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At least 307 records · Page 17Linked to original sources

PubMed2002

Limb muscle development.

Skeletal muscle precursors for the limbs originate from the epithelial layer of the somites, the dermomyotomes. We summarize the steps of limb muscle development from the specification of precursor cells in the dermomyotome, the directed migration of these cells to and within the limb buds to muscle growth and differentiation. All steps are controlled by local signaling between embryonic structures. In dermomyotome development, signals from the neural tube, the ectoderm and the intermediate and lateral mesoderm result in a medio-lateral patterning. Only the lateral portions of the dermomyotomes give rise to muscle precursor cells destined to enter the limb buds. As a prerequisite for migration, precursor cells have to de-epithelialize as a result of interactions between SF/HGF and its receptor c-met. Precursor cells adopt a mesenchymal morphology without losing their myogenic specification. This is achieved by the expression of the transcription factors Pax3, Pax7 and myf5. During migration, premature differentiation has to be kept at bay to enable motility and proliferation. After having reached their target sites, the dorsal and ventral myogenic zones, myogenesis is initiated by the activation of the muscle determination factors MyoD, myogenin and MRF4. Finally, we briefly summarize the process of muscle hypertrophy and regeneration during which aspects of developmental processes are reinitiated.

Animals↗

PubMed2004

[Outcome of pregnancy in patient with cloacal dysgenesis].

The cloacal dysgenesis or persistent cloaca is an anomaly included in urogenital tract malformations (UGM) and, in particular, in anomalies due to a missed development of the urogenital septum. The UGM occur during 6-11th weeks of gestation owing to a stop and/or alteration of the normal development and subdivision process of the cloaca, the embryonic structure from which gives origin to the ano-rectal segment of midgut, bladder, ureters, vagina and uterus. The case of a patient submitted to many surgical treatments for urogenital tract congenital malformations is described; when pregnant, she carried other pregnancy until the 34th week of gestation, giving birth a newborn by cesarean section. The patient was checked constantly for her general conditions and, in particular, her renal functions by an active collaboration between internist, nephrologist and gynecologist.

Adult↗

PubMed2005

A rare case of classic biphasic pulmonary blastoma.

Biphasic pulmonary blastomas are rare tumors that together with pulmonary carcinosarcomas comprise less than 2 per cent of all lung neoplasms. They can be defined as tumors that are composed of an admixture of immature mesenchyme and epithelium and that recapitulate morphologically the embryonal structure of the lung. First described in 1945 by Barnett and Barnard, their existence is well documented although their occurrence is rare. We present a case of a 40-year-old Hispanic female that presented with a 2-month history of retrosternal and midepigastric pain. A GI etiology was initially treated unsuccessfully with antireflux medications. A chest radiograph showed a 4.6-cm mass in the right upper lobe of the lung, and computed tomography showed right apical bullous formation with no lymphadenopathy. Bronchoscopy revealed no endobronchial lesions, and biopsy was nondiagnostic. The histopathologic and immunophenotypic analysis of a right upper lobectomy specimen was diagnostic of classic biphasic pulmonary blastoma. The rarity of these tumors makes easy identification difficult. Immunohistochemical analysis must be used to arrive at the proper diagnosis. It is imperative that there be good communication between the surgeon and pathologist and that institutions have access to facilities with the ability of identifying these complex tumors.

Adult↗

PubMed1991

[Development of the face in the embryo].

The facial complex and the brain develop separately from a common embryonic structure called ectoblast. The neural crest cells which migrate early on from the neural groove differentiate into facial parenchyma, so that the embryological origin of the face is a neural one. The cephalic pole has a primitive encephalofacial and encephalocervical segmentation with strict topographical correspondence: the nasofrontral and premaxillary structures are related to the anterior brain, whereas the maxillo-mandibular and anterior cervical structures are related to the brainstem and its nerves. Thus the face is a qualitative, quantitative and topographical marker of the central nervous system. At the beginning of the third month the embryo becomes a foetus due to the appearance of the first oral and pharyngeal motor sequences which are dependent upon the neurological development of the brainstem. This sum of embryological knowledge has clinical semiological applications: the face and its functions play the predictive role in the search for associated malformations of the same neural origin (brain, eye, neck, thorax). Such malformations are neurocristopathies.

Branchial Region↗

PubMed1989

[The clinical value of MRT in diseases of the testis and scrotum].

Since 1986 more than 150 patients with testicular carcinoma, trauma or chronic inflammation and subacute torsion were investigated with MRT. Using a 1.5 Tesla-Magnetom (Siemens) with surface coils and a special Helmholtz coil, we imaged T1-weighted, proton-density and T2-weighted coronary and axial slices. The excellent spatial resolution facilitated the imaging of fine structures as the septula testis. In 55 surgically proven cases the proof or rejection of a testicular tumour was always possible without false negative or positive cases. We were also able to correlate certain types of tumours with the imaged morphologic structure. Embryonal carcinomas showed typical focal hemorrhages. Pure seminomas showed a clean cut surface, correlating with that of the surgical preparation. The T2 image gave always a low intensity signal. Beta-HCG-positive seminomas showed different signal patterns. Inflammatory processes in epididymitis were detected, as well torsion of the testicles. In traumatic conditions a differentiation of a ruptured tunica albuginea as an indication for surgery was possible. MRT is an important contribution for the indication of urological surgery. Unnecessary surgery of the testes can be prevented, small tumours can be detected at an early stage and can be differentiated from other conditions.

Humans↗

PubMed1988

[Differentiation of the neural crest. Influence of growth factors].

The peripheral nervous system (PNS) is derived from a transitory embryonic structure, the neural crest with an additional contribution of the cephalic ectodermal placodes to the sensory ganglia of certain cranial nerves. In vivo grafting experiments, taking advantage of the quail/chick marker system, allowed the fate map of the neural crest to be constructed and the precise level of origin along the neuraxis of the component cells of PNS ganglia to be defined. It appeared that the neural crest is regionalized in different areas from which a limited number of phenotypes arise. However, if the position of neural crest fragments is experimentally changed prior to the onset of migration, it turns out that virtually all the cell types represented in PNS ganglia can arise from any level of the neural crest, provided it is transplanted into the appropriate level of the neuraxis. This means that the microenvironment into which the neural crest cells migrate plays a critical role in directing their differentiation. Further in vivo studies along with in vitro clonal analysis of neural crest developmental potencies revealed that, during the migratory phase, the crest cells are already highly heterogeneous in their state of commitment. When they reach the sites of gangliogenesis, they exhibit different requirements for growth and differentiation. Our current studies are aimed at identifying the factors that, in spinal and sympathetic ganglia respectively, trigger the differentiation of sensory and adrenergic sympathetic neurons. The brain-derived neurotrophic factor (BDNF) and insulin (and/or IGF1) have been shown to play a role in these processes.

Animals↗

PubMed1986

[A case of malignant degeneration of benign cystic teratoma of the ovary].

A case of malignant degeneration of benign cystic teratoma of the ovary is reported. Almost all cases of malignant degeneration in the literature are squamous cell carcinomas, and other varieties or mixed malignancies are rare. But in this case, the tumor contained squamous cell carcinoma and adenocarcinoma separately. The focus of the adenocarcinoma looked like an embryonal structure of the intestine. Immunohistochemically, CEA is positive in both malignancies, but AFP is only in adenocarcinoma. These findings suggest that the pathogenesis of adenocarcinoma is different from that of squamous cell carcinoma arising in benign cystic teratoma of the ovary.

Adenocarcinoma↗

PubMed1985

Permeability of external gill filaments in the embryonic shark. Electron microscopic observations using horseradish peroxidase as a macromolecular tracer.

External gill filaments of sharks are purely transient embryonic structures. They contain a single vascular sinusoidal loop that is continuous with the afferent and efferent branchial arteries. Each filament is comprised of a squamous epithelial bilayer that rests upon a prominent basal lamina. A collagenous stroma separates the epithelium from the underlying endothelium. The epithelium, from an embryo 4.5 cm in total length, is characterized by microvilli with smooth walled vesicles at their bases, a luminal glycocalyx, prominent tubular and vesicular elements, rough endoplasmic reticulum, a Golgi complex, a flattened nucleus, coated vesicles, lipid-like inclusion bodies and sparse cytoplasmic fibrils. Adjacent epithelial cells are joined by a zonula occludens, a zonula adherens and up to five maculae adherentes. The endothelium possesses mitochondria, rough endoplasmic reticulum, a Golgi complex, coated vesicles and many micropinocytotic vesicles on both the adluminal and abluminal surfaces. The endothelium has no basal lamina and is not associated with smooth muscle. After exposure to horseradish peroxidase (HRP) for 10 min, reaction product nearly occludes the cytoplasm of some surface epithelial cells. The deeper epithelial cells have reaction product in smooth walled vesicular and tubular elements. Reaction product is also present in smooth walled endothelial vesicles. Gill filaments from a 10 cm embryo show marked changes from earlier stages. In the epithelial cells, there is an increase in the number of cytoplasmic filaments and the formation of a dense terminal web. Fewer vesicles, tubules, rough endoplasmic reticulum and mitochondria, and a less elaborate Golgi complex characterize the epithelium. The endothelium remains unchanged. The amount of collagen increases and fibroblasts are observed in the stroma. These modifications contribute to the strength of the filaments and allow the gills to withstand increased abrasion by the developing skin denticles. These experiments establish the capability of external gill filaments to take up a macromolecular tracer in the form of horseradish peroxidase. Later in development, the yolk sac of R. terraenovae becomes modified as a yolk sac placenta which functions both in respiration and hematrophic nutrition. In viviparous sharks, the uterus elaborates nutrient-rich secretions. External gill filaments may thus serve as a nutrient absorptive membrane before the establishment of the yolk sac placenta as well as perform its respiratory function.

Animals↗

PubMed1981

An immunohistochemical study of a series of plasma proteins in the early human conceptus.

A 20-day-old human conceptus was studied by the indirect immunoperoxidase technique for the presence of a series of plasma proteins: prealbumin (PA), albumin (ALB), alpha-fetoprotein (AFP), alpha 1-antitrypsin (A1AT), carcioembryonic antigen (CEA), immunoglobulin G (IgG), ferritin (FER), transferrin (TR), fetal haemoglobin (HbF), human chorionic gonadotropin (HCG), human placental lactogen (HPL) and pregnancy specific beta 1-glycoprotein (SP1). In the embryo only FER and TR were found. The yolk sac was positively stained for several proteins: PA, ALB, AFP, A1AT, IgG, FER, TR and HbF were demonstrated in the endodermal cells and PA, ALB, IgG and TR in the mesothelial cells. The syncytiotrophoblast of the chorionic villi were heavily stained for all the placental proteins. HCG and HPL were additionally demonstrated in the cytotrophoblast. The Hofbauer cells of the chorionic and villous stroma stained positively for A1AT and FER. TR appeared as a characteristic band on the apical surface of the syncytiotrophoblast. The findings indicate that the yolk sac is the principle source of some of the plasma proteins also in the very early conceptus and the assumption that the yolk sac is the functional antecedent of the liver is supported. The distribution of the various placental proteins is in accordance with the present knowledge that the syncytiotrophoblast is the major site of synthesis of these proteins. Finally correlation of functional aspects of embryonic structures and germ cell tumours is recommended.

Blood Proteins↗

PubMed1993

Involvement of the proto-oncogene c-ets 1 and the urokinase plasminogen activator during mouse implantation and placentation.

Many of the Ets proteins have been shown to be transcription activators. In vitro, Ets 1 proteins are involved in the transcriptional induction of genes such as stromelysin 1, collagenase 1 or urokinase type plasminogen activator, which are proteases responsible for extracellular matrix degradation. In vivo, c-ets 1 is expressed in a wide variety of embryonic tissues in migrating cells, especially in endothelial cells during blood vessel formation. C-ets 1 is also expressed in stromal cells of invasive carcinomas. In the present work, we have investigated the expression of both c-ets 1 and u-PA, a putative target gene of the Ets 1 proteins, within a biological model which includes both embryonic and tumoral aspects. Implantation and placentation of the mouse embryo display migration of the trophoblastic cells, which invade the stroma of the uterine endometrium and trigger the establishment of a new vascular frame. Using in situ hybridization, we show that the overlapping of expression of c-ets 1 and u-PA is restricted to some maternal cell populations from the invasive front and to the endothelial cells of the endometrial vasculature. C-ets 1 is never expressed in trophoblasts. In contrast, u-PA expression in trophoblasts is strong and coincides with the embryo invasive phase. In the embryo proper, c-ets 1 displays a spatio-temporal expression pattern similar to that described in the chick embryo. Until E 10.5, u-PA is expressed neither in embryonic nor in extra-embryonic structures. The respective roles of c-ets 1 and u-PA and their relationship during mammalian placentation are discussed.

Animals↗

PubMed1976

[Malignant degenerative osteoneoplastic teratoma of the greater omentum (author's transl)].

A case of teratoma of the greater omentum is reported, which occurred mainly in the form of a highly differentiated osteoma. In the marginal section the tumor showed embryonal structures with signs of degeneration which were found again in metastatic colonization in lymphnodes, pancreas, liver and peritoneum. The malignant component of the neoplasm probably had its origin in the bone marrow of the osteoma.

Humans↗

PubMed1993

Making the connection: exploring classical concepts in normal and abnormal limb development using contemporary approaches.

Classical studies of the vertebrate limb have provided a firm foundation for recent investigations into the molecular control of mechanisms governing limb patterning. The early studies revealed the importance of inductive tissue interactions in developing systems, the spatiotemporal restrictions of these interactions, and the conservation of inductive signals between different tissues and even different species. They incorporated a number of different experimental approaches, including: homologous and heterologous tissue grafting and recombination, the investigation of several limb mutations, and examination of the response of normal limb tissue to a variety of teratogenic treatments. While some of the mutations studied only affected the limbs, most were highly pleiotropic, producing complex syndromes that altered the development of several embryonic structures in addition to the limbs. Some of these syndromes could be partially or completely phenocopied (mimicked) by specific chemical or physical treatments. One such gene-phenocopy pairing that we have studied is that of the mutation wingless-2 and the syndrome produced by treatment with retinoic acid. Another aspect of abnormal pattern formation we explored is the interaction between wingless-2 and eudiplopodia.

Animals↗

PubMed1993

Transcervical sonography: an investigational technique for visualization of the embryo.

A catheter-based, miniature ultrasound transducer, operating at a frequency of 12.5 MHz, was introduced transcervically into the uterine cavity of 18 pregnant women about to undergo first-trimester abortion. Transcervical sonography showed the yolk sac and embryonic structures, such as brain vesicles, limb buds, liver, spinal canal, and umbilical cord with blood flow, in eight embryos at 5-8 menstrual weeks of age. As an investigational technique, catheter-assisted transcervical sonography offers a new diagnostic approach to imaging of the first-trimester human embryo.

Abortion, Induced↗

PubMed1998

[Triploidies].

Triploidies are pregnancies that show a 69 chromosome karyotype. This chromosomal abnormality gives rise to early abortion in most cases. Triploid pregnancies, after the first three months, become molar pregnancies (molar changes inside the placenta with identifiable embryonic structures and a preeclampsia) or non molar pregnancies (isolated intauterin growth retardation). Several possibilities concerning the origin of the additional set of chromosomes exist: dispermy (the most common), diandry and digyny. The maternal and fetal clinical manifestations of this chromosomal abnormality are very diverse, which explains the difficulty of finding and recognizing this pathology. Mac Fadden's classification does not explain all the phenotypic triploid physiopathology. Formal diagnosis of triploidy depends on the fetal karyotype. The better the maternal prognosis is, the worst the fetal prognosis is. Postnatal life expectancy is not more than a few weeks. In most cases, maternal associated complications disappear with the molar evacuation. The risk of post molar tumor is discussed. However, good management of triploidy is based on an early diagnosis, before birth if that is possible.

Abortion, Spontaneous↗

PubMed2004

In vitro organogenesis of gut-like structures from mouse embryonic stem cells.

Embryonic stem (ES) cells have pluripotency and give rise to many cell types and tissues, including representatives of all three germ layers in the embryo. We have reported previously that mouse ES cells formed contracting gut-like organs from embryoid bodies (EBs). These gut-like structures contracted spontaneously, and had large lumens surrounded by three layers, i.e. epithelium, lamina propria and muscularis. Ganglia were scattered along the periphery, and interstitial cells of Cajal (ICC) were distributed among the smooth muscle cells. In the present study, to determine whether they can be a model of gut organogenesis, we investigated the formation process of the gut-like structures in comparison with embryonic gut development. As a result, we found that the fundamental process of formation in vitro was similar to embryonic gut development in vivo. The result indicates that the gut-like structure is a useful tool not only for developmental study to determine the factors that induce gut organogenesis, but also for studies of enteric neurone and ICC development.

Animals↗

PubMed1981

[Human embryonic haemoglobins. The primary structure of the zeta chains (author's transl)].

The primary structure of the embryonic zeta-chains of humans is given. Blood was obtained from a case with hydrops foetalis syndrom due to homozygous alpha-thalassemia 1. The zeta-chains were isolated by high performance liquid chromatography on reversed phase (RP8). The peptides for sequence work were generated by chemical methods (cyanogen bromide cleavage and acid cleavage at the Asp-Pro bond) and enzymatic cleavages with trypsin of unmodified and succinylated zeta-chains. The peptides were separated by high performance liquid chromatography and sequenced by automatic N-terminal degradation procedures. The N-terminal residue of the zeta-chains is blocked. Therefore the sequence of the N-terminal tryptic peptide was determined after incubation with chymotrypsin. The zeta-chains are alpha-type chains and consist of 141 amino acid residues. The alignment of the zeta-chains with the human alpha-chains shows 57 amino acid exchanges: Thus it is evident that there is a greater phylogenetic distance between the alpha type chains than between the beta-type chains.

Amino Acid Sequence↗

PubMed1994

Isolation of a receptor tyrosine kinase (DTK) from embryonic stem cells: structure, genetic mapping and analysis of expression.

Analysis of receptor tyrosine kinases expressed during mouse embryonic stem cell differentiation resulted in the cloning of a receptor designated developmental tyrosine kinase (DTK). The 850 amino acid mature receptor protein comprises an extracellular domain with two immunoglobulin-like motifs and two fibronectin type III modules, a 25 amino acid transmembrane domain and a cytoplasmic region with a catalytic kinase domain. In embryonic stem cells growing in the presence of leukemia inhibitory factor DTK is abundantly expressed and this level of expression is maintained in differentiating embryonic stem cells and cystic embryoid bodies. In mid-gestational embryos (E14.5), DTK RNA is expressed in many tissues including brain, eye, thymus, lung, heart, gut, liver, testis and limbs. In contrast, expression of DTK in adult mice becomes restricted to brain, portions of the gastrointestinal tract, bladder, testis and ovary. There is enrichment of transcripts encoding DTK in purified fetal liver hematopoietic stem cells, when compared with unfractionated fetal liver. The DTK gene maps to mouse chromosome 2, band F.

Amino Acid Sequence↗

PubMed2006

Gut-like structures from mouse embryonic stem cells as an in vitro model for gut organogenesis preserving developmental potential after transplantation.

Recently, we reported the formation of gut-like structures from mouse ESCs in vitro. To determine whether ESCs provide an in vitro model of gastrointestinal (GI) tracts and their organogenesis, we investigated the morphological features, formation process, cellular development, and regional location within the GI tract by immunohistochemistry, electron microscopy, and reverse transcription-polymerase chain reaction. We also examined the developmental potential by transplantation into kidney capsules. The results demonstrated that Id2-expressing epithelium developed first, alpha-smooth muscle actin appeared around the periphery, and finally, the gut-like structures were formed into a three-layer organ with well-differentiated epithelium. A connective tissue layer and musculature with interstitial cells of Cajal developed, similar to organogenesis of the embryonic gut. Enteric neurons appeared underdeveloped, and blood vessels were absent. Many structures expressed intestinal markers Cdx2 and 5-hydroxytryptamine but not the stomach marker H(+)/K(+) ATPase. Transplants obtained blood vessels and extrinsic nerve growth from the host to prolong life, and even grafts of premature structures did not form teratoma. In conclusion, gut-like structures were provided with prototypical tissue components of the GI tract and are inherent in the intestine rather than the stomach. The formation process was basically same as in gut organogenesis. They maintain their developmental potential after transplantation. Therefore, gut-like structures provide a unique and useful in vitro system for development and stem cell studies of the GI tract, including transplantation experiments.

Animals↗