Similar patterns of embryo development in canine oocytes cultured in vitro at oxygen tensions of 5 and 20%

Abstract

The influence of two oxygen tensions (5 and 20%) on fertilization, cleavage, development, and morphological quality of canine embryos produced in vitro was investigated. To assess embryo production, canine oocytes (N = 608) were matured in vitro at 20% oxygen tension in TCM 199 supplemented with glucose (11 mM) and 0.1% polyvinyl alcohol. Oocytes and sperm were coincubated at 37 °C for 24 hours in serum-free medium. Subsequently, presumptive zygotes were cultured in vitro in synthetic oviductal fluid in either 5% CO2 in air (20% oxygen; N = 298) or 5% O2, 5% CO2 and 90% N2 (5% oxygen; N = 310) for 7 days. Regardless of the oxygen concentration (5 vs. 20%), rates of pronucleus formation, cleavage, and embryo development up to the eight-cell stage did not differ (46/310 [14.8%] vs. 35/298 [11.7%], respectively; P > 0.05). Moreover, similar proportions of embryos developed in 20 and 5% oxygen tensions (18/298 vs. 27/310). The oocyte nuclear maturation (metaphase II), in terms of decondensed sperm heads, pronucleus formation, cleavage, and embryo development, was similar (P = 0.299) between the atmospheric (20% O2; 12.4% [37/298]) and reduced oxygen tensions (5% O2; 15.8% [49/310]) at all steps of the in vitro culture (IVC) after in vitro fertilization (IVF). To our knowledge, this was the first study that demonstrated that canine embryos can be produced using a low-oxygen in vitro culture system. Both oxygen tensions (5 and 20%) resulted in similar embryonic development and therefore were feasible for IVC of canine oocytes.

The Ovarian Antral Follicle: Living on the Edge of Hypoxia or Not?1

“…However, studies examining different pO 2 levels for in vitro oocyte maturation have not been useful in determining the optimal dissolved O 2 content, as there has been both a limited range of pO 2 levels assessed (either low, around 5-7% of gas composition, versus atmospheric ≈ 20%, depending on altitude) and a lack of consistency in results following maturation under these dissolved O 2 levels [17]. Differences in origin of species of oocyte, medium composition, macromolecule and protein supplementation and density of COC culture are examples of variables that appear to interact with the impact of different pO 2 levels under in vitro maturation conditions [17][18][19][20][21][22][23]. Perhaps more relevant is oxygen uptake data by COCs comparing competent and less-competent oocytes.…”

Efecto de factores embriotróficos a diferentes tensiones de oxígeno en cultivo in vitro sobre el desarrollo embrionario de alpacas hasta la etapa de blastocisto

“…A pesar de la importancia de las alpacas para el Perú, su reproducción se realiza principalmente por monta natural, sin considerar la variabilidad genética y el mejoramiento de la especie con fines comerciales, lo que ha llevado a una disminución de la calidad genética (Huanca, 2012). Así, la reproducción in vitro se muestra como una alternativa viable para el mejoramiento genético y el aumento de la productividad de la alpaca, ya que esta técnica está altamente desarrollada en bufalinos, bovinos, ovinos y porcinos (Liang y col., 2020;Javvaji y col., 2020;Dubeibe y col., 2019;Gonella Diaza y col., 2013;Rodrigues y col., 2013). Asimismo, se ha reportado la factibilidad de la reproducción de camélidos por inseminación artificial, transferencia de embriones y fertilización in vitro (Ruiz, 2018;Pérez, Zevallos y Perez, 2017;Pacheco, Vélez y Pezo, 2016), siendo necesario el estudio de las condiciones que permitan el desarrollo exitoso de la reproducción de alpacas mediante técnicas in vitro, de suma importancia para la región andina, ya que no existen protocolos específicos para ello.…”