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PubMed1994

The cartilaginous nasal capsule and embryonic development of human paranasal sinuses.

Embryology is of importance to the surgeon both for the study of human developmental anatomy and for the analysis of congenital conditions resulting from malformed or arrested development. The embryonic development of the nose, and especially of the paranasal sinuses, is not yet fully understood. This histologic study of 23 fetal heads aged from 8 to 40 weeks of gestation demonstrates that all four pairs of paranasal sinuses are developed from the cartilaginous nasal capsule. The outpouching of the nasal mucous membranes is only a secondary phenomenon, rather than the primary force. This observation helps to elucidate the following clinical observations: (1) the association of maxillary sinus hypoplasia with hypoplasia of the uncinate process, (2) the origin of chondrosarcoma of the maxillary bone, and (3) pneumatization of the paranasal sinuses.

Cartilage↗
PubMed1999

Development of catecholaminergic neurons in the pond snail, Lymnaea stagnalis: I. Embryonic development of dopamine-containing neurons and dopamine-dependent behaviors.

The embryonic development of the catecholaminergic system of the pond snail, Lymnaea stagnalis, was investigated by using chromatographic and histochemical methods. High performance liquid chromatography suggested that dopamine was the only catecholamine present in significant concentrations throughout the embryonic development of Lymnaea. Dopamine first became detectable at about embryonic stage (E) 15 (15% of embryonic development) and then increased in amount during early development to reach about 120-140 fmol per animal by around E40. Dopamine content remained stable during mid-embryogenesis (E40-65), increased slowing for the next couple of days, and then increased rapidly to culminate at about 400 fmol per animal by hatching. The detection of aldehyde- and glyoxylate-induced fluorescence and of tyrosine hydroxylaselike immunoreactivity indicated that the first catecholaminergic cells appeared in the late trochophore or early veliger stage of embryonic development (E32-35). The paired perikarya of these transient apical catecholaminergic (TAC) neurons were located beneath the apical plate, remained outside of the central ganglia during embryogenesis, and no longer contained detectable catecholamines close to hatching. TAC neurons bore cilia on the ends of short processes that penetrated the overlying epithelium; their long processes branched repeatedly under the ciliated apical plate. Several smaller catecholaminergic cells first appeared in the anterior margin of the foot at a stage when the embryos began to metamorphose from the veliger form (E55). Similar bipolar cells later appeared in the tentacle and lips. The axons of all of these small peripheral cells projected centrally and terminated within the neuropil of different central ganglia. Central catecholaminergic neurons, including RPeD1, differentiated only after metamorphosis was complete (E75). Development of locomotor, respiratory, and feeding behaviors correlated with maturation of catecholaminergic neurons, as indicated by histology and chromatography.

Animals↗
PubMed1987

The effect of ambient temperature on turkey embryonic development at oviposition.

Stage of embryonic development at oviposition was measured in turkey breeder hens maintained in relatively warm and cool environments. The premise was that variations in embryonic development at oviposition might account for the decreased hatchability associated with warm summer temperatures. No treatment effect was found, as judged by somite counts after 52 h of incubation. Variation in embryonic development was as great within a hen as between hens, indicating that causative factor(s) other than stage of development at oviposition is the reason for reduced hatch of fertile eggs during periods of relatively high environmental temperature.

Journal Article↗
PubMed2005

A role for CK2alpha/beta in Xenopus early embryonic development.

CK2 is expressed widely in early embryonic development in several animal models, however its developmental role is unclear. One of the substrates of CK2 that is important in embryonic development is beta-catenin, the transcriptional co-activator of the canonical Wnt signaling pathway. This pathway has been implicated in diverse aspects of embryonic development, including one of the earliest events in embryonic development, the establishment of the dorso-ventral embryonic axis. In Xenopus laevis, dorso-ventral axis formation is dependent upon stabilization of beta-catenin in the future dorsal side of the embryo. Since CK2 phosphorylation of beta-catenin stabilizes it, we hypothesized that CK2 might be critical to upregulation of beta-catenin in Xenopus embryos and to the process of axis establishment. Our results demonstrate that CK2 is required for dorsal axis formation and is for normal upregulation of Wnt signaling genes and targets. Thus, CK2 is a regulator of endogenous axis formation in vertebrates.

Animals↗
PubMed2006

mED2--a novel gene involved in mouse embryonic development.

Dissection of new genes underlying embryonic development is important for our understanding of the molecular mechanism of vertebrate embryonic development. In this study, the expression pattern and functional analysis of a new gene, called mED2, originally cloned from mouse embryos using subtractive hybridization was reported. mED2 expression patterns were characterized by RT-PCR-Southern hybridization and in situ hybridization. The results showed that mED2 was mainly expressed in the embryonic nervous system and mesoderm-derived tissues and its expression varied depending on the embryonic developmental stages. The knockdown of mED2 activity by antisense RNA injection inhibited zygote cleavage and blastocyst formation during pre-implantation in mice. Subcellular localization of mED2-eGFP fusion protein revealed a pattern of nuclear membrane and juxta-/perinuclear location such as in the rough endoplasmic reticulum and Golgi apparatus. This finding was supported by bioinformatics analysis, which indicated mED2 protein to be a transmembrane protein with partial homology to the thioredoxin family of proteins. It is inferred that mED2 gene can probably take part in early embryonic development in mouse and may be involved in target protein posttranslational modification, turnover, folding, and stability at the endoplasmic reticulum and/or the Golgi apparatus.

Animals↗
PubMed1986

Hemoglobin switching during murine embryonic development: evidence for two populations of embryonic erythropoietic progenitor cells.

Explants of normal mouse embryonic tissues and disaggregated embryonic single cells were cultured in vitro to study the erythropoietic progenitor cells present during embryonic development. The results indicate that there are two populations of erythropoietic progenitor cells committed to different hemoglobin synthetic programs. These progenitor cells are present at an early gestational stage prior to the formation of the fetal hepatic primordium. One population of progenitors can be stimulated by erythropoietin alone to form usually small erythroid colonies after culture for six days in vitro. These erythroblasts primarily synthesize embryonic hemoglobins, but produce some adult hemoglobins as well. The other population of progenitors requires stimulation by both erythropoietin and adult spleen cell-conditioned medium, and usually forms large erythroid colonies after culture for six days in vitro. These erythroblasts produce only adult hemoglobins.

Animals↗
PubMed2002

Loss of desmoglein 2 suggests essential functions for early embryonic development and proliferation of embryonal stem cells.

Desmoglein 2 (Dsg2) is a Ca(2+)-dependent adhesion molecule of desmosomes and is synthesized in all desmosome-bearing tissues from their earliest appearance onward. To examine the function of Dsg2, its gene was inactivated by homologous recombination in embryonal stem (ES) cells for the generation of knockout mice. DSG2 -/- mice and a considerable number of DSG2 +/- mice died at or shortly after implantation. On the other hand, DSG2 -/- blastocysts developed an apparently normal trophectoderm layer, the first tissue known to produce desmosomes, and hatched properly. Immunofluorescence analyses of these blastocysts showed, however, that the distribution of the desmosomal plaque protein desmoplakin was disturbed, whereas the adherens junction proteins E-cadherin and beta-catenin appeared to be unaffected. Unexpectedly, we found that Dsg2 seems to be essential for the inner cell mass and the ES cell population derived there from. We present evidence that Dsg2, which is located in desmoplakin-negative wild-type ES cells in non-desmosomal junctions, is needed for normal ES cell proliferation. Our observations thus reveal that important Dsg2 functions are desmosome-independent during early development and are needed for ES cell and early embryo survival.

Animals↗
PubMedDate not supplied

Differential effects of duplication-deficiency gametes from T (3;12) on embryonic development in the German cockroach.

Differential embryonic development, as seen within egg cases of the German cockroach, serves to distinguish matings of interchange heterozygotes from those of wild type. In T (3;12), one group of fertilized eggs ceases development during stage I of embryonic development; a second group, during stage VII. The frequency of the two groups correlates closely with that of adjacent-1 vs adjacent-2 disjunction. It also does not differ significantly from the expected frequency if zygotes fertilized by one of the two types of adjacent-1 gametes reach a more advanced stage of development than those of the other three types of duplication-deficiency gametes. The absence of a sex difference in the stages of embryonic death indicates that it makes little difference whether aneuploid gametes are of maternal or paternal origin.

Animals↗
PubMed2006

Thoc1/Hpr1/p84 is essential for early embryonic development in the mouse.

The yeast TREX complex physically couples elongating RNA polymerase II with RNA processing and nuclear RNA export factors to facilitate regulated gene expression. Hpr1p is an essential component of TREX, and loss of Hpr1p compromises transcriptional elongation, RNA export, and genome stability. Despite these defects, HPR1 is not essential for viability in yeast. A functional orthologue of Hpr1p has been identified in metazoan species and is variously known as Thoc1, Hpr1, or p84. However, the physiological functions of this protein have not been determined. Here, we describe the generation and phenotypic characterization of mice containing a null allele of the Thoc1 gene. Heterozygous null Thoc1 mice are born at the expected Mendelian frequency with no phenotype distinguishable from the wild type. In contrast, homozygous null mice are not recovered, indicating that Thoc1 is required for embryonic development. Embryonic development is arrested around the time of implantation, as blastocysts exhibit hatching and blastocyst outgrowth defects upon in vitro culture. Cells of the inner cell mass are particularly dependent on Thoc1, as these cells rapidly lose viability coincident with Thoc1 protein loss. While Hpr1p is not essential for the viability of unicellular yeasts, the orthologous Thoc1 protein is required for viability of the early mouse embryo.

Animals↗
PubMed1983

Formation of the receptive fields of leech mechanosensory neurons during embryonic development.

We have charted the embryonic development of the epidermal receptive fields of the PV and PD mechanosensory neurons present in each segmental ganglion of the ventral nerve cord of the glossiphoniid leech Haementeria ghilianii. The receptive field of either of these neurons is established by several peripheral axons, each of which grows into its own skin territory, so that the receptive field is subdivided into a quiltwork of contiguous, mutually exclusive subfields of various sizes. The largest subfield develops first from the primary peripheral axon of the PD or PV neuron. The PD and PV primary axons grow directly to their respective territories and begin to innervate them at approximately the same time (see also Kuwada, J.Y., and A.P. Kramer (1983) J. Neurosci. 3: 2098-2111). The smaller secondary and minor subfields develop later from the secondary and intersegmental peripheral axons, respectively. These axons, too, grow directly to their appropriate skin territories. The arborizations of the peripheral axons expand until the adult receptive field pattern is established late in embryogenesis; they do not appear to initially overgrow and later trim down to the normal boundaries of the adult receptive field. The receptive field of the PV neuron develops from a stereotyped skeletal branching pattern of the peripheral axons that is elaborated in a regular way to form a grid-like pattern that matches the arrangement of muscle fibers in the body wall. Thus, this branching pattern may be the result of axon growth along prespecified pathways, perhaps delineated by the muscles. Throughout embryonic development, as in the adult leech, axon branches of neighboring homologous P neurons overlap considerably, but separate axon branches of the same neuron are virtually non-overlapping. These observations suggest that developing branches of a neuron are excluded from territory occupied by other branches of the same cell, in contrast to branches belonging to different neurons which can occupy the same territory.

Animals↗
PubMed2004

Retinol improves bovine embryonic development in vitro.

Retinoids are recognized as important regulators of vertebrate development, cell differentiation, and tissue function. Previous studies, performed both in vivo and in vitro, indicate that retinoids influence several reproductive events, including follicular development, oocyte maturation and early embryonic development. The present study evaluated in vitro effects of retinol addition to media containing maturing bovine oocytes and developing embryos in both a low oxygen atmosphere (7%) and under atmospheric oxygen conditions (20%). In the first experiment, abbatoir collected bovine oocytes were matured in the presence or absence of varying concentrations of retinol. After a 22-24 hour maturation period the oocytes were fertilized, denuded 18 hours later and cultured in a modified synthetic oviductal fluid (mSOF) in a humidified atmosphere at 38.5 degrees C, 5% CO2, 7% O2 and 88% N2. Cleavage rates did not differ among control and retinol-treated oocytes in all three experiments. Addition of 5 micromolar retinol to the maturation medium (IVM) tended (p < 0.07) to increase blastocyst formation (blastocyst/putative zygote; 26.1% +/- 2.2%) compared to the controls (21.9% +/- 1.9%). Further analysis revealed when blastocyst development rates fell below 20% in the control groups, 5 micromolar retinol treatment dramatically improved embryonic development, measured by blastocyst/putative zygote rate (14.4 +/- 2.1 vs 23.7 +/- 2.5; p < 0.02). The 5 micromolar retinol treatment also enhanced the blastocyst/cleaved rate by nearly 10% (23.7% vs 34.6%; p < 0.02). In the second and third experiments addition of 5 micromolar retinol to the embryo culture medium (IVC) under low oxygen conditions did not significantly improve cleavage or blastocyst rates, but 5 micromolar retinol significantly increased blastocyst development under 20% O2 conditions (p < 0.001). These studies demonstrate that supplementation of 5 micromolar retinol to the maturation medium may improve embryonic development of bovine oocytes indicated by their increased blastocyst rate. A significant improvement in the blastocyst development with the 5 micromolar retinol treatment under atmospheric conditions suggests a beneficial antioxidant effect during embryo culture.

Animals↗
PubMed2004

A potential role for beta-carotene in avian embryonic development.

Vitamin A is essential for vertebrate embryonic development; dietary carotenoids are the primary source of vitamin A since animals cannot synthesize it de novo. To study the role of beta-carotene during embryonic development, we analyzed in chick embryos the expression of beta,beta-carotene 15,15'-oxygenase (beta-oxy) which cleaves beta-carotene to produce two molecules of retinal. Beta-oxy transcripts were detected in one-and-a-half- to five-day-old embryo homogenates and in situ hybridization in five-day-old embryos, revealing their presence in tissues including the central nervous system, lungs, limbs, and cardiovascular system. Moreover, we detected beta-oxy enzymatic activity in extracts from five-day-old embryos as well as small amounts of beta-carotene in the egg yolk. These results indicate that beta-oxy is present during early developmental stages, raising the possibility that yolk-stored beta-carotene is utilized as a source of vitamin A. Thus, our results suggest that beta-carotene could play an important role in early avian embryonic development as a local source of vitamin A in specific tissues.

Animals↗
PubMed2006

Tissue fusion and cell sorting in embryonic development and disease: biomedical implications.

Throughout embryonic development, segregated epithelial and/or mesenchymal cell populations make contact and fuse to shape new tissue units. This process, known as tissue fusion, is a key event in many essential morphogenetic mechanisms and its disruption can lead to congenital malformations. Another mechanism whereby complex tissues can arise involves a cell sorting process in which originally intermixed cells de-mix to generate distinct phases or layers. Different organisms use a combination of tissue fusion and cell sorting to acquire shape. Although the two processes appear to differ mechanistically, they are intricately linked inasmuch as they both involve the same molecular determinants and contribute to the same body plan. We aim to discuss the role of adhesion molecules and cell dynamics in tissue fusion and cell sorting, providing examples of their impact in embryonic development. Finally, we will advance the concept that malignant invasion may be viewed as cell sorting in reverse. Supplementary material for this article can be found on the BioEssays website (http://www.interscience.wiley.com/jpages/0265-9247/suppmat/index.html).

Animals↗
PubMed1988

Influence of nicotine and caffeine on rat embryonic development.

The influence on embryonic development of nicotine and caffeine at dose levels approximating human consumption was investigated in Sprague-Dawley rats. One group of animals received nicotine administered subcutaneously by an Alzet mini-osmotic pump from gestational day 6 through 12 (25 mg over 7 days; rate 149 micrograms/hr). Control animals received physiological saline in a similar manner. A second group received a single intravenous injection of caffeine (25 mg/kg) on gestational day 6. Control animals were treated with physiological saline. A further group received both nicotine and caffeine on gestational day 6 as described for the two previous groups. There were no significant differences among any of the groups with respect to maternal weight gain, litter size, embryolethality, fetal weight, or crown-rump length. The offspring of nicotine treated animals showed a significantly higher incidence of hydrocephaly when compared to the controls, but in the combined treatment group no malformed fetuses were observed. Light microscopic examination of maternal liver, kidney and placentas revealed changes in the hepatic sinusoids, glomeruli and intervillous spaces after nicotine and combined treatment. In addition, the decidua basalis was poorly developed compared to the controls. Chorionic villi and fetal kidney appeared normal in all groups. A coteratogenic effect is not evident from these findings.

Animals↗
PubMed2004

Human embryonal carcinoma stem cells: models of embryonic development in humans.

There are few reliable experimental systems available to study the molecular mechanisms that govern human embryonic development. Embryonal carcinoma (EC) cells are pluripotent stem cells derived from teratocarcinomas and are considered the malignant counterparts of human embryonic stem (ES) cells. Several of the existing human EC stem cell lines provide robust and simple culture systems to study certain aspects of cellular differentiation in a manner pertinent to human embryogenesis. Here we review the strategies used to derive and characterize the established and recognized human EC stem cell line TERA2.cl.SP12. Furthermore, we demonstrate the value of human EC stem cells as a model of early development and focus on cell fate determination in the embryonic ectoderm.

Carcinoma, Embryonal↗
PubMed2000

Growth-promoting effects of different fractions of extra-embryonic coelomic fluid on embryonic development.

In the early stages of embryonic development, many growth-promoting molecules must be provided by the maternal system. These factors may be supplied locally to the embryo, by the decidua, the placenta, or the yolk sac. In this study the growth-promoting potential of extra-embryonic coelomic fluid (EECF) and its fractions was investigated. The embryonic requirement of growth-promoting molecules may be studied by reducing the growth-supporting capacity of serum. Thus, ultrafiltration of rat serum was carried out for 8 h using Millipore filters with a molecular weight exclusion of 30 kDa. Rat embryos at 9.5 days of age were cultured for 8 days for anembryonic yolk sacs, and then EECF was collected and divided into three different molecular weight fractions by ultrafiltration. Rat embryos were cultured for 48 h in whole rat serum and the serum retenate (which has low growth-supporting capacity) in the presence and absence of EECF, its fractions, or in EECF only. Embryos grown in retenate showed severe growth retardation, and the addition of EECF significantly improved embryonic growth. The fraction which contained the molecules with molecular weight between 10 and 30 kDa had significantly more effect on embryonic development than the other fractions. This fraction of EECF was analysed by gel electrophoresis. Three of the four protein bands observed in this fraction were identified by amino-terminal sequencing as alpha-fetoprotein precursor (22 kDa), apolipoprotein A1 precursor (24 kDa) and fetal haemoglobin Y2 chain (14 kDa), none of which are likely to be responsible for the growth-promoting activity. To further investigate growth-promoting proteins, EECF was Western-blotted to nitrocellulose membranes and probed with antisera against rat prolactin, epidermal growth factor, insulin-like growth factors I and II and human placental lactogen. No immunoreactive bands were detected in the EECF, suggesting that either these proteins are not present or are present at levels too low to be detected. Although the growth-promoting effect of the EECF was demonstrated in this study, the molecules responsible remain uncharacterized.

Animals↗
PubMed1995

The effect of serum from infertile women with endometriosis on fertilization and early embryonic development in a murine in vitro fertilization model.

OBJECTIVE: To evaluate the effect of serum from infertile women with endometriosis on fertilization and embryonic development in a murine IVF model. DESIGN: Pretreatment and post-treatment comparison of murine oocyte fertilization and early embryonic development with the addition of serum supplements from infertile women with endometriosis. SETTING: Tertiary care academic medical center. PATIENTS: Sera from 10 fertile women without endometriosis and 28 infertile women with endometriosis both before and after laser laparoscopy. RESULTS: When compared with serum from fertile women, serum from infertile women with endometriosis inhibited fertilization rates (51% versus 81%) and subsequent embryonic development rates (46% versus 79%). The inhibitory effect was greater as the stage of endometriosis increased. Treatment of endometriosis by laser laparoscopy improved both fertilization (51% versus 56%) and early embryonic development rates (46% versus 58%). CONCLUSIONS: Serum from infertile women with endometriosis inhibits both fertilization and early embryonic development in the murine IVF model. Inhibition of fertilization and early embryonic development rates increases as the stage of endometriosis increases. Improved fertilization and early embryonic development rates are observed after treatment of endometriosis by laser laparoscopy.

Adolescent↗