DAZL Knockout Pigs as Recipients for Spermatogonial Stem Cell Transplantation.

Spermatogonial stem cell (SSC) transplantation into the testis of a germ cell (GC)-depleted surrogate allows transmission of donor genotype via donor-derived sperm produced by the recipient. Transplantation of gene-edited SSCs provides an approach to propagate gene-edited large animal models. DAZL is a conserved RNA-binding protein important for GC development, and DAZL knockout (KO) causes defects in GC commitment and differentiation. We characterized DAZL-KO pigs as SSC transplantation recipients. While there were GCs in 1-week-old (wko) KO, complete GC depletion was observed by 10 wko. Donor GCs were transplanted into 18 DAZL-KO recipients at 10-13 wko. At sexual maturity, semen and testes were evaluated for transplantation efficiency and spermatogenesis. Approximately 22% of recipient seminiferous tubules contained GCs, including elongated spermatids and proliferating spermatogonia. The ejaculate of 89% of recipients contained sperm, exclusively from donor origin. However, sperm concentration was lower than the wild-type range. Testicular protein expression and serum hormonal levels were comparable between DAZL-KO and wild-type. Intratesticular testosterone and Leydig cell volume were increased, and Leydig cell number decreased in transplanted DAZL-KO testis compared to wild-type. In summary, DAZL-KO pigs support donor-derived spermatogenesis following SSC transplantation, but low spermatogenic efficiency currently limits their use for the production of offspring.

CRISPR/Cas9-editing of KISS1 to generate pigs with hypogonadotropic hypogonadism as a castration free trait.

Introduction: Most male pigs are surgically castrated to avoid puberty-derived boar taint and aggressiveness. However, this surgical intervention represents a welfare concern in swine production. Disrupting porcine KISS1 is hypothesized to delay or abolish puberty by inducing variable hypogonadotropism and thus preventing the need for castration. Methods: To test this hypothesis, we generated the first KISS1-edited large animal using CRISPR/Cas9-ribonucleoproteins and single-stranded donor oligonucleotides. The targeted region preceded the sequence encoding a conserved core motif of kisspeptin. Genome editors were intracytoplasmically injected into 684 swine zygotes and transferred to 19 hormonally synchronized surrogate sows. In nine litters, 49 American Yorkshire and 20 Duroc liveborn piglets were naturally farrowed. Results: Thirty-five of these pigs bore KISS1-disruptive alleles ranging in frequency from 5% to 97% and did not phenotypically differ from their wild-type counterparts. In contrast, four KISS1-edited pigs (two boars and two gilts) with disruptive allele frequencies of 96% and 100% demonstrated full hypogonadotropism, infantile reproductive tracts, and failed to reach sexual maturity. Change in body weight during development was unaffected by editing KISS1. Founder pigs partially carrying KISS1-disruptive alleles were bred resulting in a total of 53 KISS1 +/+, 60 KISS1 +/-, and 34 KISS1 -/- F1 liveborn piglets, confirming germline transmission. Discussion: Results demonstrate that a high proportion of KISS1 alleles in pigs must be disrupted before variation in gonadotropin secretion is observed, suggesting that even a small amount of kisspeptin ligand is sufficient to confer proper sexual development and puberty in pigs. Follow-on studies will evaluate fertility restoration in KISS1 KO breeding stock to fully realize the potential of KISS1 gene edits to eliminate the need for surgical castration.

Promoter-specific expression of the imprinted IGF2 gene in bovine oocytes and pre-implantation embryos.

The bovine IGF2 locus is a genomic region with alternative transcripts controlled by five promoters (P0, P1, P2, P3 and P4). As transcriptional regulation can affect messenger RNA (mRNA) stability and translation, and thus, subsequent biological effects, this study evaluated the bovine IGF2 promoter-specific expression patterns in oocytes and pre-implantation embryos produced in vitro by our standard IVP procedures. Immature and matured oocytes, and pre-implantation embryos at the 1-, 2-, 4-, 8- and 16-cell, and at early morula, compact morula, blastocyst and expanded blastocyst stages were collected in three pools of five structures per stage, in four replicates. Total RNA was extracted and subjected to RT-qPCR, using four sets of IGF2 promoter-specific primers covering transcripts driven by promoters P0/P1, P2, P3 and P4, with fragments sequenced for confirmation. Expression of P2- and P4-derived transcripts showed an initial peak between immature (P4) or matured (P2/P4) oocytes and 2-cell embryos, gradually falling until embryo genome activation (EGA), rising again at compaction and cavitation. P0/P1-derived transcripts were identified after EGA, during compaction, whereas P3 activity was not detected at any stage. Our findings suggest that P0/P1 and P2 likely have secondary roles during early stages, whereas P3 may be more relevant later in development. P4 seems to be the main pathway for bovine IGF2 expression during oocyte maturation and embryo development and, therefore, the main target to influence IVP in modulation of embryo growth and in studies in developmental biology.

Assessment of binder of sperm protein 1 (BSP1) and heparin effects on in vitro capacitation and fertilization of bovine ejaculated and epididymal sperm.

The present study evaluated the effect of binder of sperm protein 1 (BSP1) and/or heparin on in vitro bovine capacitation and fertilization rates using epididymal and ejaculated bovine sperm. Frozen-thawed sperm were selected and used in the following treatments. Control group: Fert-TALP medium without heparin; heparin (HEP) group: Fert-TALP with heparin (10 UI/ml); BSP1 group: Fert-TALP medium with BSP1 (10 µg/ml for ejaculated sperm; 40 µg/ml for epididymal sperm); HEP + BSP1 group: Fert-TALP medium with heparin (5 UI/ml) and BSP1 (5 µg/ml for ejaculated sperm; 20 µg/ml for epididymal sperm) and determined in vitro capacitation rates in different interval times (0, 15, 30 and 60 min) using the chlortetracycline fluorescence (CTC) method. Also, we evaluated the development rates of oocytes fertilized with ejaculated or epididymal sperm into the same treatments. Capacitation was greater and faster when ejaculated sperm were treated for 60 min with heparin compared with other treatments. However, developmental rates were similar in all treatments. For epididymal sperm, the treatments with BSP1 presented higher capacitation and fertilization rates compared with heparin (P < 0.05). The effects of heparin + BSP1 on capacitation and developmental rates did not cause any increase in capacitation or blastocyst rates compared with other groups for ejaculated or epididymal sperm. In conclusion, this study confirmed that either BSP1 and heparin can be used as capacitator agents for bovine ejaculated sperm during IVF. However, BSP1 seems to be more efficient compared with heparin for epididymal sperm. Furthermore, BSP1 and heparin have no synergic effects on sperm capacitation.

Influence of oocyte selection, activation with a zinc chelator and inhibition of histone deacetylases on cloned porcine embryo and chemically activated oocytes development.

The aim of this study was to evaluate the effects of alternative protocols to improve oocyte selection, embryo activation and genomic reprogramming on in vitro development of porcine embryos cloned by somatic cell nuclear transfer (SCNT). In Experiment 1, in vitro-matured oocytes were selected by exposure to a hyperosmotic sucrose solution prior to micromanipulation. In Experiment 2, an alternative chemical activation protocol using a zinc chelator as an adjuvant (ionomycin + N,N,N',N'-tetrakis(2-pyridylmethyl)ethylenediamine (TPEN) + N-6-dimethylaminopurine (6-DMAP)) was compared with a standard protocol (ionomycin + 6-DMAP) for the activation of porcine oocytes or SCNT embryos. In Experiment 3, presumptive cloned zygotes were incubated after chemical activation in a histone deacetylase inhibitor (Scriptaid) for 15 h, with the evaluation of embryo yield and total cell number in day 7 blastocysts. In Experiment 1, cleavage rates tended to be higher in sucrose-treated oocytes than controls (123/199, 61.8% vs. 119/222, 53.6%, respectively); however, blastocyst rates were similar between groups. In Experiment 2, cleavage rates were higher in zygotes treated with TPEN than controls but no difference in blastocyst rates between groups occurred. For Experiment 3, the exposure to Scriptaid did not improve embryo development after cloning. Nevertheless, the total number of cells was higher in cloned zygotes treated with Scriptaid than SCNT controls. In conclusion, oocyte selection by sucrose as well as treatments with zinc chelator and an inhibitor of histone deacetylases did not significantly improve blastocyst yield in cloned and parthenotes. However, the histone deacetylases inhibitor produced a significant improvement in the blastocyst quality.

Editing Myosin VB Gene to Create Porcine Model of Microvillus Inclusion Disease, With Microvillus-Lined Inclusions and Alterations in Sodium Transporters.

BACKGROUND & AIMS: Microvillus inclusion disease (MVID) is caused by inactivating mutations in the myosin VB gene (MYO5B). MVID is a complex disorder characterized by chronic, watery, life-threatening diarrhea that usually begins in the first hours to days of life. We developed a large animal model of MVID to better understand its pathophysiology. METHODS: Pigs were cloned by transfer of chromatin from swine primary fetal fibroblasts, which were edited with TALENs and single-strand oligonucleotide to introduce a P663-L663 substitution in the endogenous swine MYO5B (corresponding to the P660L mutation in human MYO5B, associated with MVID) to fertilized oocytes. We analyzed duodenal tissues from patients with MVID (with the MYO5B P660L mutation) and without (controls), and from pigs using immunohistochemistry. Enteroids were generated from pigs with MYO5B(P663L) and without the substitution (control pigs). RESULTS: Duodenal tissues from patients with MVID lacked MYO5B at the base of the apical membrane of intestinal cells; instead MYO5B was intracellular. Intestinal tissues and derived enteroids from MYO5B(P663L) piglets had reduced apical levels and diffuse subapical levels of sodium hydrogen exchanger 3 and SGLT1, which regulate transport of sodium, glucose, and water, compared with tissues from control piglets. However, intestinal tissues and derived enteroids from MYO5B(P663L) piglets maintained CFTR on apical membranes, like tissues from control pigs. Liver tissues from MYO5B(P663L) piglets had alterations in bile salt export pump, a transporter that facilitates bile flow, which is normally expressed in the bile canaliculi in the liver. CONCLUSIONS: We developed a large animal model of MVID that has many features of the human disease. Studies of this model could provide information about the functions of MYO5B and MVID pathogenesis, and might lead to new treatments.

Effect of FSH treatment on cumulus oocyte complex recovery by ovum pick up and in vitro embryo production in beef donor cows.

This study was conducted to evaluate oocyte recovery and in-vitro blastocyst production of donor cows superstimulated for ovarian follicular development with FSH administered as twice-daily injections in saline or a single injection diluted in 0.5 % hyaluronan before oocyte aspiration. In Experiment 1, cows were treated with 160 mg of Folltropin-Vdiluted in saline, administered in four twice-daily i.m. injections for 2 days (Multiple FSH group); 160 mg of Folltropin-V diluted in hyaluronan and administered in a single i.m. injection (Single FSH group); or no FSH treatment (Control). In Experiment 2, donor cows were treated with either a single FSH i.m. injection or there was no treatment (Control) before ovum pick up (OPU) was performed. In both experiments, COCs collected using OPU were classified, matured, fertilized and cultured at 38.8 °C in a humidified atmosphere for 7 days. In Experiment 1, the number of follicles aspirated and COCs recovered were greater (P < 0.05) in cows treated with multiple and single doses of FSH. Number of blastocysts produced, however, did not differ among groups. In Experiment 2, mean number of follicles aspirated and COCs recovered were also greater (P < 0.05) in FSH-treated cows. Nevertheless, number of blastocysts produced did not differ. In summary, single and multiple FSH administrations induced similar follicular stimulation for OPU. Furthermore, with both FSH treatments there was induction of development of a larger number of follicles to be aspirated and COCs recovered by OPU compared with these values for donor beef cows with no FSH treatment for follicular stimulation.

In vitro development of IVF-derived bovine embryos following cytoplasmic microinjection for the episomal expression of the IGF2 gene.

Important genomic imprinting changes usually occur following the in vitro production (IVP) of bovine embryos, especially in the imprinting pattern of components of the IGF system. This study aimed to evaluate the effects of a transient episomal overexpression of the IGF2 gene in bovine IVP embryos following embryo cytoplasmic microinjection (CMI) at the 1-cell stage on embryo survival, early and late developmental kinetics and morphological quality up to Day 7 of development. Selected cumulus-oocyte complexes (COCs) were matured and fertilized in vitro and subsequently segregated into six experimental groups: non-CMI control group and five CMI groups at increasing doses (0, 10, 20, 40 and 80 ng/µl) of a GFP vector built for the episomal expression of bovine IGF2. Zygote CMI was effective in delivering the expression vector into the ooplasm, irrespective of the groups, with 58% of positive GFP fluorescence in Day 7 blastocysts. Considering developmental rates and late embryo kinetics, the 10-ng/µl CMI vector dose promoted a lower blastocyst rate (10.4%), but for blastocysts at more advanced stages of development (93.0% blastocysts and expanded blastocysts), and higher number of cells (116.0 ± 3.0) than non-CMI controls (23.3%, 75.0% and 75.0 ± 6.8 were obtained, respectively). In conclusion, CMI at the 1-cell stage did not compromise subsequent in vitro development of surviving embryos, with the 10-ng/µl group demonstrating a possible growth-promoting effect of the IGF2 gene on embryo development, from the 1-cell to the blastocyst stage.

Effects of fusion-activation interval and embryo aggregation on in vitro and in vivo development of bovine cloned embryos.

Nuclear reprogramming in somatic cell cloning is one of the key factors for proper development, with variations in the protocol appearing to improve cloning efficiency. This study aimed to determine the effects of two fusion-activation intervals and the aggregation of bovine cloned embryos on subsequent in vitro and in vivo development. Zygotes produced by handmade cloning were exposed to two fusion-activation intervals (2 h or 4 h), and then cultured in microwells either individually (1 × 100%) or after aggregation of two structures (2 × 100%). Zona-intact oocytes and zona-free oocytes and hemi-oocytes were used as parthenote controls under the same fusion-activation intervals. Day-7 cloned blastocysts were transferred to synchronous recipients. Cleavage (Day 2), blastocyst (Day 7) and pregnancy (Day 30) rates were compared by the χ2 test (P < .05). Extending fusion-activation interval from 2 to 4 h reduced cleavage (91.0 vs. 74.4%) but not blastocyst (34.8 vs. 42.0%) rates. On a microwell basis, cloned embryo aggregation (2 × 100%) increased cleavage (91.5% vs. 74.4%) and blastocyst (46.0% vs. 31.3%) rates compared to controls (1 × 100%), but did not improve the overall embryo production efficiency on Day 7 (23.0% vs. 31.3%), on a per reconstructed embryo basis, respectively. Treatments had no effects on in vitro developmental kinetics, embryo quality, and in vivo development. In summary, the fusion-activation interval and/or the aggregation of cloned bovine embryos did not affect cloning efficiency based on the in vitro development to the blastocyst stage and on pregnancy outcome.

Developmental Outcome and Related Abnormalities in Goats: Comparison Between Somatic Cell Nuclear Transfer- and In Vivo-Derived Concepti During Pregnancy Through Term.

Cloning by somatic cell nuclear transfer (SCNT) is characterized by low efficiency and the occurrence of developmental abnormalities, which are rather poorly studied phenomena in goats. This study aimed at comparing overall SCNT efficiency in goats by using in vitro-matured (IVM) or in vivo-matured oocytes and fibroblast donor cells (mock transfected, transgenic, or wild type), also characterizing symptoms of the Abnormal Offspring Syndrome (AOS) in development, comparing results with pregnancies produced by artificial insemination (AI) and in vivo-derived (IVD) embryos. The SCNT group had lower pregnancy rate (18.3%, 11/60), total number of concepti (20.0%, 12/60), term births (3.3%, 2/60), and live births (1.7%, 1/60) than both the IVD (77.8%, 7/9; 155.5%, 14/9; 122.2%, 11/9; 88.8%, 8/9) and the AI (71.4%, 10/14; 121.4%, 17/14; 100%, 14/14; 78.5%, 11/14) groups, respectively (p < 0.05). No SCNT pregnancies reached term using IVM oocytes, but in vivo-matured oocytes resulted in two term transgenic cloned kids. The proportion fetal membrane (FM) weight/birth weight reflected an increase in FM size and cotyledonary enlargement in clones, for disproportionally bigger newborns in relation to cotyledonary numbers. Overall, goat cloning showed losses and abnormality patterns similar to the AOS in cloned cattle and sheep, which have not been previously well recognized in goats.

Transient Expression of Functional Glucocerebrosidase for Treatment of Gaucher's Disease in the Goat Mammary Gland.

Gaucher disease (GD) is an orphan disease characterized by the lack or incapacity of glucocerebrosidase (hGCase) to properly process glucosylceramide, resulting in its accumulation in vital structures of the human body. Enzyme replacement therapy supplies hGCase to GD patients with a high-cost recombinant enzyme produced in vitro in mammalian or plant cell culture. In this study, we produced hGCase through the direct injection of recombinant adenovirus in the mammary gland of a non-transgenic goat. The enzyme was secreted in the milk during six days at a level up to 111.1 ± 8.1 mg/L, as identified by mass spectrometry, showing high in vitro activity. The milk-produced hGCase presented a mass correspondent to the intermediary high-mannose glycosylated protein, which could facilitate its delivery to macrophages through the macrophage mannose receptor. Further studies are underway to determine the in vivo delivery capacity of milk-hGCase, but results from this study paves the way toward the generation of transgenic goats constitutively expressing hGCase in the milk.

Survival rates of mouse blastocyst vitrified in dimethylformamide based solutions associated with ethylene glicol or 1-2 propanediol / Sobrevivência de embriões de camundongo vitrificados em soluções com dimetilformamida associadas ao etilenoglicol ou 1-2 propanediol

The aim of this study was to determine the effect of dimethylformamide (DF) associated with ethylene glycol (EG) or 1-2 propanediol (PROH) during vitrification, on the in vitro development of mouse blastocysts. Cryoprotectant toxicity was evaluated exposing embryos into three different equilibrium solutions (ES) composed by DF, EG or PROH mixtures (10 percent v/v of each) in mPBS + 0.5 percent PVA at different interval times (1, 3 and 10min). In a second experiment, embryos were exposed to the same ES (either 1 or 3min), following for the three respectively vitrification solutions (VS) (20 percent v/v of each) for 30s. After 72 hours of in vitro culture, embryo hatching and expansion rates were similar for the ES1 and ES2 equilibration solutions during the time interval of 1 or 3min. However embryos exposed for 10 min to the DF equilibration solutions, had lower survival rates than EG-PROH solution (P<0.01). Furthermore, survival rates for embryos exposed to DF-PROH (ES+VS) were lower than embryos exposed to the other solutions (P<0.01). Blastocyst vitrification was performed with the three ES+VS (for 1min and 30s, respectively), using glass micropipettes (GMP). Survival rates were lower for blastocysts vitrified with DF solutions (3 percent-3/108 and 17.1 percent-19/111) (P<0.01) than with PROH+EG vitrification solutions (69 percent-73/105). In conclusion, DF as a cryoprotectant into vitrification solutions have deleterious effects on the in vitro developmental competence of vitrified mouse blastocysts.

O objetivo deste estudo foi determinar o efeito da dimetilformamida (DF) associada com etileno glycol (EG) ou 1-2 propanediol (PROH) durante a vitrificação, no desenvolvimento in vitro de blastocistos murinos. A toxicidade dos crioprotetores foi avaliada ao expor os embriões as três soluções de equilíbrio (ES) compostas pelas misturas de DF, EG ou PROH (10 por cento v/v de cada) em mPBS + 0,5 por cento PVA, em diferentes intervalos de tempo (1, 3 e 10min). Em um segundo experimento, os embriões foram expostos as mesmas ES (durante 1 e 3min), seguido da exposição as três respectivas soluções de vitrificação (VS) (20 por cento v/v de cada) durante 30seg. Após 72 horas de cultivo in vitro, as taxas de expansão e eclosão dos embriões expostos durante os períodos de 1 e 3min às soluções de equilíbrio ES1 e ES2 foram semelhantes. No entanto, os embriões expostos durante 10min às soluções de equilíbrio com DF apresentaram taxas de sobrevivência inferiores à solução de EG-PROH (P<0,01). Além disso, as taxas de sobrevivência dos embriões expostos à DF-PROH (ES+VS) foram menores que as dos embriões expostos as outras soluções (P<0,01). A vitrificação dos blastocistos foi realizada após a exposição dos embriões nas três ES+VS (por 1min e 30seg, respectivamente), usando micropipetas de vidro (GMP). As taxas de sobrevivência foram menores nos blastocistos vitrificados nas soluções compostas por DF (3 por cento-3/108 e 17,1 por cento-19/111), em relação à solução EG-PROH (69 por cento-73/105) (P<0,01). Em conclusão, a DF adicionada como crioprotetor às soluções de vitrificação apresenta efeitos deletérios na capacidade de desenvolvimento in vitro dos blastocistos murinos vitrificados.

Survival of vitrifi ed mouse blastocysts loaded intoglass micro-capillaries / Sobrevivencia embrionaria de blastocistos murinos vitrificados en microcapilares de vidrio / Sobrevivência embrionária de blastocistos murinos vitrificados em micro capilares de vidro

The purpose of this study was to determine the in vitro expansion and hatching rates of vitrified mouseblastocysts loaded into glass micro-capillaries (Brand® - 5 μL). Early morning on day 4 of pregnancy,blastocysts were collected from donors, morphologically evaluated, and then allocated in three groups:Group 1 (Control): embryos were transferred into 100 μL of KSOM medium drops and in vitro culturedduring 72 h; Groups 2 and 3: embryos initially exposed to the equilibration solution (PBSm + 10% EG+ 10% PROH and 0.5% PVA) for 1 min, and then to vitrification solution (PBSm + 20% EG + 20%PROH + 0.5% PVA) for 30 sec. After that, blastocysts were loaded into glass micropipettes (GMP) or glassmicrocapillaries (GMC) and plunged into super-cooled liquid nitrogen (-200 °C). Embryo warming andcryoprotectant dilution were carried out into 500 μL droplets of PBSm supplemented with 0.25 M sucrosemaintained at 37 °C. After 5 min embryos were transferred to 100 mL droplets of KSOM medium andcultured in vitro for 72 h. Blastocyst expansion rates after in vitro culture were 77% (138/177) and 74%(131/175), for blastocysts vitrified in GMP and GMC, respectively. Blastocyst hatching rate (control group)was 91% (134/146), which was higher than for embryos loaded in GMP 61% (108/177) and GMC 53%(93/175). ICM number in control group embryos contained 25.7 ± 2.5 cells and did not differ from themean cell number observed in vitrified embryos loaded in GMP (24.2±2.3) or GMC (22.5±2.59). Regardingthe trophoectoderm cell number, Group 1 embryos displayed 63.1±3.0 cells, and also not differ from the cellnumbers of the embryos loaded into GMP (58.0±1.8) or GMC (58.0±.3.7). In conclusion, manufacturedGMC (Brand®) tested in this study showed same efficiency as GMP for vitrification of mouse blastocysts.

El objetivo de este estudio fue determinar las tazas de expansión y eclosión in vitro de los blastocistosmurinos vitrificados en micro-capilares de vidrio (Brand® - 5 μL). En el día 4 de preñez, los blastocistoseran colectados de las donantes, evaluados morfológicamente y localizados en tres diferentes grupos:Grupo 1 (Control): compuesto por los embriones que eran transferidos a gotas de 100 μL de medio KSOMy cultivados in vitro por un periodo de 72 h; Grupos 2 y 3: compuesto por los embriones que eran expuestosinicialmente a la solución de equilibrio (PBSm + 10% EG + 10% PROH and 0.5% PVA) por 1 min,y posteriormente a la solución de vitrificación (PBSm + 20% EG + 20% PROH + 0.5% PVA) por unperiodo de 30 seg. Posteriormente, los blastocistos, eran almacenados dentro de micro-pipetas de vidrio(GMP) o micro-capilares de vidrio (GMC) y sumergidos en nitrógeno líquido (-200 °C). La dilución delos crioprotectores y desvitrificación de los embriones fue realizada al colocarlos en gotas de 500 μLde PBSm suplementado con 0.25 M de sacarosa a una temperatura de 37 °C. Después de 5 minutos losembriones fueron transferidos a gotas de 100 μL de medio KSOM y cultivados in vitro por 72 h. Las tazasde expansión de los blastocistos, posteriores al cultivo fueron de 77% (138/177) y 74% (131/175), para losblastocistos vitrificados en GMP y GMC, respectivamente. Las tazas de eclosión fueron de 91% (134/146)para el grupo control, siendo mayores que para los embriones vitrificados en GMP 61% (108/177) y GMC53% (93/175). El número del índice de masa celular interna (ICM) para los embriones del grupo controlfue de 25.7 ± 2.5 células, no teniendo diferencia significativa con el número de células observado en losembriones vitrificados en GMP (24.2±2.3) ó GMC (22.5±2.59).

O objectivo de este estudo foi determinar as taxas de expansão e eclosão in vitro dos blastocitos murinosvitrificados em micro capilares de vidro (Brand® - 5 μL). No quarto dia de prenhes, os blastocitos foramcolectados das doadoras, avaliados morfologicamente e localizados em três diferentes grupos: Grupo 1(Controle): composto por os embriões que foram transferidos a gotas de 100 μL de KSOM e cultivados invitro por um período de 72 h; Grupos 2 e 3: composto por os embriões que foram expostos inicialmente ásolução de equilíbrio (PBSm + 10% EG + 10% PROH e 0.5% PVA) por 1 min, e posteriormente á soluçãode vitrificação (PBSm + 20% EG + 20% PROH + 0.5% PVA) por um período de 30 seg. Posteriormente,os blastocistos, foram armazenados dentro de micro pipetas de vidro (GMP) ou micro capilares de vidro(GMC) e submergidos em nitrogénio líquido super-resfriado (-200°C). A diluição dos crioprotetores edesvitrificação dos embriões foi realizada ao colocar-lhos em gotas de 500 μL de PBSm suplementadocom 0.25 M de sacarose a uma temperatura de 37 °C. Depois de 5 minutos, os embriões foram transferidosa gotas de 100 μL de KSOM e cultivados in vitro por 72 h. As taxas de expansão dos blastocistos, posterioresao cultivo foram de 77% (138/177) e 74% (131/175), para os blastocistos vitrificados em GMP e GMC,respectivamente. As taxas de eclosão foram de 91% (134/146) para o grupo controle, e foram maioresos embriões vitrificados em GMP 61% (108/177) e GMC 53% (93/175). O número do índice de massacelular interna (ICM) para os embriões do grupo controle foi de 25.7 ± 2.5 células, não havendo diferenciasignificativa com o número de células observado em embriões vitrificados em GMP (24.2±2.3) ou GMC(22.5±2.59). Alem do mais, as células do trofoectodermo, no grupo controle apresentaram 63.1±3.0células, no sendo diferente às células dos embriões vitrificados em GMP (58.0±1.8) ou GMC (58.0±.3.7).