F. Pop

The pterygopalatine ganglion in humans: A morphological study

As a rule the pterygopalatine ganglion (PPG) is considered to be a single structure of the parasympathetic nervous system, associated with the maxillary nerve in the pterygopalatine fossa (PPF). A few structural studies in humans are available in the indexed references. We designed the present study of the PPG in order to provide evidence of possible variations in morphological patterns of the PPG. We performed dissections of the PPF on 20 human adult heads, using different approaches. The dissected specimens were stained with hematoxylin-eosin and silver (Bielschowsky) or prepared for immunohistochemistry for synaptophisin and neurofilament. Four morphological types of the PPG were defined macroscopically: A (10%): partitioned PPG, the upper partition receiving the vidian nerve; B (55%): single, the upper part (base) receiving the vidian nerve; C (15%): single, but the vidian nerve reaches the lower part (tip) of the ganglion; D (20%): partitioned, the lower partition receiving the vidian nerve. We propose that it may be inappropriate to invariably regard the PPG as a single morphological structure. From individual to individual the PPG may present either as a single ganglion or as a partitioned one, with distinct superior and inferior components. Nevertheless, the presence of the dispersed pterygopalatine microganglia (DPPG) evidenced by histochemistry and immunohistochemistry serves to complete an individually variable morphological pattern of a structure usually described as single. The individual variation may be the reason for failures in ablation procedures of the PPG; partitions of the PPG and/or the DPPG may functionally correlate with specific territories and targets and further tracing studies may be helpful in validating or invalidating this theory.

The human trigeminal ganglion: c-kit positive neurons and interstitial cells.

OBJECTIVES The presence of c-kit positive neurons in sensory ganglia has been verified in various species but not in humans. Our aim has been to identify whether human primary trigeminal neurons label with c-kit/CD117 and thus, whether data gathered in animal studies can be extrapolated to humans. We also intended to establish whether, and which non-neuronal cells also label with c-kit in the trigeminal ganglion. METHODS Human adult trigeminal ganglia from eight cadavers were processed for immunohistochemistry on paraffin embedded samples using monoclonal antibodies for CD117/c-kit, and three additional trigeminal ganglia were used for transmission electron microscopy (TEM). To evaluate which neuronal type (A or B) was labeled with c-kit, we evaluated the same neurons on adjacent sections labeled with antibodies for neurofilaments (NF). RESULTS c-kit has labeled trigeminal neurons (TNs), mast cells and interstitial cells (ICs) within the trigeminal ganglion. c-kit+TNs were NF-and thus were strongly presumed to be nociceptive, as such neurons are known to be NF-poor. c-kit+ICs with long and moniliform processes intermingled with the satellite glial cells (SGCs) of the neuronal envelopes. TEM evaluations confirmed this mixed composition of the neuronal envelopes and demonstrated that the perineuronal ICs are in fact interstitial Cajal-like cells (ICLCs) and/or telocytes. CONCLUSIONS c-kit+TNs were objectified in humans and strongly presumed to be nociceptive. TNs envelopes mostly consist of SGCs, but are also combined with ICLCs/telocytes.

Extrahepatic and Intrahepatic Human Portal Interstitial Cajal Cells

Portal interstitial cells of Cajal (PICCs), acting as vascular pacemakers, were previously only identified in nonhumans. Moreover, there is no evidence available about the presence of such cells within the liver. The objective of the study is to evaluate whether or not PICCs are identifiable in humans and, if they are, whether or not they are following the scaffold of portal vein (PV) branches within the liver. We obtained extrahepatic PVs and liver samples from six adult human cadavers, negative for liver disease, in accordance with ethical rules. They were stained with hematoxylin‐eosin (HE) and Giemsa, and then we performed immunohistochemistry on formalin‐fixed paraffin‐embedded specimens for CD117/c‐kit, a marker of the Cajals cells. Immune labeling was also performed for S‐100 protein, desmin, glial fibrillary acidic protein (GFAP), neurofilaments, α‐smooth muscle actin (α‐SMA), and CD34. c‐kit‐Positive PICCs were identified within the extrahepatic PV, in portal spaces, and septa. On adjacent sections, these PICCs were negative for all the other antibodies used. In conclusion, our study confirms the presence of extrahepatic PICCs on humans, which may act as a possible intrinsic pacemaker in the human PV. However, the intrahepatic PICCs, which were evidenced here for the first time, are in need for further experimental studies to evaluate their functional role. A promising further direction of the study is the PICCs role in the idiopathic portal hypertension. Anat Rec, 2011.

Sprouting angiogenesis in human midterm uterus and fallopian tube is guided by endothelial tip cells

Five samples of human midterm fetal uterus and fallopian tube (four donor bodies) were used to assess whether or not processes of angiogenesis are guided by endothelial tip cells (ETCs), and if cytokine-receptors, such as CD117/c-kit and PDGFR-α, are expressed in the microenvironment of the endothelial tubes. CD34 labeled microvessels in the uterine wall (myometrium and endometrium) and in the wall of the uterine (fallopian) tube, and accurately identified ETCs in both organs. We conclude that sprouting angiogenesis in the developing human female tract is guided by ETCs. Moreover, CD117/c-kit antibodies labeled mural networks of pericytes, α-SMA-positive and desmin-negative, related to the endometrial (but not myometrial) microvessels, and similar labeling was identified in the wall of the uterine tube. PDGFR-α positive labeling, stromal and pericytary, was also found. Thus, sprouting angiogenesis in human fetal genital organs appears to be guided by tip cells and is influenced by tyrosine kinase receptor signaling.

The mandibular ridge oral mucosa model of stromal influences on the endothelial tip cells: an immunohistochemical and TEM study.

This study aimed to evaluate by immunohistochemistry and transmission electron microscopy (TEM) the morphological features of the oral mucosa endothelial tip cells (ETCs) and to determine the immune and ultrastructural patterns of the stromal nonimmune cells which could influence healing processes. Immune labeling was performed on bioptic samples obtained from six edentulous patients undergoing surgery for dental implants placement; three normal samples were collected from patients prior to the extraction of the third mandibular molar. The antibodies were tested for CD34, CD117(c‐kit), platelet derived growth factor receptor‐alpha (PDGFR‐α), Mast Cell Tryptase, CD44, vimentin, CD45, CD105, alpha‐smooth muscle actin, FGF2, Ki67. In light microscopy, while stromal cells (StrCs) of the reparatory and normal oral mucosa, with a fibroblastic appearance, were found positive for a CD34/CD44/CD45/CD105/PDGFR‐α/vimentin immune phenotype, the CD117/c‐kit labeling led to a positive stromal reaction only in the reparatory mucosa. In TEM, non‐immune StrCs presenting particular ultrastructural features were identified as circulating fibrocytes (CFCs). Within the lamina propria CFCs were in close contact with ETCs. Long processes of the ETCs were moniliform, and hook‐like collaterals were arising from the dilated segments, suggestive for a different stage migration. Maintenance and healing of oral mucosa are so supported by extensive processes of angiogenesis, guided by ETCs that, in turn, are influenced by the CFCs that populate the stromal compartment both in normal and reparatory states. Therefore, CFCs could be targeted by specific therapies, with pro‐ or anti‐angiogenic purposes. Anat Rec, 2013.

Immunolocalization of 200 kDa neurofilaments in human cardiac endothelial cells.

Neurofilaments usually associated with neural tissues are the type IV family of intermediate filaments. Nestin, which is a type VI intermediate filament, is a well known marker of endothelial cells in newly formed blood vessels and is developmentally and structurally related to type IV intermediate filaments. We aimed to determine whether or not cardiac endothelial cells (ECs) label with antibodies for neurofilaments (200 kDa, Novocastra-Leica, clone RT97), as is already known for nestin. We used cardiac samples (sinoatrial nodes/right atrial walls) from cadavers of normal and diabetic donors (6 normal adults, 10 type II diabetic adults, 1 child) for neurofilament immune labeling. Positive labeling of endothelial cells, microvascular and endocardial, was obtained in all samples. As this is the first such evidence, we can only presume that the neurofilament positive labeling of endothelial cells may be due to interactions of nestin and neurofilaments. Further studies are needed to evaluate the hypothesis we reached and, in order to explore whether or not neurofilament antibodies can qualify as markers of angiogenesis.

The molecular phenotypes of ureteral telocytes are layer-specific

Telocytes (TC) are the delicate interstitial (stromal) cells defined by their long, thin and moniliform processes termed telopodes. Numerous studies determined that different subsets of telocytes populate almost all tissues and attempted to relate these subsets to various functions, from cell signaling to tissue repair and regeneration. Extremely few studies addressed the urinary tract though few data on the molecular pattern of the urinary TCs actually exist. We therefore hypothesized that subsets of urinary TCs co-localize within the human ureter and we aimed at performing an immunohistochemical study to evaluate the tissue-specific molecular pattern of TCs. On sample tissues of proximal ureter drawn from ten human adult patients during surgery were applied primary antibodies against CD34, CD105, von Willebrand Factor, the heavy chain of smooth muscle myosin (SMM) and c-erbB-2. The molecular pattern indicated three different subsets of ureteral TCs which are neither endothelial nor epithelial in nature: (a) type I: the CD34-/CD105+ TCs of the superficial layer of lamina propria; (b) type II: the CD34+/CD105± myoid TCs of the deep layer of lamina propria and (c) type III: the CD34+/CD105+ perivascular TCs. Although apparently different, all these subsets of TCs could belong to the stem/progenitor niche of the ureter.

c-kit positive cells and networks in tooth germs of human midterm fetuses

Numerous studies have attempted to characterize the dental pulp stem cells. However, studies performed on prenatal human tissues have not been performed to evaluate the in situ characterization and topography of progenitor cells. We aimed to perform such a study using of antibodies for CD117/c-kit and multiplex antibody for Ki67+ caspase 3. Antibodies were applied on samples dissected from five human midterm fetuses. Positive CD117/c-kit labeling was found in mesenchymal derived tissues, such as the dental follicle and the dental papilla. The epithelial tissues, that is, dental lamina, enamel organ and oral epithelia, also displayed isolated progenitor cells which were CD117/c-kit positive. Interestingly, CD117/c-kit positive cells of mesenchymal derived tissues extended multiple prolongations building networks; the most consistent of such networks were those of the dental follicle and the perivascular networks of the dental papilla. However, the mantle of the dental papilla was also positive for CD117/c-kit positive stromal networks. The CD117/c-kit cell populations building networks appeared mostly with a Ki67 negative phenotype. The results suggest that CD117/c-kit progenitor cells of the prenatal tooth germ tissues might be involved in intercellular signaling.

Anatomical and immunohistochemical considerations on the microinnervation of trachea in humans.

The anatomy of the tracheal microinnervation is understudied in humans; the purpose of our study was to fill this gap by working on human adult tracheas, to compare the results with those obtained from animal studies, and to checking whether or not these studies are suitable to be translated from comparative to the human anatomy. The study was designed as a qualitative one. The present work was performed on human adult tracheas dissected out in 15 human adult cadavers. Microdissections were performed in eight tracheas and revealed the outer peritracheal plexus, segmentally supplied and distributed to trachea and esophagus, with longitudinal intersegmentary anastomoses but also with bilateral interrecurrential anastomoses previously undescribed in anatomy. Seven different tracheas were transversally cut and paraffin embedded. Histological stains (HE, toluidine blue, luxol fast blue, Giemsa on tissues and trichrome Gieson) and immunohistochemistry using primary antibodies for nNOS, neurofilament, SMA and the cocktail of citokeratines CK AE1-AE3+8/18 were done. According to the histological individual variation, the neural layers of the posterior wall of the human trachea could be considered as it follows: (a) an outer neural layer, ganglionated, associated with the connective covering layers, adventitia and the posterior fibroelastic membrane (external elastic lamina); (b) a submucosal ganglionated neural layer, mainly with juxtaglandular microganglia that may expand, as glands do, through the outer covering layers; (c) intrinsic nerves of the transverse trachealis muscle; (d) the neural layer intrinsic to the longitudinal elastic band (internal elastic lamina) and supplied from the inner submucosa; (e) the neural plexus of the lamina propria, with scarcely distributed neurons. We also bring here the first evidences for the in vivo nNOS phenotype of mast cells that were identified, but not exclusively, within the trachealis muscle.

Morphologic features of the fetal mandibular condyle: layers, canals and microvascular pattern.

During organogenesis the mandibular condyle is divided by a fibrovascular septum, the persistence of which in the growing cartilage can lead to a bifid condyle. In this study we have evaluated the morphology of 3rd trimester human fetal temporomandibular (TMJ) specimens in order to determine the pattern of the vascular morphology associated with the layers and vascular canals (VCs) of the developing condyle (covering layers and condyle proper). Eleven human fetuses of 27-38cm crown-rump length were used for histological (hematoxylin-eosin, Van Gieson stain) and immunohistochemical evaluation (antibodies for bcl2 and CD34) and another two of 24 and 31cm, for TMJ microvasculature studies after black ink injections. With increasing fetal age, the intermediate loose lamina (LL) of the condylar proliferative layer evolves from a vascular-mesenchymal to a fibrillar pattern, via a transitory stage of a clear space that may be misdiagnosed as lower joint cavity (LJC). Within the condyle proper VCs may be present on its entire sagittal length, deepening variably towards the erosive zone and opened superiorly in the LL loose layer. Vessels of the evolving LL enter the condyle, directly or through the VCs; these vessels retract peripherally with increasing age and the intrinsic vessels of the condyle supplied from the erosive zone become prevalent. Vascular morphogenesis at the level of the LL seems comparable to that at the level of the LJC where characteristic glomeruli regress with increasing age. Lack of vascular regression and closure of central V-shaped defects of the condyle, as observed in 2/22 condyles, may represent a developmental substrate for condylar bifidism or a predisposing condition weakening the condyle, and making it more sensitive to trauma in childhood.