Epithelial Sheath Research Articles

Revisiting the human umbilical cord epithelium. An atypical epithelial sheath with distinctive features.

The umbilical cord epithelium (UCE) is the surface tissue that covers the umbilical cord (UC). It is widely considered a single-layered epithelium composed of squamous or cuboidal cells, which are in constant contact with amniotic fluid. The objective of this study was to elucidate the distinctive structural characteristics and abundance of specific proteins in this unique epithelium, many of which have not been previously demonstrated. Samples of the UC were obtained from term pregnancies (n = 12) and processed for examination using stereo, light, electron, and 3D high-resolution confocal microscopy. Sections displayed a range of stratification, ranging from a single squamous layer to 4-5 layers of round/cuboid cells, challenging the notion of considering it as a single-layered structure. Cells are located on a well-developed basement membrane (BM), as evidenced by the expression of BM-specific proteins and PAS staining. The cells possess distinctive cytoplasmic domains that are tightly bound to each other by desmosomes and interdigitating anchoring surfaces. Desquamations and limited organelles suggest that the cells have reached the final stages of differentiation and are no longer actively synthesizing proteins, despite maintaining stratification-specific expression levels of cytoskeletal, junctional, receptor, and stem cell proteins. Although definitive keratinization was not observed, the distribution of proteins and the distinctive structural organization of the single/multi-layered cells suggest that they exhibit plasticity, likely due to adaptive mechanisms in response to chemical and/or mechanical stimuli during fetal development. These structural alterations may facilitate the active transportation of soluble ingredients between the amniotic fluid and cord blood through an intercellular route.

Taurodontism in oral-facial-digital syndrome

Oro-facial-digital syndrome (OFDS) is one of the rare hereditary conditions involving various developmental anomalies of the oral cavity, face as well as digits. Oral-facial-digital syndrome, Type I (OFDS I), a variant of OFDS, is a X-linked dominant condition showing malformations involving the oral cavity, face, and digits, predominantly affecting the females and lethal in males. Taurodontism is a clinical condition rarely encountered in OFDS I. It is a tooth developmental anomaly caused due to the failure of Hertwig’s epithelial sheath to invaginate horizontally at proper level, thereby resulting in an enlarged pulpal chamber and apical displacement of the pulp floor. A case of OFDS I, with typical clinical findings along with a unique feature of taurodontism, is presented here. Performing root canal treatment in taurodontism is a challenge. An early diagnosis and treatment will help the patient to lead a normal and healthy life.

Bioelectric stimulation controls tissue shape and size

Epithelial tissues sheath organs and electro-mechanically regulate ion and water transport to regulate development, homeostasis, and hydrostatic organ pressure. Here, we demonstrate how external electrical stimulation allows us to control these processes in living tissues. Specifically, we electrically stimulate hollow, 3D kidneyoids and gut organoids and find that physiological-strength electrical stimulation of ∼ 5 - 10 V/cm powerfully inflates hollow tissues; a process we call electro-inflation. Electro-inflation is mediated by increased ion flux through ion channels/transporters and triggers subsequent osmotic water flow into the lumen, generating hydrostatic pressure that competes against cytoskeletal tension. Our computational studies suggest that electro-inflation is strongly driven by field-induced ion crowding on the outer surface of the tissue. Electrically stimulated tissues also break symmetry in 3D resulting from electrotaxis and affecting tissue shape. The ability of electrical cues to regulate tissue size and shape emphasizes the role and importance of the electrical micro-environment for living tissues.

Case report and literature review of epithelial sheath neuroma: uncommon benign skin tumour

Case report and literature review of epithelial sheath neuroma: uncommon benign skin tumour

Dynamic BMP signaling mediates notochord segmentation in zebrafish

The vertebrate spine is a metameric structure composed of alternating vertebral bodies (centra) and intervertebral discs.1 Recent studies in zebrafish have shown that the epithelial sheath surrounding the notochord differentiates into alternating cartilage-like (col2a1/col9a2+) and mineralizing (entpd5a+) segments which serve as a blueprint for centra formation.2,3,4,5 This process also defines the trajectories of migrating sclerotomal cells that form the mature vertebral bodies.4 Previous work demonstrated that notochord segmentation is typically sequential and involves the segmented activation of Notch signaling.2 However, it is unclear how Notch is activated in an alternating and sequential fashion. Furthermore, the molecular components that define segment size, regulate segment growth, and produce sharp segment boundaries have not been identified. In this study, we uncover that a BMP signaling wave acts upstream of Notch during zebrafish notochord segmentation. Using genetically encoded reporters of BMP activity and signaling pathway components, we show that BMP signaling is dynamic as axial patterning progresses, leading to the sequential formation of mineralizing domains in the notochord sheath. Genetic manipulations reveal that type I BMP receptor activation is sufficient to ectopically trigger Notch signaling. Moreover, loss of Bmpr1ba and Bmpr1aa or Bmp3 function disrupts ordered segment formation and growth, which is recapitulated by notochord-specific overexpression of the BMP antagonist, Noggin3. Our data suggest that BMP signaling in the notochord sheath precedes Notch activation and instructs segment growth, facilitating proper spine morphogenesis.

Morphofunctional reorganization of hair follicles in C<sub>57</sub>BL/6 mice at different stages of development

The aim of the study was to determine the temporal sequence of structural and functional reorganization of hair follicles in the skin of C57BL/6 mice after anagen induction.Material and methods. 30 male mice of the C57BL/6 inbred line were used for the study. Anagen induction was carried out by depilation of the hair shafts of the skin of the back. Mice were withdrawn from the experiment on the 1st, 5th, 9th, 15th, 19th, 28th days after anagen induction. Skin samples of the depilation area were fixed in buffered neutral formalin and examined using survey microscopy, morphometry, immunohistochemistry, and statistics.Results. The study of the morphological picture from the 1st to the 28th day after anagen induction showed that cyclic changes in the thickness of the dermis, subcutaneous adipose tissue and the structure of hair follicles occur in the skin. On the 1st day after anagen induction the synchronous entry of hair follicles into the anagen stage I was observed: hair follicles were completely in the dermis, had a rounded dermal papilla, above which, towards the epidermis, there was a proliferating follicular epithelium in the form of an expanding and elongating strand . On the 5th day, morphological signs corresponding to the stage of anagen III b were observed: hair follicle bulbs were located in the upper third of the subcutaneous tissue. The dermal papillae looked friable and enlarged, around their upper pole there was a zone of melanogenesis, a hair shaft and an internal root epithelial sheath being formed. The morphological changes on the 9th and 15th days corresponded to the anagen stage VI: the tips of the pigmented hair rods emerged from the funnels of the hair follicles to the surface of the epidermis, the hair follicles were located deep in the subcutaneous fatty tissue, reaching the subcutaneous muscle. The hair follicles had a narrow dermal papilla, a zone of melanogenesis, and the forming hair shafts had regular pigmentation. A pronounced thickening of the dermis and subcutaneous adipose tissue was noted. On the 19th day, the hair follicles were in the catagen VI phase: two-row bag-like structures were observed, forming capsules of the secondary hair germ). They surrounded the keratinized brush-like depigmented proximal ends of the hair shafts. Hair follicles with a rounded dermal papilla were located in the middle of the subcutaneous adipose tissue. The dermal papillae were separated from the capsule of the secondary hair germ by a cord of follicular keratinocytes. Proximal to the dermal papillae, elements of the connective tissue sac were visible. On the 28th day, corresponding to the telogen stage, the hair follicles were located completely in the dermis, had a rounded, dense dermal papilla, which was adjacent to the germinal capsule. On the 19th and 28th days after anagen induction, a decrease in the width of the dermis and subcutaneous fat was noted.Conclusions. Thus, during the cycle of the hair follicle, its stage-by-stage remodeling and the change in the thickness of the dermis and subcutaneous fat, dependent on this process, take place. The following time sequence of the structural and functional reorganization of hair follicles was determined: on the 1st day after depilation, the hair follicles were synchronized in the anagen I stage, on the 5th day – anagen IIIb, on the 9th and 15th days – anagen VI, on Day 19 – catagen VI stage, on day 28 – telogen stage.

Морфологические изменения нервных волокон в коже овец при мелофагозе

Experimental infection of sheep with melaphagosis leads to significant structural damage to the skin and its nerve fibers. Bloodsuckers are mechanically transferred through skin scratching to endothelial cells and tissue settled macrophages from places of microtrauma caused by the piercing- sucking apparatus of the carriers and the runes themselves. Proboscis parasites injure the skin, blood vessels, causing inflammation. A synchrony of local and generalized inflammatory processes is formed, which last for a long time due to the blood-sucking of ectoparasites. Periodic suction of blood is accompanied by injection of saliva and coxal fluid into the capillary, which contain the pathogen, anticoagulants and enzymes. At the site of injury, labrocyte degranulation occurs, a large number of inflammatory mediators are released: histamine, heparin, serotonin, which initiate an inflammatory reaction and pain syndrome. Re-irritation of skin receptors, afferent pathways leads to depletion of metabolites in the nerve fibers, and dystrophic processes develop. The protective reaction at the site of the entrance gate is accompanied by the simultaneous generalization of the recovery process after the treatment of sheep with mediatrin. In the skin, compensatory- adaptive changes are observed in the epithelial sheaths of the hair roots, in the sebaceous glands and the restoration of the structure of the endothelium of the blood capillaries. Significant destructive changes in the structure of collagen and elastic fibers remain in the reticular layer of the dermis. Labrocytes, with a large number of granules, testify to a decrease in the intensity of the inflammatory process in the skin of sheep.

The IRM cell adhesion molecules Hibris, Kin of irre and Roughest control egg morphology by modulating ovarian muscle contraction in Drosophila

The Irre Cell Recognition Module (IRM) is an evolutionarily conserved group of transmembrane glycoproteins required for cell–cell recognition and adhesion in metazoan development. In Drosophila melanogaster ovaries, four members of this group – Roughest (Rst), Kin of irre (Kirre), Hibris (Hbs) and Sticks and stones (Sns) – play important roles in germ cell encapsulation and muscle sheath organization during early pupal stages, as well as in the progression to late oogenesis in the adult. Females carrying some of the mutant rst alleles are viable but sterile, and previous work from our laboratory had identified defects in the organization of the peritoneal and epithelial muscle sheaths of these mutants that could underlie their sterile phenotype. In this study, besides further characterizing the sterility phenotype associated with rst mutants, we investigated the role of the IRM molecules Rst, Kirre and Hbs in maintaining the functionality of the ovarian muscle sheaths. We found that knocking down any of the three genes in these structures, either individually or in double heterozygous combinations, not only decreases contraction frequency but also irregularly increases contraction amplitude. Furthermore, these alterations can significantly impact the morphology of eggs laid by IRM-depleted females demonstrating a hitherto unknown role of IRM molecules in egg morphogenesis.

Unicystic ameloblastoma: Literature review

The Unicystic Ameloblastoma (UA), represents an invasive polymorphic lesion whose origin is currently unknown, but it is presumed to form from the epithelial remains of the Malassez from the epithelial sheath of Hertwig. It represents the second most prevalent odontogenic tumor, which is characterized by being locally invasive and of high recurrence. It usually presents a predilection for the male sex, affecting during the second and third decade of life. Clinically, it is asymptomatic, however, it can generate swelling with facial asymmetry, causing an expansion of the bone cortical, allowing infiltration into soft tissues. Radiographically, UA presents with a well-defined radiolucent unilocular appearance and histologically can be luminal, intraluminal and mural, depending on the characteristics of the pathological cavity. Treatment usually focuses on surgical resection of the lesion, which allows removal of the tumor with safe bone margins.

Taurodontismo – Série de casos em pacientes jovens não sindrômicos e sindrômicos associado à hipodontia

Several human dentition developmental anomalies are reported in the literature. The etiology of these occurrences is related to genetic, environmental or sometimes idiopathic factors. Taurodontism is defined as apical displacement of the pulp floor and consequent enlargement of the pulp chamber in multiradicular teeth. It is a result of the failure to invaginate Hertwigs epithelial sheath horizontally and commonly expresses bilaterally. This morphological pattern of molars is observed in ruminant animals and was also found in ancient Neanderthals. Association of this condition to syndromes is not exclusive, it may be associated with genetic disorders such as Down Syndrome, Klinefelter Syndrome, among others. The diagnosis is exclusively radiographic, with no alterations in the dental element crown. Among the consequences is the complexity of endodontic treatment, greater fragility of taurodontic teeth submitted to endodontics and lower orthodontic anchorage of these elements. In this paper, three case reports of patients with taurodontism are described, two of them associated with hypodontia and one in a Down Syndrome patient. This paper also includes a literature review and discussion with the main clinical implications of this occurrence.

An Unusual Presentation of Proliferating Trichilemmal Tumor Developing in Psoriatic Plaque: A Case Report

Proliferating trichilemmal tumor (PTT) is a rare, mostly benign neoplasm which stems from the follicular outer root sheath epithelium. PTT occurs as a subcutaneous cystic nodule slowly enlarging to a larger noduler mass, and is usually localized on the scalp of elderly women. To the best of our knowledge, PTT localized on a psoriatic plaque has not been reported previously. Herein, we report an unusual case of benign PTT arising from a psoriatic plaque on the knee of a 63-year-old male patient. Keywords: proliferating trichilemmal tumor, psoriasis, trichilemmal cyst

Dermal hyperneury

Dermal hyperneury (DN) is a rarely reported form of small nerve hypertrophy characterized by an exaggerated size and prominence of dermal nerve fibers. Clinically, it can present with or without visible lesions, within a syndrome or sporadically, and in solitary or multiple fashion. The syndromes most commonly associated with DN include multiple endocrine neoplasia 2B and 2A, neurofibromatosis type II, and Cowden syndrome. Patients with syndrome-associated DN have an increased risk for various malignancies. Sporadic DN has been reported either in association with cutaneous tumors/reactive lesions, such as nodular prurigo, or in idiopathic form, where it can present with multiple DN lesions. There is a morphologic overlap between mucocutaneous neuromas and DN, as the former can have the appearance of either bulkier circumscribed lesions or tortuous and hyperplastic nerves more akin to DN. Epithelial sheath neuroma also shares a similar appearance to DN, from which it can be distinguished by a squamoid-appearing and thickened perineurium.

Topical formulations containing aptamer-functionalized nanocapsules loaded with 5-fluorouracil - An innovative concept for the skin cancer therapy

New topical gel formulations based on sodium alginate and hyaluronic acid containing AS1411 aptamer-functionalized polymeric nanocapsules loaded with an antitumoral drug (5-Fluorouracil) were designed as an innovative approach for the skin cancer treatment. Several important analyses were used to characterize these obtained topical gel formulations, namely: rheological tests, permeation assays across Strat-M® artificial membrane, ex-vivo permeation assays across chicken skin membrane, haemolysis tests, skin irritation tests, in vitro cytotoxicity assay on human basal carcinoma cells and in vivo tests. Rheological tests revealed that apparent viscosity decreases with the increase of the shear rate, for analyzed samples, which demonstrates a shear thinning behavior. Low levels of hemolysis values which ranged between 0.03 and 0.55% suggested that the tested formulations did not induce red blood cell lysis.. The gel formulations containing nanocapsules loaded with 5-FU proved to be non-irritant. Furthermore, by study the ex-vivo diffusion properties across the chicken skin membrane, it was proved that nanoencapsulation enhance the permeability properties of 5-FU. In vitro cytotoxicity assay on TE 354.T (ATCC® CRL-7762™) human basal carcinoma cell line showed that the obtained formulations loaded with 5-Fluorouracil manifest an important cytotoxic effect. Finally, the presence of Langerhans CD68 cells-positive in the epidermis and epithelial sheath of dermal hair follicles suggests a specific activation, migration and retrieval of nanoparticles by these cells. Following the results obtained in this study we can appreciate that the obtained topical gel formulations have a favourable biosafety and good antitumor effects which makes them attractive for skin cancer treatment.

Characterization of the inflammatory features of central centrifugal cicatricial alopecia.

Central centrifugal cicatricial alopecia (CCCA) is a scarring alopecia that primarily affects women of African descent. Although histopathological features of CCCA have been described, the pathophysiology of this disease remains unclear. To better understand the components of CCCA pathophysiology, we evaluated the composition of the inflammatory infiltrate, the distribution of Langerhans cells (LCs), and the relationship between fibrosis and perifollicular vessel distribution. Our data indicate that CCCA is associated with a CD4-predominant T-cell infiltrate with increased LCs extending into the lower hair follicle. Fibroplasia associated with follicular scarring displaces blood vessels away from the outer root sheath epithelium. These data indicate that CCCA is an inflammatory scarring alopecia with unique pathophysiologic features that differentiate it from other lymphocytic scarring processes.

Ultrastructural study of the ovary and oogenesis of Polyonchobothrium clarias Woodland, 1925 (Cestoda: Bothriocephalidea) infecting Clarias gariepinus from Egypt.

The ovarian tissues and different stages of oocytes development of Polyonchobothrium clarias Woodland, 1925 recovered from the intestine of Clarias gariepinus Burchell, 1822 fish was investigated by transmission electron microscope (TEM). The ovarian follicles are enveloped by compressed epithelial sheath lying on basal layer that shows epithelial projection into the lumen of each follicle. The epithelial sheath filled with glycogen, mitochondria and solitary lipid droplets. The epithelial nuclei are appeared closed to the basal part of the ovarian follicle. Numerous heterogeneous electron dense myelin-like bodies observed within the ovarian cytoplasm they appeared different irregular shaped. Each ovarian follicle contains number of oocytes loosely packed within the follicle at different stages of differentiation developmental stages starting with oogonial cells, primary, secondary and mature oocytes. The Oogonia were undergoing characteristic cytological changes that lead to oocyte maturation. Vitelline material appears in early stages of primary oocytes. Lipid droplets appeared in late stages of secondary oocyte. Mature oocytes are filled with clusters of cortical granules adjacent to the oocyte plasma membrane. Syncytial interstitial tissue and number of myelin-like bodies are observed in the ovarian cytoplasm and they fill the cytoplasmic spaces. The results of the present study were compared with the previous reports in other cestode taxa, to define the ultrastructural observations of the female reproductive tissues for clarification the reproductive fecundity of the parasite.

Sox100B is required in the ovary peritoneal muscle sheath development in Drosophila melanogaster

The transcription factor Sox100B is known to have a function in embryonic gonads differentiation and testis development. Drosophila as a model organism enabled the identification of expression patterns of Sox100B in ovaries to establish its role in proper ovarian development and function. Previous results from our lab showed that a decrease in the transcription of the Sox100B gene is associated with reduced fertility and mild defect in ovarian muscle sheath morphology. Additionally, Sox100B is expressed in the apical cells, which are the muscle cell progenitors. These results suggest that Sox100B plays an active role in the ovary muscle by regulating ovarian muscle sheath development during morphogenesis. Based on these experiments we hypothesize that Sox100B is required for the development of the ovarian muscle sheath. We approached this question by knocking down and overexpressing Sox100B using Heartless‐Gal4 (htlGal4), a driver used for studying targeted gene expression in the Drosophila wing heart and the ovary muscle. To acquire a complete understanding of the Sox100B function throughout morphogenesis, we observed ovaries of late larvae (LL3), young adults and mature adults. Experiments with Sox100B overexpression constructs proved to be fatal at embryonic stage, thus preventing the study of the ovarian phenotype in these flies. However, when we crossed the htlGal4 driver with RNAi lines for Sox100B, a significant decrease was observed in egg laying and pupariation assays. Eggs that were successfully fertilized survived to adulthood, suggesting oogenesis is not affected. We utilized immunohistochemistry (IHC) and confocal microscopy to examine adult ovaries from htlGal4>Sox100BRNAi and we observed an intact epithelial sheath but tearing of the peritoneal sheath. Based on these results we concluded that Sox100B is required for the peritoneal muscle sheath development and ovary function.Support or Funding InformationSupported by the National Institutes of Health under Award Number T34GM008419.This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Sox13 is a novel early marker for hair follicle development

Sox13, a group D member of the Sry-related high-mobility group box (Sox) transcription factor family, is expressed in various tissues including the hair follicle. However, its spatiotemporal expression patterns in the hair follicle and its role in hair development remain to be elucidated. To address these questions, we generated Sox13-LacZ-knock-in mice (Sox13LacZ/+), in which the LacZ reporter gene was inserted in-frame into exon 2, which contains the translation initiation codon. X-gal staining in Sox13LacZ/+ embryos revealed that Sox13 is initially expressed in the epithelial portion of the placode, and subsequently in the hair germ and the hair peg during early hair follicle development. In postnatal catagen and anagen, Sox13 was detected in the epithelial sheath, whereas in telogen, Sox13 was localized in the bulge region, where hair follicle stem cells reside. Immunohistochemistry with an anti-β-galactosidase antibody and anti-hair keratin antibodies that specifically mark the different layers of the hair follicle revealed that Sox13 was predominantly expressed in the outer root sheath in anagen. However, the integumentary structures of Sox13LacZ/LacZ mice were grossly and histologically indistinguishable from those of wild type mice. These results suggest that although Sox13 is dispensable for epidermal and adnexal development, Sox13 is a useful marker for early hair follicle development.

From traveler to homebody: Which signaling mechanisms sponge larvae use to become adult sponges?

Cell-to-cell signaling is responsible for regulation of many developmental processes such as proliferation, cell migration, survival, cell fate specification and axis patterning. In this article we discussed the role of signaling in the metamorphosis of sponges with a focus on epithelial-mesenchymal transition (EMT) accompanying this event. Sponges (Porifera) are an ancient lineage of morphologically simple animals occupying a basal position on the tree of life. The study of these animals is necessary for understanding the origin of multicellularity and the evolution of developmental processes. Development of sponges is quite diverse. It finishes with the metamorphosis of a free-swimming larva into a young settled sponge. The outer surface of sponge larvae consists of a ciliated epithelial sheath, which ensures locomotion, while their internal structure varies from genus to genus. The fate of larval ciliated cells is the most intriguing aspect of metamorphosis. In this review we discuss the fate of larval ciliated cells, the processes going on in cells during metamorphosis at the molecular level and the regulation of this process. The review is based on information about several sponge species with a focus on Halisarca dujardini, Sycon ciliatum and Amphimedon queenslandica. In our model sponge, H. dujardini, ciliated cells leave the larval epithelium during metamorphosis and migrate to the internal cell mass as amoeboid cells to be differentiated into choanocytes of the juvenile sponge. Ciliated cells undergo EMT and internalize within minutes. As EMT involves the disappearance of adherens junctions and as cadherin, the main adherens junction protein, was identified in the transcriptome of several sponges, we suppose that EMT is regulated through cadherin-containing adherens junctions between ciliated cells. We failed to identify the master genes of EMT in the H. dujardini transcriptome, possibly because transcription was absent in the sequenced stages. They may be revealed by a search in the genome. The master genes themselves are controlled by various signaling pathways. Sponges have all the six signaling pathways conserved in Metazoa: Wnt, TGF-beta, Hedgehog, Notch, FGF and NO-dependent pathways. Summarizing the new data about intercellular communication in sponges, we can put forward two main questions regarding metamorphosis: (1) Which of the signaling pathways and in what hierarchical order are involved in metamorphosis? (2) How is the organization of a young sponge related to that of the larva or, in other words, is there a heredity of axes between the larva and the adult sponge?

Temporospatial localization of telocytes during esophageal morphogenesis in rabbit

Telocytes (TCs) are CD34 and Vimentin positive (+) immunoreactive stromal cells with a small-sized body and several extremely long telopodes. TCs have been described to provide a mechanical support throughout the tissue by making cellular connections (homo- or hetero) to form a 3D network. Such network can transmit the intercellular signaling. Recently, TCs have been described in the esophageal wall. However, information concerning the role of these cells in esophageal organization and development is rare. Thus, we aimed to record the temporo-spatial localization pattern of TCs during esophageal morphogenesis in rabbit. Embryos and fetuses of New Zealand White rabbits (10th–30th gestational days) were collected. Using CD34 immunostaining, TCs have not been demonstrated in the wall of the developing esophagus till the end of the second third of pregnancy. On 24th gestational day, CD34+ TCs were organized in the adventitia of the esophageal wall specifically in close association with the endothelial cells lining the micro vessels. Later on 26th gestational day, CD34+TCs were additionally expressed in the sub-mucosa and in lamina propria (sub-epithelial). On 28th gestational day, additional CD34+TCs were detected among the smooth muscle bundles of the muscular layer. Reaching the last gestational day, CD34+TCs formed several sheaths in the esophageal wall namely sub epithelial sheath, sub-mucosal, muscular (circular and longitudinal) and inter-muscular sheaths and an outer adventitial one. On the other hand, vimentin immunohistochemistry revealed wider spread TCs positivity in all developmental ages. Presumptively, arrangement of CD34 and vimentin positive TCs in all layers of the developing esophageal wall hypothesizes that TC may play a potential role as a progenitor cell initially in differentiation of the epithelial and muscular precursors and finally in shaping of the various layers of the rabbit esophageal wall during its morphogenesis. TCs are also proposed to be involved in the angiogenesis of the esophageal blood capillaries.

Live imaging of stem cells in the germarium of the Drosophila ovary using a reusable gas-permeable imaging chamber.

Live imaging of stem cells and their support cells can be used to visualize cellular dynamics and fluctuations of intracellular signals, proteins, and organelles in order to better understand stem cell behavior in the niche. We describe a simple protocol for imaging stem cells in the Drosophila ovary that improves on alternative protocols in that flies of any age can be used, dissection is simplified because the epithelial sheath that surrounds each ovariole need not be removed, and ovarioles are imaged in a closed chamber with a large volume of medium that buffers oxygen, pH, and temperature. We also describe how to construct the imaging chamber, which can be easily modified and used to image other tissues and non-adherent cells. Imaging is limited by follicle cells moving out of the germarium in culture around the time of egg chamber budding; however, the epithelial sheath delays this abnormal cell migration. This protocol requires an hour to prepare the ovarioles, followed by half an hour on the confocal microscope to locate germaria and set z limits. Successful imaging time depends on germarial morphology at the time of dissection, but we suggest 10-11 h to encompass all specimens.