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PubMed1996

Effect of estrogen-treated porcine ampulla oviductal epithelial cells on early embryonic development in vitro and characterization of their protein synthetic activity.

Recent studies by Buhi et al. have demonstrated that estrogen (E2) is responsible for the induction of de novo synthesis and secretion of certain oviductal secretory proteins (OSP) and inhibition of other OSP in porcine oviductal explant cultures. The present work was undertaken to evaluate the effect of E2-treated oviductal epithelial cell coculture on the development of early porcine embryos derived from in vitro matured and fertilized oocytes. In vitro synthesis of secretory proteins by E2-treated oviductal cells used for coculture was also investigated by one-dimensional (1D) and two-dimensional (2D) sodium dodecyl sulfate (SDS) polyacrylamide gel electrophoresis (PAGE). The results showed that the cleavage rate was significantly enhanced by coculturing fertilized eggs with E2-treated oviductal epithelial cells. The in vitro protein synthetic pattern of oviductal secretory proteins was influenced by E2 treatment. These variations included the disappearance of one protein (82,000 M(r)) and the appearance of another (33,000 M(r)) in the E2-treated group as assessed by 1D-SDS-PAGE. Additional proteins of M(r) 97,000 and an M(r) 36,000-45,000 complex were increased in abundance by the E2 treatment. Analyses by 2D-SDS-PAGE revealed three major E2-dependent proteins, of M(r) 45,000 (pI 5.5), 43,000 (pI 5.5) and a 36,000-45,000 M(r) (pI 4.8) protein complex, whereas polypeptides of M(r) 97,000 (pI 5.1), 36,000 (pI 8.0) and 25,000 (pI 6.8) were inhibited by E2 treatment. The results demonstrated that porcine epithelial cell protein synthetic patterns are influenced by E2 treatment and that estradiol treatment of oviductal cells may increase the rate of zygote cleavage during early development in vitro in pigs.

Animals↗
PubMed1991

Organisation and reorganisation of blood vessels in embryonic development.

The initial establishment of blood vessels is genetically predetermined but it is subsequently supplemented by local and haemodynamic factors. The earliest embryonic vessels arise independently in the mesenchyme of the yolk sac wall, chorion and embryonic disc. The angioblasts aggregate as cords which canalise by a process which includes intracellular vacuolation. Subsequent extension of the network occurs by a combination of (1) in situ formation of new vessels, (2) sprouting and fusion of established neighbouring vessels and (3) invading angioblasts from other regions. As capillaries mature, a basement membrane is established containing collagen IV, laminin, nidogen/entactin, heparan sulphate proteoglycan and a variable amount of fibronectin. Early capillary basement membrane contains more fibronectin which promotes proliferative and migratory activity of endothelium. As vessels mature, the endothelium switches to laminin secretion which causes differentiation including cell attachment, junction formation and establishment of tubes while cell proliferation is suppressed.

Basement Membrane↗
PubMed1996

Otoconial alterations after embryonic development in hypergravity.

The relation between prolonged hypergravity and structural adaptation of otoconia was studied in hamsters (n = 56). Three groups of hamsters (n = 27), were conceived and born in a centrifuge: group 1 (n = 10) 1 month under 2.5 G, group 2 (n = 9) 5 months under 2.5 G and 4 months under 1 G, group 3 (n = 8) 1 month under 2.5 G and 8 months under 1 G. Control hamsters (n = 29) were conceived and born under 1 G (1 month old, n = 7; 9 months old, n = 22). Histological study of the otoconial layers (energy dispersive x-ray element analysis and scanning electron microscopy) showed similar calcium content, size, and shape in utricular and saccular otoconia in all groups. Different were the utricular otoconial size classes, large, medium-sized, and small. The area with small otoconia increased in group 1 (p = 0.002). In group 2, the large otoconial area decreased (p = 0.001) and the medium-sized one increased (p < 0.001). In group 3, the large otoconial area decreased (p = 0.003) and the medium-sized one increased (p = 0.007). For age-related effects we found group 1 with an increased area of large otoconia (p = 0.001) and a decreased medium-sized one compared to groups 2 (p < 0.001) and 3 (p = 0.02). Hypergravity during formation of otoconia does not affect calcium content, size, or shape, but changes relative size of the areas with large, medium-sized, or small otoconia and the development of these areas. This resulted in a structural adaptation to hypergravity.

Animals↗
PubMed1987

The effects of cryopreservation and transfer on embryonic development in the common marmoset monkey, Callithrix jacchus.

Embryos were collected at the 4-10-cell stage from the oviducts (Day 4; Day 1 = ovulation) or as morulae (Day 7) from the uterus of marmosets and frozen in 1.5 M-DMSO (Days 4 and 7) or 1.0 M-glycerol (Day 4 only), using a slow freezing and thawing technique. Of 22 Day-4 embryos frozen in DMSO, 18 were recovered and 16 of these were transferred to 10 synchronized recipients; 7 recipients became pregnant compared with all 7 control recipients receiving 10 unfrozen embryos. Fifteen frozen-thawed morulae were transferred to 9 Day-6 recipients; the pregnancy rate (55.6%) was lower than for control embryos (85.7%). Embryos frozen in glycerol suffered severe osmotic stress during glycerol addition and removal. Of 8 recipients, 3 (37.5%) became pregnant but only one fetus was carried to term. These results on embryo collection, freezing and transfer in the marmoset have important implications for developing improved methods for freezing human embryos and the breeding of endangered primates.

Animals↗
PubMed1988

Synaptic specificity in frog sympathetic ganglia during reinnervation, sprouting, and embryonic development.

B cells and C cells in frog lumbar sympathetic ganglia are specifically innervated by preganglionic B fibers and C fibers, respectively. To explore the mechanisms underlying the formation of these specific synapses, electrophysiological studies were made of sprouting and regenerating synaptic connections following interruption of the preganglionic pathways. Studies were also made of developing connections in tadpole ganglia. After partial denervation (by selective interruption of B fibers), the C fibers sprouted and innervated B cells. When B fibers regenerated, they reinnervated B cells only, and within several weeks, C fiber synapses on B cells were no longer found. After complete denervation (by interruption of both B and C fibers) specific synaptic connections were eventually restored. At least 2 experimentally separable processes underlie this specificity: First, there is a preference for appropriate connections from the outset of reinnervation, seen even in the absence of competition between the 2 groups of preganglionic fibers. Despite this preference, however, some inappropriate synapses are formed. Second, those inappropriate synapses that do arise are eliminated when appropriate synapses are allowed to reform, as a result of competitive interactions between the 2 preganglionic fiber groups. In normally developing tadpole ganglia, B and C cells were not readily distinguishable. The great majority of tadpole neurons were found to be innervated exclusively by either B or C fibers. Some neurons were innervated by both preganglionic fiber groups, a situation virtually never found in adult ganglia. It thus appears that in normal development, as in reinnervation, innervation is by and large selective; inappropriate synapses may form, but they are eliminated during maturation, presumably through competitive interactions.

Animals↗
PubMed1987

Shift of tonotopic organization in brain stem auditory nuclei of the chicken during late embryonic development.

The tonotopic organization of nucleus magnocellularis and nucleus laminaris, second and third order nuclei in the avian auditory system, was mapped in 19-20-day old chick embryos (E19-20). The characteristic frequency recorded at any given location in each nucleus was intermediate between the frequencies observed previously at E17 and one day after hatching. This indicates that tonotopic organization changes during the embryonic as well as the postnatal development of hearing in birds.

Animals↗
PubMed1989

The toxic effect of short exposures to the atmospheric oxygen concentration on early mouse embryonic development.

When culture conditions of mouse preembryos include an O2 concentration of 20%, preembryos that initiate in vitro culture at the 1-cell stage have a lower survival rate than preembryos that are harvested for culture at the 2-cell stage. This "toxic" effect of O2 is not seen at 5% O2 concentrations, suggesting that atmospheric O2 concentrations are toxic to preembryos. The present study examined the effect of short-term exposures to 20% O2, as may occur during in vitro fertilization procedures. The results demonstrated that when 1-cell preembryos were exposed to the atmospheric oxygen concentration for as little as 1 hour, their development was inhibited. Furthermore, such toxic effects did not become apparent until after four to five divisions. The authors conclude that it is critical to minimize exposure of zygotes to the atmospheric O2 concentration for optimal development to continue past the 8- to 16-cell stage, at least in the mouse.

Animals↗
PubMed2001

Impaired maturation, fertilization, and embryonic development of porcine oocytes following exposure to an environmentally relevant organochlorine mixture.

The reproductive health risks related to exposure to persistent organic pollutants in the environment remain controversial. This debate is partly because most studies have investigated only one or two chemicals at a time, whereas populations are exposed to a large spectrum of persistent chemicals in their environment. Using the pig as a toxicological model, we hypothesized that exposing immature cumulus-oocyte complexes to an organochlorine mixture during in vitro maturation (IVM) would adversely affect oocyte maturation, fertilization, and subsequent embryo development. This organochlorine mixture mimics that which contaminates the Arctic marine food chain. Cumulus-oocyte complexes were cultured in IVM medium containing increasing concentrations of the organochlorine mixture, similar to that found in women of highly exposed populations. Organochlorines reduced the quality of cumulus expansion and the viability of cumulus cells in a dose-response manner. The proportion of apoptotic cumulus cells also increased due to organochlorine exposure. Half of the oocytes were fixed after insemination, and the remainders were cultured for 8 days. Concentrations of organochlorines did not affect the rates of oocyte degeneration, sperm penetration, and development to morula. However, incidence of incompletely matured oocytes increased and polyspermy rate decreased, both in a dose-response manner with increasing organochlorine concentrations. Blastocyst formation and number of cells per blastocyst declined with organochlorine concentration. Exposing porcine cumulus-oocyte complexes to an environmentally pertinent organochlorine mixture during IVM disturbs oocyte development, supporting recent concerns that such pollutants harm reproductive health in humans and other mammalian species.

Animals↗
PubMed1995

Expression of catenins during mouse embryonic development and in adult tissues.

Classical cadherins are cell-surface glycoproteins that mediate calcium-dependent cell adhesion. The cytoplasmic domain of these glycoproteins is linked to the cytoskeleton through the catenins (alpha, beta and gamma). The catenins are intracellular polypeptides that are part of a complex sub-membranous network modulating the adhesive ability of the cells. One approach to elucidate the role of these molecules in the cell is to investigate their distribution during mouse development and in adult tissues. This study reports that catenins are widely expressed but in varying amounts in embryos and adult tissues. The expression of all three catenins is most prominent in the adult heart muscle and in epithelia of all developmental stages. In other embryonic and adult tissues, lower expression of catenins was detected, e.g., in smooth muscle or connective tissue. Catenins are coexpressed with various cadherins in different tissues. Gastrulation is the first time during embryogenesis when a discrepancy occurs between the expression of catenins and E-cadherin. E-cadherin expression is suppressed in mesodermal cells but not the expression of catenins. This discrepancy suggests that another cadherin may interact with catenins. Similarly, E-cadherin is generally expressed in adult liver but not in the regions surrounding the central veins. In contrast, catenins are uniformly expressed in the liver, suggesting that they are associated with other cadherins in E-cadherin negative cells. Finally, the three catenins are not always concurrently expressed. For example, in peripheral nerves, only beta-catenin is observable, and in smooth muscle plakoglobin is not detectable.

Animals↗
PubMed1993

Chromosome length and DNA loop size during early embryonic development of Xenopus laevis.

The looped organization of the eukaryotic genome mediated by a skeletal framework of non-histone proteins is conserved throughout the cell cycle. The radial loop/scaffold model envisages that the higher order architecture of metaphase chromosomes relies on an axial structure around which looped DNA domains are radially arranged through stable attachment sites. In this light we investigated the relationship between the looped organization and overall morphology of chromosomes. In developing Xenopus laevis embryos at gastrulation, the bulk of the loops associated with histone-depleted nuclei exhibit a significant size increase, as visualized by fluorescence microscopy of the fully extended DNA halo surrounding high salt treated, ethidium bromide stained nuclei. This implies a reduction in the number of looped domains anchored to the supporting nucleoskeletal structure. The cytological analysis of metaphase plates from acetic acid fixed whole embryos, carried out in the absence of drugs inducing chromosome condensation, reveals a progressive thickening and shortening of metaphase chromosomes during development. We interpret these findings as a strong indication that the size and number of DNA loops influence the thickness and length of the chromosomes, respectively. The quantitative analysis of chromosome length distributions at different developmental stages suggests that the shortening is timed differently in different embryonic cells.

Animals↗
PubMed1986

Changes in insulin and transferrin requirements of pure brain neuronal cultures during embryonic development.

A pure neuronal culture grown in a defined serum-free environment has been developed and characterized. Insulin was the only hormone found to enhance the growth of neurons obtained from embryonic chicken brains during the early proliferative stage, a time when many neurons survived without the addition of any growth factors to the culture. With increasing embryonic age, there was an increase in the number of neurons requiring transferrin. By the time neurons reached a postmitotic state in older brains, they were completely dependent on both insulin and transferrin for survival and growth. Because this culture is free of glial cells and serum, it provides an effective basis for investigating molecular mechanisms underlying neuronal development.

Age Factors↗
PubMed1998

Normal and abnormal embryonic development of the anorectum in human embryos.

In the literature, some controversy still exists about the normal and abnormal development of the human anorectum. Therefore, a three-dimensional and histological study was performed on human embryos. In early anorectal development (< or = 49 days postfertilization), the cloaca plays a crucial role, separated from the amniotic cavity by its cloacal membrane. In the cloaca, the yolk sac/primitive hindgut and allantois/primitive urogenital sinus enter. During the embryonic caudal folding process, incorporation of these structures occurs, including their surrounding extraembryonic mesoderm, which fuses to form the urorectal septum. Consequently, this septum does not grow in the direction of the cloacal membrane, and fusion of these structures is likewise never observed. The cloaca remains as such until the cloacal membrane ruptures by apoptotic cell death. The dorsal part of the cloaca then becomes part of the amniotic cavity, and is by no means involved in the development of the anorectum. The tip of the urorectal septum will become the perineal area. Soon after rupture of the cloacal membrane, during late anorectal development (> or = 49 days postfertilization), a secondary occlusion of the anorectal canal occurs, first due to adhesion, followed by formation of an epithelial "plug" at the level of the anal orifice. Recanalization, by apoptotic cell death, of this secondary occluded anal orifice occurs later during development. Based on these embryological observations, congenital anorectal malformations with an abnormal communication to the exterior are best explained as early embryonic defects. The abnormal communications, usually called fistulae, should be regarded as ectopic anal orifices. Anorectal malformations with the anus in normal position are best explained as late embryonic defects.

Anal Canal↗
PubMed2003

Choline availability during embryonic development alters the localization of calretinin in developing and aging mouse hippocampus.

Choline availability in the diet during pregnancy alters fetal brain biochemistry with resulting behavioral changes that persist throughout the lifetime of the offspring. In the present study, the effects of dietary choline on the onset of GABAergic neuronal differentiation in developing fetal brain, as demarcated by the expression of calcium binding protein calretinin, are described. In these studies, timed-pregnant mice were fed choline supplemented, control or choline deficient AIN-76 diet from day 12-17 of pregnancy and the brains of their fetuses were studied on day 17 of gestation. In the primordial dentate gyrus, we found that pups from choline deficient-dams had more calretinin protein (330% increase), and pups from choline supplemented-dams had less calretinin protein (70% decrease), than did pups from control-dams. Importantly, decreased calretinin protein was still detectable in hippocampus in aged, 24-month-old mice, born of choline supplemented-dams and maintained since birth on a control diet. Thus, alterations in the level of calretinin protein in fetal brain hippocampus could underlie the known, life long effects of maternal dietary choline availability on brain development and behavior.

Aging↗
PubMed2004

Expression patterns of beta1-related alpha integrin subunits in murine lens during embryonic development and wound healing.

PURPOSE: To study the expression patterns of b1-related alpha integrin subunits in murine lens epithelial cells, comparing embryonic fiber differentiation with injury-induced epithelial mesenchymal transition (EMT). METHODS: Adult mice type C57BL/6, pregnant as well as with an eye injured, were sacrificed at different time-course intervals. The embryonic and the injured eyes were obtained and deparaffinized sections of these eyes were processed for immunohistochemistry staining for detection of integrin a subunits. RESULTS: Embryonic lens epithelial cells expressed primarily a3 and a5 subunits, whereas embryonic fiber cells expressed a2, a5, and a6 subunits. Adult lens epithelial cells expressed a3, and a6 subunits,whereas injured lens cells expressed a2, a3, and a6 integrin subunits. CONCLUSIONS: The phenotypic changes of lens epithelial cells during embryonic fiber differentiation and EMT are characterized by different expression of integrin subunits as a result both of the altered extracellular matrix conditions and of the altered cell signaling pathways recruited in each process.

Animals↗
PubMedDate not supplied

[The temperature dependence of selection efficiency and the expression of the genes controlling the rate of embryonic development in Drosophila melanogaster].

We have already shown that selection of heterogeneous D. melanogaster populations for the rate of embryogenesis at 32 degrees C may produce populations, in which 50% of the larvae are hatched 20-40 min earlier, i.e., 2-4% more rapidly than, in the control. Highly inbred strains were obtained from the selected populations and develop 5-7% more rapidly than the control populations. Here we studied separately the effects of temperature on the efficiency of selection and expression of the selected genotype. With this in view, multiple (9-15 rounds) selection of the first 10% of the larvae was performed at 17, 25, and 32 degrees C and the mean duration of embryogenesis (hatching of 50% larvae) at these three temperatures was determined in the entire selected population. Selection proved to be almost equally efficient at all temperatures. On the contrary, expression of the selected genotypes markedly depended on temperature: the rate of embryogenesis of the selected populations exceeded that in the control at 17 degrees C by 1.1%, at 25 degrees C by 2.5%, and at 32 degrees C by 3.5%. In the inbred strains this dependence was even more pronounced: 1.2%, 2.7%, and 5.7%, respectively. The temperature dependence of expression of the genes collected by selection and coding for accelerated development means that these genes affect the rate of development as the function of temperature by changing the angle of the curve inclination. Possible mechanisms of this phenomenon are discussed.

Animals↗
PubMed2002

Modulation of CREB activity by the Rho GTPase regulates cell and organism size during mouse embryonic development.

Rho GTPases regulate several aspects of tissue morphogenesis during animal development. We found that mice lacking the Rho-inhibitory protein, p190-B RhoGAP, are 30% reduced in size and exhibit developmental defects strikingly similar to those seen in mice lacking the CREB transcription factor. In p190-B RhoGAP-deficient mice, CREB phosphorylation is substantially reduced in embryonic tissues. Embryo-derived cells contain abnormally high levels of active Rho protein, are reduced in size, and exhibit defects in CREB activation upon exposure to insulin or IGF-1. The cell size defect is rescued by expression of constitutively activated CREB, and in wild-type cells, expression of activated Rho or dominant-negative CREB results in reduced cell size. Together, these results suggest that activity of the Rho GTPase modulates a signal from insulin/IGFs to CREB that determines cell size and animal size during embryogenesis.

Animals↗
PubMed1993

Embryonic development in vitro following short-duration exposure to heat.

Gestation day (GD) 10 rat embryos (10-12 somites) were exposed in vitro for 10 to 25 minutes at 42 or 43 degrees C and evaluated 24 hrs later for alterations in growth and specific morphological parameters, using a modified Brown-Fabro (Brown and Fabro: Teratology, 24:65-78, '81) scoring system that allowed evaluation of development relative to gestational age. At 42 degrees C, crown-rump length appeared to be particularly sensitive, responding to only 10 mins exposure. A 15-min exposure resulted in decreased total protein, somite number and morphological score. No system was uniquely sensitive, since all parameters demonstrated some degree of response. Rather, systems affected were those that would be developing most rapidly at this time in gestation. At 43 degrees C, all of the parameters measured were affected by a 10-min exposure. These results demonstrate alterations in vitro after much shorter exposure periods than previously reported on GD10, which may be due, in part, to the use of a modified scoring system that permitted the evaluation of graded individual end point changes relative to gestational age. The response patterns demonstrated a clear temperature- and exposure duration-dependency, with a shift from a more shallow duration-response curve to a more dramatic inhibition of development as temperature increased from 42 degrees C to 43 degrees C.

Animals↗