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Mature Ovaries (mature + ovary)
Selected AbstractsOvary development in Greenland halibut Reinhardtius hippoglossoides in west Greenland watersJOURNAL OF FISH BIOLOGY, Issue 5 2005C. S. Simonsen Maturity in adult female Greenland halibut Reinhardtius hippoglossoides was studied in three areas in west Greenland waters: the inshore area in Disko Bay and two offshore areas, Baffin Bay and Davis Strait. The aim was to monitor maturity changes in the inshore fjords of Disko Bay over an extended period from winter to autumn and compare these findings with specimens from Baffin Bay and the presumed spawning area in Davis Strait. A significant difference in maturity level was observed in and between the three areas. In Disko Bay maturity indices increased significantly in August and September both with respect to the gonado-somatic index (IG) and the size in the leading oocyte cohort. In the period February to May no significant changes were observed. Mature ovaries were only observed among fish >80 cm total length and only among a fraction of these large fish. Offshore areas of Baffin Bay, even though poorly sampled, showed similar signs in the maturity indices as in Disko Bay. Relative to Disko Bay and Baffin Bay, female fish in Davis Strait had more progressed maturity indices. Furthermore, almost all fish in Davis Strait showed signs of progressed maturity contrary to Disko and Baffin Bay. A large proportion of the Greenland halibut in Disko and Baffin Bay apparently did not begin the maturation cycle until very late in their life history or were repeat spawners with a multi-year maturation cycle. These observations could thus support the hypothesis that Greenland halibut have a prolonged adolescent phase. Atresia was highest in the early phases of maturation in Greenland halibut but relatively high levels of atresia were also observed in fish in more advanced maturity phase. The first was ascribed to fecundity regulation while the latter could be linked to the fish's fitness condition but it was not possible to show this with the available condition index. [source] The biology of the bigeye grenadier at South GeorgiaJOURNAL OF FISH BIOLOGY, Issue 6 2004S. A. Morley The biology of the bigeye grenadier Macrourus holotrachys caught as by-catch in the Patagonian toothfish Dissostichus eleginoides longline fishery conducted around South Georgia was investigated to improve data available for fisheries management. Age estimates suggest that M. holotrachys is a moderately slow growing species (K = 0·10), reaching ages of >30 years and attaining total lengths (LT) >80 cm (L, = 33). The size at which 50% of females had started to mature (Lint50) for M. holotrachys was 21 cm pre-anal length (LPA) and occurred at c. 9 years old. Estimates of natural mortality and Pauly's growth performance index were found to be low (M = 0·09 and , = 2·82 respectively). Gonad maturity stage was described from macroscopic and histological investigation. Mature ovaries had oocytes at all developmental stages with between 22 and 55% likely to be spawned each year. Absolute fecundity ranged from 22 000 to 260 000 eggs and was positively correlated with both pre-anal length and mass. A highly skewed sex ratio of 32 : 1, females : males, was found for specimens caught by longlines but not for a small sample of shallower trawl-caught specimens. It is suggested that females are far more susceptible to longline capture than males. Macrourus holotrachys is a bentho-pelagic predator and scavenger that feeds on a wide range of fishes and invertebrates. The fish are long lived, slow-growing species typical of deep-water grenadiers; fisheries management strategies should reflect their probable susceptibility to overfishing. [source] Reproductive biology of two co-occurring mugilids, Liza argentea and Myxus elongatus, in south-eastern AustraliaJOURNAL OF FISH BIOLOGY, Issue 4 2008B. W. Kendall The reproductive biology of Liza argentea and Myxus elongatus occurring in two estuaries (Lake Macquarie and St Georges Basin) was found to differ. Gonado-somatic index values and macroscopic staging of gonads identified the peak spawning period of L. argentea occurred between March and November in Lake Macquarie and January and April in St Georges Basin. In contrast, peak spawning of M. elongatus was concentrated between January and March in both estuaries. Spawning of L. argentea probably occurred in the lower reaches of estuaries as well as in nearshore coastal waters, whereas evidence indicated M. elongatus spawned only in ocean waters. The mean fork length at maturity (LF50) was greater for females than males in both species, and it also occurred at a larger mean LF in M. elongatus (males = 230 mm and females = 255 mm) than L. argentea (males = 180 mm and females = 207 mm). Estimates of total potential fecundity were also greater for M. elongatus (425 484,1 157 029) compared to L. argentea (159 933,548 954). Both species had determinate fecundity and displayed a group synchronous pattern of oocyte development, with two distinct size classes of oocytes present in mature ovaries. Liza argentea probably release the larger class of oocytes in one spawning event, but this could not be established for M. elongatus. [source] Reproductive performance and offspring quality of Chinese mitten crab Eriocheir sinensis (H. Milne-Edwards) females fed an optimized formulated diet and the razor clam Sinonovacula constrictaAQUACULTURE RESEARCH, Issue 12 2009Xugan Wu Abstract After feeding female Eriocheir sinensis on an optimized formulated diet or fresh razor clam Sinonovacula constricta for 7 months, their reproductive performance and offspring quality were compared. To evaluate diet nutrient contents, the proximate, fatty acid and amino acid compositions of the formulated diet and the razor clam were analysed. The nutritional value of the diets was determined by assessing survival, gonadosomatic index (GSI) and hepatosomatic index (HSI) of female crabs from both diet treatments, together with the percentage of females that spawned, total egg production per female and fecundity (number of eggs g,1 female wet weight). Furthermore, the quality of eggs and newly hatched larvae from the two dietary treatments were determined using the following parameters: egg diameter, wet weight and dry weight, hatchability, proximate and fatty acid profile of eggs, larval carapace length, resistant to starvation and osmotic shock, larval survival and development to the zoea II stage. Higher protein, phospholipids (PL) and amino acids (AA) contents were found in the razor clam while the formulated diet contains higher levels of ash, total lipid (TL) and 18:1n-9, 18:2n-6 and 22:6n-3 fatty acids. Although female crabs fed the two different diets showed similar reproductive performances, newly hatched zoea I larvae produced by the crabs fed the formulated diet had significantly longer mean carapace length and shorter development time to the zoea II stage under identical culture condition (P<0.05). Moreover, dietary fatty acid appeared to have more significant effects on the fatty acid composition of the hepatopancreas than it did on mature ovaries or eggs. This suggests that the fatty acid profile of mature ovaries is indicative of the specific fatty acid required for ovarian development in E. sinensis. In conclusion, our results show that the optimized formulated diet developed in this laboratory can totally replace the razor clam, a broodstock food widely used in E. sinensis hatcheries in China. This encouraging result should facilitate more reliable hatchery production of this important aquaculture species. [source] Ovarian maturation stages of the mud crab Scylla serrataAQUACULTURE RESEARCH, Issue 14 2007Emilia T Quinitio Abstract Ovarian maturation in adult wild-sourced and pond-grown Scylla serrata (Forsskål) was determined based on gross morphology and histological appearance. There were no significant differences noted in the histological features of both wild and pond-reared S. serrata females. Ovarian maturation was classified into five stages: immature, early maturing, late maturing, fully mature and spent. The immature ovaries are thin and translucent to off white and contain oogonia, primary oocytes with large nuclei. The follicle cells were found around the periphery of the lobes and an area among groups of oogonia and oocytes. The follicle cells gradually enclosed the oocytes. The early-maturing ovaries were yellow and small yolk globules started to appear in larger oocytes. In late-maturing ovaries, the colour became light orange and lobules were apparent. Yolk globules occurred in the cytoplasm with larger globular inclusions towards the periphery, while follicle cells were hardly recognizable. Fully mature ovaries were orange to deep orange and had swollen lobules. Large yolk globules were apparent in the entire cytoplasm. Follicle cells were hardly seen. Spent ovaries were similar to the early-maturing and late-maturing stage in partially spawned females. The ovarian development was correlated closely to the gonadosomatic index, oocyte diameter, and ovarian histology. The classification of ovarian maturation provides baseline information for further studies on reproductive biology. Likewise, the information provides a guide for broodstock management in the hatchery. [source] Life stages and reproductive components of the Marmorkrebs (marbled crayfish), the first parthenogenetic decapod crustaceanJOURNAL OF MORPHOLOGY, Issue 3 2004Günter Vogt Abstract Recently, we briefly reported on the first case of parthenogenesis in the decapod Crustacea which was found in the Marmorkrebs or marbled crayfish, a cambarid species of unknown geographic origin and species identity. Curiously, this animal is known only from aquarium populations, where it explosively propagates. By means of light and electron microscopic techniques we have now investigated the reproductive components of this crayfish, using more than 100 specimens ranging from hatchling to repeatedly spawned adult. Additionally, we documented its principal life stages. Our results revealed that the external sexual characters and also the gonads of the marbled crayfish are purely female, making this fast-reproducing species a good model for investigating female reproductive features in crayfish. Testicular tissues, ovotestes, or male gonoducts, gonopores, or gonopods were never found, either in small juveniles or large adult specimens, confirming the parthenogenetic nature of this crayfish. Parthenogenesis may have arisen spontaneously or by interspecific hybridization since Wolbachia -like feminizing microorganisms were not found in the ovaries. The external sexual characters of the marbled crayfish are first recognized in Stage 4 juveniles and are structurally complete ,2 months after hatching in specimens of ,2 cm total length. In the same life stage the ovary is fully differentiated as well, although the oocytes are in previtellogenic and primary vitellogenic stages only. The architecture of the mature ovary and also the synchronous maturation of cohorts of primary vitellogenic oocytes by secondary vitellogenesis are in general agreement with data published on ovaries of bisexual crayfish. New results were obtained with respect to the muscular nature of the ovarian envelope and its extensive proliferation after the first spawning, the distribution of hemal sinuses in the ovarian envelope and in the interstitium around the oogenetic pouches, the high transport activity of the follicle cells, and the colonization of oogenetic pouches by previtellogenic oocytes that originate in the germaria. Investigation of the nuclei of oocytes in the germaria and oogenetic pouches revealed no signs of meiosis, as usually found in females of bisexual decapods, suggesting that parthenogenesis in the marbled crayfish might be an apomictic thelytoky. The detection of new rickettsial and coccidian infections in the ovary and further organs raises fears that the marbled crayfish might endanger native European species by transmission of pathogens once escaped into the wild. J. Morphol. 261:286,311, 2004. © 2004 Wiley-Liss, Inc. [source] Characterization of heat shock protein 90 in the shrimp Metapenaeus ensis: Evidence for its role in the regulation of vitellogenin synthesisMOLECULAR REPRODUCTION & DEVELOPMENT, Issue 5 2008Long Tao Wu Abstract Estrogen hormones play a vital role in the regulation of female reproductive maturation. In oviparous vertebrates, the synthesis of vitellogenin (VTG) is tightly controlled by estrogen hormone signal transduction pathway, which is mediated by estrogen receptor and heat shock protein 90 (Hsp90). In order to investigate whether a similar mechanism exists in crustaceans, the Hsp90 gene was cloned and isolated from the shrimp Metapenaeus ensis by homology cloning strategy. The Hsp90 is 2,524 bp in length, containing an open reading frame of 2,163 bp that encodes a 720 amino acid polypeptide (83 kD). The Hsp90 -coding region is interrupted by four introns. MeHsp90 is differentially expressed in eyestalk, ovary, and hepatopancreas at different ovarian maturation stages, and consistently expressed in other tissues including heart, gill, gut, muscle, and central nervous system. In vitro ovary explant assay reveals that MeHsp90 expression in immature ovary can be induced by the addition of exogenous estradiol-17,, but expression in fully mature ovary exhibits no response to estradiol-17, treatment. In situ hybridization shows that MeHsp90 is highly expressed in previtellogenic oocytes and its expression decreases with the progress of maturation, and finally stops in late-vitellogenic oocytes. Our results indicate a strong correlation between estrogen hormones and Hsp90 expression in shrimp, suggesting that the expression of VTG may be under the regulation of estrogen hormones through a mechanism similar to that in vertebrates. The result provides insights on the control of vitellogenesis in invertebrates. Mol. Reprod. Dev. 75: 952,959, 2008. © 2008 Wiley-Liss, Inc. [source] | |||||||||||||