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PubMed1985

The allantois of the North American opossum (Didelphis virginiana) with preliminary observations on the yolk sac endoderm and trophectoderm.

During the middle of prenatal day 10, the opossum allantois forms as a ventral outgrowth of the hindgut. By day 11 it appears as a large, fluid filled sac and by the middle of day 12 (just prior to birth) it reaches its maximal development. The simple squamous epithelium lining the allantois consists of only one cell type that often contains numerous filaments in the apical cytoplasm. At the luminal surface, the apices of the cells are united by junctional complexes and desmosomes are present between adjacent cells. The luminal surface is irregular, whereas laterally and basally the cell membranes show few if any infoldings. Mitotic figures and presumptive degenerating cells occasionally occur in the allantoic epithelium which rests on a delicate basal lamina. The allantois is covered by a simple squamous mesothelium that lacks a distinct basal lamina. Between the two epithelial sheets lie mesenchymal cells, collagen fibers, and blood vessels. No specializations of cell membranes were noted in either of the epithelial layers. The yolk sac endoderm consists of a single layer of squamous cells whose cytoplasm contains scattered profiles of rough endoplasmic reticulum and mitochondria. Extensive lateral and basal infoldings of the plasmalemma were not observed in these endodermal cells. The morphology of the trophectodermal (trophoblastic) cells indicates a cell type that is active in the transport of materials. Since the endodermal cells that line the allantois lack morphological features that would suggest the presence of mechanisms for transport or exchange, and because they remain relatively unchanged throughout pregnancy, it is thought that the allantois functions primarily in the storage of urinary wastes during prenatal life.(ABSTRACT TRUNCATED AT 250 WORDS)

Allantois↗
PubMed2004

Flow cytometric isolation of endodermal progenitors from mouse salivary gland differentiate into hepatic and pancreatic lineages.

Experimental injury is useful to induce tissue stem cells, which may exist in small numbers under normal conditions. The salivary glands originate from the endoderm and consist of acinar and ductal epithelial cells, which have exocrine function. After salivary gland duct ligation, acinar cells disappear as a result of apoptosis, and duct epithelium subsequently proliferates. In this study, we analyzed the tissue stem cells induced by salivary gland duct ligation in mice using immunohistochemistry and flow cytometry. We sorted the Sca-1(+)/c-Kit(+) fraction from adult mice salivary glands by way of fluorescence-activated cell sorting. The sorted cells were apparently homogeneous and were designated mouse salivary gland-derived progenitors (mSGPs). mSGP cells differentiated into a hepatic lineage when cultured in matrigel. In spherical culture in the presence of glucagon-like peptide-1 (GLP-1), these cells differentiated into a pancreatic endocrine lineage. When spheroidal bodies of mSGP, 20 to 30 microm in diameter, were transplanted into liver via the portal vein, the cells integrated into hepatic cords and expressed albumin and alpha1-antitrypsin, suggesting that they had differentiated into hepatic-type cells. Moreover, ductlike structures formed by mSGP cells also appeared, epithelial cells of which were positive for cytokeratin 19. In conclusion, fluorescence-activated cell sorting (FACS) based on histologic evidence is efficient in isolating adult tissue stem cells of the salivary gland. Tissue stem cells of endodermal origin (e.g., hepatic oval cells, pancreatic epithelial progenitor cells, and salivary gland progenitor cells) have similarities in their molecular markers and tissue location. Our findings suggest the existence of common tissue stem cells in endoderm-derived organs.

Animals↗
PubMed1984

Endogenous peroxidase in the visceral endoderm of early mouse embryos.

Endogenous peroxidase activity was demonstrated in early mouse embryos by means of the diaminobenzidine staining reaction. This enzyme was observed in visceral endoderm on the seventh to eighth day of gestation in vivo, but was no longer detected on the ninth day of development. In cell layers developing from blastocysts or isolated inner cell masses cultured for 96-144 h (developmental stage equivalent to 6-7.5-day-old embryos), diaminobenzidine product was also observed in visceral endodermal cells. Most of the endogenous peroxidase was localized inside or close to the numerous apical vacuoles in the endoderm. Ectoderm, mesoderm, ectoplacental cone, and trophoblast cells did not contain endogenous peroxidase.

Animals↗
PubMed1983

An Ultrastructural study of oocyte growth within the endoderm and entry into the mesoglea in Actinia fragacea (Cnidaria, Anthozoa).

Sea anemone gametes arise in the endoderm but migrate into the mesoglea at an early stage. In order to observe this process, large individuals of Actinia fragacea were collected from the same intertidal location at regular intervals over a 2-year period, and their gonads were examined by light and electron microscopy. The cellular origin of the oocytes is unclear, but the smallest recognizable oocytes are rounded cells, 6-8 microns in diameter, with relatively large nuclei which may contain synaptinemal complexes. Their cytoplasm contains numerous ribosomes, a flagellar basal-body-rootlet complex, and distinctive dense structures also present in male germ cells but not found in anemone nongerminal cells. During the endodermal phase of growth, the density of the oocyte nucleus increases, a single nucleolus becomes prominent, and mitochondria and glycogen accumulate in the cytoplasm. Most oocytes, but not all, only begin major vitellogenesis after entry into the mesoglea. Most oocytes enter the mesoglea vitellogenesis after entry into the mesoglea. Most oocytes enter the mesoglea before they attain a diameter of 25 microns. The oocytes migrate toward and enter the mesoglea by a process resembling amoeboid movement. During entry, the oocytes are constricted into a characteristic "hourglass" shape and become covered by a basal lamina continuous with that of the gonad epithelium. The last part of the oocyte to enter the mesoglea forms an intimate relationship with the surrounding endodermal cells, which is maintained after entry is complete, and is thought to be important in the establishment of the trophonema.

Animals↗
PubMed1993

Continued expression of the chicken caudal homologue in endodermally derived organs.

We show that the CHox-cad gene is continuously expressed throughout embryogenesis from Days 1 to 14 of development. In the adult chicken, CHox-cad appears to be expressed exclusively in the gut. Genomic Southern blot hybridization experiments suggest that there may be only a single CHox-cad gene per haploid genome from which RNAs of 2.9 and 1.6 kb are transcribed. In situ hybridization to sections of 80-hr to 12-day chick embryos with a CHox-cad probe reveals that this gene is expressed at high levels in organs of endodermal origin: the developing liver, pancreas, lung, and in the epithelial lining of the entire intestine. By Day 16 of development, CHox-cad signals are observed in the epithelial lining of the gut but no longer in the other endodermally derived organs. The coincidence of CHox-cad expression with the onset of development of these endoderm-derived organs may indicate an important role for that gene during the early steps of organogenesis.

Animals↗
PubMed1996

Genetic analysis of the Drosophila beta3-tubulin gene demonstrates that the microtubule cytoskeleton in the cells of the visceral mesoderm is required for morphogenesis of the midgut endoderm.

We have investigated the cellular basis for lethality of mutant alleles of the Drosophila melanogaster beta3-tubulin gene, betaTub60D. Lethal beta3 mutations can be grouped into two classes: the most severe mutations (Class I alleles) cause death during the first larval instar, while weaker alleles (Class II) cause death in later larval stages or in early pupal development. Since beta3 is not expressed during larval development, lethality of the Class I mutations must reflect essential functions of beta3 in embryogenesis. Beta3-tubulin is zygotically expressed during midembryogenesis in the developing mesoderm, and the major site of beta3 accumulation is in the developing muscles during myogenesis. We show that the embryonic pattern of beta3 expression, including accumulation in the developing musculature, is conserved in other Drosophila species. However, we found that loss of beta3 function does not cause discernible defects in either the ultrastructure or function of the larval muscle. Thus beta3-tubulin is dispensable in its highest site of accumulation. Rather, the essential site of function of beta3 in embryos is in cells of the visceral mesoderm. Lethality of Class I alleles is caused by defects in midgut morphogenesis and failure of gut function. Although the folding pattern is irregular and the gut is smaller than normal, a complete folded gut forms in mutant larvae, and the visceral muscle functions normally to move food through the gut. However, mutant larvae cannot absorb nutrients across the gut wall. Thus loss of beta3 function in the mesoderm results in defects in the underlying endodermally derived layer of the gut. Our data provide an assay for cellular interactions between mesoderm and endodermal tissues and reveal a role for the microtubule cytoskeleton of the visceral mesodermal cells in differentiation of the endodermal cell layer of the larval gut.

Animals↗
PubMed1998

Protein tyrosine kinase activity following fertilization is required to complete gastrulation, but not for initial differentiation of endoderm and mesoderm in the sea urchin embryo.

The egg activation process functions to implement developmental programs that act much later in embryogenesis. One example of this is the fact that application of protein tyrosine kinase inhibitors to the fertilized sea urchin egg for a 15-min period results in a defect in the gastrulation process occurring over 24 h later (Kinsey, W. H., Dev. Biol. 172, 704-707, 1995). In the present study, we show that the window of sensitivity is not due to differential uptake of inhibitor, and establish that the inhibitor inhibits tyrosine kinase activity at the time of application. We also demonstrate that inhibition of protein tyrosine kinase activity in the zygote causes a specific defect in the morphogenetic movements associated with gastrulation without interfering with the initial specification and differentiation of endoderm and mesoderm. Differentiation events occurring concurrent with or subsequent to gastrulation were also suppressed in embryos derived from treated zygotes. These findings indicate that fertilization initiates a signaling cascade involving protein tyrosine kinase activity that is required specifically for events at gastrulation. This signaling event is required to complete the developmental program of both endoderm and mesoderm, but is different from those events necessary for initial specification of endodermal and mesodermal cell fate.

Animals↗
PubMed1998

Late specification of Veg1 lineages to endodermal fate in the sea urchin embryo.

Single blastomeres of the sixth-cleavage veg1 and veg2 tiers of Strongylocentrotus purpuratus embryos were labeled with DiI lineage tracer, and the disposition of the progeny was followed through the blastula and gastrula stages in order to determine their respective endodermal and ectodermal contributions. In the endoderm of postgastrula embryos, veg1-derived cells constituted nearly all of the prospective hindgut and about half of the prospective midgut, while veg2-derived cells made up the prospective foregut and half the midgut. Oral veg1 clones consistently contributed more cells to endoderm than aboral veg1 clones. Oral veg1 clones extended along the archenteron up to the foregut region, while aboral veg1 clones contributed only small numbers of hindgut cells but large patches of ectoderm cells that extended out to the prospective larval vertex. The oral/aboral asymmetry in veg1 allocations was also demonstrated using chimeric embryos, the animal halves of which were labeled with a rhodamine-dextran. Lineages expressing the vegetal plate marker Endo16 were more precisely determined by combining lineage tracer injection with whole-mount in situ hybridization. Endo16 expression was found in all cells that are going to participate in gastrulation. Recruitment of new cells to the Endo16 domain occurs in advance of the actual invagination of those cells. During the blastula stages Endo16 expression expands radially until all cells in the veg2 lineages express this gene. The first phase of gastrulation, including the normal buckling of the vegetal plate and primary invagination of the archenteron, involves only the Endo16-expressing cells of the veg2 lineages. As the archenteron begins to elongate, marking the onset of the second phase of gastrulation, there is an asymmetric expansion of Endo16 into the veg1-derived cells that will contribute to the hindgut and midgut in accordance with lineage tracing observations. The results indicate a relatively late specification of veg1-derived cells, resulting in late recruitment to the periphery of the vegetal plate territory as gastrulation proceeds. Differential recruitment of veg1-derived cells on the oral side of the embryo introduces an oral bias to gastrulation by disproportionately increasing the number of cells on the oral side that are competent to participate in gastrulation.

Animals↗
PubMed2001

Ovarian endodermal sinus tumor in a postmenopausal woman.

BACKGROUND: Ovarian endodermal sinus tumor is rare in postmenopausal women. CASE: We report the case of a 75-year-old woman with a pure endodermal sinus tumor of the ovary. CONCLUSION: We believe this to be the oldest patient reported with an ovarian endodermal sinus tumor. The histogenesis of this entity in older patients may be different than when it occurs in young women.

Age Factors↗
PubMed1987

Differentiation of gut endoderm in dependence of the notochord.

Presumptive intraembryonic endoderm, either isolated or together with adhering mesoderm, from 19-h chick embryos, was grafted to the coelom of 50-h host embryos. The viability of such grafts was low and endodermal differentiation was poor. In a second series the endoderm (with or without adhering mesoderm) was combined with a fragment of notochordal tissue from 48-60-h donor embryos. Then the recovery was much higher, notably after longer periods of in vivo culture. After 10 days of cultivation well-developed entero-endocrine (argyrophilic) cells were found among the regular enterocytes in both series.

Animals↗
PubMed1976

Spinal endodermal cysts without associated vertebral or other congenital abnormalities. Report of four cases and review of the literature.

Four cases of spinal cysts lined by simple columnar epithelium of endodermal origin, without associated vertebral or other congenital anomalies, are reported. Pathology, pathogenesis and nomenclature of such cysts are discussed. Misplacement of endodermal cells is though to be the common developmental error leading to the formation of such cysts, as well as of those replicating intestinal wall or containing other endodermal derivatives such as bronchial tissue.

Adolescent↗
PubMed1986

Differences in the histogenesis and keratin expression of avian extraembryonic ectoderm and endoderm recombined with dermis.

The responses of the chorionic ectoderm and allantoic endoderm (from 8-day chick embryos) to dermal induction were compared through tissue recombinants grafted onto the chorioallantoic membrane. The chorionic epithelium formed the appropriate epidermis with a fully developed stratum corneum in response to both spur and scutate scale dermises. Analysis of these recombinant epidermal tissues by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) demonstrated that tissue-specific expression of the alpha (alpha) and beta (beta) keratin polypeptides occurred. In addition, indirect immunofluorescence studies with antisera to alpha or beta keratins showed that the beta stratum, which characterizes the epidermis of spurs and scutate scales, was formed, and the alpha keratins were distributed as in the normal epidermal tissues. In contrast, although the allantoic endoderm became stratified in association with either spur or scutate scale dermis, a stratum corneum with a beta stratum did not develop. SDS-PAGE analysis demonstrated that while the characteristic beta keratins of scutate scales and spur were not detected, most of the alpha keratins normally elaborated by these structures were present, suggesting that even without histogenesis of a stratum corneum the expression of alpha keratins of endoderm could be regulated in a tissue-specific manner by dermis. This study also demonstrated that there are differences in the abilities of the chorionic and allantoic epithelia to respond to the same dermal cues, which may reflect earlier restrictions in their developmental potentials.

Allantois↗
PubMed1986

Precardiac cell migration: fibronectin localization at mesoderm-endoderm interface during directional movement.

The pathway of directional movement of chick precardiac mesoderm cells was studied by indirect immunofluorescence and by scanning electron microscopy. Directional movement of the precardiac cells begins at stage 6 from the lateral sides of the embryo at the level of Hensen's node. The cells move anteriorly in an arc to the embryo's midline. By stage 8 the cells arrive at the lateral sides of the anterior intestinal portal and movement ceases. The interval of this directional movement is approximately 10 hr. During migration the precardiac cells are in close association with the underlying endoderm. As migration proceeds, the cells encounter increasing amounts of fibrils in the substratum at the mesoderm-endoderm interface. Concomitant with increasing fibril formation there is an increase in fibronectin (FN) in the heart-forming region. During stage 5 FN first appears in the lateral heart-forming regions and increases in amount during the period of cell migration. By stage 7 a concentration difference of FN is apparent in the lateral regions with more FN cephalad and decreasing amounts caudad. At stages 7 and 8 large amounts of extracellular FN-associated fibrils are observed at the lateral sides of the anterior intestinal portal where the cells stop moving. The precardiac cells moving into this region are oriented perpendicular to the anterior intestinal portal and in close association with these fibrils. There is no evidence that the fibrillar meshwork forming the substratum of the precardiac mesoderm cells is physically oriented as a guide for directional movement. The correlations between FN distribution at the mesoderm-endoderm interface and directional cell movement suggest that the precardiac cells may migrate by haptotaxis, i.e., by moving along the substratum toward areas of greater adhesiveness.

Animals↗
PubMed1987

Vegetal pole cells and commitment to form endoderm in Xenopus laevis.

In order to compare their states of commitment with their normal developmental fate, single vegetal pole cells from early Xenopus embryos were labeled and transplanted into the blastocoels of host embryos. In a previous study we showed, using this single cell transplantation assay, that vegetal pole cells become committed to endoderm by the early gastrula stage. In this paper we examine some properties of the commitment process. First, we show that it is gradual. When vegetal blastomeres are taken from progressively older embryos an increasing number of them enter only the endoderm, until by the early gastrula stage they all do. Second, we show that commitment can continue in vitro when an appropriate tissue mass is present. We suggest that commitment to form endoderm may be, in the right conditions, a cell autonomous process.

Animals↗
PubMed1989

Gastrulation in the sea urchin is accompanied by the accumulation of an endoderm-specific mRNA.

Spatial diversification of the endoderm during gastrulation in the sea urchin Lytechinus variegatus was examined with an endoderm-specific cDNA clone. This cDNA clone, LvN1.2, was identified by a differential cDNA screen between the ectoderm and endoderm/mesoderm fractions from prism stage embryos. The LvN 1.2-kb mRNA was first detectable by Northern blots at the mesenchyme blastula stage just prior to gastrulation and then accumulated approximately 15-fold from gastrulation to the pluteus stage. In situ hybridization analysis demonstrated that the mRNA accumulated specifically in endoderm and was restricted to the hindgut-midgut regions. This restricted localization was apparent during gastrulation and predicted the morphological distinction between foregut and midgut eventually seen at prism and pluteus stages. Sequence analysis showed that the 189-amino acid open reading frame represented a novel protein. In vitro translation of synthetically produced LvN1.2 mRNA and Western blot analysis with antibodies to the protein sequence yielded the same 25-kDa polypeptide on SDS-PAGE. The LvN1.2 protein resided within discrete granules of the hindgut and midgut cells. These particles were concentrated to the luminal aspect of the cells, suggesting the LvN1.2 protein participates in the digestive function of this region of the gut.

Amino Acid Sequence↗
PubMed1989

Embryonal carcinoma cells adhere preferentially to fibronectin and laminin but their endodermal differentiation leads to a reduced adherence to laminin.

F9 and PC13 embryonal carcinoma (EC) cells adhered rapidly to growth substrata coated with fibronectin or laminin. When F9 cells were induced to differentiate into visceral or parietal endoderm-like cells, their ability to adhere to laminin diminished, but their adherence to fibronectin remained unchanged. Correspondingly, permanently differentiated teratocarcinoma-derived endoderm cells (PYS-2 and PSA-5e) adhered markedly less efficiently to laminin than to fibronectin. F9 cells adhered to proteolytic fibronectin fragments containing the cell-binding site but not to fragments containing gelatin- or heparin-binding sites. They also adhered slowly to gelatin, but this adhesion was completely blocked by cycloheximide. The results show that the teratocarcinoma stem cells may have specific mechanisms mediating adhesion to fibronectin and laminin and that endodermal differentiation leads to a reduction in their capacity to adhere to laminin but not to fibronectin.

Cell Adhesion↗
PubMed1990

In vitro production of Reichert's membrane by mouse embryo-derived parietal endoderm cell lines.

We report the isolation of eight independent cell lines from preimplantation mouse embryos, which have a parietal endoderm phenotype. When grown as aggregates, these cell lines produce large amounts of a basement membrane matrix, that contains laminin, nidogen, heparan sulfate proteoglycan, collagen IV, and BM-40. The biosynthetic profiles of all eight cell lines are very similar to parietal endoderm cells in vivo which synthesize Reichert's membrane. The structure of the matrix produced by the parietal endoderm cell lines (PEC lines) resembles more closely Reichert's membrane than the Engelbreth-Holm-Swarm (EHS) tumor in susceptibility to proteolytic degradation. Since these cell lines produce large quantities of basement membrane they will be useful for structural and functional comparison of a Reichert's membrane matrix with the basement membrane produced by the EHS tumor.

Animals↗
PubMed1980

Hormonal induction of differentiation in teratocarcinoma stem cells: generation of parietal endoderm by retinoic acid and dibutyryl cAMP.

It has previously been shown that retinoic acid induces multiple phenotypic changes in cultures of F9 teratocarcinoma stem cells. In this paper we demonstrate that these retinoid-generated cells can be converted to yet another cell type by compounds that elevate cAMP concentrations. The phenotype of the new cell type is characterized by the synthesis of plasminogen activator, laminin and type IV collagen, and by very low levels of alkaline phosphatase and lactate dehydrogenase. The secretion of plasminogen activator and type IV collagen, and low levels of alkaline phosphatase and lactate dehydrogenase, have been previously shown to be properties of parietal endoderm, an extraembryonic cell which is generated early in mouse embryonesis. We show here that parietal endoderm also synthesizes laminin. The cell type generated by retinoic acid and dibutyryl cAMP treatment is therefore indistinguishable from definitive parietal endoderm. Analysis of the final phenotype indicates that it is not dependent upon the continued presence of either compound, and that cAMP agents are active only on cells that have been treated with retinoic acid.

Animals↗