy of cerebral vessels. For final diagnosis, the patient underwent an intravital pathomorphological examination of the biopsy of the musculoskeletal flap; the results obtained made it possible to make a reliable diagnosis of CADASIL. Conclusion: Understanding and knowledge of such a rare pathology as CADASIL is crucial for the rapid recognition of a characteristic clinical picture for further appointment and interpretation of the results of morphological and molecular genetic diagnostics, making it possible to make the correct diagnosis and treatment.

In vivo photoacoustic monitoring of vasoconstriction induced by acute hyperglycemia

Postprandial hyperglycemia, blood glucose spikes, induces endothelial dysfunction, increasing cardiovascular risks. Endothelial dysfunction leads to vasoconstriction, and observation of this phenomenon is important for understanding acute hyperglycemia. However, high-resolution imaging of microvessels during acute hyperglycemia has not been fully developed. Here, we demonstrate that photoacoustic microscopy can noninvasively monitor morphological changes in blood vessels of live animals’ extremities when blood glucose rises rapidly. As blood glucose level rose from 100 to 400 mg/dL following intraperitoneal glucose injection, heart/breath rate, and body temperature remained constant, but arterioles constricted by approximately –5.7 ± 1.1% within 20 min, and gradually recovered for another 40 min. In contrast, venular diameters remained within about 0.6 ± 1.5% during arteriolar constriction. Our results experimentally and statistically demonstrate that acute hyperglycemia produces transitory vasoconstriction in arterioles, with an opposite trend of change in blood glucose. These findings could help understanding vascular glucose homeostasis and the relationship between diabetes and cardiovascular diseases.

In Vivo Anchoring Bis-Pyrene Probe for Molecular Imaging of Early Gastric Cancer by Endoscopic Techniques.

With the development of blue laser endoscopy (BLE) technique, it's often used to diagnose early gastric cancer (EGC) by the morphological changes of blood vessels through BLE. However, EGC is still not obvious to identify, resulting in a high rate of missed diagnosis. Molecular imaging can show the changes in early tumors at molecular level, which provides a possibility for diagnosing EGC. Therefore, developing a probe that visually monitors blood vessels of EGC under BLE is particularly necessary. Herein, a bis-pyrene (BP) based nanoprobe (BP-FFVLK-(PEG)-RGD, M1 ) is designed, which can target angiogenesis and self-assemble into fibers in situ, resulting in stable and long-term retention in tumor. Moreover, M1 probe can emit yellow-green fluorescence for imaging under BLE. M1 probe is confirmed to steadily remain in tumor for up to 96 hours in mice transplanted subcutaneously. In addition, the M1 probe is able to target angiogenesis for molecular imaging of isolated human gastric cancer tissue under BLE. Finally, M1 probe i.v. injected into primary gastric cancer model rabbits successfully highlighted the tumor site under BLE, which is confirmed by pathological analysis. It's the first time to develop a probe for diagnosing EGC by visualizing angiogenesis under BLE, showing great clinical significance.

Risks and possible complications in maxillofacial surgery patients during or after coronavirus infection

This review/prognostic article briefly shows the pandemic features of COVID-19, morphological changes in blood vessels in COVID-19, mainly related to endotheliitis and thrombosis of small vessel branches. Cases of COVID-19 complications occurring in the practice of maxillofacial surgeons are given. Regarding possible complications during invasive interventions on the head and neck, we believe it is possible to consider COVID-19 in the anamnesis of patients in the departments of maxillofacial surgery as a new risk factor, and in case of severe course and prognosis of possible complications, as a contraindication for manipulations in the head and neck area.

The role of the muscular system in the pathogenesis of thrombotic complications of the lower extremities in cancer patients

Introduction. Thrombosis occurs in 15 % of cancer patients, most of these thrombosis is localized in the venous system of the lower extremities. In addition to biological and chemical factors that increase thrombosis, changes in the muscles of the lower extremities play an important role. Disorders of hemodynamic and metabolic processes in the muscles of the lower extremities lead to morphological changes and increase the risk of thrombosis in cancer patients. The aim of the study. Investigate morphological changes in the muscles of the lower extremities and evaluate their role in the formation of thrombosis in cancer patients. Materials and methods. Histological examination of 90 patients, which were divided into four groups depending on the location of the cancer process and the cause of death. The first group A – 34 patients with colon cancer, the second group B – 20 patients with pancreatic cancer, patients from these groups died as a result of thromboembolism. Group B – 19 patients, and group G – 17 patients - people whose cause of death was not thromboembolism. The analysis of biomaterial by means of histological and polarization methods of research is carried out. Additionally, electron microscopy of the obtained biopsy materials was performed. The number of citrate blood endothelial cells was determined in all subjects according to the method of J. Hladovez. Research results and their discussion. The study revealed a large number of morphological changes in blood vessels and muscle fibers. The data obtained indicate that patients with cancer of the pancreas and colon have significant changes in the endothelial lining of the venules and areterioles. All cells have signs of interstitial edema, changes in organelles and signs of hemodynamic disturbances. In some areas, there were complete atrophy of some muscle fibers and compensatory hypertrophy of others. Studies have shown areas of sarcoplasmic homogenization and myocytolysis. Conclusions. In the case of cancer of the pancreas or/and colon, there is significant damage to the endothelium of the vessels of the lower extremities, there are dystrophic-atrophic changes in the muscles with impaired function. Cells suffer from interstitial and perivascular edema, there are contractures of change, myocytolysis. Morphological changes lead to disruption of their function of damage, myocytolysis and remodeling of muscle fibers. The result is an increased risk of thrombosis with subsequent thrombus consideration and a possible risk of pulmonary embolism.

A 3D tissue model-on-a-chip for studying the effects of human senescent fibroblasts on blood vessels.

All human tissues experience aging that eventually causes organ dysfunction and disease. Cellular senescence was discovered in fibroblasts cultured in vitro. In adults, it is a primary defense mechanism against cancer, but also a major contributor to lifespan limits and disorders associated with aging. To assess how human blood vessels change in an aged environment, we developed an elementary tissue model-on-a-chip that comprises an in vitro three-dimensional model of a blood vessel embedded in a collagen gel with young or senescent skin fibroblasts. We found that senescent fibroblasts mechanically altered the surrounding extracellular matrix by exerting excessive traction stress. We then found that senescent fibroblasts induced sprouting angiogenesis of a microvessel via their senescence-associated secretory phenotype (SASP). Finally, we gathered evidence that the mechanical changes of the microenvironment play a role in sustaining SASP-induced angiogenesis. The model proved useful in monitoring morphological changes in blood vessels induced by senescent fibroblasts while controlling the proportion of senescent cells, and enabled the study of SASP inhibitors, a class of drugs useful in aging and cancer research.

Effect of Activated Protein Kinase C Beta Type Mediated Phosphorylation of Signal Transducer and Activator of Transcription 4 on Proliferation and Phenotypic Transformation of Vascular Smooth Muscle Cells After Vascular Injury Induced by Nano-SiO₂.

The excessive proliferation, endothelial migration, and phenotype transformation of vascular smooth muscle cells (VSMC) lead to increased extracellular matrix secretion, which induces vascular intimal hyperplasia, which is an important restenosis mechanism after vascular injury. In our study, we verified the cytotoxicity of SiO₂ nanoparticles to VSMC. To explore the role of endothelial repairs and molecular mechanisms after vascular injuries, we sequenced the transcriptome of injured vessels in the carotid artery of mice. The results showed the differentially expressed genes in normal vascular tissues, and that vascular tissues were mainly enriched with NF-κB signaling pathways, chemokine signaling pathways and other biological functions, by the leukocyte activation and adhesion of the KEGG pathway in the immune response, and by DNA binding, DNA transcription regulatory region binding, and other molecular functions. Core proteins included PRKCB, STAT4, CCL5, and BCL-2. To verify the roles of these core proteins, RT-qPCR andWestern blot techniques were used to detect their transcription and translation levels, and HE staining was used to detect morphological changes in blood vessels. To further clarify the role of core proteins in VSMC, PRKCB over expression plasmids were constructed, and the RT-qPCR and Western blot techniques were again used to detect the expression of core proteins. The results showed that the levels of transcription and translation, and of PRKCB and STAT4 phosphorylation, increased significantly after vascular injury, and then noticeably decreased three days later- and that CCL5 and Bcl-2 expression trends were consistent with this. HE staining showed that when the vascular endothelium was damaged, smooth muscle cells proliferated significantly, and that the intima thickened three days after vascular injury. After over expression of PRKCB, the expression and activation of STAT4, CCL5, and Bcl-2 significantly increased, α-SMA and Vimentin were down-regulated, OPN was up-regulated, and VSMC activity was enhanced. From these results, it could be concluded that PRKCB is activated by vascular injury, and that over-activation of PRKCB promotes activation of STAT4 and the expression of CCL5 and BCL-2-which in turn leads to enhanced VSMC activity and transformation of its contraction phenotype to the secretion phenotype. We were also able to establish that the cytotoxicity of SiO₂ nanoparticles to VSMC was positively correlated with dose and time.

Morphological analysis of melasma lesions at different clinical stages by using three different skin imaging techniques

Objective To investigate morphological characteristics of female melasma lesions at different clinical stages by using three skin imaging techniques. Methods A total of 253 female outpatients with melasma were enrolled from the Third Affiliated Hospital of Zhejiang Chinese Medicine University between June 2017 and January 2018. According to the clinical staging criteria, melasma lesions at different clinical stages were observed with reflectance confocal microscopy (RCM) , VISIA skin imaging detector and dermoscopy, and correlations of clinical staging with dendritic melanocytes, subclinical melasma and morphological changes of blood vessels were analyzed. Statistical analysis was carried out with SPSS19.0 software by using chi-square test and Mann-Whitney U test for the comparison of enumeration data. Results Of 253 patients with melasma, 100 were with progressive melasma, and 153 with stable melasma. RCM showed that dendritic melanocytes were observed in 78 (78%) patients with progressive melasma, as well as in 22 (14.4%) patients with stable melasma, and there was a significant difference between the 2 groups (χ2 = 102.40, P < 0.01) . VISIA skin imaging detector showed that subclinical melasma was observed in 78 (78%) patients with progressive melasma, as well as in 25 (16.3%) patients with stable melasma, and the prevalance of subclinical melasma was significantly higher in the patients with progressive melasma than in those with stable melasma (χ2 = 95.26, P < 0.01) . Dermoscopy showed that the frequency of morphological changes in blood vessels did not differ between the patients with progressive melasma (74%, 74/100) and those with stable melasma (68.6%, 105/153; χ2 = 0.84, P = 0.39) . Conclusion The dendritic melanocytes and subclinical manifestations under RCM and VISIA skin imaging detector can serve as reference indices for clinical staging of melasma. Key words: Chloasma; Melanocytes; Microscopy, confocal; Dermoscopy; Clinical stages; Skin imaging detector

Anti-atherosclerotic activities of flavonoids from the flowers of Helichrysum arenarium L. MOENCH through the pathway of anti-inflammation

We have successfully established AS model using thoracic aortas vascular ring which evaluated by the morphological changes of blood vessels, the proliferation of VSMC, and the expression of inflammation factors VEGF, CRP, JNK2 and p38. This AS model has the advantages of low cost, convenient and short period of established time. Moreover, we investigated the anti-AS activities of 7 flavonoids Narirutin (1), Naringin (2), Eriodictyol (3), Luteolin (4), Galuteolin (5), Astragalin (6), Kaempferol (7) from flowers of Helichrysum arenarium L. MOENCH by examining the vascular morphology, the inhibition on the expression of inflammation factors CRP, VEGF, JNK2, p38. In addition, we investigated the anti-AS activities of these 7 flavonoids by examining NO secretion of RAW264.7 cells in response to LPS. All above inflammation factors have been proved to be involved in the formation of AS. After comprehensive analysis of all results to discuss the structure–activity relationship, we summarized the conclusions at follow: compounds 1–7 could inhibit the expression of VEGF, CRP, JNK2, p38 and NO at different level, and we evaluated that flavonol aglycone have more significant anti-inflammation than it’s glycoside, and the anti-AS activity of flavonols were stronger than flavanones and flavones, which means that 3-group might be the effective group. Eventually, we supposed the main anti-inflammatory mechanism of these compounds was to reduce the expression of CRP, inhibit the kinases activity of JNK2 and p38, and then the MAPK pathway was suppressed, which resulted in the decrease of NO synthesis, VEGF expression and endothelial adhesion factor expression. And eventually, the scar tissue and vascular stenosis formations were prevented. This conclusion suggested flavonoids have the potential of preventing AS formation.

Statins attenuate the development of atherosclerosis and endothelial dysfunction induced by exposure to urban particulate matter (PM10)

Exposure to ambient air particulate matter (particles less than 10μm or PM10) has been shown to be an independent risk factor for the development and progression of atherosclerosis. The 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitors (statins) have well-established anti-inflammatory properties. The aim of this study was to determine the impact of statins on the adverse functional and morphological changes in blood vessels induced by PM10. New Zealand White rabbits fed with a high fat diet were subjected to balloon injury to their abdominal aorta followed by PM10/saline exposure for 4weeks±lovastatin (5mg/kg/day) treatment. PM10 exposure accelerated balloon catheter induced plaque formation and increased intimal macrophages and lipid accumulation while lovastatin attenuated these changes and promoted smooth muscle cell recruitment into plaques. PM10 impaired vascular acetylcholine (Ach) responses and increased vasoconstriction induced by phenylephrine as assessed by wire myograph. Supplementation of nitric oxide improved the impaired Ach responses. PM10 increased the expression of inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) in blood vessels and increased the plasma levels of endothelin-1 (ET-1). Incubation with specific inhibitors for iNOS, COX-2 or ET-1 in the myograph chambers significantly improved the impaired vascular function. Lovastatin decreased the expression of these mediators in atherosclerotic lesions and improved endothelial dysfunction. However, lovastatin was unable to reduce blood lipid levels to the baseline level in rabbits exposed to PM10. Taken together, statins protect against PM10-induced cardiovascular disease by reducing atherosclerosis and improving endothelial function via their anti-inflammatory properties.

Characterization of blood vessels in brain autopsies of GBM patients who received antiangiogenic treatment

2009 Background: GBs have two types of vessels: co-opted and angiogenic. We hypothesize that antiangiogenic therapy normalizes angiogenic blood vessels and increases co-option of host vessels. However, to date the morphological changes in blood vessels of human tumors treated with antiangiogenic agents have not been studied. Methods: Interim results of a phase II clinical trial with a potent oral, pan-VEGF receptor tyrosine kinase inhibitor with activity against VEGF and PDGF receptors (Cediranib; AZD2171) showed a decrease in tumor contrast enhancement of more than 50% in 16/30 patients, decreased vessel permeability and vessel diameter - all hallmarks of vascular normalization. Autopsy specimens were obtained from 3 patients who were enrolled in this trial and received AZD2171 for 56, 120, and 140 days. All these patients had stable disease and none of these patients had radiographic progression at the time of AZD2171 termination. The interval between the last dose of AZD2171 and time of death ranged from 16 days to 3 months. Sections were stained for a series of markers relevant to microvessel integrity [CD31, CD71, MDR-1, nestin, CXCR4, SDF1a, PDGFRα,β] and analyses performed on two tumor areas and two corresponding contralateral areas free of bulk tumor for each patient. Results: Morphologically, the treated tumor vessels appeared more normal: endothelial hyperproliferation and glomeruloid-like vessels dramatically decreased and vessel density was restored close to that in the contralateral brain. PDGFRβ, which was expressed on all tumor vessels prior to treatment was nearly undetectable, and CD71 (a marker of the blood-brain-barrier) expression was partially restored. These changes were not seen in patients treated with temozolomide and radiation. Conclusions: Inhibition of VEGF and PDGF receptors led to significant changes in the tumor blood vessels. The vessel density increased while the endothelium morphology reverted to a more normal phenotype (monolayer), supporting the hypothesis that anti-VEGF therapy leads to vascular normalization and to vessel co-option. Author Disclosure Employment or Leadership Consultant or Advisory Role Stock Ownership Honoraria Research Expert Testimony Other Remuneration AstraZeneca, Dyax, Pfizer Pharmaceutical, Takeda Pharmaceutical AstraZeneca

Effect of high energy shock waves on microvessel density and cellular ultrastructure of the necrotic femoral head

Objective To investigate the effect of high energy shock waves on microvessel density and cellular ultrastructure of the necrotic femoral head,and the mechanism of avascular femoral head necrosis treated with high energy shock waves. Methods Thirty.two male adult New Zealand white rabbits,weighing 3.0 to 4.0 kg(average weight,3.4 kg),were used to establish animal models of avascular femoral head necrosis.Bilateral femoral head necroses were induced by methylprednisolone and lipopolysacchafide.The left hind limbs(treatment side)of all rabbits received shock wave treatment to the femoral heads while tlleir fight limbs(control side)received no shock wave treatment.At 4,8 and 12 weeks after the shock wave treatment,vascular infusion with Chinese ink was made to evaluate the morphological changes of blood vessels in the femoral heads and cellular uhrastructure of the femoral head was observed by transmission electron microscope(TEM). Results At 4,8 and 12 weeks after shock wave treatment,microvessel density of the fenoral heads at the treatment side was significantly higher than that at the eontrol side(P=0.001.P=0.001.P=0.000).At 8 and 12 weeks after shock wave treatment,trabecular bone area of the femoral head at the treatment side was also significantly larger than that at the controJ side(P=0.011,P=0.003).TEM showed that the number and the funotion of osteob|asts and vascular endothelia at the treatment side were hiigher than at the control side. Conclusion High energy shock waves may have promoting effect on angiogenesis of necrotic femoral head,improving the function of osteoblasts and vascular endothelia in the femoral head and accelerating repair process of the necrotic femoral head. Key words: Femoral head necrosis; Glucocorticoids; High energy shock waves

Parameters of endothelial function and insulin resistance in patients with metabolic syndrome before and after weight loss

In clinical practice, physicians of different specialties often faced with the metabolic syndrome (MS) is a set of hormonal and metabolic disorders that share a common pathophysiological mechanism - insulin resistance (IR) [1, 5, 11]. MS is important for the clinician not only how widespread pathology, but primarily as a life-threatening condition. Of course, this syndrome plays an important role in accelerating the development and progression of diseases associated with atherosclerosis, which, according to experts WHO, ranks first among the causes of mortality in industrialized countries [12, 16, 19]. This situation is particularly important for Russia due to the relatively high spread of the syndrome, component, according to several authors, about 20% of the population, and high rates of death from coronary heart disease and stroke in the Russian population [2, 4, 5]. It is known that the risk of coronary heart disease (CHD), stroke, and total coronary mortality increases with the number of components of metabolic syndrome [14, 15, 20]. The study J.H. Park et al., Which included 478 patients with ischemic stroke, MS was diagnosed in 53.4% of patients (criteria NCEP ATP III), the thickness of the complex value of the index "intima-media" of the carotid arteries was increased in direct proportion to an increase in the number of available components of MS [20] . Link between R D and cardiovascular disease, apparently, is endothelial dysfunction, which is the study at various metabolic diseases received much attention [9, 10, 22]. Endothelial dysfunction, which is typical for many patients with MS, is a marker of metabolic and vascular disorders [15, 22]. In the initial period of development of the atherosclerotic process, even when there are no obvious clinical manifestations and visible morphological changes of blood vessels, the main role is played by endothelial dysfunction [9, 21]. Endothelial dysfunction is also discussed as one of the reasons for the rapid development, progression of atherosclerosis and its complications in patients with MS [11,18]. For example, recent studies have shown that tears plaques leading to myocardial infarction, do not always occur in the zone of maximum stenosis of the coronary arteries [13]. Rather, they tend to occur in places restrictions of small - less than 50% by angiography. The study of endothelial function in patients with MS is at the initial stages of the study [8, 15, 18]. In addition, of particular interest is the study of the effect of weight loss on the state of the endothelium in the syndrome of insulin resistance.

Morphological Changes in Blood Vessels Produced by Hyperosmotic Agents and Measured by Optical Coherence Tomography ¶

Morphological Changes in Blood Vessels Produced by Hyperosmotic Agents and Measured by Optical Coherence Tomography ¶

Morphological changes in blood vessels produced by hyperosmotic agents and measured by optical coherence tomography.

Optical tissue clearing by hyperosmotic chemical agents significantly increases light depth penetration in skin and may improve light-based therapeutics such as laser treatment of cutaneous vascular lesions. A feasibility study was conducted to evaluate the potential role of optical clearing by glycerol in laser treatment of cutaneous vessels. Optical imaging was performed to investigate the morphological effects of glycerol on blood vessels of skin. Blood vessels were imaged using Doppler optical coherence tomography in in vivo hamster skin treated with glycerol. Images were obtained from the subdermal side to assess morphological changes in the blood vessels caused by glycerol and from the epidermal side to assess enhanced Doppler imaging of blood vessels. Application of glycerol to the subdermis resulted in venule stasis and for prolonged treatment times, arteriole stasis. In cases where flow remained in arterioles, an improved Doppler signal was detected from blood vessels when imaging transepidermally compared with the native condition. Intensity images indicated changes in blood optical properties and improved contrast of skin cross sections after glycerol application. The observed optical and morphological effects were reversed upon hydration of the skin with phosphate-buffered saline. The combination of increased depth of light penetration and the temporary slowing or cessation of flow in blood vessels could mean improved laser treatment of vessels.

Morphological Changes of Blood Vessels in the Brain with Alzheimer's Disease

Morphological changes of microvessels in the cerebral cortices of Alzheimer's disease and control brains were examined. From several parts of the brains, all of the vessels in blocks of tissues were isolated with ultrasound treatment and mesh filtration, and were observed by light microscopy. The results obtained were as follows: There was no difference between the relatively large arteries of the brains with Alzheimer's disease and the control brains. However, in the Alzheimer's brain irregular shapes of blood vessels and degenerated smooth muscle cells of a single layer were observed in the terminal arterioles. In the capillaries, focal constrictions and irregular shapes were observed. In addition to these changes, the nuclei of endothelial cells were irregular and unclear. These findings seem to indicate that the degeneration of microvessels in the brain of Alzheimer's disease might have occurred at the terminal arterioles and the capillaries.

An angiographic study of the fox testis in various stages of sexual activity.

The arteries and veins of the fox testis were studied using an angiographic technique. The postnatal development of the testis involved only minor modification of the vasculature. In the non-breeding season both the arteries and veins of the adult fox testis undergo extensive spiralization which completely disappears during the breeding season. When the sequence of morphological changes in blood vessels are related to available data on changes in testicular size, blood flow and connective tissue content, it is obvious that the vascular spiralization is passive and related to shrinkage of the organ and dose not primarily influence the testicular blood flow.