Temporal effects of ovine luteinizing hormone and desoxycorticosterone acetate on maturation and ovulation of oocytes of the catfish, <i>Heteropneustes fossils</i> (Bloch): An <i>In vivo</i> and <i>In vitro</i> study

Abstract

Abstract Intramuscular administration of ovine luteinizing hormone (LH) or desoxycorticosterone acetate (DOCA) into gravid catfish, Heteropneustes fossilis , shows that LH is a much less efficient maturation‐inducing agent than DOCA. Maturational changes occur two hours earlier following DOCA injection than with LH. In the second experiment, ovarian pieces obtained from catfish one to eight hours following LH or DOCA injection were cultured in Wolf and Quimby medium without hormones for 11 to 4 hours respectively; the total duration between hormone injection and termination of culture was 12 hours in every case. Oocytes sampled from catfish two hours after DOCA injection or four hours after LH injection completed the process of maturation in vitro in the absence of hormones. Further, oocytes obtained from DOCA‐injected catfish three, four and five hours after treatment and cultured for nine, eight and seven hours respectively, exhibited maturational changes far more advanced than in the oocytes of the corresponding LH‐injected groups. In LH‐injected catfish maturational changes were observed two hours later than those in DOCA‐injected group. It is suggested that this two‐hour time lag, noticed in both the experiments, represents the duration necessary for LH to act on the catfish interrenal to build up the circulating titers of corticosteroids required for maturation and ovulation of oocytes. It is tentatively concluded that the terminal hormones which act on the catfish oocytes to induce maturation and ovulation are the corticosteroids.