The changes in the levels of vertebrate-type hormones estradiol-170 and progesterone in the haemolymph and ovary of the mud crab Scylla serrata in relation to different stages of ovarian maturation has been investigated. The histological study of the ovary of the crab of 250 & 10 g average weight showed a large number of oogonial cells at stage I, oocytes with yolk granules at stage 11, oocytes filled with yolk droplets at stage I11 and fully matured oocytes having ooplasm filled with yolk globules at stage IV. The radioimmuno assay carried out to quantify the 170- estradiol and progesterone in the haemolymph indicated that the estradiol is nondeductible in the haemolymph in stage I. And it showed an increasing trend up to stage I11 with a peak of 892.47 pg/ml before decreasing in stage IV. Ovarian estradiol level gradually increased from stage I to I11 (maximum 1247.35 pg/g) and decreased in stage IV. On the contrary, progesterone level, though undetected in stage 1, continuously increased up to stage IV in the haemolymph (876.23 pg/ml). However, in the ovary it gradually increased from stage I to IV (1368.44 pg/g). The levels of progesterone and estradiol were calculated with the help of one-way analysis of variance and their significance was expressed at less than 0.001. This study clearly indicated the positive correlation of progesterone quantity with the stages of ovarian maturation, but the estradiol level was negatively correlated.

Vertebrate type steroids, ovarian maturation, mud crab