Author/Editor		Knez, Katja; Tomaževič, Tomaž; Vrtačnik-Bokal, Eda; Virant-Klun, Irma
Title		Developmental dynamics of IMSI-derived embryos
Type		članek
Vol. and No.		Letnik 27, št. 2
Publication year		2013
Volume		str. 161-171
ISSN		1472-6491 - Reproductive biomedicine online
Language		eng
Abstract		Because sperm vacuoles were marked as zones without chromatin in the sperm nucleus, which may reflect underlying chromosomal or DNA defects, this study considered whether they influence the morphology and dynamics of early developmental events in preimplantation embryos. Oocytes were injected with spermatozoa of four classes, according to the number and size of vacuoles at 6000 magnification, and derived embryos were observed under time-lapse microscopy. For each embryo, the times of pronuclei appearance and disappearance and the first, second and third divisions were determined and related to its respective class of injected spermatozoa and its developmental stage. Embryos arising from normal class-I spermatozoa (without vacuoles) reached the 4-cell stage significantly earlier than embryos developed from class-IV spermatozoa (with large vacuoles and other abnormalities) (P = 0.012). Blastocysts from class-I spermatozoa required the shortest mean time for all developmental events in comparison with blastocysts from spermatozoa of other classes (with vacuoles). Blastocysts also showed significantly earlier first division than arrested embryos in embryos arising from class-I spermatozoa (P = 0.033). An insight into the developmental dynamics of embryo development according to morphology and head vacuoles of injected spermatozoa in morphologically selected sperm-derived embryos was observed for the first time. Sperm chromosomal anomalies and inherent DNA damage may interfere with early stages of zygote formation, syngamy and cell divisions. Because sperm vacuoles were marked as zones without chromatin in the sperm nucleus, which may reflect underlying chromosomal or DNA defects, we considered whether they influence the morphology and dynamics of early developmental events in preimplantation embryos. In this prospective study, oocytes were injected with spermatozoa of four classes according to the number and size of vacuoles at 6000 magnification, and derived embryos were observed by time-lapse microscopy. For each embryo, the times of pronuclei appearance and disappearance and first, second and third divisions were determined and related to its respective class of injected spermatozoa and its developmental stage. Embryos which developed from normally shaped spermatozoa of class I (without vacuoles) reached the 4-cell stage significantly earlier than embryos developed from spermatozoa of class IV (with large vacuoles and other abnormalities). Blastocysts developed from class-I spermatozoa required the shortest average time for all developmental events in comparison with blastocysts developed after injection of spermatozoa of other classes (with vacuoles). Blastocysts also showed significantly earlier first division than arrested embryos in embryos arising from class-I spermatozoa. This study suggests that preselection of spermatozoa under high magnification for intracytoplasmic sperm injection may be important in terms of early embryo developmental dynamics in patients with poor sperm morphology. An insight into the developmental dynamics of embryo development according to morphology and head vacuoles of injected spermatozoa in intracytoplasmic morphologically selected sperm injection-derived embryos was observed for the first time.
Keywords		developmental dynamics IMSI sperm vacuoles teratozoospermia time-lapse