SEARCH · PubMed Health

Results for “Embryonic Development”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 325 records · Page 18Linked to original sources

PubMed2002

Progesterone receptor isoforms in ovary of newly-hatched chick after gonadotropin treatment during embryonic development.

We evaluated by immunohistochemistry the expression of progesterone receptor (PR) isoforms in different cell subpopulations of the ovary of newly-hatched chicks after a treatment with Follicle-stimulating hormone (FSH) or Luteinizing hormone (LH) administered on days 13, 15 and 17 of embryonic development. Two monoclonal antibodies that recognize either both PR isoforms or only PR-B, were used. The results indicate that FSH increased both the total number of cells and the number of PR-immunoreactive ones in all cell subpopulations of the ovary. In all cases, PR-B was the isoform regulated by FSH. In contrast, LH did not modify the number of total cells in any cell subpopulations of the ovary. Besides, LH decreased the number of PR-B immunoreactive interstitial cells, without modifying PR expression in any other cell subpopulations of the ovary. These results reveal differential effects of FSH and LH on PR-expression in cell subpopulations of the ovary of newly hatched chicks treated during embryonic development. We conclude that gonadotropins regulate PR-B isoform in the prefollicular ovary of the chick.

Animals↗

PubMed1987

Peculiarities of the embryonic development of Polypodium hydriforme Ussov (Coelenterata), a parasite of acipenserid oocytes.

"Unicellular" stages (107 specimens) and multicellular stages (64 specimens) of embryogenesis of Polypodium, found in 14 sterlet (Acipenser ruthenus L.) females, have been studied with light microscopy, cytophotometry, and autoradiography following incubation with 3H-uridine. All stages of the embryonic development occur inside host oocytes. The "unicellular" stage includes a binucleate cell with unequally sized nuclei; separation inside it of a small cell around the smaller nucleus, i.e. transformation of the single cell into a complex of 2 cells, the larger one enveloping the smaller; formation of a cavity inside the nucleus of the large (outer) cell, and migration of the small cell into it, and "cell-in-a-cell" stage, the small (generative) cell being inside the cavity formed by the nucleus of the large (trophic) cell. The latter gives rise to a hypertrophied but still unicellular envelope around the embryo, the trophamnion. The multicellular stages start with segmentation of the generative cell into blastomeres. These form a morula lying inside the cavity of the trophamnion. Gastrulation occurs by morular delamination. The inversion of the germ layers, typical of parasitic Polypodium stages, apparently arises during gastrulation. Both the generative cell ("egg") and the blastomeres are haploid, at least until the morula stage. The eggs of Polypodium are the smallest ones among coelenterates; they lack yolk and develop without fertilization. Diploidy seems to be restored during segmentation. The trophamnion cell grows, its nucleus becomes highly polypoid, and its cytoplasm accumulates mucoprotein inclusions. Both the blastomere nuclei and the trophamnion nucleus have large nucleoli and actively synthesize RNA. The stages of embryogenesis of Polypodium closely correspond to stages of the host oogenesis. The embryonic development of Polypodium lasts several years and is the slowest among coelenterates. However, it has some features typical of the class Hydrozoa.

Animals↗

PubMed2000

The embryonic development of the rhabdocoel flatworm Mesostoma lingua (Abildgaard, 1789).

The embryonic development of the flatworm Mesostoma lingua was studied using a combination of life observation and histological analysis of wholemount preparations and sections (viewed by both light and electron microscopy.) We introduce a series of stages defined by easily recognizable morphological criteria. These stages are also applicable to other platyhelminth taxa that are currently under investigation in our laboratory. During cleavage (stages 1 and 2), the embryo is located in the center of the egg, surrounded by a layer of yolk cells. After cleavage, the embryo forms a solid, disc-shaped cell cluster. During stage 3, the embryo migrates to the periphery of the egg and acquires bilateral symmetry. The side where it contacts the egg surface corresponds to the future ventral surface of the embryo. Stage 4 is the emergence of the first organ primordia, the brain and pharynx. Gastrulation, as usually defined by the appearance of germ layers, does not exist in Mesos-toma; instead, organ primordia emerge "in situ" from a mesenchymal mass of cells. Organogenesis takes place during stages 5 and 6. Cells at the ventral surface form the epidermal epithelium; inner cells differentiate into neurons, somatic and pharyngeal muscle cells, as well as the pharyngeal and protonephridial (excretory) epithelium. A junctional complex, consisting initially of small septate junctions, followed later by a more apically located zonula adherens, is formed in all epithelial tissues at stage 6. Beginning towards the end of stage 6 and continuing throughout stages 7 and 8, cytodifferentiation of the different organ systems takes place. Stage 7 is characterized by the appearance of eye pigmentation, brain condensation and spindle-shaped myocytes. Stage 8 describes the fully dorsally closed and differentiated embryo. Muscular contraction moves the body in the egg shell. We discuss Mesostoma embryogenesis in comparison to other animal phyla. Particular attention is given to the apparent absence of gastrulation and the formation of the epithelial junctional complex.

Animals↗

PubMed2004

Changing albumen-membrane adhesive forces during early embryonic development.

Using acoustic resonance analysis, it is possible to detect embryonic development. In fertile eggs, the resonant frequency suddenly decreases after about 100 h of incubation. Previous research has shown that this decrease coincides with changing mechanical properties of the albumen near the shell, caused by the formation of subembryonic fluid (SEF). In the present experiment, the adhesive forces between the shell, the membranes, and the albumen were measured before and after the decrease in the resonant frequency. The adhesive forces between shell and outer membrane and between the 2 membranes remained constant, whereas the adhesive force between the inner membrane and the albumen, indirectly measured by a Kjeldahl analysis, increased significantly. Whether the decrease in resonant frequency is caused by the increase of adhesive force between albumen and inner membrane or by the changed properties of the membranes (both of which are altered by dehydration of the albumen) is still open for discussion.

Adhesiveness↗

PubMedDate not supplied

[Embryonic development of Trichocephalus trichiurus and Eucoleus oesophagicola (Nematoda, Trichocephalida)].

The embryonal development of Trichocephalus trichiurus and Eucoleus oesophagicola is described. Clevage of both species is full, bilaterally-symmetrical, determined. At the two blastomere stage the epidermis material is localized in the anterior one. The development of both species lacks the rhomb figure characteristic of nematodes. The mouth opening breaks independent of blastopore. The stylet anlage formation was noted for T. trichiurus.

Animals↗

PubMed1997

The embryonic development of the human lamina cribrosa.

OBJECTIVE: To investigate the embryonic development of lamina cribrosa of human eyes. METHODS: The lamina cribrosa of 291 eyes were studied including 260 eyes taken from embryos and fetus of 7 weeks to full term and 31 eyes from infants under 1 year of age by using light microscopy (LMS), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). RESULTS: From observations, it was found that the development of the lamina cribrosa was lagged behind the development of the optic nerve. CONCLUSIONS: In eyes taken from embryos or fetus less than 4 months of pregnancy, only ectodermal primordium of the lamina cribrosa could be seen. The initial scleral part of the lamina cribrosa began its formation in the 5th month of fetus. The fibrous tissue originating from the choroid and optic nerve sheath contributed to the formation of the lamina cribrosa in the 8th month fetus. At this time, the morphology of the lamina cribrosa is similar to that of an adult, however the thickness of the structure is still getting increased up to one year after birth.

Choroid↗

PubMed1993

The effect of tolbutamide on rat embryonic development in vitro.

Tolbutamide (TOLB) is a sulfonylurea used to treat non-insulin-dependent diabetes mellitus and is a suspected teratogen. However, it is not possible to discriminate between potential teratogenic effects of TOLB and malformations produced by either drug-induced hypoglycemia or the diabetic state itself. We examined the direct effect of TOLB on rat embryos cultured in a rodent whole embryo culture system. CD strain rat embryos were cultured for 48 h beginning on day 9 of gestation (plug day = day 0). Tolbutamide was added at various concentrations (90-3,600 microM). At the end of culture, viable embryos were examined for morphological score, number of somite pairs, crown-rump and head lengths, and DNA and protein content. Tolbutamide produced dose-related decreases in all endpoints at concentrations (2,250-3,600 microM) which are two to four times the human therapeutic concentration. Sera from TOLB-treated rats were adjusted to contain equal concentrations of glucose and insulin and then used for embryo culture. Serum from TOLB-treated rats had no observable effect on embryonic development. The mechanism for the embryotoxic effect of TOLB is unknown; however, the drug was previously demonstrated to alter activity of purified yeast glutathione reductase (GR). Because GR may be important for normal embryonic development, the effect of TOLB on this enzyme activity in cultured rat embryos was evaluated. Tolbutamide (2,700 microM) reduced embryonic GR activity by 35-57%. These results indicate that TOLB has a direct embryotoxic effect at levels 2 to 4 times the usual therapeutic serum concentrations on developing rodent embryos which may be mediated by GR inhibition.

Animals↗

PubMed1994

Expression and translation of the egg-laying neuropeptide hormone genes during post-embryonic development of the pond snail Lymnaea stagnalis.

The neuroendocrine caudodorsal cells of Lymnaea stagnalis express two homologous genes, each encoding a polypeptide precursor. The precursors give rise to "cocktails" of neuropeptides that regulate egg-laying. The expression and translation of both egg-laying hormone genes during post-embryonic development were investigated by in situ hybridization and by electron-microscopic immunocytochemistry. Gene-II-specific transcripts and translation products were not found in caudodorsal cells in animals with shell heights smaller than 10 mm, in contrast to gene-I products that were present even at 3-mm shell height. The onset of expression of gene II coincides with the onset of release of products from the caudodorsal cells into the blood. Large electron-dense granules were found in caudodorsal cells of snails of all developmental stages investigated. These granules form part of the Golgi sorting and packaging pathway. Their presence suggests that differential sorting and packaging is possible during post-embryonic development, like in adults. The relationship of the differential expression of the two genes to the development of the caudodorsal cell system and its targets is discussed.

Amino Acid Sequence↗

PubMed1996

Roles of kringle domain-containing serine proteases in epithelial-mesenchymal transitions during embryonic development.

Transformation of an epithelial sheet into a migrating mesenchymal cell population implies the destruction of the basal lamina underlying the epithelium, and the subsequent localized digestion of the extracellular matrix by the migrating cells. Proteases are involved in these processes. Among them, molecules containing both a serine protease domain and at least one kringle domain have been identified as possible important effectors. Interestingly, related proteins containing an inactive serine protease domain also seem to play a role, suggesting that the function of these molecules in epithelial-mesenchymal transformation is not confined to proteolytic digestion of cell attachments. Instead, these molecules act through specific tyrosine kinase receptors in the membrane of the responding cells. In this review, we summarize data implicating this family of molecules in various epithelial-mesenchymal transitions during embryonic development. Our major focus of attention are: hepatocyte growth factor/scatter factor (HGF/SF), its tyrosine kinase receptor proto-oncogene c-met, and the related peptide factor HGF-like/macrophage-stimulating protein (HGF1/MSP), whose receptor is the Ron tyrosine kinase. c-met and Ron also have another close homolog in the chick, called Sea, whose ligand remains unknown. Interestingly, HGF/SF is activated by other plasminogen-related molecules which, apart from a specific activator, include the protease urokinase. HGF/SF, c-met and HGF/MSP are expressed in dynamic ways during early embryonic development, correlating with regions undergoing epithelial/mesenchymal transformations. Moreover, several assays are now starting to reveal great pleiotropism of function during development, including both the loss and the acquisition of epithelial morphology according to the cell type and assay used, as well as angiogenesis, kidney tubule morphogenesis, cell motility, the maintenance of competence for neural induction and some aspects of the later development of the musculoskeletal and nervous systems.

Animals↗

PubMed2001

Hydrosalpinx fluid affects murine embryonic development in a coculture system with epithelial endometrial cells.

OBJECTIVE: The aim of the present investigation was to assess whether a coculture system protects from the effect of hydrosalpinx fluid (HF) on murine embryo development, evaluated through blastocyst cell number. DESIGN: Controlled prospective study. SETTING: Academic research center. PATIENT(S): Endometrium and HF from six patients and endometrium from six normal patients. INTERVENTION(S): Murine embryos were exposed to the absence or presence of different concentrations of human HF: 0% HF (control), 50% HF, 70% HF in human tubal fluid, and 100% HF, in a simple culture system (SCS), epithelial coculture system (ECS), and hydrosalpinx epithelial coculture system (HECS). MAIN OUTCOME MEASURE(S): Embryonic development at 72 hours and blastocyst cell number determined by the Tarcowsky method. RESULT(S): In SCS, 91.9% of the embryos reached the blastocyst stage, and no significant differences were shown in the presence of HF. However, significant differences were observed in the blastocyst cell number. Of the embryos cultured in ECS, 97.1% reached the blastocyst stage, and high concentrations of HF caused a decrease in embryonic development. A significant difference was observed between ECS and HECS in embryo development without HF. When HF was added, a significant decrease in blastocyst cell number was seen in embryos exposed to HECS compared with ECS. CONCLUSION(S): Our data suggest that normal and hydrosalpinx endometria do not protect from the deleterious effect of HF on embryo development at the concentrations evaluated. This effect is dose dependent and was determined through the blastocyst cell number.

Adult↗

PubMed1982

Restriction patterns of adult chicken globin genes at early and late stages of embryonic development.

Globin mRNA isolated from anemic chicken was transcribed into cDNA and integrated into the Pst I cleavage site of plasmid pBR 322. After cloning in E. coli strain HB 101 and colony hybridization with 125I-labelled globin mRNA the plasmids of individual clones were characterized by hybrid arrested cell-free translation. Thus we could isolate clones containing alpha or beta globin chain nucleotide sequences. DNA was isolated from chicken blastoderms incubated for 18-20 h and from 11 d chicken embryos. A comparison of the restriction maps of the DNA from the two developmental stages with labelled nick translated plasmids and labelled cDNA did not indicate any globin gene rearrangements between these two stages of embryonic development. We conclude, that the adult chicken globin genes show a constant genomic organization during embryonic development. However, the restriction patterns of the globin gene family of the chicken strain investigated revealed some differences after 2 generations of propagation.

Animals↗

PubMed2001

Embryonic development assay with Daphnia magna: application to toxicity of aniline derivatives.

An assay system using Daphnia magna embryos was applied to investigate the adverse effects of aniline derivatives. The data were compared with our previous data for chlorophenols. This new assay provides useful information to evaluate the toxicity of chemicals and the differences in sensitivity between the life stages. The effects of 15 aniline derivatives on embryonic development of D. magna embryos were determined. At the start of exposure, 2-6-h old eggs (between stages 1 and 2, round in shape, diameter approx. 400 microm), were used. In control and solvent control groups, embryonic development from an egg to a free-swimming animal proceeded completely within 3 days with more than 90% hatchability. Median effective concentrations (EC50s) to reduce the numbers hatched were determined and gross morphological abnormalities of hatched animals recorded. Anilines induced no obvious morphological abnormalities and no developmental delay although premature deaths occurred. However, they affected the number of embryos hatching in a dose-dependent manner. In addition, this embryo assay was more sensitive to aniline derivatives (except for aniline) than acute juveniles immobilization assay. Ratios of 48-h EC50 (juvenile)/3-day EC50 (embryo) for eight anilines were greater than 5.0. Particularly, the ratios of 4-methyl-, 4-ethyl- and 3-methylaniline were 77, 23 and 11, respectively. EC50s for embryos and juveniles were poorly correlated (r = 0.41). This indicated that the sensitivities of the two life stages were different to the effects of anilines. EC50s were poorly correlated (r = -0.097) with the log Kow (1-octanol/water partition coefficient). These results were compared with previous results for phenols.

Aniline Compounds↗

PubMed2005

JAM-A expression during embryonic development.

Cell adhesion molecules of the immunoglobulin superfamily play an important role in embryonic development. We have shown recently that JAM-A, a member of this family expressed at endothelial and epithelial tight junctions, is involved in platelet activation, leukocyte transmigration, and angiogenesis. Here, we determine the expression pattern of the JAM-A gene during embryogenesis using transgenic mice expressing lacZ under the control of the endogenous JAM-A promoter. Histochemical staining for beta-galactosidase in heterozygous mouse embryos was first seen in the inner cell mass and trophectoderm of the blastocyst. By 8.5 days post coitum (dpc), JAM-A gene activity was detected in the endoderm and part of the surface ectoderm. At 9.5 dpc, JAM-A expression began to localize to certain organ systems, most notably the developing inner ear and early vasculature. Localization of JAM-A to embryonic vasculature was confirmed by double-staining with antibodies against JAM-A and platelet endothelial cell adhesion molecule-1, a known endothelial cell marker. As organogenesis progressed, high levels of JAM-A expression continued in the epithelial component of the inner ear as well as the epithelium of the developing skin, olfactory system, lungs, and kidneys. In addition, JAM-A gene activity was found in the developing liver, choroid plexuses, and gut tubes. Immunofluorescent staining with a JAM-A antibody was performed to confirm that expression of the JAM-A-beta-galactosidase fusion protein accurately represented endogenous JAM-A protein. Thus, JAM-A is prominently expressed in embryonic vasculature and the epithelial components of several organ systems and may have an important role in their development.

Animals↗

PubMed1993

Preimplantation endocrinology in the Djungarian hamster (Phodopus campbelli): progesterone, estrogen, corpora lutea, and embryonic development. G.

This study reports the results of a detailed investigation of pregnancy in the Djungarian hamster, Phodopus campbelli, with a 2-h time resolution from 2000 h on proestrus (Day 0) through 0600 h on Day 5. Comparisons of the serum levels of progesterone (P4) and estradiol-17 beta (E2), along with the extractable content of each in the corpora lutea and the nonluteal portion of the right ovary, were used to assess the sources and circulating levels of these steroids throughout preimplantation pregnancy. Simultaneous investigation of embryonic development and location within the reproductive tract permitted accurate staging of development. The time course for development and implantation was similar to that in other short-cycle rodents, with transit into the uterus on the evening of Day 3 and implantation beginning early on Day 5 of pregnancy. In three different circumstances, tissue accumulations of steroids were not associated with concurrent increases in serum levels. The first, late on proestrus to early Day 1 of pregnancy, was a significant accumulation of P4 in the nonluteal ovary while serum levels remained basal. The second, throughout Day 2 of pregnancy, was an accumulation of P4 in the corpora lutea that paralleled the pattern of serum P4 during a normal estrous cycle, but which, in these pregnant females, was not seen as elevated serum P4 levels. This response is likely to be coitally induced and thus advances the first maternal steroid response to pregnancy by 24 h relative to other short-cycle rodents studied.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed2002

Influence of oocytes and spermatozoa on early embryonic development.

OBJECTIVE: To evaluate the effect of oocytes and spermatozoa on early embryonic development. DESIGN: Retrospective study. SETTING: Infertility Clinic, the Family Federation of Finland. PATIENT(S): Fifty-nine oocyte donation cycles with oocytes shared among 118 recipient couples. INTERVENTION(S): Culture of all fertilized oocytes. MAIN OUTCOME MEASURE(S): Standard sperm (concentration, progressive motility, and morphology according to Tygerberg strict criteria) and embryo (morphology and cleavage stage) characteristics. RESULT(S): A marked effect of the oocyte on both embryo morphology and blastomere cleavage rate was demonstrated. In addition, a significant sperm effect on blastomere cleavage rate was found. Sperm morphology as determined according to strict criteria rather than sperm count or progressive motility was positively associated with the blastomere cleavage rate. None of the measured sperm characteristics influenced embryo morphology. CONCLUSION(S): Embryo morphology, i.e., fragmentation and blastomere uniformity, are predominantly determined by oocyte quality, whereas both the oocyte and spermatozoa influence the blastomere cleavage rate.

Adult↗

PubMed2004

Expression and release patterns of neuropeptides during embryonic development and hatching of the green shore crab, Carcinus maenas.

Crustacean ecdysis is controlled by at least three neuropeptides: moult-inhibiting hormone (MIH), which represses ecdysteroid synthesis; crustacean hyperglycaemic hormone (CHH), which not only influences ecdysteroid synthesis but also water uptake during moulting; and crustacean cardioactive peptide (CCAP), which is involved in stereotyped ecdysis behaviour. During embryonic development, moulting takes place in the egg, but there is little information regarding developmental expression of these neuropeptides during this period or during hatching--an event that is analogous to eclosion in insects. To address this problem, we determined expression profiles of MIH and CHH mRNA by quantitative RT-PCR, together with developmental peptide expression studies [confocal immunocytochemistry (ICC) and radioimmunoassay (RIA)]. Likely homologous events relating to neuropeptide surges of both CHH and CCAP were seen during larval hatching, when compared to the adult moult, and cell-specific copy concentration of both MIH and CHH mRNAs was identical to that of the adult during late embryonic development. We measured parallel mRNA and peptide expression of two neuropeptides (red pigment-concentrating hormone RPCH) and pigment-dispersing hormone (PDH) during development, as these have roles as neuromodulators and as classical neurohormonal roles. For MIH and CHH, gene expression was in accordance with peptide expression, but novel sites of CHH expression were found (abdominal peripheral neurones), the expression and release patterns of which may be related to larval eclosion and water uptake necessary for eggshell rupture and hatching. For RPCH and PDH, gene transcription and peptide expression were not in accordance. A significant contribution of maternally derived (non-translated) PDH mRNA to the embryo was seen, and for RPCH, high-level mRNA and peptide expression during late embryogenesis is related to a long ignored, but potentially important release site--the enigmatic post-commissural organs--which are the most prominent structures expressing RPCH during late embryogenesis.

Animals↗

PubMed2006

Estimation of the critical effect level for pollution prevention based on oyster embryonic development toxicity test: the search for reliability.

In spite of the consideration that toxicity testing is a reduced approach to measure the effects of pollutants on ecosystems, the early-life-stage (ELS) tests have evident ecological relevance because they reflect the possible reproductive impairment of the natural populations. The procedure and validation of Crassostrea rhizophorae embryonic development test have shown that it meets the same precision as other U.S. EPA tests, where EC(50) is generally used as a toxicological endpoint. However, the recognition that EC(50) is not the best endpoint to assess contaminant effects led U.S. EPA to recently suggest EC(25) as an alternative to estimate xenobiotic effects for pollution prevention. To provide reliability to the toxicological test results on C. rhizophorae embryos, the present work aimed to establish the critical effect level for this test organism, based on its reaction to reference toxicants, by using the statistical method proposed by Norberg-King (Inhibition Concentration, version 2.0). Oyster embryos were exposed to graded series of reference toxicants (ZnSO(4) x 7H(2)O; AgNO(3); KCl; CdCl(2)H(2)O; phenol, 4-chlorophenol and dodecyl sodium sulphate). Based on the obtained results, the critical value for C. rhizophorae embryonic development test was estimated as EC(15). The present research enhances the emerging consensus that ELS tests data would be adequate for estimating the chronic safe concentrations of pollutants in the receiving waters. Based on recommended criteria and on the results of the present research, zinc sulphate and 4-chlorophenol have been pointed out, among the inorganic and organic compounds tested, as the best reference toxicants for C. rhizophorae ELS-test.

Animals↗

PubMed1995

Vitrification of human oocytes following minimal exposure to cryoprotectants; initial studies on fertilization and embryonic development.

Investigations were made into the low temperature preservation of pre-ovulatory human oocytes by vitrification using a method of brief exposure of the oocytes to the vitrification solution at room temperature. Assessments of morphological survival, fertilization and embryonic development were recorded. All those oocytes exposed to the vitrification solution alone were morphologically normal and 86% of them were fertilized after incubation with spermatozoa. All the fertilized ova (86%) underwent cell division. Following cooling to -196 degrees C, morphological survival (65%) and fertilization (45%) rates remained high. However, in all vitrified oocytes, embryonic cell division and further development were inhibited. From our study it appears that fresh human oocytes can be vitrified using only brief exposure to cryoprotective agents and survive to undergo fertilization. However, progress remains to be made in achieving further embryonic development.

Cell Survival↗