Search results for "Embryonic Structures"
showing 10 items of 623 documents
The Embryonic Central Nervous System Lineages ofDrosophila melanogaster
1997
Abstract In Drosophila, central nervous system (CNS) formation starts with the delamination from the neuroectoderm of about 30 neuroblasts (NBs) per hemisegment. They give rise to approximately 350 neurons and 30 glial cells during embryonic development. Understanding the mechanisms leading to cell fate specification and differentiation in the CNS requires the identification of the NB lineages. The embryonic lineages derived from 17 NBs of the ventral part of the neuroectoderm have previously been described (Bossing et al., 1996). Here we present 13 lineages derived from the dorsal part of the neuroectoderm and we assign 12 of them to identified NBs. Together, the 13 lineages comprise appro…
Expression and inducibility of drug-metabolizing enzymes in preneoplastic and neoplastic lesions of rat liver during nitrosamine-induced hepatocarcin…
1987
The expression, inducibility, and regulation of four different cytochrome (cyt.) P-450 isoenzymes (PB1, PB2, MC1, and MC2) NADPH-cytochrome P-450 reductase, the glutathione transferases (GSTs) B and C and microsomal epoxide hydrolase (mEHb) have been studied during nitrosamine-induced hepatocarcinogenesis using immunohistochemical techniques. The investigations revealed basic differences in the expression of the individual drug metabolizing enzymes in the course of neoplastic development. While the two GSTs and mEHb were increased in all preneoplastic and benign neoplastic lesions, the levels of the distinct cyt. P-450 isoenzymes were characteristically different from each other. Following …
Assessment of Toxic Effects of Ochratoxin A in Human Embryonic Stem Cells
2019
Ochratoxin A (OTA) is a mycotoxin produced by different Aspergillus and Penicillium species, and it is considered a common contaminant in food and animal feed worldwide. On the other hand, human embryonic stem cells (hESCs) have been suggested as a valuable model for evaluating drug embryotoxicity. In this study, we have evaluated potentially toxic effects of OTA in hESCs. By using in vitro culture techniques, specific cellular markers, and molecular biology procedures, we found that OTA produces mild cytotoxic effects in hESCs by inhibiting cell attachment, survival, and proliferation in a dose-dependent manner. Thus, we suggest that hESCs provide a valuable human and cellular model for to…
Gatekeeper of pluripotency: A common Oct4 transcriptional network operates in mouse eggs and embryonic stem cells
2011
Abstract Background Oct4 is a key factor of an expanded transcriptional network (Oct4-TN) that governs pluripotency and self-renewal in embryonic stem cells (ESCs) and in the inner cell mass from which ESCs are derived. A pending question is whether the establishment of the Oct4-TN initiates during oogenesis or after fertilisation. To this regard, recent evidence has shown that Oct4 controls a poorly known Oct4-TN central to the acquisition of the mouse egg developmental competence. The aim of this study was to investigate the identity and extension of this maternal Oct4-TN, as much as whether its presence is circumscribed to the egg or maintained beyond fertilisation. Results By comparing …
Synaptogenesis in the mouse olfactory bulb during glomerulus development
2008
Synaptogenesis is essential for the development of neuronal networks in the brain. In the olfactory bulb (OB) glomeruli, numerous synapses must form between sensory olfactory neurons and the dendrites of mitral/tufted and periglomerular cells. Glomeruli develop from E13 to E16 in the mouse, coincident with an increment of the neuropil in the border between the external plexiform (EPL) and olfactory nerve layers (ONL), coupled to an extensive labelling of phalloidin and GAP-43 from the ONL to EPL. We have tracked synaptogenesis in the OB during this period by electron microscopy (EM) and immunolabelling of the transmembrane synaptic vesicle glycoprotein SV-2. No SV-2 labelling or synapses we…
Functional Studies of Regulatory Genes in the Sea Urchin Embryo
2008
Sea urchin embryos are characterized by an extremely simple mode of development, rapid cleavage, high transparency, and well-defined cell lineage. Although they are not suitable for genetic studies, other approaches are successfully used to unravel mechanisms and molecules involved in cell fate specification and morphogenesis. Microinjection is the elective method to study gene function in sea urchin embryos. It is used to deliver precise amounts of DNA, RNA, oligonucleotides, peptides, or antibodies into the eggs or even into blastomeres. Here we describe microinjection as it is currently applied in our laboratory and show how it has been used in gene perturbation analyses and dissection o…
The nucleus negatively controls the synthesis of mitochondrial proteins in the sea urchin egg.
1983
Enucleation of Paracentrotus lividus eggs, followed by parthenogenetic activation induces a sharp increase in the synthesis of mitochondrial proteins as shown by electrofluorography after in vivo labeling with radioactive amino acids. These results further substantiate the hypothesis that the cell nucleus negatively controls mitochondrial replication in the sea urchin egg.
Geographical variation in egg size of the Great Tit Parus major: a new perspective
2002
A recent study on geographical variation in egg size of Great Tits Parus major concluded that: (1) mean egg size tended to increase with increasing latitude; and (2) mean egg size was positively correlated with mean clutch size. Including new data on both egg and clutch size, we reanalysed the relationships between egg size, clutch size and latitude, and investigated the possible effects of habitat type, female body size and egg shape on these relationships. We found that (1) egg volume showed minimum values around 51 ° N, increasing both north and southwards; (2) female body size increased linearly with increasing latitude; (3) female body size was positively correlated with egg breadth, b…
CD15 – A new marker of pathological villous immaturity of the term placenta
2014
Abstract Introduction Idiopathic immaturity is one of the main reasons for latent placental insufficiency and antenatal hypoxia. Postnatal identification of the immature placental phenotype may help early stratification of a heterogeneous population of newborns and individually identify risk of disease in the immediate postnatal life. The aim of the study was to determine the relevant diagnostic markers associated with pathological placental immaturity. Methods 111 tissue samples from normal and pathological term placentas with persisting villous immaturity comprised the comparative immunohistochemical study (CD15, CD34). Positive immunohistochemical reactions were quantitatively assessed i…
Nature of a Pigmented Substance in the Labyrinth
1964
The pigment existing in the loose connective tissue of the posterior labyrinth is originated by hemorrhage, pathological or “physiological” inflammations and wearing out of tissues. Such pigment is contained in macrophages.