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PubMed1992

VIP-immunoreactive nerve structures of the gastrointestinal tract in the developing and adult domestic duck.

The first appearance and distribution of VIP-containing nerve structures were studied in the gut of embryonal, newly hatched and adult domestic ducks. Immunoreactive structures appeared in the mesenchyme of the gizzard-duodenum junction (antrum) at 5 days of incubation, and soon after diffused both cranially and caudally. Early in development, VIP-positive cell bodies were more numerous than positive fibres, appearing 3 days before the latter. Later on, the positive cell bodies decreased in number while the fibres increased. In the foregut, VIP-positive structures firstly appeared in the myenteric plexus while in the mid- and hindgut they appeared simultaneously in the myenteric and submucous-plexuses. The gastrointestinal VIP-innervation in newly hatched ducks differed from that of the adult because of the incomplete development of its mucosal component. The findings obtained indicated following: The time interval from 13 to 17 days of incubation seems critical for the growth of the gastrointestinal VIP-containing neurons. The molecular factors regulating the appearance of neuronal phenotypes are probably synthesized early in the avian gizzard development. VIP is widely diffused in the rectum where it may play important roles in regulating the onset and synchronism of peristaltic and anti-peristaltic movements.

Animals↗
PubMed1994

Differential organization of desmin and vimentin in muscle is due to differences in their head domains.

In most myogenic systems, synthesis of the intermediate filament (IF) protein vimentin precedes the synthesis of the muscle-specific IF protein desmin. In the dorsal myotome of the Xenopus embryo, however, there is no preexisting vimentin filament system and desmin's initial organization is quite different from that seen in vimentin-containing myocytes (Cary and Klymkowsky, 1994. Differentiation. In press.). To determine whether the organization of IFs in the Xenopus myotome reflects features unique to Xenopus or is due to specific properties of desmin, we used the injection of plasmid DNA to drive the synthesis of vimentin or desmin in myotomal cells. At low levels of accumulation, exogenous vimentin and desmin both enter into the endogenous desmin system of the myotomal cell. At higher levels exogenous vimentin forms longitudinal IF systems similar to those seen in vimentin-expressing myogenic systems and massive IF bundles. Exogenous desmin, on the other hand, formed a reticular IF meshwork and non-filamentous aggregates. In embryonic epithelial cells, both vimentin and desmin formed extended IF networks. Vimentin and desmin differ most dramatically in their NH2-terminal "head" regions. To determine whether the head region was responsible for the differences in the behavior of these two proteins, we constructed plasmids encoding chimeric proteins in which the head of one was attached to the body of the other. In muscle, the vimentin head-desmin body (VDD) polypeptide formed longitudinal IFs and massive IF bundles like vimentin. The desmin head-vimentin body (DVV) polypeptide, on the other hand, formed IF meshworks and non-filamentous structures like desmin. In embryonic epithelial cells DVV formed a discrete filament network while VDD did not. Based on the behavior of these chimeric proteins, we conclude that the head domains of vimentin and desmin are structurally distinct and not interchangeable, and that the head domain of desmin is largely responsible for desmin's muscle-specific behaviors.

Amino Acid Sequence↗
PubMed2005

Effect of allo- and xenotransplantation of embryonic nervous tissue and umbilical cord blood-derived stem cells on structural and functional state of cerebral cortex of albino rats in posttraumatic period.

Comparative study of the structural and functional state of cerebral cortex of adult albino rats after intracerebral allo- and xenotransplantation of embryonic nervous tissue and intravenous injection of umbilical cord blood-derived stem cells at different terms after diffuse-focal cerebral trauma revealed the best cerebroprotective effect on day 7 of posttraumatic period in animals receiving embryonic nervous tissue.

Animals↗
PubMed1991

Immunochemical comparison of the major intrinsic protein of eye-lens fibre cell membranes in mice with hereditary cataracts.

Expression of the major intrinsic protein (MIP) of eye-lens fibre cell membranes was compared in normal (DBA), cataractous (CAT, LOP, NCT) and chimaeric (CBA-LOP) mice at different stages of development using immunofluorescence microscopy and immunoblotting techniques. MIP of apparent molecular mass 26 kDa was detected in extracts of adult DBA, LOP and CBA-LOP lenses, but only low molecular mass (less than 26 kDa) immunoreactive proteins were detected in similar extracts from adult CAT and NCT lenses. The corresponding MIP distribution patterns confirmed the highly organised fibre-cell histology in embryonic DBA and adult CBA-LOP lenses and also highlighted the severe fibre-cell degeneration in the LOP lens. In contrast, however, no immunoreactive MIP was detected in situ in embryonic CAT and NCT lenses. These results suggest that a structural alteration of MIP occurs during embryonic lens development in the cataractous CAT (dominant) and NCT (recessive) mutant mice.

Animals↗
PubMed1975

The "imaged-desmosome": a component of intercalated discs in embryonic guinea pig myocardium.

A heretofore undescribed structural variation of the desmosomes of the intercalated disc is found in myocardial cells of the embryonic guinea pig. These desmosomes consist of the usual pair of opaque leaflets, each of the pair contributed by one of the apposed muscle cells. In addition, in the cytoplasm of one of the cells there appears a pair of linear densities (facsimile-lines) parallel to the nearest desmosomal plaque and separated from it by a 60 mm space. The facsimile lines superficially resemble the desmosomal leaflets in length and thickness, thus forming a cytoplasmic "image" of the desmosome. These "imaged-desmosomes" are found predominantly in the longitudinally-running portions of the intercalated discs and are common in 7-week embryos. Their incidence drops sharply by eight weeks of gestation, and they are virtually absent from the heart of the newborn animal. Often tubules of the sarcoplasmic reticulum (SR) are found in apposition to the facsimile-lines; thus it appears that association of SR tubules with desmosomes is responsible for the formation of imaged-desmosomes.

Animals↗
PubMedDate not supplied

Blood flow regulators in the arterial system.

Based on literature data and own results, the author describes the morphological peculiarities of arterial blood flow regulators. Terminology and opinions concerning these structures are discussed. Also pointed out is the importance of axially disposed smooth muscle cells, which --- together with the two lamina of internal elastic membrane, and the adventitia --- form a functional flow modulating system. Author concludes that the endothelial cushions are not pathological formations, but normal structural variations appearing during embryonal and perinatal life, as consequences of certain hemodynamic circumstances with local characteristics. Suggestions are given for re-estimation of classical data concerning the supposed blood flow regulating function of the embryo-fetal obliterated cords attached to vessels. New arguments are brought in support of the contribution of the close relations between large arteries and the surrounding osseous, muscular and fibrous structures to the control and modulation of the blood stream.

Animals↗
PubMed1983

[Development and structure of the lymphoepithelial pharyngeal ring in the Macacus rhesus].

The lymphoepithelial pharyngeal ring has been studied in fetuses and 6-8-month-old monkeys (Macacus rhesus) by means of macro- and microscopical methods. The pharyngeal, palatile and lingual tonsils and a poorly manifested laryngeal tonsil have been revealed. The anlage of the lingual tonsil occurs later than that of the other ones (in fetuses of 60-73 mm of the parietal-coccygeal length), when the palatile and pharyngeal tonsils are already inhabited with lymphocytes. By the end of the embryonal period, the main structural components are already formed in all the tonsils, but their functional activity is not yet manifested. During the postembryonic period certain differences are revealed in the tonsil structure, they are presented as the germinative centers formation, appearance of active macrophages and plasma cells. A close connection between the lingual, pharyngeal and laryngeal tonsils with the glandular tissue is noted.

Animals↗
PubMed1991

The sinoatrial ring bundle: a cardiac neural communication system?

The sinoatrial ring bundle (SARB), was originally described as a "whitish bundle of tissue which describes an almost complete loop around the two venae cavae and the coronary sinus" in the adult rabbit heart (Paes de Carvalho et al., 1959). The histologically and electrophysiologically differentiated structure, derived from the embryonic venous valves, was suitably placed for rapid conduction from sinoatrial (SA) to atrioventricular (AV) node, but no evidence was found for this role. Today, the function of the SARB remains obscure. Cholinesterase/silver staining reveals the neural pattern associated with the SARB and suggests a function. Throughout its extent, the SARB contains a bundle of parallel muscle fibers and accompanying long nerves. The nerves distribute to structures at either side of the loop: superolaterally to pectinate muscle and inferomedially to the region of the AV node. Along the curve of the right SARB, the nerves contribute to a dense neural plexus with nerves coiled around muscle. The plexus communicates with the nearby SA node and with the ganglia inferior to the node near the inferior vena cava. The morphological pattern of neural elements is suitably organized to suggest tension monitoring and internodal, neural communication.

Animals↗
PubMed1981

The fine structure of continuous human neuroblastoma lines SK-N-SH, SK-N-BE(2), and SK-N-MC.

Cell cultures of the continuous human neuroblastoma lines SK-N-SH, SK-N-BS(2), and SK-N-MC at exponential and stationary growth phase have been examined by electron microscopy. At the level of fine structure these cells did not show typical neuronal differentiation such as extensive granular endoplasmic reticulum or neurites with microtubules and neurofilaments. Instead they were characterized by abundant free ribosomes, moderate Golgi complexes, and usually scant granular endoplasmic reticulum, features similar to the fine structure of early normal embryonic autonomic neurons. However, in several respects appearance of differentiated features of the neuroblastoma cells did not follow the pattern observed for normal neurons, suggesting noncoordinate expression of neuronal phenotypic properties. First, an occasional neuroblastoma cell had as extensive granular endoplasmic reticulum as would be found at later stages in normal developing neurons. Second, the cellular processes of these neuroblastoma cells did not have the fine structure of developing or mature axons in vivo. Third, few dense core vesicles were found in SK-N-SH and SK-N-BE(2), though these organelles are numerous in early normal adrenergic neurons and the adrenergic character of these two lines is apparent from other studies that have demonstrated expression of neurotransmitter synthesizing enzymes (SK-N-MC is cholinergic). The fine structural characterization of these continuous human neuroblastoma cell lines will allow this parameter to be utilized with other approaches in future experimental studies.

Cell Line↗
PubMed1999

Functional analysis and chromosomal mapping of Gata5, a gene encoding a zinc finger DNA-binding protein.

The GATA family of zinc finger proteins are transcriptional regulators with critical functions in lineage differentiation and embryonic development. Based on structural and expression pattern comparisons, the GATA proteins have been subdivided into two groups. The first subgroup consists of GATA-1, -2, and -3, which are all highly expressed in the hematopoietic system, whereas GATA-4, -5, and -6 are present essentially in the heart and gut. We have isolated and functionally characterized the rat GATA-5 cDNA, which encodes a 45-kDa protein with 71%, 73%, and 97% homology to its amphibian, avian, and murine homologs, respectively. Northern blot analysis showed that rat GATA-5 is expressed in a dynamic pattern during embryonic and postnatal development. In the midgestation embryo, GATA-5 transcripts are most abundant in the heart and decrease dramatically in the postnatal heart; in contrast, GATA-5 expression is upregulated in the lung and gut during postnatal development. Functional studies with recombinant GATA-4, -5, and -6 proteins show that GATA-5 has preferential affinity for a subset of GATA elements found on cardiac promoters and differentially activate cardiac gene transcription. Structure-function analysis revealed the presence of an activation domain within the carboxy terminal region of GATA-5 that is essential for transcriptional regulation of target promoters. Linkage analysis localized Gata5 to distal mouse Chromosome (Chr) 2 in a conserved linkage group with genes localized to rat Chr 3q43 and human Chr 20q13.2-q13.3. The results suggest that GATA-5 may have specific downstream targets and that GATA-4, -5, and -6 can only partially substitute for each other in cardiogenesis. Thus, Gata5 probably plays a specialized evolutionary conserved role in cardiac development.

Amino Acid Sequence↗
PubMed1993

Birth of mice after transplantation of early cell-cycle-stage embryonic nuclei into enucleated oocytes.

The present study was conducted to investigate the influence of cell cycle stage of the donor nucleus on chromatin structure and development of mouse embryonic nuclei transplanted into enucleated oocytes. Donor cell-cycle stage was controlled in order to examine, in addition, the developmental potential of nuclei from 2-, 4-, and 8-cell-stage embryos. The cell cycle stage of donor nuclei was classified as early, middle, or late. After nuclear transfer, electrofusion, and activation, early-stage transplants formed a single pronucleus-like structure, but middle-stage transplants formed very irregular types of structures and late-stage transplants extruded a polar body. A high proportion of development to the blastocyst stage (77.8%) and an increased cell number (62.1 cells) were obtained from the early 2-cell-stage transplants as opposed to the middle- (0%) and late-stage (20.8%, 37.0 cells) transplants (p < 0.001). With transplantation of early-stage nuclei, high proportions of development to the blastocyst stage and of offspring were obtained from nuclear transplant embryos with a nucleus from a 2-, 4-, or 8-cell-stage embryo. The results confirm that the donor cell-cycle stage critically affects the chromatin structure and development of nuclear transplant embryos. The results also demonstrate that the nuclei from 2-, 4-, and 8-cell-stage mouse embryos in the early stage of each cell cycle can be reprogrammed when transplanted into enucleated mature oocytes.

Animals↗
PubMed1997

who encodes a KH RNA binding protein that functions in muscle development.

The Drosophila who (wings held-out) gene functions during the late stages of somatic muscle development when myotubes migrate and attach to specific epidermal sites. Animals lacking who function are capable of forming multinucleate myotubes, but these cells are restricted in migration. who mutants die at the end of embryogenesis with the posterior end of their cuticles arrested over the dorsal surface. Animals that possess weak who mutations either die as pupae, or survive as adults with defects in wing position. These phenotypes indicate that who also functions during metamorphosis, when muscles are reorganized to support adult structures and behavior. These embryonic and metamorphosis defects are similar to the phenotypes produced by previously identified genes that function in either muscle development or steroid signaling pathways. who transcription occurs in muscle and muscle attachment site cells during both embryogenesis and metamorphosis, and is inducible by the steroid ecdysone at the onset of metamorphosis. who encodes a protein that contains a KH RNA binding domain. Animals that possess a mutation in a conserved loop that links predicted alpha and beta structures of this RNA binding motif lack who function. These results indicate that who plays an essential role in steroid regulation of muscle development.

Amino Acid Sequence↗
PubMed2005

Vax genes ventralize the embryonic eye.

The vertebrate retina and optic nerve are strikingly different in terms of their size, organization, and cellular diversity, yet these two structures develop from the same embryonic neuroepithelium. Precursor cells in the most ventral domain of this epithelium give rise only to the astrocytes of the optic nerve, whereas immediately adjacent, more dorsal precursors give rise to the myriad cell types of the retina. We provide genetic evidence that two closely related, ventrally expressed homeodomain proteins-Vax1 and Vax2-control this neuroepithelial segregation. In the absence of both proteins, we find that the optic nerve is transformed in its entirety into fully differentiated retina. We demonstrate that this transformation results from the loss of ventralizing activity in the developing eye field, and that ventralization is mediated, at least in part, via Vax repression of the Pax6 gene, a potent inducer of retinal development.

Animals↗
PubMed1996

Regulation and function of the tissue-specific transcription factor HNF1 alpha (LFB1) during Xenopus development.

We review the data available on the structure, developmental appearance and embryonic regulation of the tissue-specific transcription factor HNF1 alpha (LFB1) in Xenopus. The expression of the HNF1 alpha gene starts early in embryogenesis shortly after mid-blastula transition and the protein accumulates in the region of the embryo where liver, pronephros and gut--tissues that contain HNF1 alpha in the adult--are developing. The cofactor DCoH, known to stabilize dimer formation of HNF1 alpha, is present as a maternal factor in the egg and has a partially distinct tissue distribution compared to HNF1 alpha. This implies that DCoH does not only modulate HNF1 alpha dimerization but may also cooperate with other transcription factors. By injecting HNF1 alpha promoter CAT constructs into fertilized Xenopus eggs we obtained activation of the injected gene restricted to the region of the developing larvae expressing endogenous HNF1 alpha. Deletion analysis allowed to define the OZ-element that is essential for embryonic activation. This element also occurs in other promoters activated at mid-blastula transition in the embryo and interacts with the maternal factor OZ-1. As the HNF1 alpha promoter also contains functional binding sites for HNF4 and HNF1, we postulate that all of these transcription factors contribute to the cascade leading to proper embryonic activation of the HNF1 alpha gene.

Animals↗
PubMedDate not supplied

Ubiquitous embryonic expression of the norepinephrine transporter.

We report that the norepinephrine transporter (NET) is expressed in avian and mouse embryos by numerous tissues that are derived from all three germ layers. In the nervous system, NET is expressed in the neuroepithelium of the brain and the spinal cord (ventral horn and floor plate), forming mesencephalic nuclei, neural crest, dorsal root ganglion, sympathetic ganglion and spinal nerve. Nonneuronal embryonic NET-expressing structures include the olfactory epithelium, the notochord, the somitic dermamyotome and mesenchymal cells in the limb bud. NET is expressed prominently in the cardiovascular system, including endothelial cells of forming blood vessels, the walls of the aorta and veins, the epicardium, myocardium and a subset of blood cells. The gut, lung buds, and in particular the kidneys, are intensely NET immunoreactive. Since neurotransmitters are known to affect proliferation, survival and differentiation of many mesenchymal cell types, NET function may be a physiologically relevant regulatory element in embryonic development. A working model is proposed for neurotransmitter transporter function in the embryo as a system for the concentration and targeted delivery of neurotransmitter.

Animals↗
PubMed1997

PLAB, a novel placental bone morphogenetic protein.

Bone morphogenetic proteins (BMP) constitute a sub-group of the large transforming growth factor-beta (TGF-beta) family. They play important roles in the embryonic development of multiple structures and in adult bone modeling. We have recently isolated a novel member of the BMP family from placenta, termed PLAB. PLAB is expressed highly in placenta, but can be found upon stringent analysis in low levels in most other tissues. At the amino acid level, PLAB is most closely related to BMP-8/OP-2, another member of the BMP family. Like TGF-beta, PLAB inhibits the proliferation of primitive hematopoietic progenitors. The high expression of PLAB by placenta raises the possibility that it may be a mediator of placental control of embryonic development.

3T3 Cells↗
PubMed1977

[Developmental anomalies of the liver and carcinoma of the liver in infants and children (author's transl)].

Several forms of intrahepatic developmental anomalies were found on histological examination in 40 children, among them several siblings and polyovular twins. These anomalies affect in principle all structural elements of the liver. In several cases--some of them complicated by cholangitis-there was cholangiofibrosis and cholangiodysplastic pseudo-cirrhosis. In addition, in six children there developed hepatocellular carcinoma between the ages of six months and twelve years. In the course of the development of hepatic carcinoma obligatory nodular for occur. They are made up of light, glycogen-loaded epithelial cells, which later are transformed into small atypical, basophilic cells. These dark cells have a high mitosis rate, have already escaped from the physiological regulation of proliferation. Presumably the various embryonic disorders of liver structure and carcinoma of the liver are based on the action of the same causative factor, which may be of chemical-toxic origin and transferred across the placenta.

Age Factors↗
PubMed2001

Early-generated preplate neurons in the developing telencephalon: inward migration into the developing striatum.

Specialized subsets of early-generated neurons provide the cellular cues that are necessary for the establishment of characteristic cell and fiber interactions in each brain region. During the development of the mammalian cerebral cortex, the early-generated cells line up in the most superficial part of the telencephalic pallium forming the preplate. It has been generally thought that the preplate derivatives are exclusively located in the cortical region and govern the early histogenetic phase of cortical development. However, we here disclose an unexpected evidence that a subset of early-generated neurons of the piriform preplate migrate inward into and disperse within the subcortical structure striatum during the embryonic stage. Their migratory route is unique and its direction is opposite to the ordinary migration of neuronal precursors directed outward from the periventricular germinal zone. After immigrating into the developing striatum, these early-generated cells are closely associated with the intrastriatal fascicules of axons. The majority of these cells are eliminated by apoptotic cell death during the early postnatal stage. Based on these findings, we propose a new concept: the preplate neurons may not only direct cortical histogenesis but also change their location to play a role in the development of subcortical structures.

Animals↗