Browsing by Author "Soria Parra, Manuel Elías"

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Adición de fluido folicular en la maduración de ovocitos de cerdas prepúberes
(Asociación Latinoamericana de Producción Animal, 2018) Argudo Garzon, Daniel Ernesto; Borja Tello, Diana Carolina; Wilches Correa, Veronica Elizabeth; Agurto Miranda, Valewska Andrea; Ayala Guanga, Luis Eduardo; Perea Ganchou, Fernando Pedro; Méndez Álvarez, María Silvana; Soria Parra, Manuel Elías; Argudo Garzon, Daniel Ernesto
La producción in vitro de embriones en los porcinos y otras especies de interés zootécnico es indispensable para el desarrollo productivo e investigativo. Diariamente se faenan cientos de cerdos en el camal municipal de Cuenca, Ecuador; donde sería posible rescatar material genético (complejos cúmulos ovocitos; Coc´s) valioso si se recuperan los ovarios de las cerdas; sin embargo, estos animales son beneficiados antes de la pubertad (<5 meses de edad) en cuyo caso la maduración de los Coc´s es deficiente. Se estableció como objetivo del estudio determinar el efecto del fluido folicular porcino (FFP) en maduración de Coc´s de cerdas prepúberes. Se obtuvieron ovarios (n=30) de cerdas faenadas en el camal municipal de Cuenca, los cuales fueron transportados al Laboratorio de Biotecnología de la Reproducción Animal de la Universidad de Cuenca, Ecuador. Inmediatamente se puncionaron los folículos antrales de 2-8mm con una aguja 18x1.5 pulgadas acoplada a una jeringa. El líquido folicular resultante fue filtrado para posteriormente realizar la búsqueda y recuperación de los Coc´s. Adicionalmente, se recuperó FFP, que fue centrifugado a 2000g x 20 minutos, esterilizado por doble filtración con filtros de jeringa estériles de 0.22µm y congelado hasta su uso. Para la maduración, los Coc´s de excelente y buena calidad (n=245) se dividieron aleatoriamente en tres grupos a los que se adicion diferentes porcentajes de FFP: 0% (n=79) ,10% (n=94) y 20%(n=72). Los Coc´s fueron incubados por 48hs en medio de maduración compuesto por TCM199, suero fetal bovino, FSH-p, HCG, piruvato de sodio, L-glutamina, gentamicina y FFP en una estufa con 5% de CO2, 38.5°C y 90%rh. Luego de madurados, los Coc´s fueron denudados por pipeteo en una solución dehialuronidasa 0.1% (p/v), inmediatamente teñidos conHoechst 33342 y observados en un microscopio de fluorescencia. Aquellos que presentaron la expulsión del corpúsculo polar fueron consideraron maduros y el resultado se expresó en porcentaje. Se aplicó un análisis de varianza (ANOVA) seguido de un test de Tukey. El grupo de Coc´s que no fue suplementado con FFP (0%) tuvo menor tasa de maduración (21,33+1,4 %) que los grupos suplementados con 10 (51,53+3,4%) y 20 % (52,93+5,7%) (P<0.05). Se concluye que, irrespectivamente del porcentaje adicionado el FFP fue necesario para mejorar la maduración de Coc´s de cerdas prepúberes
Análisis morfométrico y funcional de ovocitos bovinos obtenidos de ovarios de matadero y por aspiración folicular transvaginal en vacas criollas del altiplano ecuatoriano
(2020) Alvarado Ulloa, Jhonatan Marcelo; Perea Ganchou, Fernando Pedro; Soria Parra, Manuel Elías; Méndez Álvarez, María Silvana; Bueno Leon, Hernan Patricio; Iñiguez Gutierrez, Carlos Ulises; Argudo Garzón, Daniel; Galarza Lucero, Diego Andrés
This study assessed the morphometric and functional characteristics of oocytes from 10 native cows to the Ecuadorian Andes, collected by transvaginal follicular aspiration (OPU) and oocytes collected post mortem (PM) from abattoir ovaries. For this purpose, 1157 cumulus-oocyte complexes (CCOs) of the OPU group (n=271) and PM group (n=886) were recovered in 10 repetitions per group by follicular aspiration at 90 mm Hg pressure and classified as A, B or C, according to the characteristics of the cytoplasm and cumulus cells. The activity of the enzyme glucose 6 phosphate dehydrogenase (G6PD) and the integrity of the plasma membrane was determined by staining two groups of CCOs with cresyl brilliant blue (BCB +) and trypan blue, respectively. The size (diameter and volume) of the oocytes was evaluated using CaptaVisio® software v. 5.1. The data were analysed by logistic regression and by the SAS general linear model, and the means were compared by the least square method. The results showed that the oocytes of the PM group had a larger diameter (126.0 ± 0.48 vs. 122.7 ± 0.79 μm; p<0.01) and integrity of the plasma membrane (86.0 vs. 76.8%; p<0.05) than the OPU group. However, quality A and B oocytes did not show significant differences between groups with respect to plasma membrane integrity and BCB + values. The results suggest that, although the fact that the size and viability were more affected in the oocytes aspirated by OPU, those of quality A and B from both sources showed similar values regarding the integrity of the plasma membrane and metabolic condition to continue maturation.
Aplicación de la didáctica universitaria al microcurriculum de la materia de Equinotecnia
(2009) Bernardi Villavicencio, Cristina; Soria Parra, Manuel Elías
La aplicación de las pasantias en las précticas de cobayos
(2009) Esquivel, Carolina; Soria Parra, Manuel Elías
Bovine corpus luteum affects embryo developmental competence and production
(CSIRO, 2019) Alvarado Ulloa, Jhonatan Marcelo; Tenemaza Cumbe, Milton Alejandro; Merchan Vargas, Shirley Lissette; Argudo Garzón, Daniel; Méndez Álvarez, María Silvana; Soria Parra, Manuel Elías; Galarza Alvarez, Luis Rodrigo; Ayala Guanga, Luis Eduardo; Hernandez Fonseca, Hugo Jose; Perea Ganchou, Fernando Pedro; Merchan Vargas, Shirley Lissette
This study was conducted with the aim to determine the effect of bovine corpus luteum on in vitro embryo production. Immature cumulus–oocyte complexes (COCs) were aspirated from abattoir ovaries from cows with (ipsilateral; CL+) and without (contralateral; CL-) corpus luteum (CL), and from cows without CL in any of the ovaries. The experiment was completed within 12 replicates (100 ovaries per group). COCs were cultured in maturation medium (TCM-199 supplemented with 10% fetal bovine serum, 100 µg/ml sodium pyruvate, 0.75 mg/ml L-glutamine, 4 µg/ml FSH-p, 2 µM cysteamine and 250 µg/ml gentamicin) followed by in vitro fertilization (hepes synthetic oviductal fluid medium supplemented with 10 µg/ml heparin) and in vitro culture (citrate synthetic oviductal fluid medium). On day 7 after in vitro fertilization the embryos were evaluated and classified into morulae (M), early blastocysts (EB), blastocysts (B), expanded blastocysts (ExB) and hatched blastocysts (HB), and the embryos with better quality were recorded. Data were analyzed by logistic regression and general linear model of the SAS, and means compared by least-squares means method. Results of cleavage, embryo rate at day 7, and rates of M + EB, B, ExB and HB are shown in Table 1. The number of embryos per ovary was greater (P < 0.01) in CL+ (1.16 ± 0.11) than in CL- (0.45 ± 0.15) and C (0.55 ± 0.15). Also, the number of embryos per cultured oocyte was significantly greater in CL + than in CL- and C (0.27 ± 0.02 vs 0.14 ± 0.03 and 0.15 ± 0.03 respectively, P < 0.01). The results of this study reveal that the presence of the corpus luteum in the ovary at the time of the oocytes recovery affects the developmental capacity of the bovine embryos, and such influence probably occur through intraovarian interactions.
BoviPure® density-gradient centrifugation procedure enhances the quality of fresh and cryopreserved dog epididymal spermatozoa
(2022) Perea Ganchou, Fernando Pedro; Muñoz León, Esteban Mauricio; Santiago Moreno, Julián; Galarza Lucero, Diego Andrés; Jara Jimbo, Diana Isabel; Paredes Quito, Efraín Bernardo; Samaniego Campoverde, Jorge Xavier; Méndez Álvarez, María Silvana; Soria Parra, Manuel Elías
BoviPure® is a salt solution containing colloidal silica particles coated with silane used to select sperm (e.g., ruminants) by density-gradient centrifugation (DGC). This research assessed the suitability of the BoviPure-DGC and swim-up methods for selecting dog epididymal sperm in fresh, chilled and frozen-thawed samples on post-treatment sperm quality. Sperm samples (n = 60 epididymides) were recovered by retrograde flushing from thirty orchiectomized adult dogs. Thereafter, 20 sperm pools, containing sperm aliquots of three randomly selected animals, were used for chilling (at 5 ºC for 24 h) and freezing (in liquid nitrogen vapors). Sperm selection by BoviPure-DCG and swim-up was performed in both individual and pooled samples, including non- selected samples as controls. Overall, after BoviPure-DGC selection a higher sperm retrieval rate was obtained than the swim-up selection in both individual (P < 0.05) and pooled (P < 0.01) samples. BoviPure-DGC improved (P < 0.05) the total (TM) and progressive (PSM) sperm mo- tilities, curvilinear (VCL) and straight-line (VSL) velocities, linearity (LIN), wobble (WOB), beat- cross frequency (BCF), and integrity of plasmatic (IPM) and acrosomal (IAM) membranes of in- dividual samples in comparison with non-selected samples. In pooled samples, however, the BoviPure-DGC improved (P < 0.05) the PSM, VCL, WOB, and IPM of chilled and frozen-thawed samples. The swim-up method improved (P < 0.05) only some kinematic variables of the indi- vidual (VCL, WOB and BCF) and cryopreserved pooled samples (VCL and ALH) in comparison with non-selected samples. In conclusion, BoviPure-DGC was more effective for recovering and selecting both fresh and cryopreserved dog epididymal sperm than the swim-up procedure improving the kinematic variables, and membranes intactness
Características génicas de las poblaciones de bovinos criollos americanos en base a microsatélites
(2019) Guevara Viera, Guillermo Emilio; Vallecillo Maza, Antonio Javier; Méndez Álvarez, María Silvana; Soria Parra, Manuel Elías; Palacios Ordóñez, Teofilo Estuardo; Andrade Guzmán, Omar Santiago; Bustamante Ordóñez, Jorge Gualberto; Pesántez Pacheco, José Luis; Vázquez Mosquera, Juan Mesías
The objective of this study is to analyze the major gene parameters found in different genotypes of cattle of Iberian origin in the Americas. The work was based on the review of different results of the genetic markers analyzed in blood of Creole cattle incountries of North America until cattle in Patagonia in the southern part of South America. Presents results of the markers most used and recommended for ca ttle. Population genetic parameters analyzed were: total number of alleles (Na), by microsatellite marker allele 189 frequencies), the factors observed (Ho) and expected (He), the coefficients of inbreeding (Fis), polymorphic information content) CIP) and compliance with the assumption of Hardy-Weinberg equilibrium. The percentage of variance between populations and the (Fst) is also reported. 20 papers on microsatellites in cattle, analysed 19 of them with informa tion from Creoles of America. Highlights a number of alleles locus of 4 to 13, higher by more than 0.6 heterozygosity and polymorphic information content high. Creole ca ttle have very little variation among their populations, the distance that separates them is not very marked, but they have a Kingdom with many alleles at the loci analyzed and their heterozygosity and polymorphism is high of them with information
Continuación de estudios en buiatria
(2013) Brito Pintado, Boris Javier; Soria Parra, Manuel Elías
Cryopreservation of dog epididymal spermatozoa by conventional freezing or ultra-rapid freezing with nonpermeable cryoprotectant
(2021) Landi Loja, Blanca Gabriela; Santiago Moreno, Julián; Mejia Jara, Edisson Leonardo; Galarza Lucero, Diego Andrés; Castaño, Cristina; Sánchez Calabuig, María Jesús; Taboada Pico, Juan Wualverto; Soria Parra, Manuel Elías; Méndez Álvarez, María Silvana; Samaniego Campoverde, Jorge Xavier
This study was aimed to assess the effectiveness of two methods for cryopreservation of dog epididymal spermatozoa, one by conventional freezing (CF) with shortening both equilibration and cooling times, and the other by ultra-rapid freezing (URF) with nonpermeable cryoprotectant. Sixty epididymides were recovered from thirty orchiectomized adult dogs and the sperm samples were retrieved by retrograde flushing using TCG-EY (tris, citric acid, glucose + 20% egg yolk) extender and then 20 pools were conformed. Each pool was divided into 2 aliquots and then cryopreserved by CF and URF methods respectively. The CF method maintained the cooled-pool samples for 2h (1h without and 1h with 5% glycerol) and then were frozen by liquid nitrogen (LN2) vapors for 2 min. The URF method cryopreserved the cooled-pool samples using TCG-EY+250 mM sucrose, equilibrating during 30 min (5 ◦C) and submerging 30-μL drops directly in LN2. The results showed that the URF method produced a lower percentage of total and progressive motilities and acrosome integrity (P < 0.05) than the CF method. However, the kinetic variables (curvilinear and straight-line velocities, straightness, linearity, wobble, amplitude of lateral head displacement, and beat-cross frequency) and plasma membrane integrity did not differ (P > 0.05) between both cryopreservation methods. Unlike the URF method, the width, area and perimeter of sperm head were reduced after the CF method (P < 0.05). In conclusion, despite the low motility achieved after the ultra-rapid freezing method, the similar values of kinetic, viability and head morphometric dimensions to those obtained after conventional freezing, suggest that ultra-rapid freezing with sucrose may be a useful alternative for the cryopreservation of canine epididymal sperm.
Determinación de hembras bovinas gestantes faenadas en los camales de Cuenca, Azogues; e influencia con producción y despoblación
(1993) Duy Neira, Enrique; San Martín Tamayo, Felipe; Soria Parra, Manuel Elías
Determinación del pH. vaginal en hembras bovinas normales y con vulvovaginitis granulosa durante el estro, y, su influencia en la concepción
(1995) Duy García, Jaime Remigio; Quizhpe Peralta, John Wilson; Soria Parra, Manuel Elías
Diagnóstico de neosporosis en ganado lechero
(2009) Criollo Ayala, Sandra Isabel; Soria Parra, Manuel Elías
Diagnóstico de tricomoniasis genital bovina en las parroquias de Tarqui, Cumbe y Victoria del Portete
(1989) Abambari V., Carlos; Soria Parra, Manuel Elías
Efecto de la presión de vacío sobre las características morfológicas de ovocitos bovinos obtenidos de ovarios de matadero
(Asociación Latinoamericana de Producción Animal, 2018) Argudo Garzon, Daniel Ernesto; Quezada Contreras, Adrian Ignacio; Mocha Zhispon, Armando Ramiro; Soria Parra, Manuel Elías; Méndez Álvarez, María Silvana; Ayala Guanga, Luis Eduardo; Galarza Alvarez, Luis Rodrigo; Perea Ganchou, Fernando Pedro; Perea Ganchou, Fernando Pedro
El efecto adverso de la presión de vacío sobre la competencia de los ovocitos recuperados mediante ovum pick up (OPU), y de los embriones obtenidos de estos, ha sido documentado previamente, pero poco se sabe sobre su efecto en las características morfológicas de los ovocitos. Se estableció como obejtivo del estudio evaluar el efecto de la presión de vacío sobre las características morfométricas de ovocitos bovinos recuperados de ovarios de matadero. El estudio se realizó en el Laboratorio de Biotecnología de la Reproducción Animal de la Universidad de Cuenca, Ecuador. Los ovarios recolectados (n=252) de un matadero local fueron divididos al azar de manera homogénea en tres grupos con diferente presión de aspiración folicular: 50, 65 y 80mmHg. Se aspiraron los folículos entre 2-8 mm de diámetro; para la punción se utilizó una aguja 18Gx1.5 pulgadas conectada a una bomba de vacío. Se recuperaron y seleccionaron los mejores COC´s (complejos cúmulos ovocito) de cada grupo: 50 (n=283), 65 (n=263) y 80 mmHg (n=226). Un 30% de cada grupo fueron colocados en un medio con hialuronidasa al 0,1% (p/v) y denudados por pipeteo sucesivo. Los ovocitos se fotografiaron con una cámara montada sobre un microscopio provisto con un software (AmScope V.3.7) calibrado para realizar mediciones microscópicas. El otro 70% de COC´s fueron incubados por 24hs en medio de maduración a base de TCM199, suero fetal bovino, FSH-p, estradiol, piruvato de sodio, L-glutamina y gentamicina en una estufa con 5% de CO2, 38.5°C y 90%rh. Luego de madurados, los COC´s fueron denudados y medidos como se indicó anteriormente. Los datos se analizaron con el programa estadístico SAS. Los ovocitos aspirados con 50mmHg antes de la maduración tuvieron un diámetro (sin zona pelúcida) y un volumen (125.8±0.5 µm y 1052327.9±11792.9 µm3) mayor que los obtenidos con 65 (123.3±0.5 µm y 990510.6±12603.9 µm3) o 80 mmHg (122.2±0.5 µm y 992296.4 ± 13652.9 µm3) (P<0,001). Luego de ser madurados, los ovocitos obtenidos con 50 mmHg tuvieron un diámetro y un volumen (121.9±0.6 µm y 954686.4±14072.2 µm3) mayor que los recuperados con 65 (120.1±0.6 µm y 913819.1±14879.8 µm3) (P<0,05), pero fueron similares a los obtenidos con 80 mmHg (121.4±0.7 µm y 945211.9±16359 µm3). Como conclusión, a mayor presión de vacío los ovocitos tendieron a ser más pequeños, es decir, tuvieron menor diametro y volumen. Asimismo, independientemente de la presión de aspiración, los ovocitos redujeron su diámetro y volumen como consecuancia de la maduración.
Efecto crioprotector de la dimetilformamida, glicerol y su combinación sobre la criosupervivencia de espermatozoides equinos
(Universidad de Cuenca, 2022-07-18) Ochoa Guillen, Juan Diego; Alvarez Palacios, David Alejandro; Soria Parra, Manuel Elías
The combination of cryoprotective penetrating agents (CPA), such as glycerol (GLY) and dimethylformamide (DMF), has shown encouraging results in equine sperm cryosurvival. In this sense, this research evaluated the cryoprotective effect of GLY, DMF, and its combination: DMF-GLY, on equine sperm quality and cryosurvival. For this purpose, twenty-four semen ejaculates were collected from four healthy, sexually adult Arabian horses (6 ejaculates/stallion). Each ejaculate was initially diluted with BotusemenSpecial extender and then frozen with Botusemen-Gold extender supplemented with GLY (5%), DMF (5%), and DMF-GLY (3%-3%) using static liquid nitrogen vapors. The fresh and frozen-thawing sperm samples were evaluated for their kinematics variables and membranes integrity using the CASA computerized system (SCA-Evolution-2018) and the double fluorescent test (PI / PNA-FITC), respectively. The results showed that DMF alone or combined with GLY (DMF-GLY) was more effective in protecting equine spermatozoa and producing higher values (P< 0,05) of total (MT, %) and progressive (MP, %) motilities, curvilinear velocity (VCL), the amplitude of lateral head displacement (ALH) and beat-cross frequency (BCF) compared to GLY. The combination of DMF-GLY yielded higher (P < 0.05) strain-line (VSL) and average path velocities (VAP), plasma membrane integrity (IMP, %), and acrosomal membrane integrity (IMA, %) compared to DMF alone or GLY alone. In conclusion, the combination of DMF-GLY supplemented to the 'Botusemen-Gold' non-synthetic-based extender, was more suitable for cryoprotecting Arabian horse sperm based on higher kinematics and membrane integrity compared to glycerol cryoprotectant agent.
Efecto de idebenona en la congelación y vitrificación de espermatozoides ovinos
(Universidad de Cuenca, 2025-08-06) Chuya Sigche, Erika Paulina; Narváez Arcentales, María José; Soria Parra, Manuel Elías
This study evaluated the effect of Idebenone (IDB) supplementation in conventional slow freezing (CC) and kinetic vitrification (VIT) media on the cryosurvival of ram spermatozoa. For that, eighteen ejaculates were collected from three adult rams (six/male) using an artificial vagina. Each ejaculate was diluted with TEST extender (tris, tes, glucose, and 6% egg yolk), supplemented with IDB (10 µM and 0 µM [control]), and cryopreserved using CF and VIT, establishing four treatments: CC+IDB, CC-Control, VIT+IDB, and VIT- Control. The CC was performed using 5% glycerol and exposing the samples to static liquid nitrogen (LN₂) vapor; while the VIT was done using 100 mM sucrose and direct immersion of 30 µL droplets into LN₂. The results showed that supplementation with IDB in the freezing medium (CC+IDB) significantly (P < 0.05) improved sperm kinematics and membrane integrity, and reduced DNA fragmentation post-thaw compared to its control (CC-Control). Additionally, IDB in the vitrification medium (VIT+IDB) significantly (P < 0.05) reduced oxidative stress and DNA fragmentation compared to VIT-Control. Nevertheless, VIT+IDB samples showed a significant (P < 0.05) undesirable decrease in several kinematic parameters (velocities, linearity, and oscillation) after warming compared to VIT-Control. In conclusion, IDB improved kinematics, viability, and acrosomal integrity, and reduced DNA fragmentation in frozen-thawed ram spermatozoa. Despite its undesirable effect on post-warming kinematics, IDB reduced oxidative stress and DNA fragmentation following the vitrification process.
Efecto de la adición de melatonina en el medio de maduración y/o vitrificación de ovocitos sobre la producción in vitro de embriones bovinos
(2020) Méndez Álvarez, María Silvana; Argudo Garzon, Daniel Ernesto; Soria Parra, Manuel Elías; Galarza Alvarez, Luis Rodrigo; Perea Ganchou, Fernando Pedro
The effect of the addition of melatonin (Mt) on the maturation and / or vitrification of bovine oocytes on cleavage and subsequent embryonic development was evaluated.Oocyte-cumulus cell complexes (COCs) were obtained from creole cows by ovum pick up (OPU) and by follicular aspiration from abattoir ovaries (AO). From the pool of oocytes obtained from both sources, those with homogenous cytoplasm and three or more compact layers of cluster cells were selected. The selected COCs were randomly assigned to five treatments: T1, matured with Mt and vitrified without Mt; T2, matured and vitrified with Mt; T3, matured without Mt and vitrified with Mt; T4 (control) matured and vitrified without Mt; T5, matured without Mt and not vitrified. The concentration of Mt in the maturation and vitrification media was 0.01 µM (10-9 M). The oocytes were matured, vitrified, fertilized and the presumed zygotes cultured until day 7 post-fertilization in vitro. The data were analysed by logistic regression. Regardless of the origin of the oocytes, cleavage rate (C) and embryo production (EP) was similar between treatments. The C in the OPU oocytes was greater in T4, and the EP was similar between treatments. In AO, the results did not vary between treatment in C and EP. In conclusion, Mt reduced the C in oocytes collected by OPU, while it did not affect EP. In the AO oocyte source, the addition of Mt did not affect the C nor the EP.
Efecto de la melatonina en la criopreservacion de espermatozoides equinos
(2018) Tamay Siguenza, Erika Fabiola; Vélez Sandoval, Frixon Augusto; Soria Parra, Manuel Elías
The objective of this research was to evaluate the effect of melatonin in the cryopreservation of equine spermatozoa. Three Appaloosa horses from farms located in the Victoria del Portete parish, Azuay Province, were used. Semen samples were collected twice a week, with an artificial vagina, until five ejaculates per animal were complete. Treatment, stallion and repetition were considered as independent variables, whereas as dependent variables were studied the individual progressive motility, the percentages of spermatozoa live/dead, with abnormalities, with the intact plasma and acrosomal membrane, undergoing oxidative stress, bovine oocytes fertilized by equine sperm. Data were processed by the analysis of variance of SAS. The post-thaw evaluation indicated that the semen diluted without melatonin had a greater percentage of live sperm (85.1 ± 1.7 vs 80.0 ± 1.7%) and less sperms with the intact plasma membrane (25.2 ± 1.8 vs 31.3 ± 1.8% respectively) than with melatonin (P<0.05). The proportion of sperm without oxidative stress and with slight or moderate stress were statistically similar between treatments. Regarding to heterologous in vitro fertilization (IVF), it was found that there was no difference between treatments in the percentages of union, penetration, polyspermia and pronuclei by 18 and 24 hours. However, a greater percentages of union, of pronuclei by 18 and 24 hours and of cleavage was observed in the homologous than in the heterologous IVF.
Efecto del benzoato de estradiol en la morfometria del foliculo y cuerpo lúteo en vacas holstein sincronizadas con D-Cloprostenol
(2013) Soria Parra, Manuel Elías; Narváez Terán, Jhonny Alfredo
Efecto del cuerpo lúteo sobre la producción in vitro de embriones bovinos y su posterior tolerancia a la criopreservación
(2019-05-13) Tenemaza Cumbe, Milton Alejandro; Merchán Vargas, Shirley Lissette; Soria Parra, Manuel Elías
This research was conducted to determine the effect of the corpus luteum on the rate of cleavage of bovine oocytes and the subsequent competence to develop to blastocysts and to tolerate the cryopreservation. The ovaries selected for this study were recovered from the municipal slaughterhouse of Cuenca, from non-pregnant cows with a corpus luteum (CCL) in one ovary (ipsilateral, group 1, CCL) and without CL in the contralateral ovary (group 2; SCL), and of cows without CL in both ovarys (control, group 3; C). The cumulus-oocyte complexes (COCs) were categorized and only those with apt (A and B) quality were included for maturation for 18-24 hours. The COCs were fertilized in vitro and the blastocysts obtained were cryopreserved by vitrification or freezing. From 348 ovaries, 2532 oocytes were obtained in 13 replicates, which, according to quality, 63.8% corresponded to categories (A and B) apt and 36.2% to (C and D) not apt. The proportion of AB oocytes was grater (P <0.05) in CCL (66.6%) than in SCL (61.9%) and C (62.7%). A greater proportion of oocytes from the CCL group cleaved in comparison to the SCL and C (68.3 versus 43.8 and 46.6% respectively; P<0.01). Likewise, a greater proportion of total embryos was obtained in CCL (39.0%) than in SCL (29.2%) and C (29.8%) (P <0.05). From the total of clivated embryos, a greater percentage (P <0.01) of embryos attained the blastocyst stage on day 7 and were cryopreserved, in the CCL group (68.2%) than in SCL (39.8%) and C (38.7%). Embryonic survival after vitrification or freezing determined at 2, 24 and 48 hours was statistically similar among the three study groups. General, the presence of a corpus luteum in the ovary at the time of recovering the oocytes affected the percentage of cleavage and embryo production on day 7, but did not influence the cryotolerance of the blastocysts. In addition, according to these results it is presumed that the effect of the corpus luteum occurred trough local mechanisms.