title: The blastocyst production rate and incidence of chromosomal abnormalities by developmental stage in in vitro produced porcine embryos.
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 x 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.
authors.affiliation: United Graduate School of Agriculture, Tokyo University of Agriculture and Technology, Tokyo, Japan.
authors.forename: Carlos Manuel
authors.initials: CM
authors.lastname: Ulloa Ullo
authors.forename: Midori
authors.initials: M
authors.lastname: Yoshizawa
authors.forename: Eiji
authors.initials: E
authors.lastname: Komoriya
authors.forename: Akinori
authors.initials: A
authors.lastname: Mitsui
authors.forename: Takashi
authors.initials: T
authors.lastname: Nagai
authors.forename: Kazuhiro
authors.initials: K
authors.lastname: Kikuchi
mesh_terms: D000818:Animals; D001755:Blastocyst / Q000166:cytology*; D002869:Chromosome Aberrations / Q000196:embryology / Q000662:veterinary*; D047108:Embryonic Development / Q000502:physiology*; D005260:Female; D005307:Fertilization in Vitro / Q000009:adverse effects / Q000662:veterinary*; D008297:Male; D013552:Swine; D013553:Swine Diseases / Q000196:embryology*