Re: Ductus venosus blood velocity in myeloproliferative disorders.
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Blood Flow Velocity↗
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Results for “Embryonic Structures”
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Early sonographic detection of a 'human tail': a case report.
We report on a newborn in whom an echogenic protrusion arising in the caudal region was detected at 12 weeks' gestation. Subsequent ultrasound examinations at weeks 15 and 22 failed to demonstrate this finding. After birth, the infant was found to have a pilonidal sinus. The pilonidal sinus may represent a remnant of the embryonic appendage ('human tail') that usually disappears by the end of the 8th week of gestation. This case might support the theory of congenital pilonidal sinus origin.
Adult↗
Fluorescence microscopy of rat embryo sections stained with haematoxylin-eosin and Masson's trichrome method.
The fluorescence pattern induced by haematoxylin-eosin (HE) and Masson's trichrome (MT) staining methods on paraffin sections of rat embryos (from 13 to 18 days old) has been studied. Using optimal excitation (green light, 545 nm), HE- or MT-stained sections showed a selective red emission of the acidophilic tissue components, which was due to eosin Y in the case of HE and to acid fuchsin and/or xylidine ponceau in the case of MT. The fluorescence intensity induced by these anionic dyes was variable and related to the substrate nature and the embryo age. Whereas in young embryos only the immature red blood cells showed a noticeable fluorescence, in the oldest embryos there were also other tissue components that selectively fluoresced with these dyes, in particular fibre lens cells, elastic fibres, zymogen granules and muscle cells. Spectrofluorometric studies on free dyes and densitometric analysis of protein blots confirmed microscopical observations. Our results indicate that the standard HE and MT staining methods can be used in recognizing the appearance of specific protein structures in embryonic tissues by means of fluorescence microscopy.
Animals↗
Possible roles of beta-catenin in evagination of the optic primordium in rat embryos.
The roles of beta-catenin in evagination of the optic primordium in rat embryos were studied using immunostaining. High levels of beta-catenin appeared transiently in the evaginating optic primordium. Evagination of the optic primordium was suppressed in embryos treated with LiCl. In deficient optic vesicles of these embryos, accumulation of beta-catenin was decreased. Deficient optic vesicles also showed suppression of cyclin D1 accumulation and bromodeoxyuridine incorporation, no break in the deposition of laminin and type IV collagen at the basement membrane (BM) and prevention of the change in distribution of microtubules and microfilaments. These results suggest that beta-catenin regulates cell proliferation, breakdown of BM and changes in cell shape in the evaginating optic primordium to cause optic vesicle formation.
Actin Cytoskeleton↗
Development of the popliteomeniscal fasciculi in the fetal human knee joint.
PURPOSE: The purpose of this study is to better understand the function of the popliteomeniscal fasciculi and their relationship to the popliteus tendon and the lateral meniscus by describing these structures during embryonic development. TYPE OF STUDY: Anatomic dissection and histologic evaluation. METHODS: Twelve fresh-frozen lower extremity specimens (6 paired limbs) from second and third trimester human fetuses were obtained from spontaneous abortions. Each specimen was fixed in formalin and decalcified in 9.0% nitric oxide. The specimens were prepared by removal of all skin and most of the soft tissues before dissection of the lateral meniscus, parts of the posterolateral joint capsule, and the popliteus tendon and muscle. The right-side specimens were sectioned in the transverse plane, and the left-side specimens in the coronal plane. Histologic sections were prepared with H&E and Masson's trichrome stains. Light microscopy was used to evaluate the lateral meniscal attachment, with detailed attention to the popliteomeniscal fasciculi. RESULTS: The close interrelationship of lateral meniscus and popliteus tendon, especially during embryologic development, does give a better understanding how the fasciculi stabilize the lateral meniscus and allow the popliteus tendon to function as a retractor of the lateral meniscus. The fasciculi consist of 3 layers including a dense collagen layer, a vascular layer, and a synovial or capsular layer. CONCLUSIONS: During embryologic development, the fasciculi appeared to provide a vascular supply to the lateral meniscus adjacent to the popliteal hiatus where the meniscus is devoid of capsular attachments.
Collagen↗
GATA4 is essential for formation of the proepicardium and regulates cardiogenesis.
The role of GATA4 during the earliest stages of cardiogenesis has not been defined because Gata4 knockout embryos suffer an early developmental arrest caused by deficiencies in extraembryonic visceral endoderm function. We have used tetraploid embryo complementation to rescue these defects and generated clonal embryonic day 9.5 Gata4(-/-) embryos directly from embryonic stem cells. GATA4-null embryos display heart defects characterized by disrupted looping morphogenesis, septation, and a hypoplastic ventricular myocardium. We find that myocardial gene expression is relatively normal in GATA4-null hearts including expression of GATA6. Moreover, GATA4 expression in the endocardium is dispensable for trabeculae formation. Remarkably, the proepicardium is absent in GATA4-null embryos, blocking formation of the epicardium. Therefore, we propose that the observed myocardial defects may be a secondary consequence of loss of the proepicardium. These findings definitively demonstrate a requirement for GATA4 during early cardiac development and identify an essential factor for generation of the proepicardium.
Animals↗
The Ca2+-induced methyltransferase xPRMT1b controls neural fate in amphibian embryo.
We have previously shown that an increase in intracellular Ca2+ is both necessary and sufficient to commit ectoderm to a neural fate in Xenopus embryos. However, the relationship between this Ca2+ increase and the expression of early neural genes has yet to be defined. Using a subtractive cDNA library between untreated and caffeine-treated animal caps, i.e., control ectoderm and ectoderm induced toward a neural fate by a release of Ca2+, we have isolated the arginine N-methyltransferase, xPRMT1b, a Ca2+-induced target gene, which plays a pivotal role in this process. First, we show in embryo and in animal cap that xPRMT1b expression is Ca2+-regulated. Second, overexpression of xPRMT1b induces the expression of early neural genes such as Zic3. Finally, in the whole embryo, antisense approach with morpholino oligonucleotide against xPRMT1b impairs neural development and in animal caps blocks the expression of neural markers induced by a release of internal Ca2+. Our results implicate an instructive role of an enzyme, an arginine methyltransferase protein, in the embryonic choice of determination between epidermal and neural fate. The results presented provide insights by which a Ca2+ increase induces neural fate.
Animals↗
Epidermolysis bullosa and embryonic lethality in mice lacking the multi-PDZ domain protein GRIP1.
Glutamate receptor-interacting protein 1 (GRIP1) is an adaptor protein composed of seven PDZ (postsynaptic density-95/Discs large/zona occludens-1) domains, capable of mediating diverse protein-protein interactions. GRIP1 has been implicated in the regulation of neuronal synaptic function, but its physiologic roles have not been defined in vivo. We find that elimination of murine GRIP1 results in embryonic lethality. GRIP1(-/-) embryos develop abnormalities of the dermo-epidermal junction, resulting in extensive skin blistering around day 12 of embryonic life. Ultra-structural characterization of the blisters (or bullae) revealed cleavage of the dermo-epidermal junction below the lamina densa, an alteration reminiscent of the dystrophic form of human epidermolysis bullosa. Blisters were also observed in the lateral ventricle of the brain and in the meninges covering the cerebral cortex. These genetic data suggest that the GRIP1 scaffolding protein is required for the formation and integrity of the dermo-epidermal junction and reveal the importance of PDZ domains in the organization of supramolecular structures essential for mammalian embryonic development.
Animals↗
Two human homeobox genes, c1 and c8: structure analysis and expression in embryonic development.
Two human cDNA clones (HHO.c1.95 and HHO.c8.5111) containing a homeobox region have been characterized, and the respective genomic regions have been partially analyzed. Expression of the corresponding genes, termed c1 and c8, was evaluated in different organs and body parts during human embryonic/fetal development. HHO.c1.95 apparently encodes a 217-amino acid protein containing a class I homeodomain that shares 60 out of 61 amino acid residues with the Antennapedia homeodomain of Drosophila melanogaster. HHO.c8.5111 encodes a 153-amino acid protein containing a homeodomain identical to that of the frog AC1 gene. Clones HHO.c1 and HHO.c8 detect by blot-hydridization one and two specific polyadenylylated transcripts, respectively. These are differentially expressed in spinal cord, backbone rudiments, limb buds (or limbs), heart, and skin of human embryos and early fetuses in the 5- to 9-week postfertilization period, thus suggesting that the c1 and c8 genes play a key role in a variety of developmental processes. Together, the results of the embryonic/fetal expression of c1 and c8 and those of two previously analyzed genes (c10 and c13) indicate a coherent pattern of expression of these genes in early human ontogeny.
Amino Acid Sequence↗
Polychlorinated biphenyls are selectively neurotoxic in the developing Spisula solidissima embryo.
Polychlorinated biphenyls (PCBs) are ubiquitous environmental pollutants that accumulate to toxic levels in the food chain. Using Spisula solidissima (surf clam) embryos as a developmental model, it was shown that Aroclor 1254 specifically targets two neuronal structures during embryonic development. Embryos were exposed to 1, 10), or 100 ppm Aroclor 1254 or an acetone vehicle control posthatching for 24, 48, and 72 h. Embryos labeled with a serotonin antibody or a neural antigen antibody and a rhodamine-conjugated secondary antibody were viewed by confocal microscopy. The cerebropleural ganglion showed a decrease both in serotonin production and in the size of the serotonin-synthesizing region upon exposure to 10 and 100 ppm Aroclor 1254. These decreases were detectable as early as 48 h postfertilization. When exposed to 100 ppm Aroclor 1254, the primitive neural plexus, which coordinates the movements of the mouth and velum, showed a delay in onset and cessation of expression of a molluscan-specific neural antigen. Exposure to Aroclor 1254 did not affect the overall growth and morphology of the embryos. In addition, analyses of total protein profiles and heat-shock protein 70 levels showed that exposure to Aroclor 1254 did not trigger protein degradation or cause a stress or shock response. These results show that exposure of Spisula embryos to Aroclor 1254 specifically targets neurogenesis while having no effect on the overall growth of the embryo.
Animals↗
Common critical pathways in embryogenesis and cancer.
Cancer may arise because the developmental programs that create the dramatic alterations in form and structure in embryonic development are potentially corrupted. The cells in our bodies retain memories of these processes and cancer can occur later in life if imperfections occur in the fidelity of these pathways. This article is particularly interested in the phenomenon of epithelial to mesenchymal transition, which occurs in embryogenesis. Also reviewed are the small molecules and pathways that are involved both in homeostasis in adult epithelium and embryogenesis in utero. There are five such pathways in particular selected for review in this article: the Wnt pathway, Hedgehog, Notch, PAR and Bone morphogenetic peptide/TGF beta. These are usually conserved throughout mammalian evolution. Though they have been arbitrarily separated in this article they are not exclusive from one another. Their pathologically altered expression is found especially frequently in childhood tumours where they may recapitulate their developmental role, and in tumours that resemble primitive precursor cells. These pathways are important for selecting cell fates, cellular rearrangements, cytological context and morphologic design in embryology as well as participating in epithelial function in adults.
Animals↗
Wnt-5a inhibits the canonical Wnt pathway by promoting GSK-3-independent beta-catenin degradation.
Wnts are secreted signaling molecules that can transduce their signals through several different pathways. Wnt-5a is considered a noncanonical Wnt as it does not signal by stabilizing beta-catenin in many biological systems. We have uncovered a new noncanonical pathway through which Wnt-5a antagonizes the canonical Wnt pathway by promoting the degradation of beta-catenin. This pathway is Siah2 and APC dependent, but GSK-3 and beta-TrCP independent. Furthermore, we provide evidence that Wnt-5a also acts in vivo to promote beta-catenin degradation in regulating mammalian limb development and possibly in suppressing tumor formation.
Adenomatous Polyposis Coli Protein↗
Brain heterotopia in the lungs. A rare cause of respiratory distress in the newborn.
This article documents the presence of multifocal, bilateral glial heterotopia in the lungs manifesting as symptomatic lung masses during the newborn period. Prior to the present report, this rare form of heterotopia was known to occur exclusively in anencephalic infants. The observed bilateral pulmonary disease had an important cystic component, clinically and radiologically similar to cystic adenomatoid malformation. Theoretically, several explanations may be elaborated to account for the presence of central nervous tissue in the lungs: embolic events; protrusion of embryonic brain structures that are subsequently dislodged from their normal site; in-situ transformation of local developing tissues; and teratoma with predominance of neural tissue. The evidence is insufficient to conclude in favor of any of these explanations.
Brain↗
Retinoids regulate the anterior expression boundaries of 5' Hoxb genes in posterior hindbrain.
We describe the regulatory interactions that cause anterior extension of the mouse 5' Hoxb expression domains from spinal cord levels to their definitive boundaries in the posterior hindbrain between embryonic day E10 and E11.5. This anterior expansion is retinoid dependent since it does not occur in mouse embryos deficient for the retinoic acid-synthesizing enzyme retinaldehyde dehydrogenase 2. A retinoic acid response element (RARE) was identified downstream of Hoxb5 and shown to be essential for expression of Hoxb5 and Hoxb8 reporter transgenes in the anterior neural tube. The spatio-temporal activity of this element overlaps with rostral extension of the expression domain of endogenous Hoxb5, Hoxb6 and Hoxb8 into the posterior hindbrain. The RARE and surrounding sequences are found at homologous positions in the human, mouse and zebrafish genome, which supports an evolutionarily conserved regulatory function.
5' Flanking Region↗
Reactive oxygen species level in follicular fluid--embryo quality marker in IVF?
BACKGROUND: The impact of oxidative stress in female reproduction is not clear. Contradictory reports on the effect of various oxidative stress markers on follicular fluid, oocytes and embryo quality and fertilization potential exist. The objectives of this study were to examine reactive oxygen species (ROS) levels in follicular fluid of women undergoing IVF and to relate these levels to embryo formation and quality. METHODS AND RESULTS: A total of 208 follicular fluid samples were obtained from 78 women undergoing controlled ovarian stimulation and analysed for ROS and lipid peroxidation (LPO). These samples were divided into groups I and II which represented follicular fluid containing grade III and grade II oocytes, respectively. These groups were further subdivided into groups IA, IB, IIA and IIB according to embryo quality. Subgroups IA and IIA consisted of follicular fluid samples corresponding to grade I/II embryo formation. Subgroups IB and IIB represented fertilization failure/pro-nucleolus (PN) arrest/grade III embryos. No significant correlation was observed in ROS levels on comparing groups I and II (P > 0.05). However, ROS levels were observed to be significantly different on comparing groups IA and IB (P < or = 0.01) and groups IIA and IIB (P < or = 0.05). LPO levels further supported our results. CONCLUSION: ROS levels in follicular fluid appear to play a significant role in embryo formation and quality.
Embryo Culture Techniques↗
Ultrastructural characteristics of fresh and frozen-thawed ovine embryos using two cryoprotectants.
Cryopreservation of sheep embryos with ethylene glycol as a protectant appears to be more effective than glycerol, particularly at the morula stage, as has been demonstrated on the basis of in vitro and in vivo development rates after thawing. In this study we compare the ultrastructure of fresh morulae, thawed morulae, and blastocysts cryopreserved with either ethylene glycol or glycerol at the electron microscopic level, to look for cellular damage that could be responsible for proven differences in embryo survival after transfer. Embryos cryopreserved with glycerol showed unequal degrees of conservation even among blastomeres within a single embryo. In morulae, inner blastomeres were completely damaged, whereas external ones appeared to be intact. Both morulae and blastocysts cryopreserved with ethylene glycol showed a higher uniformity in blastomere conservation than embryos with glycerol. The most remarkable features in this experimental group were the presence of desmosomes following tight junctions between blastomeres and the presence of many microvilli on the outer surface of external blastomeres. These characteristics are similar in fresh embryos of the control group. Our results show that ethylene glycol protects membrane and cytoplasmic structures of embryonic cells from cryoinjury much better than glycerol. In vivo survival of embryos confirmed the ultrastructural observations. A limited permeability of glycerol would explain the observed ultrastructural differences in blastomere integrity, which depends on blastomere location and the differences between morulae and blastocysts. We conclude that the low reproductive yield after cryopreservation using glycerol can be attributed to the lack of protection of inner cells.
Animals↗
Anatomical study of the proximal femur in the fetus.
Two angles effectively describe the upper femur geometry: The neck shaft angle (NSA) and anteversion (AV). AV and NSA decrease from birth until they reach their adult values, but little work has focused on in-utero life. Our aim was to determine if and how AV and NSA change through the fetal life. Eighty-seven femurs from 44 formalin preserved fetuses were sampled to achieve a biometry. Correlation tests and linear regression showed that AV was highly correlated with age: AV increases during the second half of gestation. No conclusion can be given concerning NSA. It is speculated that these changes may be caused by mechanical stresses.
Biometry↗
The morphogenesis of the tympanic part of the temporal bone.
The aim of this report is to describe the relative movement of the tympanic membrane and its supporting structures during embryonic and postnatal life, leading to its final position in a vertical plane. Previous studies were based on ultra thin sections which led to changes in orientation during development being missed. The importance of the present description is to provide a baseline with which abnormal ear development in certain congenital syndromes may be compared.
Humans↗