[Reimplantation of a maxillary incisor in rats after resection of their embryonic structures. Histologic study].
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Dentistry↗
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Results for “Embryonic Structures”
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[Residues of embryonic structures in human cardiac atria. A contribution to their significance in heart catheterization].
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Aged↗
[Theoretical analysis of the tridimensional reconstruction of embryonal structures: proposed mathematical method].
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Animals↗
Glycoprotein-bound large carbohydrates of early embryonic cells: structural characteristic of the glycan isolated from F9 embryonal carcinoma cells.
The high-molecular-weight glycopeptides characteristic of early embryonic cells were isolated from F9 embryonal carcinoma cells grown in vitro and also from the cells grown in vivo as subcutaneous tumors. The two preparations had similar carbohydrate compositions. The major components were galactose and N-acetylglucosamine (molar ratio 1:0.86) in the glycan isolated from the cultured cells. In addition, small amounts of fucose, N-acetylgalactosamine and mannose were present. The glycan from the in vitro grown cells was found to have a molecular weight of more than 10,000 by gel filtration after mild alkaline treatment or hydrazinolysis. The structural characteristics of the core portion of the glycan were studied by using the radioactively labeled glycopeptide from the in vitro grown cells. Methylation analysis provided the following informations. 1) The glycan was highly branched at galactosyl residues. 2) Large numbers of galactosyl residues were also present at non-reducing termini. 3) Monosubstitution of galactose occurred at C-3. 4) Glucosamine residues were mainly monosubstituted. That the disaccharide GlcNAc-Gal was the major structural unit of the glycan was suggested by the isolation of the deacetylated disaccharide after alkaline thiophenol cleavage followed by acid hydrolysis. Furthermore, methylation analysis of the glycan from the in vivo grown tumors indicated that monosubstitution of glucosamine occurred at C-4 and that disubstitution of galactose occurred at least mainly at C-3 and C-6. We propose that the basic structural unit of the core portion is 4GlcNAc 1 leads to 3Gal, and that the galactosyl residue serves as a branching point at C-6. Thus, the structural unit of the core portion of the large glycan appears to be the same as that of lactosaminoglycans found in adult cells.
Amino Acids↗
Classification of tubal gestations by transvaginal sonography.
Transvaginal sonographic images of tubal pregnancies were correlated with the surgical findings in 191 patients having this condition. The sonographic appearance of the ectopic gestations was classified by the absence or presence of structures such as a 'tubal ring' containing the yolk sac, embryonic structures, heart activity, a sonolucent or irregularly echogenic gestational sac, dilated Fallopian tube with amorphous content, fluid in the pelvis and an empty uterus. The following classifications were made: Type Ia (n = 43) A well-defined 'tubal ring' and a beating heart with or without discrete embryonic or extra-embryonic structures. Type Ib (n = 48) A 'tubal ring' containing embryonic and/or extra-embryonic structures without heart beats. Type II (n = 64) An ill-defined or thin tubal wall containing sonolucent or an irregularly echogenic core but not embryonic or extra-embryonic structures. Type III (n = 28) Free pelvic fluid and an empty uterus in patients with positive serum beta-hCG levels. The outline of the tube cannot be visualized. Surgery revealed unruptured tubal pregnancies in 90 patients of the combined groups of Types Ia and Ib. In one additional patient, a tubal rupture was found. In the Type II patients, 26 tubal pregnancies with blood clots in the tube but no evidence of bleeding into the pelvis, and 38 tubal ruptures or abortions were diagnosed. All Type III patients had ruptured tubal pregnancies or bleeding tubal abortions. In eight patients (4.2%), the only sonographic finding was an empty uterus, and these cases were erroneously diagnosed as not having an ectopic pregnancy (false negatives). There were two false-positive cases in which a tubal ring was detected, and this was related to an hemorrhagic corpus luteum. When used for diagnosing tubal pregnancy, the transvaginal scanning technique (together with beta-hCG in Type III cases) carries a sensitivity of 95.8% and specificity of 99.9%. It is an invaluable tool in the diagnostic work-up and management of patients with suspected ectopic gestation.
Journal Article↗
The tenascin family of ECM glycoproteins: structure, function, and regulation during embryonic development and tissue remodeling.
The determination of animal form depends on the coordination of events that lead to the morphological patterning of cells. This epigenetic view of development suggests that embryonic structures arise as a consequence of environmental influences acting on the properties of cells, rather than an unfolding of a completely genetically specified and preexisting invisible pattern. Specialized cells of developing multicellular organisms are surrounded by a complex extracellular matrix (ECM), comprised largely of different collagens, proteoglycans, and glycoproteins. This ECM is a substrate for tissue morphogenesis, lends support and flexibility to mature tissues, and acts as an epigenetic informational entity in the sense that it transduces and integrates intracellular signals via distinct cell surface receptors. Consequently, ECM-receptor interactions have a profound influence on major cellular programs including growth, differentiation, migration, and survival. In contrast to many other ECM proteins, the tenascin (TN) family of glycoproteins (TN-C, TN-R, TN-W, TN-X, and TN-Y) display highly restricted and dynamic patterns of expression in the embryo, particularly during neural development, skeletogenesis, and vasculogenesis. These molecules are reexpressed in the adult during normal processes such as wound healing, nerve regeneration, and tissue involution, and in pathological states including vascular disease, tumorigenesis, and metastasis. In concert with a multitude of associated ECM proteins and cell surface receptors that include members of the integrin family, TN proteins impart contrary cellular functions, depending on their mode of presentation (i.e., soluble or substrate-bound) and the cell types and differentiation states of the target tissues. Expression of tenascins is regulated by a variety of growth factors, cytokines, vasoactive peptides, ECM proteins, and biomechanical factors. The signals generated by these factors converge on particular combinations of cis-regulatory elements within the recently identified TN gene promoters via specific transcriptional activators or repressors. Additional complexity in regulating TN gene expression is achieved through alternative splicing, resulting in variants of TN polypeptides that exhibit different combinations of functional protein domains. In this review, we discuss some of the recent advances in TN biology that provide insights into the complex way in which the ECM is regulated and how it functions to regulate tissue morphogenesis and gene expression.
Adult↗
Apoptosis is associated with formation and persistence of the embryonic fissure.
PURPOSE: The role of apoptosis in the transitory ocular embryonic structures has not been clarified yet, therefore, in the present study we focused on one of the transitory ocular structures, the embryonic fissure. To elucidate the developmental mechanism of the embryonic fissure, we observed cell death by apoptosis in the optic cup during early development in mice. METHODS: Pairs of C57BL6N/Jcl mice, each comprising an estrous female and a potent male, were caged together overnight. Females that had vaginal plugs the next morning were considered at day 0 of pregnancy. The embryos or fetuses were removed by laparotomy on days 9, 10, 11, 12, 13, 14, 16, and 18 of gestation. Tissue blocks of the eyes were fixed and embedded in paraffin wax. Serial frontal sections of the eye were cut and stained with the TUNEL method and then counterstained by hematoxylin or methyl green solution. We examined TUNEL-positive cells in the optic cup by light microscopy. RESULTS: TUNEL-positive cells were seen at the lower nasal side of the optic cup, corresponding to the presumed embryonic fissure area, on day 9 of gestation before the formation of the embryonic fissure. Many TUNEL-positive cells were present at the lips of the embryonic fissure on days 10, 11, and 12. In contrast, TUNEL-positive cells were not detectable in the corresponding area on day 13 after the complete closure of the embryonic fissure. CONCLUSIONS: Apoptosis is anatomically closely associated, and appears to be essential for the formation and persistence of the embryonic fissure.
Animals↗
Embryonic velar structure and function of two sibling species of Crepidula with different modes of development.
The structure and function of the embryonic velum of two closely related species of Crepidula with different modes of development are examined. The velum of C. dilatata, a direct developer whose embryos feed on nurse eggs, does not differ substantially from the velum of C. fecunda, a species with planktotrophic larvae. Although velar ciliation develops earlier in embryos of C. dilatata, embryos of both species were able to feed on small particles, using the opposed-band ciliary mechanism. However, the embryos of C. dilatata lose this ability as they grow. The embryos of C. dilatata were not able to swim, whereas those of C. fecunda swam consistently in vials of seawater. This difference in swimming ability is probably due to differences in velum-body size allometry between the two species.
Animals↗
[Reconstruction of the organotypic structure of embryonic lung tissue from a suspension of dissociated cells].
The formation and development of organotypic structure of the embryonic lung tissue was studied upon the cultivation of a suspension of dissociated cells of the lungs of 8-11 days old chick embryos as a hanging drop. The successive developmental stages of organotypic structures are discussed: 1) passive sedimentation of dissociated cells on the "bottom" of hanging drop; 2) redistribution of sedimented cells on the tension surface of the drop with the formation of multiple cell aggregations (centers of aggregation) connected by monolayer mesenchyme constrictions; 3) formation of a primary aggregate as a flat celled structure; 4) formation of a space organotypic aggregate with the structure characteristic for the initial lung tissue.
Animals↗
Histological features of axial structures during embryonic and fetal stages of human craniorachischisis.
Histological characteristics of developing axial structures in human conceptuses with craniorachischisis were investigated during the embryonic and fetal periods and compared with normal samples. The morphological relationship of the notochord to the axial skeleton and neural tube was analyzed along cervical and thoracic vertebral segments using serial paraffin sections. The embryonic stage of malformed conceptuses disclosed a correlated affection of the notochord and vertebral column, as well as the overlying central nervous system. The degree of histological changes within the spinal cord depended on the level of the vertebral axis examined: completely unorganized nervous tissue was overlying cervical and upper thoracic vertebrae, while more caudally it resembled a normal spinal cord. During the fetal period the histological disturbances of all axial structures were more pronounced. Extensive notochordal branching was associated with the malformed formation and ossification of the vertebral column. At this stage we found no correlation of histological changes between the spinal cord and the mesodermally derived structures (notochord, vertebral column) along the cranio-caudal body extent, as neural tissue had completely transformed into area cerebrovasculosa. We speculate that our histological observations could be the result of primary affection of mesodermal structures during very early stages of development. Divergence in histological findings within axial structures between the embryonic and fetal periods support recent mutational investigations on animals.
Brain↗
Neural repair of the injured spinal cord by grafting: comparison between peripheral nerve segments and embryonic homologous structures as a conduit of CNS axons.
To study the differences between peripheral nerve (PN) and embryonic homologous CNS structures as a conduit for CNS axons, spinal cord segments in neonatal rats were removed at the mid-thoracic level and PN or embryonic spinal cord (ESC) segments were grafted into the vacancy. Neural connections across the graft were examined by the anterograde and retrograde tracing methods. Anterogradely labeled pyramidal tract fibers entered the PN segment meanderingly and were dispersed; most stopped at the caudal end of the graft. Although a small fraction of fibers re-entered the host spinal cord, they terminated near the graft-host interface without further extension. By contrast, similarly labeled fibers entering the ESC segments crossed the graft and extended further to reach the lumbar segments. The fibers were defasciculated in the graft but became fasciculated and oriented dorsally near the caudal end of the graft, and descended in the normal path. Consistent with these findings, the retrograde tracing study revealed that in animals with ESC segment grafts but not in those with PN segment grafts, many neurons in the upper brain structures were labeled with Fast Blue that was injected into the lumbar enlargement. The difference between the two kinds of graft as a conduit for CNS axons is likely to be due to differences in matching growing axons and their guidance cues through the graft-host interface.
Animals↗
Pelvic ultrasound performed by emergency physicians for the detection of ectopic pregnancy in complicated first-trimester pregnancies.
STUDY OBJECTIVE: To determine the accuracy and application of pelvic ultrasound performed by emergency physicians in detecting ectopic pregnancy (EP) in complicated first-trimester pregnancies. METHODS: We studied consecutive pelvic ultrasounds performed in all women who presented with abdominal pain or vaginal bleeding during the first trimester of pregnancy over a 6-month period. Patients with clinical evidence of incomplete abortion were not included. We compared ultrasound results with subsequent ultrasound findings by the radiology department and correlated them with follow-up diagnoses and outcomes. RESULTS: Of the 136 eligible patients, a final diagnosis was rendered in 125; 11 were lost to follow-up. These ED ultrasound findings were recorded: established intrauterine pregnancy (IUP) with embryonic structures, 87 (70%); indeterminate scan revealing no distinct evidence of IUP or EP, 15 (12%); early intrauterine gestational sac of less than 6 weeks without embryonic structures, 12 (10%); EP, 8 (6%); blighted ovum, 2 (2%); and molar pregnancy, 1 (1%). The initial ED ultrasound determination was consistent with radiology department findings, final outcome, or both in 121 (96%) (95% confidence interval [CI], 91% to 97%). ED ultrasound accurately identified 87 pregnancies with intrauterine embryonic structures, including 5 patients with fetal demise (95% Cl, 97% to 100%). Diagnosis of pregnancy location in these 87 patients effectively ruled out EP, with a negative predictive value of 100%. The sensitivity and specificity of ED ultrasound in the detection of EP were 90% and 88%, respectively. CONCLUSION: Pelvic ultrasonography performed by emergency physicians can be used to rule out EP and make an accurate diagnosis in most patients with complicated first-trimester pregnancies during the initial ED visit. The remaining patients at risk can be identified and a diagnosis made by means of follow-up ultrasound and serial hCG determinations.
Adult↗
Changes of ribonucleoproteic structures of embryonic epidermal cell nuclei during differentiation and maturation.
The nuclear structure of the epiblast and skin cells was studied during the development of the chick embryo (Gallus domesticus). Ribonucleoproteic structures (RNPs) and chromatin were characterized with preferential staining techniques. The changes of the frequency of a type of RNP particle, the perichromatin granule, from gastrulating embryos to newly hatched chick, were analyzed by electron microscopic quantitative stereology. The changes of nuclear and nucleolar volume were estimated using the light microscope. The differentiation of ectoderm from epiblast is characterized by a significant increase in the nucleolar volume and in the frequency of perichromatin granules. These features suggest that ectoderm differentiation involves a general increment of mRNA and rRNA transcription. At the beginning the synthesis of a sulfhydryl-rich protein, which is coincident with the thickening of the bilayered epithelium to a multilayered epithelium, a large increase of the numerical density of perichromatin granules not accompanied by any modification of the nucleolar volume was found. The same changes characterize the acquisition of epidermal mature cell features immediately after hatching. These findings as well as previous results concerning the differentiation of central nervous system and striated muscle suggest that the increases of the number of perichromatin granules take place during the acquisition of new cytophysiological states related to functional maturation and not to early stages of cell differentiation.
Animals↗
Regionalization within the mammalian telencephalon is mediated by changes in responsiveness to Sonic Hedgehog.
The cortex and basal ganglia are the major structures of the adult brain derived from the embryonic telencephalon. Two morphologically distinct regions of the basal ganglia are evident within the mature ventral telencephalon, the globus pallidus medially, and the striatum, which is positioned between the globus pallidus and the cortex. Deletion of the Sonic Hedgehog gene in mice indicates that this secreted signaling molecule is vital for the generation of both these ventral telencephalic regions. Previous experiments showed that Sonic Hedgehog induces differentiation of ventral neurons characteristic of the medial ganglionic eminence, the embryonic structure which gives rise to the globus pallidus. In this paper, we show that later in development, Sonic Hedgehog induces ventral neurons with patterns of gene expression characteristic of the lateral ganglionic eminence. This is the embryonic structure from which the striatum is derived. These results suggest that temporally regulated changes in Sonic Hedgehog responsiveness are integral in the sequential induction of basal telencephalic structures.
Animals↗
The neural tube patterns vessels developmentally using the VEGF signaling pathway.
Embryonic blood vessels form in a reproducible pattern that interfaces with other embryonic structures and tissues, but the sources and identities of signals that pattern vessels are not well characterized. We hypothesized that the neural tube provides vascular patterning signal(s) that direct formation of the perineural vascular plexus (PNVP) that encompasses the neural tube at mid-gestation. Both surgically placed ectopic neural tubes and ectopic neural tubes engineered genetically were able to recruit a vascular plexus, showing that the neural tube is the source of a vascular patterning signal. In mouse-quail chimeras with the graft separated from the neural tube by a buffer of host cells, graft-derived vascular cells contributed to the PNVP, indicating that the neural tube signal(s) can act at a distance. Murine neural tube vascular endothelial growth factor A (VEGFA) expression was temporally and spatially correlated with PNVP formation, suggesting it is a component of the neural tube signal. A collagen explant model was developed in which presomitic mesoderm explants formed a vascular plexus in the presence of added VEGFA. Co-cultures between presomitic mesoderm and neural tube also supported vascular plexus formation, indicating that the neural tube could replace the requirement for VEGFA. Moreover, a combination of pharmacological and genetic perturbations showed that VEGFA signaling through FLK1 is a required component of the neural tube vascular patterning signal. Thus, the neural tube is the first structure identified as a midline signaling center for embryonic vascular pattern formation in higher vertebrates, and VEGFA is a necessary component of the neural tube vascular patterning signal. These data suggest a model whereby embryonic structures with little or no capacity for angioblast generation act as a nexus for vessel patterning.
Angiogenesis Inhibitors↗
Correlation between karyotype and ultrasound findings in patients with failed early pregnancy.
The aim of this retrospetive study was to identify any consistent patterns between ultrasound findings in failed pregnancies and either normal or abnormal karyotypes. The study involved 102 women in whom the diagnosis of early pregnancy failure was made sonographically. The criteria for a failed pregnancy were: a gestational sac with a mean diameter of > 12 mm without a yolk sac; a yolk sac of > 6 mm mean diameter with or without abnormal morphology that ultimately failed to develop an embryonic structure; and an embryo with a crown--rump length (CRL) of > 5 mm without cardiac activity, or the loss of previously identified cardiac activity. All patients underwent elective dilatation and curettage (D & C) and products of conception were sent for karyotyping. Forty-four pregnancies (43%) had abnormal karyotypes. Of these, 33 (75%) were trisomies. The other 11 included four triploidies, one tetraploidy, two with monosomy X, and four others (unbalanced complement, isochromosome, terminal deletion and translocation). Fifty-eight pregnancies (57%) had normal karyotypes, of which 52 were 46,XX and six were 46,XY. The furthest sonographic anatomic landmark achieved did not differ with respect to karyotypic findings. An abnormal yolk sac was found in 10/58 cases (17.2%) with normal karyotypes and 8/44 cases (18.2%) with abnormal karyotypes. There were eight cases of trisomy 16, of which only two manifested an embryonic structure, but neither of which had cardiac activity; the largest was 4 mm. There were four cases of trisomy 22, of which three developed embryos with a CRL of > 10 mm with cardiac activity (11, 11 and 18 mm, respectively). In three cases of mosaicism, embryos developed cardiac activity, and were 9, 19 and 16 mm. Two cases of monosomy X had embryos of 14 and 24 mm. Only one out of five cases with multiple trisomies developed to a point at which any embryonic structure was identifiable on ultrasound examination. The ultrasound appearance of early pregnancy failure in terms of furthest anatomic landmark reached was not significantly different in cases with normal or abnormal karyotype. An abnormally enlarged yolk sac, presumably secondary to hydropic change, is a non-specific finding of failed pregnancy, and did not correlate with karyotypic abnormality (trisomy 22, mosaic, monosomy X) seem to develop further prior to embryonic demise than those with certain others (trisomy 16, multiple trisomies and unusual other variants.
Abortion, Spontaneous↗
Genomic structure and embryonic expression of the rat type 1 vasoactive intestinal polypeptide receptor gene.
The genomic structure of the rat vasoactive intestinal polypeptide type 1 receptor (VIPR I) gene was characterized using polymerase chain reactions (PCR) and DNA sequencing. These studies show that the rat VIPR I gene spans more than 20 kb of DNA sequence and includes thirteen exons separated by twelve introns, ranging from 0.2 to 4.5 kb. VIP is known to play an important role early in embryonic development. To elucidate the receptor-mediated biological functions of VIP in development, the temporal and spatial expression of VIPR I during rat embryonic development was examined in this study. Using in situ hybridization histochemistry with 35S-labeled riboprobe, VIPR I mRNA was detected as early as embryonic day 11 (E11), in the neuroepithelium, foregut, heart and in cells lining the blood vessels. From E14 through E18, VIPR I mRNA was detected in multiple tissues derived from all three germ layers. These include neuronal cells in brain and spinal cord (ectoderm); smooth muscle cells of intestines, cells lining the wall of the heart and blood vessels, kidney, adrenal gland (mesoderm); epithelial cells of airway and of liver (endoderm). The early onset and wide tissue expression of VIPR I suggests that binding of VIP to this receptor may play an important role in rat embryonic development.
Animals↗
The homeotic gene Sex Combs Reduced of Drosophila: gene structure and embryonic expression.
The homeotic gene Sex Combs Reduced (Scr) of Drosophila is required during embryogenesis for labial and first thoracic segment development. We define the Scr gene structure, showing that the major embryonic transcript is proximal to the fushi tarazu gene, and report the sequence of the transcript, which encodes a 413-amino acid, homeodomain-containing protein. We describe Scr protein distribution throughout embryogenesis. Expression begins at gastrulation and is eventually apparent in three tissues, epidermis, nervous system and visceral mesoderm, though there are clear contrasts in the domains of expression in these three tissues.
Amino Acid Sequence↗