The most important point in embryo transfer success is the evaluation of the stage of development and quality of embryos. Therefore, the purpose of this study was to compare the morphological evaluation of embryos using stereoscopy, light microscopy and electron microscopy in order to establish the accuracy of former method compared with more invasive and accurate procedures. For this purpose, 23 Brahman x Swiss cows were used and synchronized with Norgestomet 6 mg plus, 5 mg Estradiol valerate (Syncromate B(R), Rhone Merieux, Mexico, Mexico City) and superovulated with Folltropin-V 240 mg (Vetrepharm, Mexico, Mexico City). Non-surgical embryo collection was performed 7.5 days after insemination. Descriptive statistics analysis was used to assess the data. Seventy-eight embryos were collected and classified by stereoscopic microscopy, finding 51.2% (40) of good quality, 25.6% (20) fair and 24.3% (19) poor. Later, under light microscopy observation, evaluation of the same embryos resulted in 25.6% (20) good, 32.0% (25) fair and 42.3% poor quality. Finally, in the evaluation of embryos under electron microscopy 24.3% (19) were found to be of good quality, 29.3% (23) fair and 46.1% (36) poor. Evaluation of embryos with stereoscopic microscopy was found to be very subjective, as nearly 50% of embryos classified by this method as good quality, showed features of degenerative stages under light and electron microscopy. Embryos with these features are generally frozen and transferred, which could be one of the reasons for having low fertility rate in embryo transfer programmes.

El efecto del calor de entrada (Qnet) sobre la calidad, microestructura y dureza Vickers en uniones soldadas con doble cordón robotizadas GTAW-P en acero aleado variando la corriente de soldadura, voltaje del arco, velocidad de soldadura y precalentamiento fue evaluado mediante inspección visual, estereoscopia, microscopia óptica y prueba de microdureza. Los resultados indicaron que Qnet alto (0.600 kJ/mm) favoreció unión GTAW5 con adecuada calidad, sin defectos, menor ancho de zona afectada por calor recalentada (ZACR) promedio (2.43 mm) con formación de ferrita de grano grueso y martensita con mayor microdureza promedio de 597 HV, mientras que en metal de soldadura se observaron agujas finas de martensita y granos alargados de ferrita primaria resultando la mayor dureza (644 HV). Sin embargo, con el mayor Qnet (0.645 kJ/mm) se generó corrida GTAW7 produciendo mayor ancho de ZAC (4.41 mm) con socavado y microestructura de ferritas idiomorfica y de grano fino resultando la menor dureza (536 HV), así como soldadura conteniendo ferritas acicular y primaria generando 540 HV. Se encontraron dos perfiles de microdureza: tipo A donde la ZACR alcanzo mayor dureza que metal de soldadura y tipo B con mayor endurecimiento en soldadura que en ZACR