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PubMed1984

Interhemispheral neuroepithelial (glio-ependymal) cysts, associated with agenesis of the corpus callosum and neocortical maldevelopment. A case study.

Callosal agenesis and interhemispheral cysts containing ependyma, choroid plexus and glial cells are reported in a male infant. To the authors' knowledge this represents the 4th recorded case. Other findings were: nodular neuronal heterotopias with fully differentiated spiny neocortical neurons, widespread neocortical microgyria, cerebellar hypoplasia and bony abnormalities of the foramen magnum and atlas. This study confirms that glio-ependymal cysts are heterotopias of embryonic ventricular epithelium. The existence of more than one type of heterotopia (i.e. neuronal and ependymal) in 1 individual is significant. This indicates an error of cell generation and cell migration affecting the original structure from which both cell types are derived: the embryonic (sub)ventricular zone.

Agenesis of Corpus Callosum↗
PubMed2006

Cholesterol modification is necessary for controlled planar long-range activity of Hedgehog in Drosophila epithelia.

The Hedgehog morphogen is a major developmental regulator that acts at short and long range to direct cell fate decisions in invertebrate and vertebrate tissues. Hedgehog is the only known metazoan protein to possess a covalently linked cholesterol moiety. Although the role of the cholesterol group of Hedgehog remains unclear, it has been suggested to be dispensable for the its long-range activity in Drosophila. Here, we provide data in three different epithelia - ventral and dorsal embryonic ectoderm, and larval imaginal disc tissue - showing that cholesterol modification is in fact necessary for the controlled long-range activity of Drosophila Hedgehog. We provide an explanation for the discrepancy between our results and previous reports by showing that unmodified Hh can act at long range, albeit in an uncontrolled manner, only when expressed in squamous cells. Our data show that cholesterol modification controls long-range Hh activity at multiple levels. First, cholesterol increases the affinity of Hh for the plasma membrane, and consequently enhances its apparent intrinsic activity, both in vitro and in vivo. In addition, multimerisation of active Hh requires the presence of cholesterol. These multimers are correlated with the assembly of Hh into apically located, large punctate structures present in active Hh gradients in vivo. By comparing the activity of cholesterol-modified Hh in columnar epithelial cells and peripodial squamous cells, we show that epithelial cells provide the machinery necessary for the controlled planar movement of Hh, thereby preventing the unrestricted spreading of the protein within the three-dimensional space of the epithelium. We conclude that, as in vertebrates, cholesterol modification is essential for controlled long-range Hh signalling in Drosophila.

Animals↗
PubMed1995

Mirror-image duplication of the primary axis and heart in Xenopus embryos by the overexpression of Msx-1 gene.

The Msx-1 gene (formerly known as Hox-7) is a member of a discrete subclass of homeobox-containing genes. Examination of the expression pattern of Msx-1 in murine and avian embryos suggests that this gene may be involved in the regionalization of the medio-lateral axis during earlier development. We have examined the possible functions of Xenopus Msx-1 during early Xenopus embryonic development by overexpression of the Msx-1 gene. Overexpression of Msx-1 causes a left-right mirror-image duplication of primary axial structures, including notochord, neural tube, somites, suckers, and foregut. The embryonic developing heart is also mirror-image duplicated, including looping directions and polarity. These results indicate that Msx-1 may be involved in the mesoderm formation as well as left-right patterning in the early Xenopus embryonic development.

Animals↗
PubMed1980

[Cytological study of the post-embryonic development of the digestive gland of Sepia officinalis L. Mollusca : Cephalopoda (author's transl)].

A histological and ultrastructural study of the development of the digestive gland of Sepia officinalis L. was carried out on young Sepia reared in the laboratory, during the first month of post-embryonic life. The increasing complexity of the histological structure of the gland is related to the successive appearance of several cell types : immature cell, synthetizing cell, mature digestive cell ("cellule à boules"), and resting cell. These types are, in fact, just the evolutive stages of the same cell, the digestive cell. The sequence of appearance of the different cell types and the changes occurring in feeding can be used to define three stages in the post-embryonic development of the Sepia officinalis L. digestive gland : a multiplication stage (from hatching to the 5th day), a maturation stage (5th to 30th day), and adult stage (after the first month of post-embryonic life). These stages are identical to the three periods previously described by Richard and Decleir (1969) in the life of Sepia.

Animals↗
PubMedDate not supplied

[Decoding of the primary structure of the son3 region in human genome: identification of a new protein with unusual structure and homology with DNA-binding proteins].

From the human embryonic cDNA library a son3 transcript was cloned and sequenced (1454 base pairs). Determination of its sequence revealed only one open reading frame, whereas five other frames contained a number of termination codons. Translation of the son3 sequence in the unique open reading frame into the amino acid sequence by computer and comparison with the NBRF protein data bank showed that the son3 fragment codes for a new previously unknown polypeptide with the following properties: a) it contains a cluster of short tandemly arranged repeats 7-12 amino acid in length located in the middle part of son3; b) it comprises a region homologous to DNA binding structural proteins (for example, gallin, 55%) and to regulatory proteins coded by the family of proto-oncogene myc; c) it comprises a region homologous to the oncoprotein coded by proto-oncogene mos (human, murine).

Amino Acid Sequence↗
PubMed1995

Signs of the principle body axes prior to primitive streak formation in the rabbit embryo.

An early common element during anterior-posterior axis formation amongst amniotes is the primitive streak, running longitudinally in the two-layered embryonic disc. In mammals the primordium of this transient structure is the first definite morphological sign of the anterior-posterior axis, while in avian embryos the axis is visible and apparently defined earlier. Here we scrutinize suggestions that in mammals also there are earlier signs of axis formation by using correlative low- and high-resolution light microscopy on tissues from rabbit embryos at 6.3 and 6.5 days post-conception, i.e. immediately before and after primitive streak formation. A series of semithin sections were cut from resin-embedded embryonic discs that had been photographed previously at low power. In embryos at 6.5-days post-conception the primitive streak is as long as up to half the diameter of the embryonic disc, extending anteriorly from a thickening, here called the posterior node, at the posterior margin, which contains the first mesoderm cells ingressing from the epiblast. On both sides of the primitive streak there is a triangular area that appears light in surface views of fixed embryos and correlates with stretches of low-columnar simple epithelium in an otherwise high-columnar pseudostratified epiblast. Within the anterior margin, which has a sharper contour than the rest of the circumference of the embryonic disc, there is a narrow, crescent-shaped dark zone caused by increased cellular height and number in both epiblast and hypoblast. These characteristics of the anterior margin are also found at 6.3 days post-conception, at which stage there is no sign of a primitive streak or a posterior node. The posterior margin, in contrast, is ill-defined in these earlier embryos, or there is a light crescent within the posterior margin, which has the same histological characteristics as the bilateral posterior triangular areas of primitive streak stages. Because the anterior differentiation occurs prior to primitive streak formation and is a sign of both the anterior-posterior and the transverse axes of the embryonic disc, and because some of its histological characteristics are found in primate and human embryos, we propose to name this structure the 'anterior marginal crescent' and to add it to the list of transient structures that gradually establish the principal body axes in mammals. The anterior manifestation of body axes in mammals is thus essentially different from axis development in the avian embryo, where differentiation of these axes is first manifest at the posterior margin.

Animals↗
PubMed1983

Stage-specific embryonic antigens (SSEA-3 and -4) are epitopes of a unique globo-series ganglioside isolated from human teratocarcinoma cells.

Two monoclonal antibodies (MC631 and MC813-70) raised against 4- to 8-cell stage mouse embryos and a human teratocarcinoma cell line, respectively, detect the stage-specific embryonic antigens, the previously defined SSEA-3 and SSEA-4, described herein. These antibodies were both reactive with a unique globo-series ganglioside with the structure shown below: (formula; see text) The antibodies were found to recognize sequential regions of this ganglioside, i.e., MC813-70 recognizes the terminal 'a' structure whereas antibody MC631 recognizes the internal 'b' structure. Thus, a set of two antibodies defines this unique embryonic antigen. During differentiation of human teratocarcinoma 2102Ep cells, the globo-series glycolipids defined by these antibodies decrease and the lacto-series glycolipids, reacting with the SSEA-1 antibody appear. This antigenic conversion suggests that a shift of glycolipid synthesis from globo-series to lacto-series glycolipids occurs during differentiation of human teratocarcinoma and perhaps of pre-implantation mouse embryos.

Animals↗
PubMed1999

Cloning and functional expression of novel N-type Ca(2+) channel variants.

Voltage-dependent Ca(2+) channels are structurally and functionally diverse. As Ca(2+) currents recorded from embryonic chick dorsal root ganglion (DRG) neurons differ significantly from their mammalian counterparts, information on the primary sequence of the chick channels will help define the structural underpinnings of Ca(2+) channel function. Here, we report the cloning and functional expression of full-length Ca(2+) channel alpha(1B) subunit cDNAs derived from chick DRGs. Two variable regions (A and B) have been identified in the cytoplasmic linker between repeats I and II; a third (C) in the carboxyl terminus extends the open reading frame by 525 nucleotides. The A and C inserts are absent, and the B insert is present in all other class B clones reported to date. The unique shorter channels appear to predominate in DRG neurons. Results represent a requisite first step in defining the structural elements that underlie variations in function and modulation of Ca(2+) channels.

Amino Acid Sequence↗
PubMed1990

Normal structure and expression of Zfy genes in XY female mice mutant in Tdy.

Zfy-1 and Zfy-2 are candidate genes for Tdy, the testis-determining gene in mice. We have analysed these genes in a line of XY female mice that have been shown to be mutated in Tdy. We have used Southern blot analysis to show that the Zfy genes have not undergone any major structural alterations, and have also demonstrated that both genes are transcribed normally from the mutant Y chromosome (Y) in both adult XYY testis and XY female embryonic gonads. The fact that these genes show a normal structure and expression pattern in mice with a Y chromosome known to carry a mutation in Tdy and that mutant embryos develop into females despite Zfy-1 expression, strongly supports other recent evidence that Zfy genes are not directly involved in primary testis determination.

Animals↗
PubMed2006

Angiogenic potential of CD44+ CD90+ multipotent CNS stem cells in vitro.

Although it is now clear that several subpopulations of neural stem cells (NSCs) exist during early development and adulthood, the angiogenic potential of NSCs remains a subject of debate. Here, we report that CD44(+) CD90(+) cells isolated from primary neurospheres can form vascular-tube structures in vitro. NSCs isolated from the mouse embryonic cortex formed neurospheres when cultured in serum-free medium containing 20ng/ml basic fibroblast growth factor (bFGF). CD44(+) CD90(+) cells were enriched from the neurospheres using an EPICS ALTRA flow cytometer, and antibodies against CD44 and CD90. The purified CD44(+) CD90(+) cells generated neurospheres, and differentiated into neurons and astrocytes. When the cells were inoculated into collagen gels and cultured with 20% fetal bovine serum plus bFGF for 7 days, vascular tube-like structures were formed. These results indicate that CD44(+) CD90(+) cells have the ability to generate neurospheres and to form vascular tubes.

Animals↗
PubMed1985

[Rhabdomyosarcoma in childhood. I. Histologic structure].

Histological structure of rhabdomyosarcoma was studied in a group of 37 children. The classification was: embryonal rhabdomyosarcoma in 28 cases, alveolar rhabdomyosarcoma in 9 cases. 5 cases showed an ambivalent structure. The diagnosis of rhabdomyosarcoma is based on cytology: various rhabdomyoblasts are to be identified as well as distinguished from similar cells. The structural point of view is helpful but diagnostic only in typical cases of sarcoma botryoides and alveolar rhabdomyosarcoma. Undifferentiated cells maturating into rhabdomyoblasts combined with numerous polymorphic cells were found consecutive investigations of individual cases.

Adolescent↗
PubMed2005

Embryonic stem cells that differentiate into RPE cell precursors in vitro develop into RPE cell monolayers in vivo.

A culture system to generate eye-like structures consisting of lens, neural retina, and retinal pigmented epithelium (RPE) cells from undifferentiated embryonic stem cells has been established. Precursors of RPE cells that differentiated in the cultures were responsive to Wnt2b signaling and identified retrospectively to form secondary colonies consisting of only RPE-like cells in eye-like structures. These transplanted eye-like structures were capable of populating the developing chick eye as neuronal retina and RPE cells. The outgrowth of a single cell layer of mature RPE cells from the grafted eye-like structures confirmed the existence of precursors for RPE cells. These results suggest that the eye-like structures resulted from the normal developmental pathway responsible for generating eyes in vivo. If a functional effect of these cells can be established, such eye-like structures may be potentially used to establish therapy models for various eye diseases.

Animals↗
PubMedDate not supplied

Tripartite mushroom body architecture revealed by antigenic markers.

We have explored the organization of the axonal lobes in Drosophila mushroom bodies by using a panel of immunohistochemical markers. These markers consist of antibodies to eight proteins expressed preferentially in the mushroom bodies: DAMB, DCO, DRK, FASII, LEO, OAMB, PKA RII, and RUT. Previous to this work, four axonal lobes, two projecting dorsally (alpha and alpha') and two medially (beta and gamma), had been described in Drosophila mushroom bodies. However, our analysis of immunohistochemically stained frontal and sagittal sections of the brain revealed three medially projecting lobes. The newly distinguished lobe, which we term beta', lies along the dorsal surface of beta, just posterior to gamma. In addition to resolving a fifth lobe, our studies revealed that there are specific lobe sets defined by equivalent marker expression levels. These sets are (1) the alpha and beta lobes, (2) the alpha' and beta' lobes, and (3) the gamma lobe and heel (a lateral projection formed by a hairpin turn of some of the peduncle fibers). All of the markers we have examined are consistent with these three sets. Previous Golgi studies demonstrate that each mushroom body cell projects one axon that branches into a dorsal lobe and a medial lobe, or one unbranched axon that projects medially. Taken together with the lobe sets listed above, we propose that there are three major projection configurations of mushroom body cell axons: (1) one branch in the alpha and one in the beta lobe, (2) one branch in the alpha' and one in the beta' lobe, and (3) one unbranched axon projecting to the heel and the gamma lobe. The fact that these neuron types exhibit differential expression levels of a number of mushroom body genes suggests that they may have corresponding functional differences. These functions may be conserved in the larvae, as several of these genes were expressed in larval and embryonic mushroom bodies as well. The basic mushroom body structure, including the denritic calyx, peduncle, and lobes, was already visible by the late stages of embryogenesis. With new insights into mushroom body organization, and the characterization of markers for developing mushroom bodies, we are beginning to understand how these structures form and function.

Animals↗
PubMed2003

Fate map of mouse ventral limb ectoderm and the apical ectodermal ridge.

The apical ectodermal ridge (AER) is a critical signaling center at the tip of the limb that promotes outgrowth. In mouse, formation of the AER involves a gradual restriction of AER gene expression from a broad ventral preAER domain to the tip of the limb, as well as progressive thickening of cells to form a multilayered epithelium. The AER is visible from embryonic day 10.5 to 13.5 (E10.5-E13.5) in the mouse forelimb. Previous short-term fate mapping studies indicated that, once a cell is incorporated into the AER, its descendents remain within the AER. In addition, some preAER cells appear to become incorporated into the ventral ectoderm. In the present study, we used an inducible CreER/loxP fate mapping approach in mouse to examine the long-term contribution of preAER cells to limb ventral ectoderm, as well as the ultimate fate of the mature AER cells. We used a CreER transgene that contains Msx2 regulatory sequences specific to the developing AER, and demonstrate by marking preAER cells that, at stage 2 of mouse limb bud development, the majority of the ventral ectoderm that protrudes from the body wall later covers only the paw. Furthermore, when Msx2-CreER-expressing preAER cells are marked after the onset of preAER gene expression, a similar domain of paw ventral ectoderm is marked at E16.5, in addition to the AER. Strikingly, mapping the long-term fate of cells that form the mature AER showed that, although this structure is indeed a distinct compartment, AER-derived cells are gradually lost after E12.5 and no cells remain by birth. A distinct dorsal/ventral border nevertheless is maintained in the ectoderm of the paw, with the distal-most border being located at the edge of the nail bed. These studies have uncovered new aspects of the cellular mechanisms involved in AER formation and in partitioning the ventral ectoderm in mouse limb.

Animals↗
PubMed2003

Evolutionary transformations of the fetal membranes of viviparous reptiles: a case study of two lineages.

The reptilian placenta is a composite structure formed by a functional interaction between extraembryonic membranes and the maternal uterus. Study of placental structure of squamate reptiles over the past century has established that each of the multiple independent origins of placentation, which characterize the reproductive diversity of squamates, has resulted from the evolutionary transformation of these homologous structures. Because each evolutionary transformation is an independent novel relationship between maternal and embryonic tissues, the resulting placentae are not homologous, even though the individual components may be. The evolution of reptilian placentation should reveal much about evolutionary patterns and mechanisms because similar structural-functional systems have been transformed along parallel trajectories on multiple occasions. We compared extraembryonic membrane and placental development and pattern of embryonic nutrition in thamnophiine snakes and Pseudemoia lizards in the context of recent hypotheses of phylogenetic relationships. Two primary types of placentation, chorioallantoic and yolk sac, evolved in each lineage. Smooth, highly vascular regions of chorioallantoic placentation are indistinguishable homoplasies that evolved in parallel, likely to facilitate respiratory exchange. The yolk sac placenta of each lineage is specialized for histotrophic nutrient transfer, yet composition of these structures differs because of variation in the ancestral snakes and lizards. In addition, the omphalopleure that contributes to yolk sac placentation persists to later embryonic stages compared to oviparous outgroups, but the two lineages have evolved different structures that prevent replacement of the omphalopleure by the allantois. Each lineage has also evolved unique structural specializations of the chorioallantoic placenta.

Allantois↗
PubMed1987

Glycolipid core structure switching from globo- to lacto- and ganglio-series during retinoic acid-induced differentiation of TERA-2-derived human embryonal carcinoma cells.

We have analyzed the glycolipid markers of a recently cloned human embryonal carcinoma (EC) cell line, NTERA-2, which differentiates extensively into a variety of somatic cell types when exposed to retinoic acid. These tumor cells provide a model system that can be used to study the ontogeny of glycolipid diversity during human embryonic development. Glycolipid antigens were identified by cell surface immunofluorescence and thin-layer chromatography immunostaining using a comprehensive set of anticarbohydrate monoclonal antibodies. Undifferentiated NTERA-2 cells were found to express predominantly globo-series glycolipids, including Gb3, Gb5 (IV3GalGb4), globo-ganglioside (IV3NeuAc alpha 2----3GalGb4), globo-H (IV3Fuc alpha 1----2GalGb4), and globo-A (IV3GalNAc alpha 1----3[Fuc alpha 1----2]GalGb4). When NTERA-2 cells were induced to differentiate by culturing in the presence of 10(-5) M retinoic acid, a remarkable shift of cellular glycolipids from globo-series to lacto- and ganglio-series was observed: Globo-series structures declined, particularly during the period 7-20 days after first exposure to retinoic acid, while lacto-series structures, including fucosyl alpha 1----3 type 2 chain (Lex) and sialosyl type 2 chain, and ganglio-series structures, including GM3, GD3, 9-O-acetyl-GD3, GM2, GD2, and GT3, increased. The presence of globo-A and globo-H as the major ABH blood group antigens in undifferentiated NTERA-2 cells suggests that globo-series blood group antigens are embryonic antigens, synthesis of which switches to lacto-series during human development. Two-color immunofluorescence analysis indicated preferential expression of several ganglio- and lacto-series antigens on different subsets of differentiated cells and permitted the relationship of these subsets to the development of neurons in NTERA-2 cultures to be determined. The results suggest that glycosyltransferase, particularly those involved in controlling glycoconjugate core structure assembly, are key enzymes regulated during the differentiation of human EC cells and, by implication, during human embryogenesis.

Antigens↗