17 F. Aziz Z. Mehboob S. Jalali S. A. Shami I. Z. Qureshi Journal of Animal and Plant Sciences JAPS 20122012/06/01 22 3 147-152 1018-7081 NA <p>The present study evaluated in-vitro toxicity of organophosphate insecticide, malathion on nuclear maturation, fertilization and subsequent embryo development of the oocytes obtained from abattoir ovaries of Nili-Ravi Buffalo (Bubalus bubalis). The cumulus-oocyte complexes (COCs) in culture medium were exposed to four different regimens of malathion, 1.56 &micro;mol, 3.12 &micro;mol, 6.25 &micro;mol and 12.5 &micro;mol. Results demonstrated dose dependent significant difference (P &lt; 0.05) in nuclear competence, oocyte maturation and degeneration. Cumulus expansion showed significant increase (P &lt; 0.05) while oocyte diameter increased non significantly (P &gt; 0.05). The COCs that attained nuclear maturation (MII) and were subjected to IVF and, subsequent embryonic development also showed dose dependent non-significant (P &gt; 0.05) decrease in fertilization and embryonic development, however, hatched blastocyst formation was significantly compromised (P &lt; 0.05). The blastocyst development with inner cell mass was again non- significantly different (P &gt; 0.05). The study concludes that malathion may effect quality of preimplantation embryos developed in-vitro from immature oocytes pre-exposed to the pesticide.</p> Malathion; organophosphorous insecticides; in-vitro maturation; buffalo oocytes Pakistan Agricultural Scientists Forum https://thejaps.org.pk/AbstractView.aspx?mid=2012-JAPS-3006