Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Embryos”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

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

At least 1,513 records · Page 84Linked to original sources
PubMed1998

Regulation of preimplantation development of bovine embryos by interleukin-1beta.

Experiments were performed to determine the actions of recombinant bovine interleukin-1beta (IL-1beta) on the growth of preimplantation embryos. In the first series of studies, IL-1beta was added at 8-10 h after insemination, and the percentage of oocytes developing to the blastocyst stage was evaluated. IL-1beta increased development to the blastocyst stage when embryos were cultured at high density ( approximately 25-30 embryos/drop) but decreased or had no effect on development when cultured at low density ( approximately 10 embryos/drop). Thus, the positive effect of IL-1beta depends upon some other embryo-derived product. The effect of IL-1beta on embryonic development was maintained in completely denuded embryos, indicating that cumulus cells do not mediate the actions of IL-1beta. Maximum development of embryos cultured at approximately 25-30/drop occurred at 0.1-1 ng/ml; 10 ng/ml was less effective. Addition of IL-1beta to groups of approximately 25-30 embryos/drop at 8-10 h after insemination also increased embryo cell number at Day 5 postinsemination by increasing the proportion of embryos that reached the 9- to 16-cell stage. However, IL-1beta had no effect on the proportion of blastocysts when added at Day 5 postinsemination. Thus, IL-1beta probably acts to increase blastocyst numbers by exerting actions on embryo growth before Day 5. In contrast to its effect on embryos, addition of IL-1beta during oocyte maturation did not affect cumulus expansion, cleavage rate of oocytes, or subsequent development to the blastocyst stage. In conclusion, IL-1beta can modulate growth of bovine embryos at early stages of development in a manner dependent upon embryo density.

Animals↗
PubMed1999

Ontogeny of expression of a receptor for platelet-activating factor in mouse preimplantation embryos and the effects of fertilization and culture in vitro on its expression.

Platelet-activating factor (PAF; 1-o-alkyl-2-acetyl-sn-glycero-3-phosphocholine) is a potent ether phospholipid. It is one of the preimplantation embryo's autocrine growth/survival factors. It may act via a G protein-linked receptor on the embryo; however, the evidence for this is conflicting. The recent description of the intracellular form of the PAF:acetlyhydrolase enzyme as having structural homology with G proteins and Ras also suggests this as a potential intracellular receptor/transducer for PAF. This study used reverse transcription-polymerase chain reaction to examine the ontogeny of expression of the genes for these proteins in the oocyte and preimplantation-stage embryo. Transcripts for the G protein-linked PAF receptor were detected in the late 2-cell-stage embryo and in all stages from the 4-cell stage to blastocysts. They were also present in unfertilized oocytes and newly fertilized zygotes but only at relatively low levels. The incidence of expression was generally low and variable in late zygotes and early 2-cell embryos. Expression past the 2-cell stage was alpha-amanitin sensitive. The results indicated that mRNA for this receptor is a maternal transcript that was degraded during the zygote-2-cell stage. New expression of the receptor transcript required activation of the zygotic genome. Fertilization of embryos in vitro caused this transcript not to be expressed in the zygote. Culture of zygotes (irrespective of their method of fertilization) caused expression from the zygotic genome to be retarded by more than 24 h. This retardation did not occur if culture commenced at the 2-cell stage. The transcripts for the subunits of intracellular PAF:acetylhydrolase were not detected in oocytes or at any stage of embryo development examined, despite their being readily detected in control tissue. This study confirms the presence of the G protein-linked PAF receptor in the 2-cell embryo and describes for the first time its normal pattern of expression during early development. The adverse effects of in vitro fertilization (IVF) and embryo culture on the expression of this transcript may be a contributing factor for the poor viability of embryos produced in this manner. The reduced expression of PAF-receptor mRNA following IVF predicts that such embryos may have a deficiency in autocrine stimulation and also suggests that supplementation of growth media with exogenous PAF would be only partially beneficial. The effect of IVF and culture may also explain the conflicting literature.

Animals↗
PubMed1988

Developmental appearance of factors that bind specifically to cis-regulatory sequences of a gene expressed in the sea urchin embryo.

Previous gene-transfer experiments have identified a 2500-nucleotide 5' domain of the CyIIIa cytoskeletal actin gene, which contains cis-regulatory sequences that are necessary and sufficient for spatial and temporal control of CyIIIa gene expression during embryogenesis. This gene is activated in late cleavage, exclusively in aboral ectoderm cell lineages. In this study, we focus on interactions demonstrated in vitro between sequences of the regulatory domain and proteins present in crude extracts derived from sea urchin embryo nuclei and from unfertilized eggs. Quantitative gel-shift measurements are utilized to estimate minimum numbers of factor molecules per embryo at 24 hr postfertilization, when the CyIIIa gene is active, at 7 hr, when it is still silent, and in the unfertilized egg. We also estimate the binding affinity preferences (Kr) of the various factors for their respective sites, relative to their affinity for synthetic DNA competitors. At least 14 different specific interactions occur within the regulatory regions, some of which produce multiple DNA-protein complexes. Values of Kr range from approximately 2 x 10(4) to approximately 2 x 10(6) for these factors under the conditions applied. With one exception, the minimum factor prevalences that we measured in the 400-cell 24-hr embryo nuclear extracts fell within the range of 2 x 10(5) to 2 x 10(6) molecules per embryo, i.e., a few hundred to a few thousand molecules per nucleus. Three developmental patterns were observed with respect to factor prevalence: Factors reacting at one site were found in unfertilized egg cytoplasm at about the same level per egg or embryo as in 24-hr embryo nuclei; factors reacting with five other regions of the regulatory domain are not detectable in egg cytoplasm but in 7-hr mid-cleavage-stage embryo, nuclei are already at or close to their concentrations in the 24-hr embryo nuclei; and factors reacting with five additional regions are not detectable in egg cytoplasm and are low in 7-hr embryo nuclei, i.e., less than or equal to 10% per embryo of the level they attain in 24-hr embryo nuclei. The rise in concentration of factors of the latter class could provide the proximal cause for the temporal activation of the CyIIIa gene at the early blastula stage.

Animals↗
PubMed1995

Experimentally derived model for the locomotor pattern generator in the Xenopus embryo.

1. Simulations of Xenopus embryo spinal neurons were endowed with Hodgkin-Huxley-style models of voltage-dependent Na+, Ca2+, slow K+ and fast K+ currents together with a Na(+)-dependent K+ current. The parameters describing the activation, inactivation and relaxation of these currents were derived from previous voltage-clamp studies of Xenopus embryo spinal neurons. Each of the currents was present at realistic densities. 2. The model neurons fired repetitively in response to current injection. The Ca2+ current was essential for repetitive firing in response to current injection. The fast K+ current appeared mainly to control spike width, whereas the slow K+ current exerted a powerful influence on the reptitive firing properties of the neurons without markedly affecting spike width. 3. The properties of the model neurons could be made more consistent with those previously reported for Xenopus embryo neurons during intracellular recordings in vivo, if the shunting effect of the sharp microelectrode was incorporated into the model. 4. The model neurons were then used to create a simplified version of the spinal network that controls swimming in the frog embryo. This model network could generate the motor pattern for swimming: the activity between the left and right sides alternated with a cycle period that varied from 50 to 120 ms. This is very similar to the range of cycle periods observed in the real embryo. The shunting effect of the microelectrode was once again taken into account. 5. Reductions of the K+ currents perturbed the motor pattern and gave three forms of aberrant motor activity very similar to those previously seen during the application of K+ channel blockers to the real embryo. The ability to generate the correct motor pattern for swimming in the model depended on the balance between the K+ currents and the inward Na+ and Ca2+ currents rather than their absolute values. 6. The model network could generate a motor pattern for swimming over a very wide range of excitatory (2-10 nS) and inhibitory (2-400 nS) synaptic strengths. Rough estimates of the physiological synaptic strengths in the real circuit (around 20-60 nS for inhibition and 2-5 nS for excitation) fall within the range of synaptic strengths that gave simulation of the swimming motor pattern in the model. 7. The cycle period of the motor activity in the model shortened either as the excitatory synapses were strengthened or as the inhibitory synapses were weakened. 8. The prediction that the strength of the mid-cycle inhibition determines cycle period has been tested by using low levels of strychnine to reduce glycinergic reciprocal inhibition in a graded manner in the real embryo. As the inhibition was reduced, the cycle period of fictive swimming in the embryo shortened by amounts very close to those predicted by the model. 9. This new experimentally derived model can replicate many of the known features of fictive swimming in the real embryo and may be of value as an analytical tool in attempting to understand how the spinal circuitry of the Xenopus embryo and related amphibian embryos control a variety of motor behaviours.

Animals↗
PubMed2005

Follicular fluid and cumulus cells synergistically improve mouse early embryo development in vitro.

The development of preimplantation mammalian embryos in vitro is less than optimal. Follicular fluid and cumulus cells have both been used independently, to improve preimplantation embryo quality in culture. This study was undertaken to evaluate the influence of a cumulus cell monolayer in human follicular fluid on mouse early embryo development in vitro. One-cell embryos were obtained from NMRI mice after superovulation with eCG and hCG. Cumulus cells were prepared from mouse egg-cumulus mass. These cells were separated from red blood cells using a Percoll gradient. Follicular fluid was collected from patients undergoing an IVF program during oocyte pick-up. The cumulus cell monolayer was prepared in follicular fluid (FC) and Ham's F10 (HC). Mouse one-cell embryos were cultured in FC, HC, Ham's F10 (HF) and follicular fluid (FF) for 120 h. Only 10.5% of embryos passed the two-cell block in HF. However, the proportions of embryos passing the two-cell block were 23.1%, 21.4% and 68.5% in FF, HC, and FC treatments, respectively; which were significantly different from HF (p<0.05). The differences between FC and the two other treatments were also significant (p<0.001). In FC, 33.7% of one-cell embryos continued to grow to the blastocyst stage whereas only 2.1% and 1.9% of one-cell embryos in FF and HC reached this stage and no embryos developed to blastocyst in HF. The proportion of blastocysts in FC was significantly higher than all other treatments (p<0.001). It can be concluded that follicular fluid and cumulus cells in monolayer form synergistically improve the early embryo culture condition.

Animals↗
PubMed1992

The effect of experimental infection of mouse preimplantation embryos with paramyxovirus Sendai.

Zona-intact and zona-free mouse embryos at the morula stage were exposed to Sendai virus in vitro, and then transferred to the uteri of recipient foster mothers. Both embryos developed into expanded blastocyst stage after 48 hr of culture. Zona-intact embryos were resistant to infection and subsequent transfer resulted in the development of fetuses, indicating that the zona pellucida plays a role of a barrier to virus infection. On the other hand, zona-free embryos were susceptible to infection and only one fetus out of 64 transfers developed to term. Implantation sites were scarcely observed in the uteri of the foster mothers that received zona-free embryos, suggesting that most of the embryos did not develop after embryo transfer. Sendai virus was shed in the culture fluid of the zona-free embryos indicating viral replication in the embryonic cells. By immunofluorescence assay, viral antigens were detected in the embryos, tissues of the fetus and implantation site derived from the zona-free embryos. These findings indicate that replication of Sendai virus in the embryonic cells interfere with early embryonic development and fetal growth of the embryo.

Animals↗
PubMed1989

An improved culture medium supports development of random-bred 1-cell mouse embryos in vitro.

One-cell CF-1 x B6SJLF1/J embryos, which usually exhibit a 2-cell block to development in vitro, have been cultured to the blastocyst stage using CZB medium and a glucose washing procedure. CZB medium is a further modification of modified BMOC-2 containing an increased lactate/pyruvate ratio of 116, 1 mM-glutamine and 0.1 mM-EDTA but lacking glucose. Continuous culture of one-cell embryos in CZB medium allowed 83% of embryos to develop beyond the 2-cell stage of which 63% were morulae at 72 h of culture, but blastocysts did not develop. However, washing embryos into CZB medium containing glucose after 48 h of culture (3-4-cell stage) was sufficient to allow development to proceed, with 48% of embryos reaching the blastocyst stage by 96 h of culture. Exposure of embryos to glucose was only necessary from the 3-4-cell stage through the early morula stage since washing back into medium CZB without glucose at 72 h of culture still promoted the development of 50% of embryos to the blastocyst stage. The presence of glucose in this medium for the first 48 h of culture (1-cell to 4-cell stage) was detrimental to embryo development. Glutamine, however, exerted a beneficial effect on embryo development from the 1-cell to the 4-cell stage although its presence was not required for development to proceed during the final 48 h of culture. Blastocysts which developed under optimum conditions contained an average of 33.7 total cells. The in-vitro development of 1-cell embryos beyond the 2-cell stage in response to the removal of glucose and the addition of glutamine to the culture medium suggests that glucose may block some essential metabolic process, and that glutamine may be a preferred energy substrate during early development for these mouse embryos.

Animals↗
PubMed1996

A comparison of the number of inner cell mass and trophectoderm cells of preimplantation Meishan and Yorkshire pig embryos at similar developmental stages.

Day 12 blastocysts from Meishan gilts contain fewer cells than do day 12 blastocysts from Yorkshire gilts. The purpose of this study was to evaluate the effect of breed on the relative numbers of inner cell mass and trophectoderm cells in Meishan and Yorkshire embryos at similar stages. Embryos were collected on days 5.5-6.5 of gestation and were subjected to image analysis and differential cell staining. No breed differences were detected in the thickness of zona pellucida or in the areas of the perivitelline space, embryo proper, blastocoel and inner cell mass at any of the developmental stages examined (compact morula, early blastocyst or blastocyst). However, differences were observed in the pattern of growth of embryos from Meishan versus Yorkshire gilts. The total number of cells of Meishan embryos from Meishan gilts increased progressively from the compact morula through the blastocyst stage, whereas the total number of cells of embryos from Yorkshire gilts remained constant from compact morula through to early blastocyst, and then increased markedly from the early blastocyst to the blastocyst stage. At the blastocyst stage, Meishan embryos contained fewer (P < 0.05) cells than did Yorkshire embryos, and this lower number of cells was due entirely to fewer (P < 0.05) trophectoderm cells. As the number of inner cell mass cells increased during embryonic growth, Meishan embryos exhibited a slower (P < 0.02) increase in the number of trophectoderm cells than did Yorkshire embryos. These results demonstrate that the reduced number of cells present in Meishan embryos results from a selective reduction in the number of trophectoderm, but not inner cell mass, cells.

Animals↗
PubMed2004

Differences in heat tolerance between preimplantation embryos from Brahman, Romosinuano, and Angus breeds.

Exposure to 41 degrees C reduces development of embryos of heat-sensitive breeds (Holstein and Angus) more than for embryos of the heat-tolerant Brahman breed. Here it was tested whether embryonic resistance to heat shock occurs for a thermotolerant breed of different genetic origin than the Brahman. In particular, the thermal sensitivity of in vitro produced embryos of the Romosinuano, a Bos taurus, Criollo-derived breed, was compared to that for in vitro produced Brahman and Angus embryos. At d 4 after insemination, embryos > or = 8 cells were randomly assigned to control (38.5 degrees C) or heat shock (41 degrees C for 6 h) treatments. Heat shock reduced the proportion of embryos that developed to the blastocyst stage on d 8 after insemination. At 38.5 degrees C, there were no significant differences in development between breeds. Among embryos exposed to 41 degrees C, however, development was lower for Angus embryos than for Brahman and Romosinuano embryos. Furthermore, an Angus vs. (Brahman + Romosinuano) x temperature interaction occurred because heat shock reduced development more in Angus (30.3 +/- 4.6% at 38.5 degrees C vs. 4.9 +/- 4.6% at 41 degrees C) than in Brahman (25.1 +/- 4.6% vs. 13.6 +/- 4.6%) and Romosinuano (28.3 +/- 4.1% vs. 17.5 +/- 4.1%). Results demonstrate that embryos from Brahman and Romosinuano breeds are more resistant to elevated temperature than embryos from Angus. Thus, the process of adaptation of Brahman and Romosinuano breeds to hot environments resulted in both cases in selection of genes controlling thermotolerance at the cellular level.

Animals↗
PubMed2000

Effects of embryotrophic factors on the embryogenesis and organogenesis of mouse embryos in vitro.

In order to study embryogenesis and organogenesis in vitro, two cell mouse embryos were cultured with alpha-MEM supplemented 10% FCS and embryotrophic factors (ETFs). The ETFs were separated from the conditioned medium of a SKG-II-SF cell line derived from a human uterine cervical epidermoid carcinoma. IL-1 beta, IL-6, IL-8, EGF, GH, PDGF-AB, basic FGF, VEGF were also detected in the conditioned media of this cell line. Using ETFs and a 10% FCS supplemented culture medium, 23% of the mouse two cell stage embryos developed to the bilaminar disc stage, 13% to the trilaminar germ disc stage, 9% were observed with blood islets in the yolk sac, and the heart beat was noted in 7% (28 embryos) of the embryos. Furthermore, primordial organs, such as the liver, heart, kidney, notochord, retina-like structure, etc. were observed. Usually, structures associated with the primordial streak stage (bilaminar germ disc embryo) developed in vitro using ETFs from two cell stage embryos. These closely resemble structures found at the same stage in the normal embryo in vivo. After the primordial streak stage, the cultured embryos showed no resemblance to the same stage in normal embryos. None of the external appearances of these embryos appeared normal. On the other hand, trilaminar disc stage embryos never developed when using only a 10% FCS supplemented culture system.

Animals↗
PubMed2001

Ribosomal RNA gene expression and chromosome aberrations in bovine oocytes and preimplantation embryos.

This review focuses on the key features of development of the bovine oocyte and embryo, with comparisons of the developmental characteristics of embryos produced in vivo and in vitro. The oocyte is transcriptionally quiescent in the primordial and primary follicle. In the secondary follicle transcription is initiated in the oocyte and a ribosome-synthesizing nucleolus is established in this cell. Transcription and nucleolar activity are enhanced in the tertiary follicle during oocyte growth. When the oocyte reaches approximately 110 microm in diameter, corresponding to a follicle of about 3 mm in diameter, transcription ceases and the nucleolus is inactivated, forming a dense spherical remnant. During the final phase of follicular dominance this remnant becomes vacuolated and, in conjunction with resumption of meiosis, it disperses. The rRNA genes are apparently re-activated during the four-cell stage, that is, the third cell cycle after fertilization, but a nucleolus is not formed. During the subsequent cell cycle, that is, during the eight-cell stage, ribosome-synthesizing nucleoli are again established. Bovine embryos produced in vitro apparently display the same pattern of nucleolus development as that in embryos developed in vivo. Examination of the ploidy of embryonic cells using fluorescence in situ hybridization has revealed that the production of bovine embryos in vitro is associated with increased chromosome aberrations in the embryos. Blastocysts produced in vitro display a significantly higher rate of mixoploidy, that is, when the embryo consists of both normal diploid and abnormal polyploid cells, than that in embryos developed in vivo. The rate of mixoploidy among embryos produced in vitro increases with increasing developmental stage. Moreover, after fertilization in vitro, initially there is a high rate of 'true' polyploidy, that is, when all cells of the embryos are polyploid. However, the polyploid embryos are eliminated before they cleave beyond the eight-cell stage, the stage at which major activation of the embryonic genome occurs in cattle.

Animals↗
PubMed2001

[Transforming growth factor alpha (TGFalpha) modulates the effect of genomic imprinting and prolongs the development of parthenogenetic murine embryos].

The effect of transforming growth factor alpha (TGF alpha) on the development of diploid parthenogenetic mouse embryos (CBA x C57BL/6)F1 was studied. The embryos were in vitro treated with the TGF alpha at the stage of morula. Upon reaching the blastocyst stage, each embryo was implanted into uterus of a pseudopregnant female. At a dose of 5 ng/ml, the TGF alpha was found to improve development of parthenogenetic embryos before implantation, increase significantly the number of developing blastocysts, and promote embryo implantation into uterus. After treatment with TGF alpha at a dose of 10 ng/ml, 4% of parthenogenetic embryos reached the stage of 30-45 somites and had forelimb and hindlimb buds; the embryo size from vertex to sacrum was 2.0 to 3.8 mm. A well-developed placenta was observed in 6% of TGF alpha-treated parthenogenetic embryos that reached the somite stages. In the parthenogenetic embryos with the most prominent development (42-45 somites) treated with 10 ng/ml of TGF alpha, the placental diameter was 4.0 to 4.2 mm on day 12 of gestation, which is close to the placental size of the normal (fertilized) 11-day-old mouse embryos. Our results suggest that endogenous TGF alpha can modulate the effects of genomic imprinting significantly improving formation of trophoblast derivatives and promoting longer postimplantation development of parthenogenetic embryos.

Animals↗
PubMed2002

Regeneration from mature and immature embryos and transient gene expression via Agrobacterium-mediated transformation in emmer wheat (Triticum dicoccum Schuble).

The present study establishes a regeneration protocol and optimizes conditions for Agrobacterium-mediated transformation of the tetraploid emmer wheat, Triticum dicoccum. Regeneration from mature and immature embryos was accomplished as a two-step process involving callus induction in the presence of 2,4-D followed by regeneration on a 2,4-D free, cytokinin-containing medium (RM1). Higher concentrations of 2,4-D (4 mg/l) though conducive for callusing (89.39% in mature embryos and 96% in immature embryos) proved detrimental for further regeneration. At lower 2,4-D (1 mg/ml) although callusing was suboptimal, (56.8% and 84% from mature and immature embryos, respectively) the regeneration response was the highest on RM1 medium (64.4% and 56.6% from mature and immature embryos, respectively). Overall, the regeneration response of immature embryos was lower than the mature embryos by 10-12%. Due to the ease of availability of mature embryos the mature embryo-derived calli were chosen as the target tissue for Agrobacterium-mediated transformation in the two Indian varieties DDK1001 and DDK1009. Histochemical GUS expression revealed the suitability of the mature embryo-derived calli for such investigations. Of the CaMV35S and Act1 promoters employed, the monocot promoter Act1 displayed higher GUS gene activity in the mature embryo derived calli when co-cultivated with LBA4404 (pBI101::Act1).

2,4-Dichlorophenoxyacetic Acid↗
PubMed2004

Modified laser-assisted zonal opening method for human embryo biopsy in preimplantation genetic diagnosis: preliminary experience.

OBJECTIVE: To test the safety and efficacy of a modified laser-assisted zonal opening method for human embryo biopsy. STUDY DESIGN: The embryo was treated with a modified method to create an ample perivitelline space between the zona pellucida and underlying blastomeres. This was done to protect the blastomeres from damage by laser treatment of the zona pellucida. Subsequently, the zona pellucida was completely perforated using a diode laser, and the targeted blastomere was aspirated. In vitro embryo development of the 40 biopsied embryos was compared with that of 322 corresponding control embryos without embryo biopsy. RESULTS: Forty targeted blastomeres were successfully extracted from 40 human embryos. The incidence of embryo development to the blastocyst stage was not different between the biopsied and nonbiopsied groups (55% vs. 54.3%). Furthermore, the percentage of top-scoring blastocysts from biopsied embryos was also similar to that of control embryos (77.3% vs. 78.9%). CONCLUSION: These preliminary results demonstrate that the modified technique for human embryo biopsy in preimplantation genetic diagnosis is simple and safe.

Adult↗
PubMed1987

Morphometric analysis of the forebrain anomalies in the delayed Splotch mutant embryo.

The early development of delayed Splotch mouse embryos was examined histologically using scanning electron microscopy and morphometric techniques. Embryos obtained from matings of mice heterozygous for the delayed Splotch gene exhibited a high incidence of lumbosacral (25%) or cephalic (7%) neural tube defects. The lumbosacral neural tube defects extended from the posterior neuropore region to the tip of the tailbud; cephalic neural tube closure defects were found in the hindbrain and midbrain regions. The frontal region of affected embryos was abnormal in that it was reduced in size, particularly in the developing midface. Histologically, the forebrain region of affected embryos appeared reduced, and the luminal surface of the neuroepithelium was often irregular and infolded. To quantify these alterations and to determine their contribution to the final form of the region, size and areal measurements were recorded and served as input for principal component and cluster analytic techniques. In affected embryos, significant reductions were found in lumen size, in neuroepithelial area but not thickness, and in overall area of forebrain but not hindbrain. Principal component analysis of data from unaffected embryos produced two factors, one containing hindbrain variables and the second forebrain variables; for the affected embryos, three factors were extracted. The first loaded on variables that measured the thickness and area of the neuroepithelium, the second on forebrain variables, and the third on hindbrain variables. Factor scores were then generated from a pooled analysis of normal and affected cases and were analyzed using cluster analysis. Three clusters were identified: one contained eight affected embryos with cephalic neural tube defects; another contained nine affected embryos with lumbosacral neural tube defects and five normal embryos; and the final cluster contained ten unaffected embryos. These results suggest a major role of the delayed Splotch gene on the neuroepithelium itself and support the suggested role of cerebrospinal fluid pressure in normal forebrain histogenesis.

Animals↗
PubMed1984

Plasma membrane regionalization and compaction of mouse cleaving embryos: effect of microtubule and microfilament inhibitors.

Two-cell embryos were incubated during 44 h in media containing either microtubule or microfilament inhibitors. The lowest doses that inhibit cleavage were found to be 0.5 micrograms/ml for colchicine and colcemid, 5 micrograms/ml for cytochalasin B and 0.5 micrograms/ml for cytochalasin D. After incubation with the minimal doses of these drugs, embryos were either fixed immediately or transferred to fresh media without drugs and cultured for different times before fixation. Then, embryos were processed for scanning electron microscopy. Following incubation with microtubule inhibitors, less than 10% of the embryos were compacted and about 20% became so in fresh medium. Regionalization was revealed by the cytochemical demonstration of alkaline phosphatase or 5'-nucleotidase on the apposing surfaces of blastomeres in 50% of the embryos, including all those that were compacted. By scanning microscopy microvilli were seen evenly distributed on the embryo surface, as they are observed in normal 2-cell embryos. Following incubation with microfilament inhibitors, few embryos were compacted and about 90% compacted within 4 h in fresh medium. Alkaline phosphatase activity was detected between blastomeres in all compacted embryos and in one half of those still uncompacted. Scanning microscopy showed patches of microvilli on the outer surface which had become otherwise smooth. During incubation in fresh medium, microvilli concentrated in two large patches placed at the antipodes of the embryo. From these results we conclude that cytokineses is not required for cell membrane regionalization, that blastomeres regionalize before they compact, that microtubule and microfilament inhibitors affect differently the array of microvilli on the external surface of arrested embryos.

5'-Nucleotidase↗
PubMed1995

The chromosome pattern of embryos derived from tripronuclear zygotes studied by cytogenetic analysis and fluorescence in situ hybridization.

OBJECTIVE: To detect the chromosomal complement of embryos, which developed from tripronuclear zygote, using nonradioactive centromeric probes. DESIGN: The chromosome pattern of embryos developing from tripronuclear zygote, studied by fluorescence in situ hybridization, was compared with that of embryos studied by standard cytogenetic methods. SETTING: These embryos were obtained from superovulated patients undergoing IVF treatment. RESULTS: We have attempted to examine the chromosomal complement of 72 embryos derived from tripronuclear zygotes using both traditional cytogenetic analysis and fluorescence in situ hybridization. Of these 72 embryos, 22 were analyzed with fluorescence in situ hybridization and 50 were analyzed with traditional cytogenetic analysis. For fluorescence in situ hybridization analysis, probes specific for the centromeric regions of chromosomes 1, 16, and X were used, with results being obtained from 18 embryos. One embryo was haploid (5.6%), five were triploid (27.8%), and one was hexaploid (5.6%). Eleven (61%) embryos were mosaic. Traditional cytogenetic analysis could be performed on 25 of 50 embryos. Five (20%) were haploid, one (4%) was diploid, seven (28%) were triploid, one (4%) were tetraploid, and two were hexaploid. Nine (36%) were mosaic. CONCLUSION: These findings indicate that not all tripronuclear human zygotes develop into triploid embryos. This study also demonstrates the usefulness of fluorescence in situ hybridization for preimplantation diagnosis and screening for chromosome abnormalities.

Cell Nucleus↗
PubMed1993

Development to blastocysts of one- to two-cell equine embryos after coculture with uterine tubal epithelial cells.

Development of 1- to 2-cell in vivo fertilized equine embryos cultured with or without uterine tubal epithelial cells (UTEC) was studied. One- to 2-cell embryos (n = 26) were collected surgically from the uterine tubes of pony mares 1 day after ovulation. Four- to 8-cell embryos (n = 9) were collected 2 days after ovulation. Presumptive zygotes and 2-cell embryos were cultured with (n = 17) or without (n = 9) UTEC, and all 4- to 8-cell embryos were cocultured with UTEC as positive controls. Uterine tubal epithelial cells were used as cell suspensions within 2 weeks after initiation of cultures. Embryos were cultured to blastocysts or until the embryo had morphologic degeneration. Six presumptive zygotes failed to cleave in vitro. Development to blastocysts of 1-cell (4 of 11) and 2-cell (2 of 6) embryos cocultured with UTEC was similar. Coculture of 1- to 2-cell embryos with UTEC significantly (P = 0.05) improved development to blastocysts, compared with culture in medium alone (35 vs 0%, respectively); however, development to blastocysts of 1- to 2-cell embryos cocultured with UTEC was less (P < 0.025) than that of 4- to 8-cell embryos cocultured with UTEC (35 vs 89%, respectively).

Analysis of Variance↗