L-Cysteine improves bovine oocyte developmental competence in vitro via activation of oocyte-derived growth factors BMP-15 and GDF-9.

This study was designed to investigate the effect of different concentrations of L-cysteine supplementation into the maturation medium on the oocyte nuclear maturation, cumulus cell expansion, ultrastructure of the oocytes and the expression of oocyte-derived growth factors BMP-15, GDF-9 and CB-1 genes. Cumulus oocyte complexes (COCs) were collected from cow's ovaries obtained from abattoir and incubated at 38.5°C in maturation media supplemented with 0, 0.6, 0.8 or 1 mM L-cysteine in 5% CO2 under humidified air for 24 hr. We found that a significantly higher percentage of oocytes progressed to metaphase II stage in the in vitro maturation (IVM) medium supplemented with L-cysteine, particularly 0.8 mM group, compared with untreated control oocytes. Additionally, L-cysteine treatment significantly increased the number of expanded COCs and the degree of expansion of individual COCs. Results of RT-qPCR showed significant increase in expression levels of BMP-15 and GDF-9 in L-cysteine-treated groups compared with control one. Electron microgram showed improvement of cytoplasmic maturation regarding ultrastructure of the oocytes and oocyte-cumulus cell gap junction communication in all L-cysteine-treated groups especially 0.8 mM L-cysteine-treated one. In conclusion, supplementation of IVM medium with a potential anti-oxidant, L-cysteine can effectively improve in vitro oocytes cytoplasmic and nuclear maturation via activation of oocyte maturation related BMP-15 and GDF-9 genes in bovine oocytes, benefiting the extended researches about the potential applications of L-cysteine in mammalian breeding technologies.

Vascular endothelial growth factor: A novel marker for torsion-induced incomplete cervical dilatation in Egyptian buffaloes.

Background: Uterine torsion, the most complicated cause of maternal dystocia recorded in bovine, usually followed by incomplete cervical dilatation after successful detorsion, which interfere with vaginal fetal delivery. Aim: This study aimed to evaluate the histopathological changes, variable collagen concentrations, and vascular endothelial growth factor expressions in uterine and cervical tissues following successful detorsion. Methods: Animals were classified into four groups; normally calved cases (group A), cases that respond successfully to detorsion and followed by vaginal fetal delivery without (group B) or with (group C) cervical laceration, and cases that suffered from failure of complete cervical dilatation after successful detorsion (group D). Results: Histopathological findings revealed variable changes in all uterine torsion affected groups, which were characteristic and marked in animals that suffered from failure of complete cervical dilatation following successful detorsion. Moreover, failure of cervical dilatation was associated with the highest collagen concentrations as shown by Masson trichrome stain. On the other hand, immunohistochemical findings showed that the normally calved cases have the highest vascular endothelial growth factor expression compared with animals that suffered from failure of complete cervical dilatation. Conclusion: Our results showed that the vascular endothelial growth factor is essential for cervical dilatation and its lower expression is accompanied by incomplete cervical dilatation following successful detorsion.