The Blastocyst Production Rate and Incidence of Chromosomal Abnormalities by Developmental Stage in In Vitro Produced Porcine Embryos

Abstract

Abstract. The present study was conducted to determine the relationship between embryonic development speed at different stages (the cleaved stage at 52 h and the blastocyst stage at 6 days post insemination) and incidences of chromosome abnormalities in in vitro produced porcine embryos. Porcine oocytes were collected from 3-6-mm ovarian follicles obtained at a slaughterhouse and matured in modified NCSU-37 medium for 44-46 h. Following in vitro fertilization with a final concentration of 1 × 10 5 sperm/ml for 3 h, all oocytes were cultured in vitro for 52 h. Day-2 (52 h after insemination) embryos were classified according to their cleaved stages into 2-cell, 3-to 4-cell, 5-to 8-cell, and >8-cell stages; these were cultured separately for additional 4 days (Day 6). The resultant Day-6 blastocysts were classified according to the morphological diameter into 3 grades: Grade A, expanded blastocysts; Grade B, expanding blastocysts; and Grade C, early blastocysts. They were then analyzed chromosomally. The 3-to 4-cell and 5-to 8-cell embryos had significantly high blastocyst development rates (46.1 and 36.9%, respectively), and these blastocysts contained significantly more cells (40.2 and 42.4 cells, respectively) than those derived from 2-cell embryos and >8-cell embryos (28.6 and 26.5 cells, respectively). The incidence of chromosomal abnormalities was significantly higher in the blastocysts derived from 2-cell and >8-cell stage embryos than in the blastocysts derived from the other stage embryos. Furthermore, the grade A blastocysts had the lowest incidence of chromosomal abnormalities (35.3%) and contained the most cells (48.7 cells). Porcine in vitro production (IVP) yielded a high blastocyst rate and an excellent embryo quality when 3-to 4-cell and 5-to 8-cell stage embryos were selected on Day 2 after insemination. The same criteria yielded a higher quality of expanded blastocysts based on the stage of embryo development and morphology. Key words: Blastocyst, Chromosomal abnormality, Embryo, In vitro production (IVP), Pig (J. Reprod. Dev. 54: [22][23][24][25][26][27][28][29] 2008) n mammals, the technology of in vitro production (IVP) of embryos, which involves in vitro maturation and fertilization of oocytes and in vitro culture of the resultant embryos, has become important for increasing the number of offspring from selected high-quality animals and for reducing the generation intervals for breed improvement in livestock [1,2]. Moreover, IVP technology has been used in the production of cloned and transgenic animals, which can be used in biomedical research [3][4][5]. In swine, although embryos have been successfully produced using the IVP system, the development rates to the blastocyst stage and to full term after embryo transfer are still low [6][7][8]. The viability of porcine embryos produced by IVP is low compared with that of in vivo-derived porcine embryos. For example, porcine embryos produced by IVP are of poor quality in terms of the number of cells compared with those produced in vivo [9].A...

CXADR is required for AJ and TJ assembly during porcine blastocyst formation

“…Thus, the cavity of blastocyst is expanded by paracellular sealing via TJ at the TE and continuous fluid influx into the blastocoel. Furthermore, blastocyst development and stage status can be classified according to the morphological diameter (expansion) (Gardner et al 2000, Ulloa Ullo et al 2008.…”

Energy substrate influences the effect of the timing of the first embryonic cleavage on the development of in vitro‐produced porcine embryos in a sex‐related manner

“…For example, the proportion of two‐cell stage embryos was higher in earlier‐cleaving embryos, whereas slower‐cleaving embryos exhibited greater degrees of asymmetry and fragmentation at first zygotic cleavage. In this regard, it is worth mentioning that the developmental stage and cell number of embryos at a given time are thought to be linked to the time of embryonic genome activation (Minami et al, ) and to the rate of chromosomal abnormalities (Ulloa Ullo et al, ; Dang‐Nguyen et al, ). Although blastomeres of early mammalian embryos, especially those of porcine embryos, cleave asynchronously (Dang‐Nguyen et al, ), selection of embryos with a greater number of blastomeres at the presumed time of first cleavage may instead result in the selection of zygotes with abnormal nuclear status and reduced developmental potential (Booth et al, ; Dang‐Nguyen et al, ; Jeon et al, ).…”

“…Although the mechanisms underlying early developmental failure are not fully understood, and considering that polyspermic fertilization (Kochhar et al, ; Ulloa Ullo et al, ) and suboptimal in vitro culture conditions (Lonergan et al, ; Somfai et al, ) may influence embryo development, inherent oocyte quality seems to be the main factor that determines whether an embryo will yield to premature embryonic failure or develop appropriately (Lonergan et al, ; Isom et al, ). Several recent studies have shown a strong correlation between oocyte competence and early zygotic cleavage, the latter also being conditioned by the abundance of maternal transcripts, the number of mitochondria within the oocyte, and the oocyte diameter (reviewed in Lechniak et al, ).…”

Two cases of Reciprocal Chromosomal Translocation (4; 7)(p+; q−) (2; 8)(q−; q+) in Piglets Produced by ICSI

“…2000), and some authors suggest the in vitro conditions of culture could increase the prevalence of cytogenetic abnormalities. In this sense, cytogenetic analysis of porcine blastocysts produced in vitro by IVF has revealed that 39.1–45.9% of the blastocysts are chromosomally abnormal embryos (Ulloa Ullo et al. 2008; Hornak et al.…”