Effect of Methyl Farnesoate Administration on Ovarian Growth and Maturation in the Freshwater Crab Travancoriana schirnerae

This study assessed the effect of exogenous administration of methyl farnesoate on growth and maturation of ovary in the freshwater crab Travancoriana schirnerae. Results provide strong evidence that methyl farnesoate administration induced ovarian growth in all phases of oogenesis as judged by the increased ovarian indices, oocyte diameter and oocyte proportion values of experimentals over controls. Our observations also revealed that methyl farnesoate treatment induced avitellogenic and previtellogenic ovaries to grow into vitellogenic and early vitellogenic to middle vitellogenic ovaries as evidenced by the presence of a large number of vitellogenic oocytes in avitellogenic and previtellogenic ovaries and enhanced yolk deposition in early vitellogenic ovaries. However, methyl farnesoate injection during late vitellogenic phase effected no significant change in morphology or histology of the ovary. From the results it is evident that methyl farnesoate administration caused a marked increase in gonial proliferation in both reproductive and non-reproductive phases. The elevated ovarian index, mean oocyte diameter and oocyte proportion values of experimentals over controls in the present investigation may be attributed to the increased growth and yolk deposition in oocytes triggered by methyl farnesoate. It is concluded that methyl farnesoate administration is effective in inducing ovarian growth and maturation thereby reducing the duration of the ovarian cycle which is highly advantageous for a species of aquaculture potential.