To examine the chromosomal number content in the blastomeres of embryos achieved from fertilization of immature oocytes at MI stage recruited following COH for IVF.

comparison of the genetic number content of embryos and their quality in terms of cleavage rate and morphological score reached after fertilization of immature oocytes at MI stage whether arrested at the MI stage or extruded the polar body, after in vitro maturation for a variable length of time.

Patients undergoing routine IVF, following informed consent, donated some of their unusable, immature- MI stage oocytes for our research. Following in vitro maturation for up to 2, 4, 8 and 24 hours after harvest, all immature oocytes in these 4 study groups underwent intracytoplasmic donor sperm injection (ICSI), whether they extruded their polar body (MI-PB or rescued MI) or not (arrested MI). Oocyte fertilization rate after 24 hours and embryonic development in terms of cleavage rate and morphology were assessed, for another 48 hours. Then the whole embryo was prepared for molecular cytogenetic evaluation using FISH (Fluorescence in situ hybridization) analysis of chromosomes x, y and 18.

Inclusion Criteria:

• Patients with presence of immature oocytes after ART stimulation

Exclusion Criteria:

• Patients with less than total 7 oocytes