Development and Validation of a Deep Learning Model for Histopathological Slide Analysis in Lung Cancer Diagnosis.

Lung cancer is the leading cause of cancer-related deaths worldwide. Two of the crucial factors contributing to these fatalities are delayed diagnosis and suboptimal prognosis. The rapid advancement of deep learning (DL) approaches provides a significant opportunity for medical imaging techniques to play a pivotal role in the early detection of lung tumors and subsequent monitoring during treatment. This study presents a DL-based model for efficient lung cancer detection using whole-slide images. Our methodology combines convolutional neural networks (CNNs) and separable CNNs with residual blocks, thereby improving classification performance. Our model improves accuracy (96% to 98%) and robustness in distinguishing between cancerous and non-cancerous lung cell images in less than 10 s. Moreover, the model's overall performance surpassed that of active pathologists, with an accuracy of 100% vs. 79%. There was a significant linear correlation between pathologists' accuracy and years of experience (r Pearson = 0.71, 95% CI 0.14 to 0.93, p = 0.022). We conclude that this model enhances the accuracy of cancer detection and can be used to train junior pathologists.

Perception of Pathologists in Poland of Artificial Intelligence and Machine Learning in Medical Diagnosis-A Cross-Sectional Study.

BACKGROUND: In the past vicennium, several artificial intelligence (AI) and machine learning (ML) models have been developed to assist in medical diagnosis, decision making, and design of treatment protocols. The number of active pathologists in Poland is low, prolonging tumor patients' diagnosis and treatment journey. Hence, applying AI and ML may aid in this process. Therefore, our study aims to investigate the knowledge of using AI and ML methods in the clinical field in pathologists in Poland. To our knowledge, no similar study has been conducted. METHODS: We conducted a cross-sectional study targeting pathologists in Poland from June to July 2022. The questionnaire included self-reported information on AI or ML knowledge, experience, specialization, personal thoughts, and level of agreement with different aspects of AI and ML in medical diagnosis. Data were analyzed using IBM® SPSS® Statistics v.26, PQStat Software v.1.8.2.238, and RStudio Build 351. RESULTS: Overall, 68 pathologists in Poland participated in our study. Their average age and years of experience were 38.92 ± 8.88 and 12.78 ± 9.48 years, respectively. Approximately 42% used AI or ML methods, which showed a significant difference in the knowledge gap between those who never used it (OR = 17.9, 95% CI = 3.57-89.79, p < 0.001). Additionally, users of AI had higher odds of reporting satisfaction with the speed of AI in the medical diagnosis process (OR = 4.66, 95% CI = 1.05-20.78, p = 0.043). Finally, significant differences (p = 0.003) were observed in determining the liability for legal issues used by AI and ML methods. CONCLUSION: Most pathologists in this study did not use AI or ML models, highlighting the importance of increasing awareness and educational programs regarding applying AI and ML in medical diagnosis.

Chronic kidney disease predictors in obese adolescents.

BACKGROUND: Glomerular hyperfiltration, initiating development of obesity-related glomerulopathy, results in an enlargement of the glomeruli and unsealing of the filtration barrier. It can be followed by adaptive focal segmental glomerulosclerosis and chronic kidney disease (CKD). The aim of the study was to determine the expression pattern of lipid metabolism and selected kidney damage markers in obese adolescents and to identify potential factors which can predict CKD. METHODS: The study group consisted of 142 adolescents with a BMI z-score > 2. Sixty-two healthy and normal-weight individuals served as controls. The factors associated with the rate of glomerular filtration in obese adolescents were assessed by linear regression methods using univariate and multivariate analyses. The risk of developing CKD was estimated using the Fisher's exact test. RESULTS: The study group was divided into "elevated," "normal," and "decreased" glomerular filtration rate (GFR) patients. Increased urine galectin-3 (Gal-3) concentration was diagnosed in all patients. "Decreased GFR" subjects expressed increased urine concentration of neutrophil gelatinase-associated lipocalin (NGAL) and daily megalin excretion. Thirty-nine study participants developed CKD. Increased uric acid (UA) concentration was associated with CKD development both in "normal" and "decreased GFR" patients. Additionally, in "normal" GFR patients, increased concentrations of cholesterol (Ch), triglycerides (TG), and NGAL were associated with CKD. CONCLUSIONS: Increased serum concentrations of Ch, TG, and UA and increased urine concentration of NGAL might predict CKD development in obese adolescents with normal and decreased GFR. A higher resolution version of the Graphical abstract is available as Supplementary information.

A pre-conditioning protocol of peripheral blood derived endothelial colony forming cells for endothelialization of tissue engineered constructs.

In regenerative medicine, autologous endothelial colony forming cells (ECFCs) bear the greatest potential to be used for surface endothelialization of tissue engineered constructs, as they are easily attainable and possess a high proliferation rate. The aim of this study was to develop a standardized pre-conditioning protocol under dynamic conditions simulating the physiology of human circulation to improve the formation of a flow resistant monolayer of ECFCs and to enhance the antithrombogenicity of the endothelial cells. The main focus of the study was to consequently compare the cellular behavior under a steady laminar flow against a pulsatile flow. Mononuclear cells were isolated out of peripheral blood (PB) buffy coats and plated on uncoated tissue culture flasks in anticipation of guidelines for Advanced Therapy Medicinal Products. ECFCs were identified by typical surface markers such as CD31, CD146 and VE-Cadherin. To explore the effects of dynamic cultivation, ECFCs and human umbilical vein endothelial cells were comparatively cultured under either laminar or pulsatile (1 Hz) flow conditions with different grades of shear stress (5 dyn/cm2versus 20 dyn/cm2). High shear stress of 20 dyn/cm2 led to a significant upregulation of the antithrombotic gene marker thrombomodulin in both cell types, but only ECFCs orientated and elongated significantly after shear stress application forming a confluent endothelial cell layer. The work therefore documents a suitable protocol to pre-condition PB-derived ECFCs for sustainable endothelialization of blood contacting surfaces and provides essential knowledge for future cultivations in bioreactor systems.

How important to dairies is selling tobacco? Views of dairy owners and managers on tobacco retailing.

AIM: Given the Government's commitment to reducing tobacco availability to minimal levels by 2025, finding ways to decrease the number of tobacco retailers is an important task. We assessed the perceived importance of selling tobacco among dairy owners and managers. METHOD: We conducted a face-to-face survey to explore retailers' views on selling tobacco products, tobacco retailer licensing and tobacco-free retailing. Descriptive statistics were used to analyse the data. RESULTS: Of the 112 individuals invited to participate, 62 (55.4%) completed the survey. Most respondents felt that selling tobacco was important for their business, and almost two-thirds had concerns about tobacco products being a security risk. Twice as many respondents thought tobacco retail outlet licensing was a potentially viable option as those who expressed caution. Almost one-third of respondents were potentially interested in becoming a tobacco-free retailer. CONCLUSION: Selling tobacco products is perceived as important for many dairies, and just over half were not interested in becoming a tobacco-free retailer. However, there is some support among dairy owners/managers for tobacco product licensing. These findings strengthen the case for regulatory measures to decrease tobacco availability, as voluntary adoption of tobacco-free retailing is unlikely to result in substantial reductions in outlet numbers.

Aptamer-based detection of adenosine triphosphate via qPCR.

Sensitive and specific detection and quantification of small molecules often remain challenging. We developed a novel magnetic bead-based aptamer-assisted real-time PCR (Apta-qPCR) assay to provide a versatile platform for quantification of small molecules. The assay has been realized for the detection of ATP as a model system. The assay relies on a combination of qPCR with the target-induced dissociation (TID) of ATP aptamer from an oligonucleotide, complementary to the ATP binding site of the aptamer. The complementary oligonucleotide was immobilized on deoxythymidine (dT)-modified magnetic beads (dT-beads) and hybridized with the aptamer. The presence of ATP resulted in dissociation of the aptamer from the dT-beads and the dissociated aptamer was quantified using qPCR. The Apta-qPCR assay was able to detect 17nM ATP with a broad dynamic range from 50nM to 5mM. The assay is label-free, and real-time PCR-based detection of aptamer facilitates high sensitivity. The presented method is highly versatile and can be applied to various aptamer-target pairs to allow detection of a broad range of target analytes.

Caveolin 2: a facultative marker of unfavourable prognosis in long-term patency rate of internal thoracic artery grafts used in coronary artery bypass grafting. Preliminary report.

OBJECTIVES: Intimal hyperplasia leading to graft failure in patients undergoing coronary artery bypass grafting (CABG) is related to vascular smooth muscle cells (SMCs) proliferation. SMCs respond to a variety of mediators, the most important of which is platelet-derived growth factor (PDGF). The platelet-derived growth factor-induced cellular response has been shown to be mediated by caveolins. The aim of this study was to analyze CAV1-3 expression in internal thoracic artery (ITA) grafts used in CABG and correlate their expression with graft occlusion. METHODS: Six hundred patients undergoing CABG with the use of ITA grafts between 2008 and 2014 were enrolled into this prospective study. CAV1-3 expression in the ITA grafts was analyzed prior to graft transplantation into the coronary circulation via immunohistochemistry. Estimated caveolins expression pattern was then correlated with the occurrence of ITA graft failure observed within 24-months of surgery. RESULTS: Thirty-four patients developed ITA graft failure (subgroup A) and 566 study participants presented no adverse events (subgroup B). CAV1 and CAV3 expression levels in SMCs of the tunica media of the ITA grafts did not differ between the study subgroups and were not associated with the risk of graft failure. CAV2 was expressed within SMCs of the ITA grafts in 94.1% of the patients from subgroup A and 2.5% from subgroup B, and its expression was associated with ITA graft occlusion observed within 24-months after CABG. CONCLUSIONS: CAV2 expression in SMCs of the tunica media in autologous ITA transplants might indicate the risk of graft failure.

Novel subventricular zone early progenitor cell-specific adenovirus for in vivo therapy of central nervous system disorders reinforces brain stem cell heterogeneity.

Neural stem/progenitor cells (NSPCs) have the potential to self-renew and to generate all neural lineages as well as to repopulate damaged areas in the brain. Our previous targeting strategies have indicated precursor cell heterogeneity between different brain regions that warrants the development of NSPC-specific delivery vehicles. Here, we demonstrate a target-specific adenoviral vector system for the in vivo manipulation of progenitor cells in the subventricular zone of the adult mouse brain. For this purpose, we identified a series of peptide ligands via phage display. The peptide with the highest affinity, SNQLPQQ, was expressed in conjunction with a bispecific adaptor molecule. To verify the targeting potential of the specific peptide, green fluorescent protein-expressing Ad vectors were coupled with the adaptor molecule and injected into the subventricular region of adult mice by stereotaxic surgery. An efficient and selective transduction of NSPCs in the SVZ was achieved, whereas hippocampal NSPCs were negative. Our results offer an expeditious and simple tool to produce retargeted viral vectors for a specific and direct in vivo manipulation of these progenitor cells. This powerful technique provides an opportunity to develop innovative strategies and express therapeutic genes in specific types of neural progenitor cells to allow success in treatment of brain disorders.

A Comparative Morphometric Analysis of Three Cranial Nerves in Two Phocids: The Hooded Seal (Cystophora cristata) and the Harbor Seal (Phoca vitulina).

While our knowledge about the senses of pinnipeds has increased over the last decades almost nothing is known about the organization of the neuroanatomical pathways. In a first approach to this field of research, we assessed the total number of myelinated axons of three cranial nerves (CNs) in the harbor (Phoca vitulina, Pv) and hooded seal (Cystophora cristata, Cc). Axons were counted in semithin sections of the nerves embedded in Epon and stained with toluidine blue. In both species, the highest axon number was found within the optic nerve (Pv 187,000 ± 8,000 axons, Cc 481,600 ± 1,300 axons). Generally, considering absolute axon numbers, far more axons were counted within the optic and trigmenial nerve (Pv 136,700 ± 2,500 axons, Cc 179,300 ± 6,900 axons) in hooded in comparison to harbor seals. The axon counts of the vestibulocochlear nerve are nearly identical for both species (Pv 87,100 ± 8,100 axons, Cc 86,600 ± 2,700 axons). However, when comparing cell density, the cell density is almost equal for all nerves for both species except for the optic nerve in which cell density was particularly higher than in the other nerves and higher in hooded in comparison to harbor seals. We here present the first comparative analysis of three CNs in two phocid seals. While the CNs of these closely related species share some general characteristics, pronounced differences in axon numbers/densities are apparent. These differences seem to reflect differences in e.g. size, habitat, and/or functional significance of the innervated sensory systems.

Development of a novel injectable drug delivery system for subconjunctival glaucoma treatment.

In this study we present the development of an injectable polymeric drug delivery system for subconjunctival treatment of primary open angle glaucoma. The system consists of hyaluronic acid sodium salt (HA), which is commonly used in ophthalmology in anterior segment surgery, and an isocyanate-functionalized 1,2-ethylene glycol bis(dilactic acid) (ELA-NCO). The polymer mixtures with different ratios of HA to ELA-NCO (1/1, 1/4, and 1/10 (v/v)) were investigated for biocompatibility, degradation behavior and applicability as a sustained release system. For the latter, the lipophilic latanoprost ester pro-drug (LA) was incorporated into the HA/ELA-NCO system. In vitro, a sustained LA release over a period of about 60days was achieved. In cell culture experiments, the HA/ELA-NCO (1/1, (v/v)) system was proven to be biocompatible for human and rabbit Tenon's fibroblasts. Examination of in vitro degradation behavior revealed a total mass loss of more than 60% during the observation period of 26weeks. In vivo, LA was continuously released for 152days into rabbit aqueous humor and serum. Histological investigations revealed a marked leuko-lymphocytic infiltration soon after subconjunctival injection. Thereafter, the initial tissue reaction declined concomitantly with a continuous degradation of the polymer, which was completed after 10months. Our study demonstrates the suitability of the polymer resulting from the reaction of HA with ELA-NCO as an injectable local drug delivery system for glaucoma therapy, combining biocompatibility and biodegradability with prolonged drug release.

Morphological analysis of quiescent and activated keratocytes: a review of ex vivo and in vivo findings.

Keratocytes are specialized, neural crest-derived mesenchymal cells occupying approximately 3% of the corneal stromal volume. They reside between the collagen lamellae and are responsible for the secretion of extracellular matrix macromolecules, thus contributing to the corneal transparency and integrity. During the regeneration process after infection, traumata and refractive surgery, the keratocytes undergo transition into divergent phenotypes, which are referred to as "activated keratocytes". Quite shortly after injury, the keratocytes lose their quiescence, enter into the cell cycle and migrate toward the site of injury. In certain types of injury, which affect the integrity of basement membrane, activated keratocytes also participate in wound closure by production of α-smooth muscle actin (α-SMA). Since the activated keratocytes are the major cell type contributing to tissue repair during corneal wound healing, their morphological and biochemical properties have been studied in details in experimental studies using light and electron microscopy. More recently, emerging of in vivo microscopy techniques has opened new possibilities to investigate cornea in vivo. The non-invasive nature of this imaging modality enables repeated examination of the same tissue over time and is an ideal tool to rapidly and accurately investigate corneal wound healing. However, the in vivo data on activated keratocytes are not as uniform as data from experimental ex vivo studies. There is still inconsistency in the literature findings on activated phenotypes, and often the described morphologies cannot be appreciated in in vivo images. In this article, a literature review was performed in order to interpret the morphology of different activated phenotypes, based on biological processes underlying the morphological alterations.

Smokefree outdoor areas in New Zealand: how far have we come?

AIM: This research examined 1) the extent and nature of smokefree outdoor area (SFOA) policies in New Zealand, and 2) the process of developing, implementing and promoting compliance with a SFOA policy. METHOD: An online survey was carried out with 43 of the 67 Local and District Councils, supplemented by other means. The survey assessed whether the council had a smokefree policy and if so, what locations the policy covered, the process of developing, implementing and promoting compliance with a smokefree policy, the challenges associated with policy development, and plans for future policies. RESULTS: SFOA policies had been enacted by a total of 47 councils, 31 of which responded to the survey, covering a combination of playgrounds, sports grounds, parks, and council run events. Lack of public health priorities, and resources were common issues preventing other councils from developing a policy. Letters from health advocacy groups strongly influenced councils to introduce SFOA policies. The biggest barriers to implementation of SFOA policy were time and resource commitment required from staff, and the financial cost for signage. Voluntary compliance was used to ensure compliance with the policies; no councils used active enforcement. Few councils have evaluated their policies, but most felt that it had been successful. CONCLUSION: Health groups can take heart that their advocacy is resulting in policy change within local government. However, continued efforts are required to undertake evaluations of current SFOA policies which may provide evidence to extend SFOAs, to assist those councils without a SFOA policy to develop one, and to increase funding for implementation.

Ultra high-field magnetic resonance imaging of a glaucoma microstent.

PURPOSE: The aim of the present study was to use 7.1T magnetic resonance imaging (MRI) to determine the correct anatomical position of a non-metallic glaucoma microstent following implantation in rabbit eyes. MATERIALS AND METHODS: In an in vitro experiment three microstents (made from silicone, polyurethane, and nickel titanium) were embedded in a standard vial filled with agar. In a second series of experiments a prefabricated polyurethane microstent connecting the anterior chamber with the suprachoroidal space (SCS) was implanted in rabbit eyes (n = 12). High-resolution images were acquired ex vivo (n = 6) and in vivo (n = 6) on an ultra high-field MRI unit using a 2-channel coil with four coil elements and T2-weighted turbo spin-echo sequences. Finally, the eyes were dissected and processed for histology. RESULTS: Artifact-free MR imaging of silicone and polyurethane microstents was achieved in vitro, with slightly higher contrast for silicone stents. Image quality for the nickel titanium stent was greatly reduced due to artifacts. MRI examination of rabbit eyes ex vivo and in vivo following polyurethane microstent implantation presented no problems in terms of the size and placement of the coil. The sequences showed good image quality; the full length of the microstent was visualized in cross-section and longitudinal section, and correct anatomical placement was demonstrated from the anterior chamber into the SCS. These findings were verified by histology. CONCLUSIONS: The excellent image quality obtained with both of the non-metallic materials generates detailed information about microstent placement, including the surrounding tissues. High-resolution MRI can be used to monitor the anatomical position of a microstent after glaucoma surgery in animal experiments and is therefore a valuable tool for documenting experimental research findings ex vivo and in vivo.

Olfactory mucosa in nasal polyposis: implications for FESS outcome.

OBJECTIVE: This study investigates olfactory epithelium biopsies from patients with nasal polyposis, in correlation with olfactory test results and ratings of olfactory dysfunction pre- and postoperatively. MATERIAL & METHODS: Twenty-seven patients with nasal polyposis were included. Olfactory function was tested with the "Sniffin Sticks" test. Biopsies from the olfactory region performed at the end of endoscopic surgery and studied with immunohistochemistry. Patients used a visual analogue scale to report their olfactory dysfunction when re-examined one year postoperatively. RESULTS: Subjects with little or no inflammation in olfactory and respiratory biopsies had short-er duration of disease and better olfactory function. Pathological changes of olfactory mucosa included replacement by respiratory metaplasia, degenerated epithelium, rupture of epithelial surface and infiltration by inflammatory cells. Postoperative olfactory test results showed improvement of olfaction in 74% of patients. Although this improvement seemed to be better in subjects with little or no inflammation, this was not significant. Preoperative and postoperative olfactory test results were positively correlated. CONCLUSIONS: The disease process includes loss of structural organization and inflammatory infiltration of the olfactory epithelium. The inflammation severity is related to the olfactory test results; however, it cannot be the only predictive factor postoperatively.

Expression and distribution of the intermediate filament protein nestin and other stem cell related molecules in the human olfactory epithelium.

The olfactory epithelium (OE) is unique in regenerating throughout life and thus is an attractive target for examining neurogenesis. The nestin protein was shown to be expressed in the OE of rodents and is suggested to be essentially involved in the process of regeneration. Here we report the expression and distribution of nestin in the human OE at RNA and protein level. Moreover, we analysed the expression profiles in dependence on age and olfactory capacity. After sinus surgery, biopsies were taken from the olfactory epithelium of 16 patients aged 20-80 years with documented differences in their olfactory function. Our studies revealed that nestin is constantly detectable in the apical protuberances of sustentacular cells within the human OE of healthy adults. Its expression is not dependent on age, but rather appears to be related to the olfactory function, as a comparison with specimens obtained from patients suffering either from persistent anosmia or hyposmia suggests. Particularly, in the course of dystrophy, often accompanied with impaired olfaction, nestin expression was occasionally decreased. Contrarily, the expression of the p75-NGFR protein, a marker for human OE basal cells, was not altered, indicating that at least in the tested samples olfactory impairment is not connected with abnormalities at the basal cell level. These observations emphasize an essential role of nestin for the process of regeneration, and also highlight this factor as a candidate marker for sustentacular cells in the human olfactory epithelium.

Theophylline induces changes in the electro-olfactogram of the mouse.

Options for the treatment of hyposmia are limited;available therapies do not provide a long-lasting effect.A recent study suggests that an unspecific phosphodiesterase inhibitor (PDE-I) increases olfactory sensitivity due to interaction with the signal transduction in the olfactory epithelium. The aim of the present study was to investigate whether theophylline, an unspecific PDE-I, evokes changes in the electro-olfactogram (EOG) which would support the hypothesis of a drug-related impact on signal transduction.In addition, the uptake of topically administered theophylline in the olfactory epithelium should be investigated. EOG was obtained in 29 samples of supravital mouse olfactory epithelia. Olfactory stimulation (phenylethyl alcohol, PEA and hydrogen sulfide, H2S) was performed using an air dilution olfactometer. Theophylline concentration in the olfactory epithelium of five samples was measured by means of high pressure liquid chromatography. Administration of theophylline resulted in a tendency towards smaller EOG amplitudes (p = 0.055), being reduced by 13 and 25% in response to stimulation with PEA or H2S,respectively. In comparison to the application of Ringer's solution, theophylline resulted in a significant (p = 0.031)decrease of the EOG amplitude. Latency was not significantly(p = 0.10) influenced by drug administration. The theophylline concentration in the olfactory epithelium ranged from 0.21 to 1.53 microg/mg. Theophylline seems to be taken up into the olfactory epithelium of supravital mice and to interact with the olfactory signal transduction.

Expression of galectin-3 in nephrotic syndrome glomerulopaties in children.

BACKGROUND: Galectins are a family of ancient animal carbohydrate binding proteins; the name is from their description as beta-galactoside-specific lectins. They have been strongly implicated in inflammation and cancer. Studies of the association of galectins with various aspects of kidney disease in humans are still at an early stage. In line with the above, the aim of the present report was to analyse the immunohistochemical expression of galectin-3 (the only chimera galectin currently identified) in renal biopsy specimens of children with idiopathic nephrotic syndrome (INS). PATIENTS AND METHODS: Eighteen children with minimal change disease (MCD), 30 with diffuse mesangial proliferation (DMP) and 11 with focal segmental glomerulosclerosis (FSGS) treated between 2003 and 2006 in the Department of Paediatric Cardiology and Nephrology, Poznan University of Medical Sciences. An indirect immunohistochemical protocol using a polyclonal rabbit antibody against human galectin-3 was employed. RESULTS: In the control, MCD and DMP children who responded to steroid therapy anti-galectin-3 reactivity was present both in renal cortex and medulla. It was the strongest within cortical collecting ducts and subjectively less expressed in distal tubules. The total number of galectin-3 positive cortical and medullary segments of collecting ducts was significantly higher in the subjects who did not respond to steroid therapy These patients revealed also immunohistochemical reactivity of galectin-3 within nuclei of individual glomerular mesangial cells (p<0,001). CONCLUSIONS: A suggested galectin-3 authority in mature human glomeruli during proteinuric glomerulopathies may indicate, on the one hand, its anti-inflammatory effect, but on the other can prognosticate a further glomerular reconstruction leading to FSGS. Taken together, both glomerular and extraglomerular galectin-3 immunoreactivity in certain DMP individuals could be regarded as the factor of unfavourable prognosis.

Rostro-caudal gradual loss of cellular diversity within the periventricular regions of the ventricular system.

Neurogenesis occurs constitutively within the periventricular region (PVR) of the lateral ventricles (LV) of the adult mammalian brain. The occurrence of adult neurogenesis within the PVR outside the neurogenic niche of the LV remains controversial, but neural stem cells can be isolated from PVR of the whole ventricular system. The histological basis of this phenomenon including the regional differences of cellular phenotypes within the PVRs is still enigmatic. The occurrence of neurogenesis or manipulable progenitor cells in caudal parts of the adult brain is however one prerequisite for orthotopic regenerative approaches in Parkinson's disease (PD) and other disorders of the midbrain/brainstem. Using quantitative immunohistochemical techniques and electron microscopy, we found a rostro-caudal gradual loss of cellular diversity within the PVR throughout the whole ventricular axis with loss of transit amplifying epidermal growth factor-receptor(+) type C cells in all parts caudal to the LV, a gradual reduction from rostral to caudal of both stem cells (type B cells or astrocytes) without signs of proliferation outside the PVR of the LV as well as neuroblasts-like cells (polysialylated neural cell adhesion molecule [PSA-NCAM](+), but doublecortin negative cells) with a different morphology compared with neuroblasts of the PVR of the LV. Electron microscopy confirmed these immunohistochemical data. The proportion of Nestin(+)/CD24(+) cells and Nestin(+)/S100beta(+) ependymal cells were consecutively increased in the PVR from rostral to caudal, and ultrastructural analysis showed a region-specific morphology with darker cytoplasm with occasional large lipid droplets as well as indented nuclei within the caudal PVRs. The strong correlation of neuroblast-like cells with the number of neurosphere-forming cells suggests that a quiescent subtype of PSA-NCAM(+) cells might be a source of neurosphere-forming cells. We did not find any evidence for neurogenesis or the occurrence of neuroprogenitors within the substantia nigra or other parts of the midbrain/brainstem outside the PVR. Our data provide the histological framework for future studies on orthotopic regenerative approaches in PD by recruiting endogenous predopaminergic progenitors from the midbrain PVR.