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Mammalian Embryos (mammalian + embryo)
Selected AbstractsLeft-asymmetric expression of Galanin in the linear heart tube of the mouse embryo is independent of the nodal co-receptor gene crypticDEVELOPMENTAL DYNAMICS, Issue 12 2008Axel Schweickert Abstract Only very few left/right asymmetrically expressed genes are known in the mammalian embryo. In a screen for novel factors we identified the gene encoding the neuropeptide Galanin in mouse. At embryonic day (E) 8.5 asymmetric mRNA transcription was found in the left half of the linear heart tube. During heart looping and morphogenesis expression became restricted to the atrio-ventricular (AV) canal, followed by specific staining of the AV-node and AV-rings in the four-chambered heart. Expression was inverted in inv/inv and randomized in homozygous iv mutant embryos. Left-sided heart-specific transcription of mouse Gal thus should be controlled by the left-right pathway. The asymmetric pattern was retained in cryptic mutant embryos, in which the Nodal signaling cascade is disrupted. Surprisingly, Pitx2c was found to be expressed in 50% of cryptic mutant hearts as well, suggesting that some aspects of asymmetric gene expression in the heart are independent of cryptic. Developmental Dynamics 237:3557,3564, 2008. © 2008 Wiley-Liss, Inc. [source] Three types of cilia including a novel 9+4 axoneme on the notochordal plate of the rabbit embryoDEVELOPMENTAL DYNAMICS, Issue 12 2006Kerstin Feistel Abstract Motile monocilia play a pivotal role in left-right axis determination in mouse and zebrafish embryos. Cilia with 9+0 axonemes localize to the distal indentation of the mouse egg cylinder ("node"), while Kupffer's vesicle cilia in zebrafish show 9+2 arrangements. Here we studied cilia in a prototype mammalian embryo, the rabbit, which develops via a flat blastodisc. Transcription of ciliary marker genes Foxj1, Rfx3, lrd, polaris, and Kif3a initiated in Hensen's node and persisted in the nascent notochord. Cilia emerged on cells leaving Hensen's node anteriorly to form the notochordal plate. Cilia lengthened to about 5 ,m and polarized from an initially central position to the posterior pole of cells. Electron-microscopic analysis revealed 9+0 and 9+2 cilia and a novel 9+4 axoneme intermingled in a salt-and-pepper-like fashion. Our data suggest that despite a highly conserved ciliogenic program, which initiates in the organizer, axonemal structures may vary widely within the vertebrates. Developmental Dynamics 235:3348,3358, 2006. © 2006 Wiley-Liss, Inc. [source] Morphological changes in mouse embryos cryopreserved by different techniquesMICROSCOPY RESEARCH AND TECHNIQUE, Issue 4 2007A.R.S. Coutinho Abstract Cryopreservation of mammalian embryos is an important tool for the application of reproductive biotechnologies. Subjective evaluation to determine embryo viability is often used. The determination of the best cryopreservation protocol depends on morphological and molecular analysis of cellular injuries. The main objective of this study was to compare two methods of cryopreservation by assessing morphological alterations of frozen embryos using light, fluorescence, and transmission electron microscope. Fresh (control), slow frozen, and vitrified mouse embryos were composed. To evaluate the viability of the embryos, the cell membrane integrity was assessed using Hoechst33342 and propidium iodide (H/PI) staining. Morphological analyses using hematoxylin and eosin (HE) staining were performed to test different techniques (in situ, paraffin, and historesin) by both light and fluorescence microscopy. Transmission electron microscope was used to detect ultrastructural alterations in Spurr- and Araldite-embedded samples. H/PI staining detected more membrane permeability in the vitrification (69.8%) than in the slow freezing (48.4%) or control (13.8%) groups (P < 0.001). Historesin-embedded samples showed to be more suitable for morphological analyses because cellular structures were better identified. Nuclear evaluation in historesin sections showed the induction of pycnosis in slow freezing and vitrification groups. Cytoplasm evaluation revealed a condensation and an increase in eosinophilic intensity (indicating apoptosis) in the slow freezing group, and weakly eosinophilic structures and degenerated cells (indicating oncosis) in the vitrification group (P < 0.05). Ultrastructural analyses confirmed HE morphological findings. It was concluded that both cryopreservation techniques resulted in oncosis and apoptosis injuries. However, vitrification caused more severe cellular alterations and reduced embryonic viability compared to slow freezing. Microsc. Res. Tech., 2007. © 2006 Wiley-Liss, Inc. [source] Use of picosecond infrared laser for micromanipulation of early mammalian embryosMOLECULAR REPRODUCTION & DEVELOPMENT, Issue 10 2009Artashes V. Karmenyan A high repetition rate (80 MHz) picosecond pulse (,2 psec) infrared laser was used for the inactivation (functional enucleation) of oocytes and two-cell mouse embryos and also for the fusion of blastomeres of two-cell mouse embryos. The laser inactivation of both blastomeres of two-cell mouse embryos by irradiation of nucleoli completely blocked further development of the embryo. The inactivation of one blastomere, however, did not affect the ability of the second intact blastomere to develop into a blastocyst after treatment. Laser inactivation of oocytes at Metaphase II (MII) stage and parthenogenetically activated pronuclear oocytes also completely blocked their ability for further development. Suitable doses of irradiation in cytoplasm region did not affect the ability of embryos and activated oocytes to development. The efficiency of laser induced fusion for blastomeres of two-cell embryos was 66.7% and all the tetraploid embryos developed successfully into blastocysts in culture. Our results demonstrate unique opportunities of the applications of a suitable infrared periodic pulse laser as a universal microsurgery tool for individual living cells. Mol. Reprod. Dev. 76: 975,983, 2009. © 2009 Wiley-Liss, Inc. [source] Characterization and multilineage differentiation of embryonic stem cells derived from a buffalo parthenogenetic embryoMOLECULAR REPRODUCTION & DEVELOPMENT, Issue 10 2007Hathaitip Sritanaudomchai Abstract Embryonic stem (ES) cells derived from mammalian embryos have the ability to form any terminally differentiated cell of the body. We herein describe production of parthenogenetic buffalo (Bubalus Bubalis) blastocysts and subsequent isolation of an ES cell line. Established parthenogenetic ES (PGES) cells exhibited diploid karyotype and high telomerase activity. PGES cells showed remarkable long-term proliferative capacity providing the possibility for unlimited expansion in culture. Furthermore, these cells expressed key ES cell-specific markers defined for primate species including stage-specific embryonic antigen-4 (SSEA-4), tumor rejection antigen-1-81 (TRA-1-81), and octamer-binding transcription factor 4 (Oct-4). In vitro, in the absence of a feeder layer, cells readily formed embryoid bodies (EBs). When cultured for an extended period of time, EBs spontaneously differentiated into derivatives of three embryonic germ layers as detected by PCR for ectodermal (nestin, oligodendrocytes, and tubulin), mesodermal (scleraxis, ,- skeletal actin, collagen II, and osteocalcin) and endodermal markers (insulin and ,- fetoprotein). Differentiation of PGES cells toward chondrocyte lineage was directed by supplementing serum-containing media with ascorbic acid, ,-glycerophosphate, and dexamethasone. Moreover, when PGES cells were injected into nude mice, teratomas with derivatives representing all three embryonic germ layers were produced. Our results suggest that the cell line isolated from a parthenogenetic blastocyst holds properties of ES cells, and can be used as an in vitro model to study the effects of imprinting on cell differentiation and as an a invaluable material for extensive molecular studies on imprinted genes. Mol. Reprod. Dev. 74: 1295,1302, 2007. © 2007 Wiley-Liss, Inc. [source] Developmental effects of physiologically weak electric fields and heat: An overview,BIOELECTROMAGNETICS, Issue S7 2005Richard D. Saunders Abstract This study summarizes the possible effects on prenatal development of physiologically weak electric fields induced in the body by exposure to extremely low frequency (ELF) electromagnetic fields and of elevated temperature levels that might result from exposure to radiofrequency (RF) radiation. Both topics have been discussed at recent international workshops organized by WHO in collaboration with other bodies. Mammalian development is characterized by a highly ordered sequence of cell proliferation and differentiation, migration, and programmed cell death. These processes, particularly proliferation and migration, are susceptible to a variety of environmental agents including raised maternal temperature. In addition, there is growing evidence that physiologically weak endogenous DC electric fields and ionic currents have a role in guiding developmental processes, including cell orientation and migration, by establishing electrical potential gradients. Disruption of these fields can adversely affect development in amphibian and bird embryos, which are experimentally accessible, and may well do so in mammalian embryos. The extent to which induced ELF electric fields might influence these and other processes that take place during prenatal development, childhood, and adolescence is less clear. Organogenesis, which takes place primarily during the embryonic period, is susceptible to raised maternal temperatures; a large number of studies have shown that RF exposure produces developmental effects that can be attributed to heat. The development of the central nervous system is particularly susceptible to raised temperatures; a reduction in brain size, which results in a smaller head, is one of the most sensitive markers of heat-induced developmental abnormalities and can be correlated with heat-induced behavioral deficits. However, some aspects of CNS development have been less well explored, particularly effects on corticogenesis. In addition, the persistence of CNS developmental sensitivity through to childhood and adolescence is not clear. Bioelectromagnetics Supplement 7:S127,S132, 2005. © 2005 Wiley-Liss, Inc. [source] | ||||||||||