ABSTRACT
Japan is lagging in cervical cancer prevention. The effectiveness of a self-sampling human papillomavirus (HPV) test, a possible measure to overcome this situation, has not yet been evaluated. A randomized controlled trial was performed to evaluate the effectiveness of a self-sampling HPV test on detection of cervical intraepithelial neoplasia grade 2 or worse (CIN2+) and screening uptake. Women between 30 and 58 years old who did not participate in the cervical cancer screening program for ≥3 years were eligible and assigned to the intervention group (cytology or self-sampling HPV test) or control group (cytology). Participants assigned to the intervention group were sent a self-sampling kit according to their ordering (opt-in strategy). A total of 7337 and 7772 women were assigned to the intervention and control groups, respectively. Screening uptake in the intervention group was significantly higher than that in the control group (20.0% vs. 6.4%; risk ratio: 3.10; 95% confidence interval [CI]: 2.82, 3.42). The compliance rate with cytology triage for HPV-positive women was 46.8% (95% CI: 35.5%, 58.4%). CIN2+ was detected in five and four participants in the intervention and control groups, respectively; there was no difference for intention-to-screen analysis (risk ratio: 1.32; 95% CI: 0.36, 4.93). Self-sampling of HPV test increased screening uptake; however, no difference was observed in the detection of CIN2+, probably due to the low compliance rate for cytology triage in HPV-positive women. Efforts to increase cytology triage are essential to maximize precancer detections.
Subject(s)
Early Detection of Cancer , Papillomavirus Infections , Uterine Cervical Dysplasia , Uterine Cervical Neoplasms , Humans , Female , Middle Aged , Adult , Papillomavirus Infections/diagnosis , Papillomavirus Infections/virology , Papillomavirus Infections/epidemiology , Japan/epidemiology , Uterine Cervical Neoplasms/diagnosis , Uterine Cervical Neoplasms/virology , Early Detection of Cancer/methods , Uterine Cervical Dysplasia/diagnosis , Uterine Cervical Dysplasia/virology , Uterine Cervical Dysplasia/epidemiology , Papillomaviridae/isolation & purification , Vaginal Smears/methods , Specimen Handling/methods , Mass Screening/methods , Precancerous Conditions/diagnosis , Precancerous Conditions/virology , Human Papillomavirus VirusesABSTRACT
PURPOSE: In terms of medical policy for cervical cancer prevention, Japan lags far behind other industrialized countries. We initiated a randomized controlled trial to evaluate the self-sampling human papillomavirus (HPV) test as a tool to raise screening uptake and detection of pre-cancer. This study was conducted to explore the acceptability and preference of self-sampling using a subset of the data from this trial. METHODS: A pre-invitation letter was sent to eligible women, aged 30-59 years who had not undergone cervical cancer screening for three or more years. After excluding those who declined to participate in this trial, the remaining women were assigned to the self-sampling and control groups. A second invitation letter was sent to the former group, and those wanting to undergo the self-sampling test ordered the kit. A self-sampling HPV kit, consent form, and a self-administered questionnaire were sent to participants who ordered the test. RESULTS: Of the 7,340 participants in the self-sampling group, 1,196 (16.3%) administered the test, and 1,192 (99.7%) answered the questionnaire. Acceptability of the test was favorable; 75.3-81.3% of participants agreed with positive impressions (easy, convenient, and clarity of instruction), and 65.1-77.8% disagreed with negative impressions (painful, uncomfortable, and embarrassing). However, only 21.2% were confident in their sampling procedure. Willingness to undergo screening with a self-collected sample was significantly higher than that with a doctor-collected sample (89.3% vs. 49.1%; p<0.001). Willingness to undergo screening with a doctor-collected sample was inversely associated with age and duration without screening (both p<0.001), but that with a self-collected sample was not associated. CONCLUSIONS: Among women who used the self-sampling HPV test, high acceptability was confirmed, while concerns about self-sampling procedures remained. Screening with a self-collected sample was preferred over a doctor-collected sample and the former might alleviate disparities in screening rates.
Subject(s)
Papillomavirus Infections , Uterine Cervical Neoplasms , Female , Humans , Vaginal Smears/methods , Human Papillomavirus Viruses , Early Detection of Cancer/methods , Papillomavirus Infections/diagnosis , Japan , Papillomaviridae , Self Care/methods , Specimen Handling/methods , Surveys and Questionnaires , Mass Screening/methodsABSTRACT
A self-sampling human papillomavirus (HPV) test could improve the morbidity and mortality of cervical cancer in Japan. However, its effectiveness and feasibility have not been demonstrated sufficiently. Hence, we launched a randomized controlled trial, which is ongoing, and report the results of a secondary analysis. To ensure autonomous participation with a minimum selection bias, opt-out consent was obtained from women who met the inclusion criteria, and written consent was obtained from those who underwent a self-sampling test. The number of women who met the inclusion criteria was 20,555; 4283 and 1138 opted out before and after the assignment, respectively. Of the 7340 women in the self-sampling arm, 1372 (18.7%) ordered and 1196 (16.3%) underwent the test. Younger women in their 30 s and 40 s tended to undertake the test more frequently than older women in their 50 s (P for trend < 0.001). Invalid HPV test results were rare (1.3%), and neither adverse events nor serious complaints were reported. Despite adopting the opt-out procedure, more women than expected declined to participate, suggesting the need for a waiver of consent or assignment before consent to reduce selection bias. A self-sampling HPV test can be implemented in Japan and would be more accessible to young women, the predominant group affected by cervical cancer.
Subject(s)
Papillomavirus Infections , Uterine Cervical Neoplasms , Aged , Early Detection of Cancer/methods , Female , Humans , Japan , Mass Screening/methods , Papillomaviridae , Self Care , Specimen Handling , Vaginal Smears/methodsABSTRACT
INTRODUCTION: Recently, the incidence of cervical cancer has increased in Japan, probably because of an interruption in human papillomavirus (HPV) vaccination and a low cervical cancer screening rate. There is a lack of evidence for self-sampling HPV testing as a cervical cancer screening tool in Japan. The Accelerating Cervical Cancer Elimination by Self-Sampling test trial aims to compare the effectiveness of screening using the self-sampling HPV test with that of routine screening concerning screening uptake and precancer detection. METHODS AND ANALYSIS: This trial has a single-municipality, open-label, parallel, superiority and randomised design. Approximately 20 000 women who have not undergone cervical cancer screening for at least 3 years will be assigned randomly to the self-sampling arm and the control arm using a 1:1 ratio. Participants assigned to the control arm will undergo routine cervical cancer screening (cytology test) provided by Ichihara City, while those assigned to the self-sampling arm will choose the routine screening or self-sampling HPV test. HPV tests will be performed using the cobas 8800 system (Roche Diagnostics, Rotkreuz, Switzerland). Participants who will undergo the self-sampling HPV testing will be recommended to undergo routine screening. The results of the cytology test and further tests, such as colposcopy and biopsy, will be collected and used for this trial. The risk ratio and risk difference in the proportion of participants with cervical intraepithelial neoplasia two or worse between the two arms will be calculated. The test for the null hypothesis (the detection rates are equal between the two arms) will be performed using Pearson's χ2 test. ETHICS AND DISSEMINATION: This trial was approved by the Research Ethics Committees of the Chiba Foundation for Health Promotion and Disease Prevention and the collaborating research institutes. The results will be disseminated through peer-reviewed journals and conference presentations. TRIAL REGISTRATION NUMBER: jRCT1030200276. Pre-results.
Subject(s)
Alphapapillomavirus , Papillomavirus Infections , Uterine Cervical Neoplasms , Early Detection of Cancer/methods , Female , Humans , Mass Screening/methods , Papillomaviridae , Papillomavirus Infections/epidemiology , Randomized Controlled Trials as Topic , Uterine Cervical Neoplasms/diagnosis , Uterine Cervical Neoplasms/pathology , Uterine Cervical Neoplasms/prevention & control , Vaginal SmearsABSTRACT
In pigs, the efficiency of embryo production after intracytoplasmic sperm injection (ICSI) is still low because of frequent failure of normal fertilization, which involves formation of two polar bodies and two pronuclei. To clarify the reasons for this, we hypothesized that ICSI does not properly trigger sperm-induced fertilization events, especially intracellular Ca2+ signaling, also known as Ca2+ oscillation. We also suspected that the use of in vitro-matured oocytes might negatively affect fertilization events and embryonic development of sperm-injected oocytes. Therefore, we compared the patterns of Ca2+ oscillation, the efficiency of oocyte activation and normal fertilization, and embryo development to the blastocyst stage among in vivo- or in vitro-matured oocytes after ICSI or in vitro fertilization (IVF). Unexpectedly, we found that the pattern of Ca2+ oscillation, such as the frequency and amplitude of Ca2+ rises, in oocytes after ICSI was similar to that in oocytes after IVF, irrespective of the oocyte source. However, half of the oocytes failed to become activated after ICSI and showed no Ca2+ oscillation. Moreover, the embryonic development of normal fertilized oocytes was reduced when in vitro-matured oocytes were used, irrespective of the fertilization method employed. These findings suggest that low embryo production efficiency after ICSI is attributable mainly to poor developmental ability of in vitro-matured oocytes and a lack of Ca2+ oscillation, rather than the pattern of oscillation.
Subject(s)
Calcium Signaling/physiology , Fertilization/physiology , In Vitro Oocyte Maturation Techniques/veterinary , Oocytes/metabolism , Sperm Injections, Intracytoplasmic/veterinary , Spermatozoa/metabolism , Animals , Calcium/metabolism , Female , Male , SwineABSTRACT
Pigs with severe combined immunodeficiency (SCID) are versatile animal models for human medical research because of their biological similarities to humans, suitable body size, and longevity for practical research. SCID pigs with defined mutation(s) can be an invaluable tool for research on porcine immunity. In this study, we produced RAG2-knockout pigs via somatic cell nuclear transfer and analyzed their phenotype. The V(D)J recombination processes were confirmed as being inactivated. They consistently lacked mature T and B cells but had substantial numbers of cells considered to be T- or B-cell progenitors as well as NK cells. They also lacked thymic medulla and lymphoid aggregations in the spleen, mesenteric lymph nodes, and ileal Peyer's patches. We showed more severe immunological defects in the RAG2 and IL2RG double-knockout pig through this study. Thus, SCID pigs could be promising animal models not only for translational medical research but also for immunological studies of pigs themselves.
Subject(s)
DNA-Binding Proteins/deficiency , DNA-Binding Proteins/genetics , Gene Knockout Techniques/veterinary , Severe Combined Immunodeficiency/veterinary , Swine Diseases/genetics , Swine Diseases/immunology , Animals , Animals, Genetically Modified , Disease Models, Animal , Female , Gene Knockout Techniques/methods , Humans , Interleukin Receptor Common gamma Subunit/deficiency , Interleukin Receptor Common gamma Subunit/genetics , Killer Cells, Natural/immunology , Killer Cells, Natural/pathology , Lymphoid Progenitor Cells/immunology , Lymphoid Progenitor Cells/pathology , Lymphoid Tissue/immunology , Lymphoid Tissue/pathology , Male , Severe Combined Immunodeficiency/genetics , Severe Combined Immunodeficiency/immunology , Sus scrofa , Swine , Swine Diseases/pathologyABSTRACT
The humanized pig model, in which human cells or tissues can be functionally maintained in pigs, can be an invaluable tool for human medical research. Although the recent development of immunodeficient pigs has opened the door for the development of such a model, the efficient engraftment and differentiation of human cells may be difficult to achieve. The transplantation of human cells into fetal pigs, whose immune system is immature, will ameliorate this problem. Therefore, we examined the development of porcine fetal thymus, which is critical for the establishment of the immune system. We first analyzed the levels of mRNA expression of genes that are relevant to the function of thymic epithelial cells or thymocytes in whole thymi from 35 to 85 days of gestation (DG) and at 2 days postpartum (DP) by quantitative RT-PCR. In addition, immunohistochemical analyses of thymic epithelial cells from DG35 to DG55 and DP2 were performed. These analyses showed that the thymic cortex was formed as early as DG35, and thymic medulla gradually developed from DG45 to DG55. These findings suggested that, at least before DG45, the thymus do not differentiate to form fully functional T cells.
Subject(s)
Thymus Gland/embryology , Thymus Gland/immunology , Animals , Cell Differentiation/genetics , Cell Differentiation/immunology , Female , Gene Expression , Gestational Age , Humans , Immunohistochemistry , Models, Animal , Pregnancy , RNA, Messenger , Reverse Transcriptase Polymerase Chain Reaction , Sus scrofa , Thymus Gland/cytology , Transcription, GeneticABSTRACT
The present study was conducted to examine the feasibility of in vitro embryo production and transfer technologies for producing Middle White piglets. After collection from three retired Middle White sows, a total of 222 oocytes were matured, fertilized and cultured in vitro, and a total of 50 embryos from the 4-cell to blastocyst stage were produced by the 4th or 5th day. These embryos were transferred individually into three recipients along with 5 in vivo-derived Duroc blastocysts. All of the recipients became pregnant, and they farrowed a total of 9 Middle White and 9 Duroc piglets. These results suggest that in vitro embryo production using ovaries from retired sows is useful for reproduction of pigs of pure breeds including the Middle White for breeding activities and conservation/utilization of genetic resources.
Subject(s)
Embryo Transfer/veterinary , Embryo, Mammalian/cytology , Fertilization in Vitro/veterinary , Swine , Animals , Animals, Newborn , Breeding/methods , Embryo Culture Techniques/veterinary , Feasibility Studies , Female , Male , Pregnancy , Swine/embryology , Swine/physiologyABSTRACT
Collection efficacy and in vitro embryo developmental ability of oocytes obtained from Duroc-breed ovary donors at different stages of the estrous cycle (days 6, 12 and 16 after estrus) were performed. The numbers of collected oocytes did not differ significantly among the different estrous cycle groups (total 72-90 oocytes per gilt). However, the blastocyst rates of oocytes collected on days 12 and 16 (9.2% and 19.4%, respectively) were significantly higher than those on day 6 (1.1%). More oocytes were obtained on day 16 from small follicles (<2 mm in diameter; 85.3 oocytes per gilt) than from medium-sized (≥2-<6 mm) and large (≥6 mm) follicles (17.5 and 12.8 oocytes, respectively). The blastocyst rates in both the medium-sized and large follicle groups (20.0% and 19.2%, respectively) were significantly higher than that in the small follicle group (6.3%). The blastocyst cell numbers in both the medium-sized and large follicle groups (39.4 and 43.3 cells, respectively) were significantly higher than that in the small follicle group (30.6 cells). The results suggest that oocyte collection from cycling Duroc pigs can be carried out efficiently from the late luteal to follicular stage. Those oocytes collected from medium-sized and large follicles show better embryo development.
Subject(s)
Embryo, Mammalian/embryology , Embryonic Development , Estrous Cycle/physiology , Fertilization in Vitro , Oocyte Retrieval/methods , Oocytes/growth & development , Animals , Blastocyst , Cell Count , Female , Luteal Phase/physiology , Ovarian Follicle/cytology , Swine , Time FactorsABSTRACT
Octanoate is used to induce adipogenic differentiation and/or lipid accumulation in preadipocytes of domestic animals. However, information on detailed actions of octanoate and the characteristics of octanoate-induced adipocytes is limited. The aim of this study was to examine these issues by comparing the outcomes of the effects of octanoate with those of rosiglitazone, which is a well-defined activator of peroxisome proliferator-activated receptor (PPAR)-γ. The adipocytes that were differentiated with 5mM of octanoate had dispersed and diversely sized lipid droplets compared to those that were differentiated with 1 µM of rosiglitazone. The gene expression levels of adiponectin, glycerol-3-phosphate dehydrogenase, perilipin 1, and perilipin 4 were much higher in the adipocytes that were differentiated with rosiglitazone than in those differentiated with octanoate, while the gene expression levels of lipoprotein lipase and perilipin 2 were decreased in rosiglitazone-differentiated adipocytes compared to octanoate-differentiated adipocytes. However, the expressions of aP2 and CD36 genes were comparably induced. Luciferase reporter assays revealed that PPAR and liver-X-receptor activities were upregulated by octanoate more effectively than by rosiglitazone. Overall, these results suggested that the action of octanoate was complicated and may be dependent on the targeted genes and cellular status.
Subject(s)
Adipocytes/drug effects , Adipogenesis/drug effects , Adiposity/drug effects , Caprylates/pharmacology , Swine/metabolism , Adipocytes/cytology , Adipogenesis/genetics , Animals , Cells, Cultured , Cytosol/metabolism , Dexamethasone/pharmacology , Gene Expression Regulation/drug effects , Genes, Reporter/drug effects , Insulin/pharmacology , Liver X Receptors , Orphan Nuclear Receptors/genetics , PPAR gamma/genetics , Triglycerides/metabolismABSTRACT
Hemophilia A is a common X chromosome-linked genetic bleeding disorder caused by abnormalities in the coagulation factor VIII gene (F8). Hemophilia A patients suffer from a bleeding diathesis, such as life-threatening bleeding in the brain and harmful bleeding in joints and muscles. Because it could potentially be cured by gene therapy, subhuman animal models have been sought. Current mouse hemophilia A models generated by gene targeting of the F8 have difficulties to extrapolate human disease due to differences in the coagulation and immune systems between mice and humans. Here, we generated a porcine model of hemophilia A by nuclear transfer cloning from F8-targeted fibroblasts. The hemophilia A pigs showed a severe bleeding tendency upon birth, similar to human severe hemophiliacs, but in contrast to hemophilia A mice which rarely bleed under standard breed conditions. Infusion of human factor VIII was effective in stopping bleeding and reducing the bleeding frequency of a hemophilia A piglet but was blocked by the inhibitor against human factor VIII. These data suggest that the hemophilia A pig is a severe hemophilia A animal model for studying not only hemophilia A gene therapy but also the next generation recombinant coagulation factors, such as recombinant factor VIII variants with a slower clearance rate.
Subject(s)
Disease Models, Animal , Factor VIII/genetics , Hemophilia A/genetics , Swine , Animals , Blood Coagulation , Factor VIII/metabolism , Gene Order , Gene Targeting , Hemophilia A/blood , Hemophilia A/metabolism , Humans , Male , PhenotypeABSTRACT
A porcine model of severe combined immunodeficiency (SCID) promises to facilitate human cancer studies, the humanization of tissue for xenotransplantation, and the evaluation of stem cells for clinical therapy, but SCID pigs have not been described. We report here the generation and preliminary evaluation of a porcine SCID model. Fibroblasts containing a targeted disruption of the X-linked interleukin-2 receptor gamma chain gene, Il2rg, were used as donors to generate cloned pigs by serial nuclear transfer. Germline transmission of the Il2rg deletion produced healthy Il2rg(+/-) females, while Il2rg(-/Y) males were athymic and exhibited markedly impaired immunoglobulin and T and NK cell production, robustly recapitulating human SCID. Following allogeneic bone marrow transplantation, donor cells stably integrated in Il2rg(-/Y) heterozygotes and reconstituted the Il2rg(-/Y) lymphoid lineage. The SCID pigs described here represent a step toward the comprehensive evaluation of preclinical cellular regenerative strategies.
Subject(s)
Gene Targeting , Genetic Therapy , Interleukin Receptor Common gamma Subunit/genetics , Severe Combined Immunodeficiency/therapy , Animals , Disease Models, Animal , Female , Humans , Interleukin Receptor Common gamma Subunit/immunology , Killer Cells, Natural/immunology , Killer Cells, Natural/metabolism , Male , Severe Combined Immunodeficiency/genetics , Severe Combined Immunodeficiency/immunology , Swine , T-Lymphocytes/immunology , T-Lymphocytes/metabolismABSTRACT
The viability or developmental ability of porcine embryos after slow-freezing and thawing differs depending on the embryonic stage or the batch, which is defined as a group of embryos obtained from one donor at one time. We froze porcine blastocysts in batches and assessed their cryotolerance by using two expanded blastocysts (EBs) as samples to predict the developmental potential of other blastocysts from the same batch at different stages. Two EBs from the same batch that had been separately frozen were thawed and cultured in vitro for 48 h to examine their in vitro ability to develop to the hatched blastocyst stage. Thereafter, each batch was assigned to Grade A, B, or C according to the viability of the two EBs, i.e., 100% viability (2/2: number of hatched blastocysts/number of cultured EBs) was Grade A; 50% (1/2) was Grade B; and 0% (0/2) was Grade C. The viability of EBs after freeze-thawing and in vitro culture varied depending on the batch and was lower (31.0+/-10.2%, mean+/-S.E.M.; P<0.01) than that of unfrozen controls (96.8+/-2.3%). The viability of frozen-thawed hatched blastocysts (HBs) did not differ among the graded batches, but the blastocyst diameter decreased (from 409 to 326 microm) as the batch grade decreased (from A to C). When both EBs and HBs from batches of the same grade were transferred to recipients (average 11.7 EBs and 16.0 HBs per recipient), the rate of pregnancy and farrowing in recipients decreased (from 77.8% to 0%) and the number of piglets obtained decreased (from 15.3 to 0) as the batch grade decreased. However, when not only frozen-thawed EBs from Grade B or C batches, but also four helper embryos at the morula to early blastocyst stage (which were expected to support the pregnancy) were transferred, the number of piglets generated was higher from EBs from Grade B batches (16.0) than from EBs from Grade C batches (0.0). When frozen-thawed HBs and helper embryos were transferred, the number of piglets generated was higher from HBs from Grade B batches (12.7) than that from HBs from Grade C batches (1.9). After slow-freezing of porcine blastocysts, their rate of survival to the piglet stage differs batchwise, and in vitro viability assessment of sample EBs after freezing and thawing may help in assessing the post-freezing and post-thawing developmental potential of other blastocysts at different stages from the same batch.
Subject(s)
Blastocyst/physiology , Cryopreservation/veterinary , Embryo Transfer/veterinary , Embryonic Development , Swine/embryology , Animals , Blastocyst/drug effects , Cell Survival , Cryopreservation/methods , Cryoprotective Agents/adverse effects , Cryoprotective Agents/pharmacology , Embryonic Development/drug effects , Embryonic Development/physiology , Female , Male , Pregnancy , Pregnancy Outcome/veterinary , Pregnancy Rate , Specimen Handling/veterinary , Time FactorsABSTRACT
Recently, piglets have been obtained from in vitro-produced blastocysts by using in vitro maturation systems in which oocytes have been matured in North Carolina State University (NCSU) solution supplemented with porcine follicular fluid (PFF). However, PFF is not available commercially. To prepare PFF from the ovaries required time and effort and there is substantial variation in quality among batches. Furthermore, PFF is considered a potential source of infectious agents. We evaluated another commercially available potential protein source, fetal bovine serum (FBS), for in vitro maturation, to produce embryos and piglets. Cumulus-oocyte complexes were matured in NCSU-37 with PFF or with one of four batches of FBS. The proportions of oocytes with expanded cumulus cells were lower in all FBS batch groups (P < 0.05, 15-41%) than that in the PFF group (74%). The proportions of oocytes that matured were also lower in all FBS batch groups (P < 0.05, 26-41%) than in the PFF group (73%), irrespective of cumulus expansion. However, the proportions of oocytes that underwent germinal vesicle breakdown were almost the same in all groups (76-96%). After in vitro fertilization, the rate of sperm penetration into matured oocytes was higher in the PFF group (P < 0.05, 63%) than in one batch of FBS (22%) and removal of the compacted cumulus cells after maturation did not affect fertilization status (21%). Subsequent in vitro embryo culture of the PFF and FBS groups for 6 day resulted in similar rates of blastocyst formation (17 and 19%, respectively) and similar numbers of cells per blastocyst (43 and 46 cells, respectively). When blastocysts obtained from oocytes matured with FBS were transferred into two recipients, one became pregnant and farrowed seven piglets. Transfer of blastocysts obtained from oocytes matured with PFF into two other recipients resulted in one pregnancy and production of four piglets. These data suggested that porcine in vitro maturation in NCSU-37 supplemented with FBS reduced the maturational ability of oocytes, but once oocytes have matured, they have the same ability to develop to term after in vitro fertilization and embryo transfer as those matured with PFF.
Subject(s)
Culture Media/chemistry , Fertilization in Vitro/veterinary , Fetal Blood/physiology , Oocytes/growth & development , Swine/embryology , Animal Husbandry/methods , Animals , Blastocyst/drug effects , Cattle , Cell Nucleus/drug effects , Embryo Culture Techniques/methods , Embryo Culture Techniques/veterinary , Female , Fertilization/drug effects , Fertilization in Vitro/drug effects , Fertilization in Vitro/methods , Follicular Fluid/physiology , Male , Oocytes/cytology , Oocytes/drug effects , Swine/growth & developmentABSTRACT
This study was conducted to determine the efficiency of vitrification using the microdroplet (MD) method for early stage porcine embryos. Embryos at compacted morulae to early blastocyst stage were vitrified in a vitrification solution containing 40% (v/v) ethylene glycol, 0.6M sucrose and 2% (w/v) polyethylene glycol in M2 (ESP) without any pretreatment. The equilibration and dilution were carried out in third and fourth steps, respectively, at 38 degrees C. The survivability of the cryopreserved embryos was assessed for both in vitro culture (Experiment 1) and by embryo transfer (Experiment 2). In Experiment 1, the embryos were vitrified within a microdroplet or 0.25 ml straw (ST) and fresh embryos were used as a control group. The survival rates after 24h culture in the MD, ST and control groups were 21/23, 14/20 and 20/20, respectively. The hatching rates of the embryos after 48 h incubation were 14/23, 4/20 and 16/20, respectively. In Experiment 2, 171 vitrified embryos were transferred to 5 recipient gilts, and 17 healthy piglets were produced from 2 recipients (3 recipients aborted) in Group 1. In Group 2, 81 vitrified embryos and 16 fresh embryos in total were transferred to 4 recipient gilts, and 10 healthy piglets from the vitrified embryos were produced from 3 recipients. These results indicated that porcine embryos of compacted morulae to early blastocyst stage can survive cryopreservation using the microdroplet method without any special intracellular manipulation or treatment.