| The histological structure of mandibular organ in shrimp Penaeus chinensiswas investigated with light and electron microscope. The concentration ofprogesterone and estradiol in hepatopancrea, ovary, and blood of shrimp indifferent ovary development stage were detected by radioimmunoassay.Effect of 17α-hydroxyprogesterone on in vitro culture of oocyte of Penaeuschinensis was investigated. Induction of four kind of hormones injection andeyestalk remove on ovary maturation of Penaeus chinensis was investigated.Following is the main results of this dissertation.1. Function and histological structure of the mandibular organ in shrimp Penaeus chinensisThe mandibular organ of P. chinensis is located at the anterior end of thepaired chitinous tendons that extend from the mandibles to the dorsalcarapace. Channels of hemolymph subdivide the gland into cord, whichforms lobule. The gland is enveloped by a layer connective tissue, andhemolymph tact and nerve tract is associated with the organ. Near the organ,there is a termination of the nerve tract, which suggested a possible indirector direct neurohumoral stimulation of the mandibular organ. When theshrimp is in vitellogenesis stage, the cells of the mandibular organ becomehypertrophy obviously, and there are a lot of vesicles in the plasma. Thereare some binuclarted cells, which show typical of crustacean mandibularorgans. The nuclei are oval, eosinophilic, and often eccentric. Thekaryoplasm contains patches of condensed chromatin closely associated withthe nulear envelope. The most distinguishing feature of mandibular glandcells is two distinct types of smooth endoplasmic reticulum (SER). There canbe observed a lot of other cytoplasmic organelles, such as mitochondria,golgi complexes, and lipid-like inclusions. Numerous mitochondria withtubular cristae surround the nucleus and frequently are associated with SERThe plasma membrane, when adjacent to hemolymph, exhibits varyingdepressed or convolution. Adjacent plasma membranes may be in closeapposition or separated by a space filled with vesicles, or blood, orhemolymph tact. This type of ultra-structure is associated withsteroid-secreting cells. The concentrations of progesterone and estradiol weredetected by radio-immunoassay method. The results showed that in theimmature stage, both hormones could not be detected, however, duringmaturing stage both hormones can be detected. The highest levels ofprogesterone and estradiol are 106.5, 22.5 pg/one organ). When the shrimpclose to matured the concentrations of progesterone and estradiol droppedrapidly. The result suggests that there is close relationship between themandibular organ of penaeid shrimp and its reproduction.2.Changes in the Concentration of progesterone and estradiol in tissues of shrimp Penaeus chinensis at different ovary developing stage The concentrations of progesterone and estradiol in the tissues(hepatopancreas, ovary, hemolymph) of Penaeus chinensis were investigatedby radioimmunoassay during a reproductive cycle, and changes in GSI, andHSI were monitored. Progesterone and estradiol were detected in thehepatopancreas, ovary, and hemolymph of the shrimp with maturing ormatured ovary. During immature stage (length<8-10cm), the two hormoneswere undetectable, however, during previtellogenesis stage (perinucleolusstage, length>11~13cm), the concentrations of the two hormones in threetissues increased rapidly, and estradiol in ovary reached a peak(450±86.7pg/g). During vitellogenesis stage (length>13-15cm), the twohormones maintained relatively high levels. Progesterone reached peaks inovary (1975.1±175.2pg/g), and hepatopancreas (902.6±130.5 pg/g), andestradiol reached a peak in hemolymph (451.3±73.7 pg/ml). The hormonelevel decreased sharply during maturation stage, and in hepatopancreas, thehormones even became undetectable. During whole reproductive cycle, GSI(gonadosomatic index) increased continuously; however, HSI( hepatosomatic index) stopped increasing during maturation stage, andshowed a similar change like that of hormone levels in hepatopancreas andovary. The results suggested that hepatopancreas might be the site ofvitellogenin synthesis in P. chinensis.3. Effect of 17α-hydroxyprogesterone on in vitro Culture of oocytes of Shrimp Penaeus Chinensis In vitro stimulation results of oocytes of shrimp Penaeus chinensis bythree different concentration 17α-hydroxyprogesterone( 2×10-6, 2×10-7, and2×10-8 μg/ml ) are reported. The results showed that the hormone hadsignificant effect on the oocytes culture in vitro. Under identical culturecondition, the mean oocyte diameters in the experimental groups withhormone were 30-50 % larger than that in contrast groups without hormone.With increase of hormone concentration, reproduction of oocyte quickenedand oocyte diameter increased. Through a week culture, the mean...
|
PDF Full Text Request