Exocoelomic internal hernia: elucidation of Papez's concept.

Two internal herinias of the intestines were found in adult males. One was a large translucent avascular membranous sac contining the small intestine from the duodenojejunal flexure to a point 6 in. proximal to the ileocaecal junction. The other was a peritoneal sac enclosing the small intestine, appendix, caecum and 6 in. of the ascending colon. The mesenteric and colic vessels were normal. Both hernias conformed to PAPEZ's concept of the so-called paraduodenal hernia that the hernial sac is derived from the umbilical coelom. The authors suggest that most of the so-called paraduodenal hernias are derived from the embryonic umbilical peritoneal diverticulum rather than from the peritoneal recesses or mesentery of the colon.     

Metabolic surface area of the microvessels of the gastric serosa

After injecting Indian ink--gelatin mass and vegetable peroxidase, parameters of microvessels in the rat gastric tunica serosa have been measured. The capillary diameters make 3.99 and 4.1 mcm, their length--240 and 259 mcm, density of the tunica serosa are--31 and 26 per 1 mm2. Using these parameters and the value of the hydraulic conductivity, the total area of the capillaries surface (0.09 mm2) and the volume of the filtrated (3.8 X 10(3) mcm3) and reabsorbed (115 X 10(3) mcm3) liquors are calculated. Comparing the volumes of the liquor transported in the visceral layer of the peritoneum and in its other parts, it is possible to consider the mechanisms maintaining water balance in the peritoneal cavity.     

Keratin and vimentin expression in early organogenesis of the rabbit embryo

Summary The expression of vimentin and keratins is analysed in the early postimplantation embryo of the rabbit at 11 days post conceptionem (d.p.c.) using a panel of monoclonal antibodies specific for single intermediate filament polypeptides (keratins 7, 8, 18, 19 and vimentin) and a pan-epithelial monoclonal keratin antibody. Electrophoretic separation of cytoskeletal preparations obtained from embryonic tissues, in combination with immunoblotting of the resulting polypeptide bands, demonstrates the presence of the rabbit equivalents of human keratins 8, 18, and vimentin in 11-day-old rabbit embryonic tissues. Immunohistochemical staining shows that several embryonic epithelia such as notochord, surface ectoderm, primitive intestinal tube, and mesonephric duct, express keratins, while others (neural tube, dermomyotome) express vimentin, and a third group (coelomic epithelia) can express both. Similarly, of the mesenchymal tissues sclerotomal mesenchyme expresses vimentin, while somatopleuric mesenchyme (abdominal wall) expresses keratins, and splanchnopleuric mesenchyme (dorsal mesentery) expresses both keratins and vimentin. While these results are in accordance with most results of keratin and vimentin expression in embryos of other species, they stand against the common concept of keratin and vimentin specificity in adult vertebrate tissues. Furthermore, keratin and vimentin are not expressed in accordance with germ layer origin of tissues in the mammalian embryo; rather the expression of these proteins seems to be related to cellular function during embryonic development.Supported by the Deutsche Forschungsgemeinschaft and by the Netherlands Cancer Foundation     

The histophysiology and pathophysiology of the peritoneum

The peritoneum is an extensive serous organ with both epithelial and mesenchymal features and a variety of functions. Diseases such as inflammatory peritonitis and peritoneal carcinomatosis can induce disturbance of the complex physiological functions. To understand the peritoneal response in disease, normal embryonic development, anatomy in healthy conditions and physiology of the peritoneum have to be understood. This review aims to summarize and discuss the literature on these basic peritoneal characteristics.The peritoneum is a dynamic organ capable of adapting its structure and functions to various physiological and pathological conditions. It is a key element in regulation of inflammatory responses, exchange of peritoneal fluid and prevention of fibrosis in the abdominal cavity. Disturbance of these mechanisms may lead to serious conditions such as the production of large amounts of ascites, the generation of fibrotic adhesions, inflammatory peritonitis and peritoneal carcinomatosis.The difficulty to treat diseases, such as inflammatory peritonitis and peritoneal carcinomatosis, stresses the necessity for new therapeutic strategies. This review provides a detailed background on the peritoneal anatomy, microenvironment and immunologic responses which is essential to generate new hypotheses for future research.     

Spontaneous peritoneal malignant mesothelioma in a geriatric japanese macaque (Macaca fuscata).

A 28.5-year-old female Japanese macaque (Macaca fuscata) was euthanatized because of abdominal distension due to severe ascites. Nodular lesions of varying sizes up to 5 mm in diameter were distributed diffusely on the surface of the omentum, mesentery and parietal peritoneum. No neoplastic masses were detected in any visceral organ. The nodules were composed of proliferation of mono- or multi-layered epithelial-like cells occasionally showing papillary growth and sheets of small round or polygonal cells. Signet ring-like cells and tubular structures were occasionally present. Neoplastic cells were strongly positive to cytokeratin, and occasionally to vimentin. Based on gross and histopathological findings, this tumor was diagnosed as an epithelial type of peritoneal malignant mesothelioma, the first reported case in the non-human primates.     

IL-4 gene transfer to the small bowel serosa leads to intestinal inflammation and smooth muscle hyperresponsiveness

Intestinal mucosal inflammation can lead to altered function of the underlying smooth muscle, which becomes hyperreactive to most contractile stimuli. Through nematode parasite infection models, T helper type 2 (Th2) cytokines have been implicated in intestinal muscle dysfunction; however, the mechanisms involved and the relevance of these findings to other forms of intestinal inflammation are unclear. Through gene transfer, we explored whether the Th2 cytokine IL-4 can mediate changes in longitudinal muscle function in the context of an adenoviral infection. Following abdominal surgery on mice, control beta-galactosidase-encoding recombinant adenoviruses and IL-4-encoding adenoviruses were applied to the serosal surface of the jejunum, leading to infection of cells in the serosa and in the mesentery. Marker transgene expression lasted for 3 wk and was accompanied by the recruitment of macrophages, lymphocytes, and neutrophils into the peritoneal cavity and mild inflammation at the site of infection. IL-4 transgene expression led to a stronger inflammatory response characterized by tissue eosinophilia and increased numbers of peritoneal mast cells and plasma cells. Whereas control virus infection had no effect on intestinal muscle function, infection with the IL-4 virus led to significant jejunal muscle hypercontractility, evident by day 7 postinfection. This modulation of smooth muscle function was shown to be IL-4 specific, since the application of an IL-5-encoding adenovirus induced tissue eosinophilia but did not alter muscle function. These results highlight an important causal role for IL-4 in the pathological regulation of enteric smooth muscle function and identify a novel strategy for gene transfer to the intestine.     

Plasma 11-deoxycorticosterone (DOC) and mineralocorticoid receptor testicular expression during rainbow trout Oncorhynchus mykiss spermiation: implication with 17alpha, 20beta-dihydroxyprogesterone on the milt fluidity?

Background

Non-invasive micro-ultrasound was evaluated as a method to quantify intrauterine growth phenotypes in mice. Improved methods are required to accelerate research using genetically-altered mice to investigate the interactive roles of genes and environments on embryonic and placental growth. We determined (1) feasible age ranges for measuring specific variables, (2) normative growth curves, (3) accuracy of ultrasound measurements in comparison with light microscopy, and (4) weight prediction equations using regression analysis for CD-1 mice and evaluated their accuracy when applied to other mouse strains.

Methods

We used 30–40 MHz ultrasound to quantify embryonic and placental morphometry in isoflurane-anesthetized pregnant CD-1 mice from embryonic day 7.5 (E7.5) to E18.5 (full-term), and for C57Bl/6J, B6CBAF1, and hIGFBP1 pregnant transgenic mice at E17.5.

Results

Gestational sac dimension provided the earliest measure of conceptus size. Sac dimension derived using regression analysis increased from 0.84 mm at E7.5 to 6.44 mm at E11.5 when it was discontinued. The earliest measurement of embryo size was crown-rump length (CRL) which increased from 1.88 mm at E8.5 to 16.22 mm at E16.5 after which it exceeded the field of view. From E10.5 to E18.5 (full term), progressive increases were observed in embryonic biparietal diameter (BPD) (0.79 mm to 7.55 mm at E18.5), abdominal circumference (AC) (4.91 mm to 26.56 mm), and eye lens diameter (0.20 mm to 0.93 mm). Ossified femur length was measureable from E15.5 (1.06 mm) and increased linearly to 2.23 mm at E18.5. In contrast, placental diameter (PD) and placental thickness (PT) increased from E10.5 to E14.5 then remained constant to term in accord with placental weight. Ultrasound and light microscopy measurements agreed with no significant bias and a discrepancy of less than 25%. Regression equations predicting gestational age from individual variables, and embryonic weight (BW) from CRL, BPD, and AC were obtained. The prediction equation BW = -0.757 + 0.0453 (CRL) + 0.0334 (AC) derived from CD-1 data predicted embryonic weights at E17.5 in three other strains of mice with a mean discrepancy of less than 16%.

Conclusion

Micro-ultrasound provides a feasible tool for in vivo morphometric quantification of embryonic and placental growth parameters in mice and for estimation of embryonic gestational age and/or body weight in utero.     

Unusual finding of encapsulated nematode larvae (Spiruroidea) in Bartramia longicauda and Numenius americanus (Charadriiformes) in western Canada

Third-stage spiruroid larvae were found encapsulated on the serosa of the small and large intestines and in the mesentery of one of 15 adult upland sandpipers (Bartramia longicauda) from Manitoba, Canada, and three of 18 adult long-billed curlews (Numenius americanus) from Alberta, Canada. The larvae resemble third-stage larvae of Physocephalus sexalatus and birds may serve as a paratenic host of this unidentified spiruroid species.     

Embryonic and early larval development of <Emphasis Type="Italic">Cottus czerskii</Emphasis> Berg, 1913 (Scorpaeniformes: Cottidae)

The embryonic and early larval development of the Cherskii’s sculpin Cottus czerskii Berg, 1913 was studied. The duration of the embryonic period was 21 days at a water temperature of 9–10°C. Pelagic larvae of approximately 8.0 mm total length leave the egg envelopes, with a large rounded yolk sac with one large oil globule, 10–12 trunk and 30–31 precaudal myomeres and several large melanophores on the yolk sac, 2 melanophores in the peritoneal region, and 30 melanophores in a postanal ventral row. At 11 days after hatching at a length of 9.0 mm, the yolk sac is completely resorbed and the number of myomeres remains the same; seven rays become visible in the caudal fin. The fully formed larva of C. czerskii has an elongated body, a small head, a rounded snout, and an oblong tail part. The melanophores are located in the peritoneal area above the gut, in the abdominal area, and in the postanal ventral row. Armament in the form of spines on the top of the head is absent, pointing to the affiliation of the species that we studied to the Cottus–Leptocottus phenetic group.     

Serosa membrane plays a key role in transferring vitellin polypeptides to the perivitelline fluid in insect embryos

In mid-embryogenesis, the stick insect Carausius morosus comes to be comprised of three distinct districts: the embryo proper, the yolk sac and the perivitelline fluid. A monolayered epithelium, the so-called serosa membrane, encloses the yolk sac and its content of vitellophages and large yolk granules. During embryonic development, the yolk sac declines gradually in protein concentration due to Vt polypeptides undergoing limited proteolysis to yield a number of Vt cleavage products of lower molecular weights. mAbs 1D1 and 5H11 are monoclonal antibodies raised against some of the Vt cleavage products generated by this process in the yolk sac. At the confocal microscope, antibody fluorescence is initially associated with a few yolk granules, while it is gradually displaced in the cytosolic spaces of the vitellophages. With the proceeding of embryonic development, label appears also in the serosa membrane in the form of clustered dots. At the ultrastructural level, gold particles are initially associated with the vitellophages that are labeled on a few yolk granules and in the cytosolic space flanking the yolk granules. Subsequently, the serosa cells become labeled on vesicles close to the yolk granules or just underneath the plasma membrane. Inside the serosa cells, label is also associated with granules budding from the Golgi apparatus, but never with the intercellular channels percolating the serosa membrane. These observations are interpreted as indicating that Vt cleavage products leak out from the yolk granules into the cytosolic spaces of the vitellophages and are eventually transferred to the perivitelline fluid via transcytosis through the serosa cells.     

HoxB4 confers definitive lymphoid-myeloid engraftment potential on embryonic stem cell and yolk sac hematopoietic progenitors

The extent to which primitive embryonic blood progenitors contribute to definitive lymphoid-myeloid hematopoiesis in the adult remains uncertain. In an effort to characterize factors that distinguish the definitive adult hematopoietic stem cell (HSC) and primitive progenitors derived from yolk sac or embryonic stem (ES) cells, we examined the effect of ectopic expression of HoxB4, a homeotic selector gene implicated in self-renewal of definitive HSCs. Expression of HoxB4 in primitive progenitors combined with culture on hematopoietic stroma induces a switch to the definitive HSC phenotype. These progenitors engraft lethally irradiated adults and contribute to long-term, multilineage hematopoiesis in primary and secondary recipients. Our results suggest that primitive HSCs are poised to become definitive HSCs and that this transition can be promoted by HoxB4 expression. This strategy for blood engraftment enables modeling of hematopoietic transplantation from ES cells.     

Effect of smooth muscle tone on morphometry and residual strain in rat duodenum, jejunum and ileum

It is difficult to measure gastrointestinal smooth muscle (SM) tone except in sphincter regions. Since tone affects the biomechanical properties, the aim of the present study was to evaluate intestinal SM tone by studying the morphometry and biomechanical properties with and without muscle tone. Circumferential rings of 0.8-1mm in width were cut from the rat duodenum, jejunum and ileum. Sectors were obtained by cutting the rings opposite to the mesentery. The rings and the sectors were immersed in physiological Krebs solution in order to maintain the tone and into Krebs solution without Ca(++) and with EGTA to abolish the tone. The circumferences, area, the circularity and residual strain of the mucosal and serosal surfaces, opening angle, and opening angle tone/non-tone ratio were measured or computed. The tone affects the opening angle and residual strain in the intestinal sectors. The opening angle in the tissue sectors with tone was smaller (P<0.05) than those without tone in all three segments. The opening angle tone/non-tone ratio was 0.40+/-0.05, 0.43+/-0.06 and 0.36+/-0.11 for duodenum, jejunum and ileum, respectively, and did not differ among the three intestinal segments. The residual strain between sectors with and without SM tone differed in duodenal and jejunal mucosa and in the serosa of all three segments (P<0.05). The intestinal rings with tone showed axial variation for luminal area (P<0.001), for wall area (P<0.05), and for the mucosal and serosal residual strains (P<0.05). In conclusion, the intestinal mechanical properties are affected by intestinal SM tone. The tone can be evaluated by measuring the opening angle and residual strains of sectors in intestinal segments with and without SM tone.     

MORPHOGENESIS OF THE RETINAL RODS : AN ELECTRON MICROSCOPE STUDY

The morphogenesis of the retinal rods has been studied with the electron microscope in white mice from birth up to the 16th day of age. Observations have been mainly concentrated on specimens of the 8th and 12th days and on the differentiation of the inner and outer segments of the retinal rods. In the morphogenesis of the outer segment three main stages have been considered. The first stage consists in the development of a primitive cilium projecting from a bulge of protoplasm which constitutes the primordium of the inner segment. A basal body, nine pairs of peripheral filaments, a surface membrane, and a matrix filled with a fine vesicular material have been recognized as components of the primitive cilium. The vesicles are called "morphogenetic material" because it is believed that they represent the macromolecular primordium of the rod sacs of the future outer segment. The second stage corresponds to the great enlargment of the apical region of the primitive cilium due to the rapid building up of the lamellar material of the rod sacs. The primitive rod sacs appear to be connected with the ciliary filaments. The basal portion of the primitive cilium remains undifferentiated and constitutes the connecting cilium of the adult rod (1). The third stage consists in the remodelling and reorientation of the rod sacs into their permanent transverse disposition. This process starts in the middle portion of the outer segments and proceeds towards both extremities which can be considered as zones of growth of the outer segment. The inner segment is at the beginning a bulge of protoplasm containing unoriented mitochondria, a basal body, a small Golgi zone, and numerous dense particles. Then this region becomes elongated and the different components assume the stratified disposition found in the adult (1). The demonstration that the entire outer segment of the rod cell is the result of the differentiation of a primitive cilium is discussed in view of the conflicting interpretations found in the literature. The possible macromolecular mechanisms that may be involved in the submicroscopic morphogenesis of the rod sacs are discussed and the possible role of the morphogenetic material is considered. The results described in this paper confirm and extend the interpretation of the submicroscopic morphology of the adult rod cell as presented in a previous paper (1).     

Electrical pulses appear in the inferior vena cava and abdominal aorta at contraction of leg muscles.

A vascular-interstitial neuromuscular closed circuit is described anatomically and electrically. The neuromuscular unit has a high resistance due to its axons. The "outer" vascular-interstitial branch has a low resistance due to a large cross section area. When a rat spontaneously contracts leg muscles after pinching a toe, electric potential pulses appear inside the inferior vena cava, between vena cava and peritoneum, between aorta and peritoneum, between vena cava and peritoneum and between aorta and subcutis. Minor pulses between electrodes in the peritoneal fluid are interpreted as induced by the intravascular potential pulses. The use of Ag-AgCl electrodes or platinum electrodes does not appreciably change the results.     

Embryonic and post-embryonic development of the parietal and visceral peritoneum in white mice]

Light and electron microscopy were used in order to investigate histogenesis of the parietal and visceral peritoneum of white mice in embryonic and postembryonic periods of development. Four periods were distinguished, during which gradual differentiation of the primordium material into tissue structures (mesothelium and the connective tissue) of the peritoneum were observed. Asynchronous differentiation of the mesothelium as well as certain correlation in the degree of differentiation of mesothelial and mesenchymal cells took place at all stages of the embryonic and postembryonic development. More differentiated cells of prolonged shape were predominant in the mesenchyma even at early stages (11 days) in those portions where the lining of the secondary cavity of the body resembled mesothelim in its structure.     

Abdominal Lipomatosis with Secondary Self-Strangulation of Masses in an Adult Rhesus Macaque (Macaca mulatta)

An 10-y-old, intact male rhesus macaque (Macaca mulatta) presented for bilateral scrotal swelling and a distended abdomen. A soft mass in the left upper quadrant of the abdomen was palpated. A barium study did not reveal any gastrointestinal abnormalities. Exploratory laparotomy revealed a large (1.25 kg, 15.0 × 13.0 × 9.5 cm), red and tan, soft, circumscribed, spherical mass within the greater omentum and 10 to 20 smaller (diameter, 1 to 4 cm), soft to firm masses in the mesentery and greater omentum. The resected mass was a self-strangulating abdominal lipoma, a pedunculated neoplasm composed of white adipocytes arising from peritoneal adipose tissue undergoing secondary coagulation necrosis after strangulation of the blood supply due to twisting of the mass around the peduncle. The smaller masses were histologically consistent with simple or self-strangulating pedunculated abdominal lipomas. The macaque presented again 9 mo later with a firm, 5.0-cm mass in the midabdomen, with intestinal displacement visible on radiographs. Given this animal''s medical history and questionable prognosis, euthanasia was elected. Necropsy revealed numerous, multifocal to coalescing, 1.0- to 15.0-cm, pale tan to yellow, circumscribed, soft to firm, spherical to ellipsoid, pedunculated masses that were scattered throughout the mesentery, greater omentum, lesser omentum, and serosal surfaces of the gastrointestinal tract. All of the masses were pedunculated abdominal lipomas, and most demonstrated coagulation necrosis due to self-strangulation of the blood supply. To our knowledge, this report is the first to describe abdominal lipomatosis with secondary self-strangulation of masses in a rhesus macaque.Lipomas have been reported frequently in veterinary medicine as benign subcutaneous neoplasms in canines¹⁶ or as pedunculated peritoneal masses with the potential to cause intestinal strangulation in geriatric horses.⁶ Abdominal lipomatosis (multiple abdominal lipomas) in humans and dogs had been reported only rarely and have been accompanied by clinical signs of abdominal distention with or without secondary gastrointestinal complications.¹⁶ Lipomas of the skin of nonhuman primates have affected a patas monkey, an African green monkey, rhesus macaques, and chimpanzees. Lipomas within the peritoneal cavity have been diagnosed rarely in nonhuman primates. Reported cases include an omental lipoma in a mona monkey and an adrenal lipoma in a hamadryas baboon.¹⁴ Here we report the clinical signs, postmortem examination, and histopathologic features of abdominal lipomatosis in a rhesus macaque (Macaca mulatta).     

Pressure regulation in the microcirculation.

The results of direct pressure measurements are described which demonstrate that pressures in a certain fraction of mesenteric capillaries remain remarkably constant during large changes in systemic pressure. The results of isogravimetric studies, reported in the literature, are also described which indicate that this phenomenon may also occur in the intestine. The question is raised whether capillary pressures may therefore be regulated. Pressures recorded from mesenteric arterioles and capillaries are shown which indicate that maintenance of a constant capillary pressure is primarily the consequence of the vascular architecture peculiar to this tissue, and is merely a secondary reflection of mechanisms associated with flow regulation. The results of direct pressure measurements recorded in the microcirculation of intestinal muscle are also shown. These data indicate that capillary pressures in innervated, denervated, and xylocaine-treated intestinal muscle change in direct proportion to variations in arterial pressure. It is concluded that capillary pressures in the intestinal muscle layers are therefore not regulated, so that the observation that capillary pressures may be maintained is probably a phenomenon unique to the mesentery. Pressures recorded from capillaries in the mucosal villi are also shown and compared to capillary pressures measured in the microvasculature of mesentery and intestinal muscle. When systemic pressure was normal (107 +/- 10 mm Hg), capillary pressure in the mesentery averaged 30 to 33 mm Hg; capillary pressures in the intestinal muscle averaged 22 to 24 mm Hg; and capillary pressures in the mucosal villi averaged 13 to 15 mm Hg. These data suggest that mesenteric capillaries are primarily a filtering network; intestinal muscle capillaries are normally in fluid balance; whereas at rest mucosal capillaries are primarily absorptive. These pressures, recorded from the three major regions of the rat intestine, were used to calculate a weighted average for the whole organ. The calculated value, based on assumed values for relative capillary densities, was 17 mm Hg. This result compares favorably with data from whole organ, isogravimetric studies, and may clarify some of the apparent discrepancies between previous isogravimetric and servopressure studies.     

Continuity versus split and reconstitution: exploring the molecular developmental corollaries of insect eye primordium evolution

Holometabolous insects like Drosophila proceed through two phases of visual system development. The embryonic phase generates simple eyes of the larva. The postembryonic phase produces the adult specific compound eyes during late larval development and pupation. In primitive insects, by contrast, eye development persists seemingly continuously from embryogenesis through the end of postembryogenesis. Comparative literature suggests that the evolutionary transition from continuous to biphasic eye development occurred via transient developmental arrest. This review investigates how the developmental arrest model relates to the gene networks regulating larval and adult eye development in Drosophila, and embryonic compound eye development in primitive insects. Consistent with the developmental arrest model, the available data suggest that the determination of the anlage of the rudimentary Drosophila larval eye is homologous to the embryonic specification of the juvenile compound eye in directly developing insects while the Drosophila compound eye primordium is evolutionarily related to the yet little studied stem cell based postembryonic eye primordium of primitive insects.     

The adult hair follicle: cradle for pluripotent neural crest stem cells

This review focuses on the recent identification of two novel neural crest-derived cells in the adult mammalian hair follicle, pluripotent stem cells, and Merkel cells. Wnt1-cre/R26R compound transgenic mice, which in the periphery express beta-galactosidase in a neural crest-specific manner, were used to trace neural crest cells. Neural crest cells invade the facial epidermis as early as embryonic day 9.5. Neural crest-derived cells are present along the entire extent of the whisker follicle. This includes the bulge area, an epidermal niche for keratinocyte stem cells, as well as the matrix at the base of the hair follicle. We have determined by in vitro clonal analysis that the bulge area of the adult whisker follicle contains pluripotent neural crest stem cells. In culture, beta-galactosidase-positive cells emigrate from bulge explants, identifying them as neural crest-derived cells. When these cells are resuspended and grown in clonal culture, they give rise to colonies that contain multiple differentiated cell types, including neurons, Schwann cells, smooth muscle cells, pigment cells, chondrocytes, and possibly other types of cells. This result provides evidence for the pluripotentiality of the clone-forming cell. Serial cloning showed that bulge-derived neural crest cells undergo self-renewal, which identifies them as stem cells. Pluripotent neural crest cells are also localized in the back skin hair of adult mice. The bulge area of the whisker follicle is surrounded by numerous Merkel cells, which together with innervating nerve endings form slowly adapting mechanoreceptors that transduce steady skin indentation. Merkel cells express beta-galactosidase in double transgenic mice, which confirms their neural crest origin. Taken together, our data indicate that the epidermis of the adult hair follicle contains pluripotent neural crest stem cells, termed epidermal neural crest stem cells (eNCSCs), and one newly identified neural crest derivative, the Merkel cell. The intrinsic high degree of plasticity of eNCSCs and the fact that they are easily accessible in the skin make them attractive candidates for diverse autologous cell therapy strategies.