Post-embryonic development and ultrastructural characteristics of the polycephalic larva of Taenia parva Baer, 1926 (Cyclophyllidea, Taeniidae)

2007 ◽  
Vol 52 (1) ◽  
Author(s):  
Zdzisław Świderski ◽  
Jordi Miquel ◽  
Daniel Młocicki ◽  
Boyko Georgiev ◽  
Catarina Eira ◽  
...  
Keyword(s):  
Embryonic Development ◽  
Developmental Stages ◽  
Early Stage ◽  
Transmission Electron ◽  
General Similarity ◽  
Ultrastructural Characteristics ◽  
Number Of Segments ◽  
Medullary Parenchyma ◽  
Cyst Development ◽  
Taenia Parva

AbstractPost-embryonic development and fully-formed polycephalic larvae of Taenia parva Baer, 1926 were examined by light (LM) and transmission electron microscopy (TEM). Three developmental stages were recognised: (1) an early stage of exogenous budding at the surface of the central vesicle; (2) a stage of polycephalic cyst development accompanied by segmentation of the growing larval strobile and an obvious decrease in the size of the central vesicle; (3) fully-formed larval strobile and invaginated scoleces. In fully-developed encysted polycephalic larvae, there are usually 14–24 segmented larval strobilae, each terminating with an invaginated scolex; larval strobilae arise from a common central vesicle and remain attached posterior to it during the entire development. The number of segments varies between 109 and 120 per larval strobila. The polycephalic larvae examined closely resemble the strobilocercus type of taeniid larvae. The structure of developing and fully-formed larvae was examined by TEM. The tegument, scolex, subtegumental musculature of the strobilar segments, protonephridial system, calcareous corpuscles and medullary parenchyma of larvae exhibit general similarity with the same structures in adults at both LM and TEM levels. The morphogenesis of the larva of T. parva is compared with that of the polycephalic larvae of other Taenia spp. (T. krepkogorski, T. twitchelli and T. endothoracica) and with other asexually-multiplying cestode larvae (mesocestoidids, hymenolepidids and dilepidids).

A Proof for the Possibility of Ce-Oxide from CMP Residuals in Si-Wafers by Analytical TEM

2012 ◽  
Author(s):  
Wayne Zhao ◽  
Liem Do Thanh ◽  
Michael Gribelyuk ◽  
Mary-Ann Zaitz ◽  
Wing Lai
Keyword(s):  
Technology Development ◽  
Early Stage ◽  
Chemical Mechanical Planarization ◽  
Particle Cluster ◽  
Limited Region ◽  
Physical Evidence ◽  
Analytical Tem ◽  
Transmission Electron ◽  
Oxide Particles

Abstract Inclusion of cerium (Ce) oxide particles as an abrasive into chemical mechanical planarization (CMP) slurries has become popular for wafer fabs below the 45nm technology node due to better polishing quality and improved CMP selectivity. Transmission electron microscopy (TEM) has difficulties finding and identifying Ce-oxide residuals due to the limited region of analysis unless dedicated efforts to search for them are employed. This article presents a case study that proved the concept in which physical evidence of Ce-rich particles was directly identified by analytical TEM during a CMP tool qualification in the early stage of 20nm node technology development. This justifies the need to setup in-fab monitoring for trace amounts of CMP residuals in Si-based wafer foundries. The fact that Cr resided right above the Ce-O particle cluster, further proved that the Ce-O particles were from the wafer and not introduced during the sample preparation.

scholarly journals Reproductive biology, embryonic development and matrotrophy in the phylactolaemate bryozoan Plumatella casmiana

2021 ◽  
Author(s):  
Julian Bibermair ◽  
Andrew N. Ostrovsky ◽  
Andreas Wanninger ◽  
Thomas Schwaha
Keyword(s):  
Embryonic Development ◽  
Embryo Sac ◽  
The Body ◽  
Transcellular Transport ◽  
Cell Contacts ◽  
Transmission Electron ◽  
Distal Side ◽  
Early Embryos ◽  
Mesoderm Formation ◽  
Cytoplasmic Processes

AbstractBryozoa is a phylum of aquatic, colonial suspension-feeders within the Lophotrochozoa. In the Phylactolaemata embryonic development occurs in an internal brood sac on the body wall accompanied by extraembryonic nutrition. Owing to previous contradictive descriptions, many aspects of their sexual reproduction require restudy. Consequently, this study analyses embryogenesis of the freshwater bryozoan Plumatella casmiana by serial sections, 3D reconstruction and transmission electron microscopy. Early embryos cleave and soon develop into blastulae with a small central cavity. The mesoderm forms by delamination starting from the distal side towards the proximal end. In later embryos two polypides form on the posterior side that ultimately will be covered by a ciliated mantle in the larva. Embryos increase in size during development and form temporary cell contacts to the embryo sac. Mesodermal cells of the embryo sac show signs of transcellular transport indicating that embryos are nourished by transferring nutrients from the maternal coelom towards the brood cavity. This study clarifies several details such as mesoderm formation and the onset of bud development. Embryos are connected to their respective embryo sacs by a variety of temporary cytoplasmic processes formed by both tissues during embryogenesis, including a ‘placental’ ring zone. Although ultrastructural data of these cell contacts are not entirely conclusive about their function, we suggest that embryos absorb nutrients via the entire surface. The close opposition of embryos to the embryo sac implies placentation as matrotrophic mode in phylactolaemate bryozoans, with embryo sacs acting as placental analogues.

scholarly journals Wnt/β-catenin Pathway-Mediated PPARδ Expression during Embryonic Development Differentiation and Disease

2021 ◽  
Vol 22 (4) ◽  
pp. 1854
Author(s):  
Tabinda Sidrat ◽  
Zia-Ur Rehman ◽  
Myeong-Don Joo ◽  
Kyeong-Lim Lee ◽  
Il-Keun Kong
Keyword(s):  
Embryonic Development ◽  
Transcriptional Activation ◽  
Target Gene ◽  
Developmental Stages ◽  
Embryonic Stem ◽  
Hereditary Diseases ◽  
Peroxisome Proliferator ◽  
Peroxisome Proliferator Activated Receptor ◽  
Stem Cell Regulation ◽  
Early Developmental

The Wnt/β-catenin signaling pathway plays a crucial role in early embryonic development. Wnt/β-catenin signaling is a major regulator of cell proliferation and keeps embryonic stem cells (ESCs) in the pluripotent state. Dysregulation of Wnt signaling in the early developmental stages causes several hereditary diseases that lead to embryonic abnormalities. Several other signaling molecules are directly or indirectly activated in response to Wnt/β-catenin stimulation. The crosstalk of these signaling factors either synergizes or opposes the transcriptional activation of β-catenin/Tcf4-mediated target gene expression. Recently, the crosstalk between the peroxisome proliferator-activated receptor delta (PPARδ), which belongs to the steroid superfamily, and Wnt/β-catenin signaling has been reported to take place during several aspects of embryonic development. However, numerous questions need to be answered regarding the function and regulation of PPARδ in coordination with the Wnt/β-catenin pathway. Here, we have summarized the functional activation of the PPARδ in co-ordination with the Wnt/β-catenin pathway during the regulation of several aspects of embryonic development, stem cell regulation and maintenance, as well as during the progression of several metabolic disorders.

scholarly journals N-acetyl-L-cysteine Improves the Developmental Competence of Bovine Oocytes and Embryos Cultured In Vitro by Attenuating Oxidative Damage and Apoptosis

Antioxidants ◽  
2021 ◽  
Vol 10 (6) ◽  
pp. 860
Author(s):  
Wu-Sheng Sun ◽  
Hoon Jang ◽  
Mi-Ryung Park ◽  
Keon Bong Oh ◽  
Haesun Lee ◽  
...  
Keyword(s):  
Embryonic Development ◽  
Early Stage ◽  
Developmental Competence ◽  
Beneficial Effects ◽  
Developmental Rates ◽  
A Cell ◽  
Bovine Oocytes ◽  
Dose Dependent

Oxidative stress has been suggested to negatively affect oocyte and embryo quality and developmental competence, resulting in failure to reach full term. In this study, we investigated the effect of N-acetyl-L-cysteine (NAC), a cell-permeating antioxidant, on developmental competence and the quality of oocytes and embryos upon supplementation (0.1–10 mM) in maturation and culture medium in vitro using slaughterhouse-derived oocytes and embryos. The results show that treating oocytes with 1.0 mM NAC for 8 h during in vitro maturation attenuated the intracellular reactive oxygen species (ROS) (p < 0.05) and upregulated intracellular glutathione levels (p < 0.01) in oocytes. Interestingly, we found that NAC affects early embryonic development, not only in a dose-dependent, but also in a stage-specific, manner. Significantly (p < 0.05) decreased cleavage rates (90.25% vs. 81.46%) were observed during the early stage (days 0–2), while significantly (p < 0.05) increased developmental rates (38.20% vs. 44.46%) were observed during the later stage (from day 3) of embryonic development. In particular, NAC supplementation decreased the proportion of apoptotic blastomeres significantly (p < 0.05), resulting in enhanced hatching capability and developmental rates during the in vitro culture of embryos. Taken together, our results suggest that NAC supplementation has beneficial effects on bovine oocytes and embryos through the prevention of apoptosis and the elimination of oxygen free radicals during maturation and culture in vitro.

scholarly journals Comparison of the Transcriptomic and Epigenetic Profiles of Gonadal Primordial Germ Cells of White Leghorn and Green-Legged Partridgelike Chicken Embryos

Genes ◽  
2021 ◽  
Vol 12 (7) ◽  
pp. 1090
Author(s):  
Aleksandra Dunislawska ◽  
Maria Siwek ◽  
Katarzyna Stadnicka ◽  
Marek Bednarczyk
Keyword(s):  
Embryonic Development ◽  
Germ Cells ◽  
Developmental Stages ◽  
Primordial Germ Cells ◽  
Genetic Material ◽  
Reproductive Traits ◽  
Germline Stem Cells ◽  
White Leghorn ◽  
Methylation Analysis ◽  
Global Methylation

The Green-legged Partridgelike fowl is a native, dual-purpose Polish chicken. The White Leghorn has been intensively selected for several decades to mainly improve reproductive traits. Primordial germ cells (PGCs) represent the germline stem cells in chickens and are the only cells that can transfer the information stored in the genetic material from generation to generation. The aim of the study was to carry out a transcriptomic and an epigenetic comparison of the White Leghorn and Green-legged Partridgelike gonadal PGCs (gPGCs) at three developmental stages: days 4.5, 8, and 12 of the embryonic development. RNA and DNA were isolated from collected gPGCs. The RNA was further subjected to microarray analysis. An epigenetic analysis was performed based on the global methylation analysis and qMSP method for the particular silenced genes demonstrated in transcriptomic analysis. Statistically significant differences between the gPGCs from both breeds were detected on the day 8 of embryonic development. Global methylation analysis showed significant changes at the methylation level in the White Leghorn gPGCs on day 8 of embryonic development. The results suggest faster development of Green-legged Partridgelike embryos as compared to White Leghorn embryos. Changes in the levels of gene expression during embryonic development are determined by genetic and environmental factors, and this variability is influenced by breed and gender.

Recherches sur le rôle de la température dans la réalisation du phénotype chez des embryons de l'Amphibien Pleurodeles waltlii homozygotes pour la mutation thermosensible ac (ascite caudale)

Development ◽  
1975 ◽  
Vol 34 (1) ◽  
pp. 221-252
Author(s):  
Par Maria Fernandez ◽  
Jean-Claude Beetschen
Keyword(s):  
Embryonic Development ◽  
Developmental Stages ◽  
Fluid Collection ◽  
Temperature Shift ◽  
Temperature Sensitive ◽  
Tail Bud ◽  
Dorsal Fin ◽  
Second Shift ◽  
Pleurodeles Waltlii

1. At the feeding stage (st. 38), a high percentage (79 %) of Pleurodeles homozygous ac/ac larvae show bent tails after a persistent ascitic blister in the dorsal part of the fin, when embryonic development occurred at 12°C; about only 25 % of them are affected by abdominal and pericardic ascites; about 40 % can feed and survive. The larval phenotype is very different when embryonic development occurred at 23 °C, in which case tail growth appears to be normal, but 95 % larvae die, due to ascitic fluid collection in the abdominal and heart regions, marked anaemia and microcephaly. 2. The exchange of posterior neural plates and dorso-lateral epidermis between normal and mutant neurulae has shown that the localization of the blister in the dorsal fin is not dependent on autonomous properties of the mutant dorsal tissues, but should be considered as resulting from general disturbances in the mutant organism. 3. Experiments were performed, involving a temperature shift from 12 to 23°C or 23 to 12°C, occurring at various developmental stages from the end of gastrulation (stage 13) to the stage of spontaneous embryonic muscle contractions (stage 26). When the temperature shift was applied after the end of neurulation (stage 21), the caudal phenotype was statistically similar to that of larvae which had been bred continuously at the first temperature. Thus temperature-sensitive phases can be characterized between neurula stages 15 and 18 (for a 12–23° shift) or 15 and 21 (for a 23–12° shift). Similarly, abdominal ascites can be induced when embryos are kept at 23 °C till stage 23 (early tail-bud) only, and occurs much less frequently when embryos are kept at 12°C till stage 23 and then transferred to 23°C. 4. It could be concluded from these experiments that the caudal mutant phenotype is already temperature-determined during neurulation, before stage 21. Nevertheless, double temperature-shift experiments showed that the second shift could modify the results which would be obtained if the first shift only occurred. Paradoxical results were obtained, more than 90 % of the tail phenotypes being of the ‘warm type’ when the embryos were first kept at 12°C, then shifted up to 23 °C between stages 22 and 26, and shifted down again to 12°C. Such a treatment markedly lowers the percentage of bent tails (‘cold type’) from the percentage which would occur if ac/ac embryos were constantly kept at 23 °C after stage 21, but this longer warm treatment is of no effect of itself as compared to the case when the whole development occurs at 12°C (bent tails are predominant in this latter case). Thus, whereas the early determination of the position of the caudal blister can be considered as a stable phenomenon under given temperature conditions, it is not irreversible. 5. As compared to cold-bred larvae, thrice as many completely anaemic larvae (66 %) were obtained from ac/ac embryos kept at 23 °C between stages 21 and 26; this offers an opportunity for the experimental study of this anaemia. 6. Implications of these results for further analysis of temperature-sensitive mutations in cold-blooded vertebrates are suggested.

scholarly journals Exogenous HGF Prevents Cardiomyocytes from Apoptosis after Hypoxia via Up-Regulating Cell Autophagy

2016 ◽  
Vol 38 (6) ◽  
pp. 2401-2413 ◽  
Author(s):  
Yunle Wang ◽  
Jiabao Liu ◽  
Zhiwen Tao ◽  
Peng Wu ◽  
Weili Cheng ◽  
...  
Keyword(s):  
Therapeutic Strategy ◽  
Protective Factor ◽  
Ventricular Myocytes ◽  
Early Stage ◽  
Neonatal Rat ◽  
Transmission Electron ◽  
Neonatal Rat Heart ◽  
Hoechst Staining ◽  
Hepatocyte Growth

Background: Hepatocyte growth factor (HGF) is widely known as a protective factor in ischemic myocardium, however HGF sensitive cellular mechanism remained ill-defined. Autophagy at early stage of hypoxia has been demonstrated to play a role in protecting myocardium both in vivo and vitro. We performed this study to investigate the association between the protective effect of HGF and autophagy. Methods: Ventricular myocytes were isolated from neonatal rat heart (NRVMs). We evaluated cardiomyocytes apoptosis by Hoechst staining and flow cytometry. Autophagy was assessed by transmission electron microscope and mRFP-GFP-LC3 adenovirus infection. Mitochondrial membrane potential was estimated by JC-1 staining. Western blotting and ELISA assay were used to quantify protein concentrations. Results: We found that autophagy in NRVMs increased at early stage after hypoxia and HGF release was consistent with the change of autophagy. Exogenous HGF enhanced autophagy and decreased apoptosis, while neutralizing HGF yielded opposite effects. Besides, inhibition of autophagy increased apoptosis of myocytes. Furthermore, exogenous HGF induced Parkin, the marker of mitochondrial autophagy, indicating increased clearance of injured mitochondria. Conclusions: Our results revealed a potential mechanism in which exogenous HGF prevented NRVMs from apoptosis after hypoxia. Upregulation of Parkin through administration of exogenous HGF may be a potential therapeutic strategy ptotecting myocytes during ischemia.

scholarly journals Influence of Parenting Styles and Developmental Stages on Identity Formation among Adolescents

2017 ◽  
Vol 4 (3) ◽  
Author(s):  
Ahmad Rezvan ◽  
H. M. Ramakrishne Gowda ◽  
Lancy D’Souza
Keyword(s):  
Identity Formation ◽  
Parenting Styles ◽  
Collective Identity ◽  
Rural Areas ◽  
Developmental Stages ◽  
Early Stage ◽  
Personality Development ◽  
Late Adolescents ◽  
Authoritarian Parenting ◽  
Significant Difference

Paternal attitudes, beliefs and behaviors that appear as family pattern or parenting styles play a key role in personality development and stabilizing the identity of adolescents. The present study assesses parenting styles and identity formation status of adolescents studying in and around Mysore city. A total of 400 adolescents (200 early and 200 late adolescents) were randomly selected covering Mysore city and nearby rural areas, of which equal number among were male and female adolescents and also equal number of them were from urban and rural areas. They were provided with Parental authority questionnaire (PAQ) developed by Buri (1991) and Aspects of Identity Questionnaire – IV (AIQ – IV) developed by Sampson (1978). PAQ measured perceived parenting styles. The AIQ scale measured personal, Relational Social and Collective areas of identity formation. The collected data were, coded and analyzed using SPSS software. The data was analyzed by Two-way ANOVA to find significant difference if any, in the developmental stages, area of living as well as gender of the participants. Results revealed that, adolescents with authoritarian Parenting styles had higher personal identity formation than adolescents with permissive and authoritarian parenting styles. Developmental stage showed significant influence on all components of identity-Personal, Relational, Social and Collective, where in early stage adolescents had higher identity than adolescents at later stage. In general, this study showed that the developmental stages had considerable effect on the collective identity formation in both early and late adolescents.

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