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Vitellogenic Oocytes (vitellogenic + oocyte)
Selected AbstractsGonadal structure of the serial-sex changing gobiid fish Trimma okinawaeDEVELOPMENT GROWTH & DIFFERENTIATION, Issue 1 2005Yasuhisa Kobayashi In order to obtain basic information about the role played by endogenous sex hormones in bringing about sex changes in the serial-sex changing gobiid fish Trimma okinawae, the gonadal structure of male and female phases were observed histologically. Steroid-producing cells (SPC; Leydig cells in a testis) were observed ultrastructurally in the ovaries and testes of both female-phase and male-phase fish. In addition, gonadal expression of P450 cholesterol side-chain-cleavage (scc) was examined immunohistochemically. Gonads of fish in female and male phases were observed to have both ovaries and testes simultaneously. Female-phase fish had matured with many developed vitellogenic oocytes, while male-phase individuals had immature ovaries with many numbers of previtellogenic oocytes at the perinucleolus stage. Testes of fish in different sexual phases had active spermatogenic germ cells. Organellae of SPC in the ovaries of female-phase fish had active structures of steroid production. In contrast, SPC in the ovaries of male-phase fish did not show active structures of steroid production. Immunopositive reactions against the scc antibody in the ovaries of female-phase fish were very strong, but immunoreactions in the ovaries of male-phase fish were very weak. In the testis, moderate immunopositive signals were obtained from dual-phase male/females. [source] Comparative folliculogenesis and spermatogenesis of four teleost fish from a Reservoir in south-eastern BrazilACTA ZOOLOGICA, Issue 4 2010Yuri Simões Martins Abstract Martins, Y.S., Moura, D.F., Santos, G.B., Rizzo, E. and Bazzoli, N. 2009. Comparative folliculogenesis and spermatogenesis of four teleost fish from a Reservoir in south-eastern Brazil. ,Acta Zoologica (Stockholm). 91: 466,473. This study provides a comparative analysis of gametogenesis of neotropical teleosts Metynnis maculatus, Megalancistrus parananus, Cichla kelberi and Satanoperca pappaterra, through histological, histochemical and histometric techniques. In the ooplasm of C. kelberi and S. pappaterra conspicuous lipid vesicles were observed, which are characteristic of pelagic eggs produced by marine fishes. Perinucleolar oocytes were identified in the testis of S. pappaterra suggesting that this species is protogynous without functional hermaphroditism, an unusual pattern for neotropical fresh-water fishes. The spermatozoa of the studied species have rounded heads, a characteristic of fish that externally fertilise their eggs. The follicular (granulosa) cells of the vitellogenic oocytes from the studied species were cuboidal or columnar, however, in C. kelberi there were columnar follicular cells at the vegetal pole and cuboidal cells at the animal pole. Variations of the histochemical content were detected in the cortical alveoli and follicular cells of vitellogenic oocytes showing differences in the mechanisms to block polyspermy and egg adhesiveness. Larger oocytes were recorded in species which demonstrated parental care behaviour and smaller oocytes were noted in those species with fractioned spawning. [source] Degeneration of germ line cells in amphibian ovaryACTA ZOOLOGICA, Issue 3 2010Maria Ogielska Abstract Ogielska, M., Rozenblut, B., Augusty,ska, R., Kotusz, A. 2010. Degeneration of germ line cells in amphibian ovary. ,Acta Zoologica (Stockholm) 91: 319,327 We studied the morphology of degenerating ovarian follicles in juvenile and adult frogs Rana temporaria, Rana lessonae and Rana ridibunda. Degeneration of primordial germ cells was never observed and was extremely rare in oogonia and early oocytes in a cyst phase in juveniles. Previtellogenic oocytes were rarely affected. Three main types of atresia were identified. In type I (subdivided into stages A,D), vitellogenic oocytes are digested by proliferating follicle cells that hypertrophy and become phagocytic. A , germinal vesicle shrinks, nucleoli fuse, oocyte envelope interrupts, and follicular cells hypertrophy; B , follicular cells multiply and invade the oocyte; C , entire vesicle is filled by phagocytic cells; D , degenerating phagocytes accumulate black pigment. Type II is rare and resembles breakdown of follicles and release of ooplasm. In type III, observed in previtellogenic and early vitellogenic oocytes, ooplasm and germinal vesicle shrink, follicle cells do not invade the vesicle, and condensed ooplasm becomes fragmented. The residual oogonia in adult ovaries (germ patches) multiply, but soon degenerate. [source] Micro- and macroscopic characteristics to stage gonadal maturation of female Baltic codJOURNAL OF FISH BIOLOGY, Issue 2 2003J. Tomkiewicz A set of histological characteristics to judge ovarian development was established and used to elaborate morphological criteria of 10 maturity stages of Baltic cod Gadus morhua sampled throughout the annual cycle to represent different macroscopic maturity stages. The applied characteristics confirmed most stages of the macroscopic scale, but the separation of late immature and resting mature females remained imprecise. Atretic vitellogenic oocytes or encapsulated residual eggs identified the resting condition morphologically, but not all ovaries with visible signs of previous spawning showed such features. One ovarian stage that was previously classified as ,ripening' was changed to ,spawning', owing to the prevalence of hydrated eggs and empty follicles. Ovaries with malfunctions were defined by a separate stage. Macroscopic criteria were revised by comparing the gross anatomy of ovaries with their histology. Female length and gonado-somatic index supported stage definitions, but substantial variation in Fulton's condition factor and the hepato-somatic index rendered these of little use for this purpose. The time of sampling influenced staging accuracy. A female spawner probability function based on the proportion of ripening and ripe specimens in early spring seems to be the most appropriate method to estimate spawner biomass and reproductive potential. [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] Hermaphroditism in Cultured Chinese Black Sleeper (Bostrichthys sinensis L.)JOURNAL OF THE WORLD AQUACULTURE SOCIETY, Issue 4 2006Wan Shu Hong Anatomical studies showed that all collected feral fish of Chinese black sleepers (Bostrichthys sinensis L.) were gonochoristic. In contrast, an average of 12.4% of cultured fish appeared to be hermaphroditic. The shape of the genital papilla of hermaphroditic specimens resembled that of gonochoristic males. The gonadosomatic index (IG) of hermaphroditic fish varied from 0.24 to 4.48%, while that of gonochoristic conspecifics varied from 6.1 to 12.2% for females and 0.11 to 0.14% for males. Histological studies revealed that the sex organs of hermaphrodites consisted of ovarian, testicular, and seminal vesicle tissues, located in the central, peripheral, and caudal region of the gonads, respectively. During the spawning season, ovarian tissue contained poorly developed oocytes, that is, hydrated oocytes were absent and only a few degenerated vitellogenic oocytes were present. Testicular tissue, however, contained fully developed spermatozoa. The fertilization rate of these spermatozoa was significantly lower than those of gonochoristic conspecifics. It is concluded that part of the cultured stock of Chinese black sleeper became hermaphroditic during culture and that the hermaphrodites are able to function as males. The lowered fertilization rate, however, indicates that hermaphroditism in cultured fish of this species is disadvantageous to reproduction. [source] Thyroglobulin type-1 domain protease inhibitors exhibit specific expression in the cortical ooplasm of vitellogenic rainbow trout oocytesMOLECULAR REPRODUCTION & DEVELOPMENT, Issue 2 2004Antony W. Wood Abstract The synthesis, uptake, and processing of yolk proteins remain poorly described aspects of oviparous reproductive development. In this study, we report the identification and characterization of two protease inhibitors in rainbow trout ovary whose expression and distribution are directly associated with yolk protein uptake in vitellogenic oocytes. The first transcript, termed "oocyte protease inhibitor-1" (OPI-1), is predicted to encode a 9.1 kDa, 87 amino acid protein containing a single thyroglobulin type-1 (TY) domain, identifying it as a putative TY domain inhibitor. The second transcript, termed OPI-2, is predicted to encode an 18.3 kDa, 173 amino acid protein with two similar, but not identical, TY domains. Messenger RNA expression of both genes was first detected in ovarian tissues at the onset of vitellogenesis, and persisted throughout the vitellogenic growth phase. We did not detect expression of either gene in previtellogenic ovaries, nor in any somatic tissues examined. Expression of OPI-1 mRNA was significantly reduced in atretic follicles as compared to healthy vitellogenic follicles, suggesting a downregulation of inhibitor expression during oocyte atresia. Western immunoblot analyses of whole yolk from vitellogenic oocytes revealed the presence of two immunoreactive proteins that corresponded to the predicted sizes of OPI-1 and OPI-2. We detected strong crossreactivity of this antiserum with specific vesicles in the cortical ooplasm of vitellogenic oocytes, in regions directly associated with vitellogenin processing. The identification of OPI-1 and OPI-2 provides new evidence for the expression of multiple TY domain protease inhibitors likely involved in the regulation of yolk processing during oocyte growth in salmonids. Mol. Reprod. Dev. 69: 205,214, 2004. © 2004 Wiley-Liss, Inc. [source] Evaluation of practical diets containing different protein levels on gonad development of female redclaw crayfish Cherax quadricarinatusAQUACULTURE NUTRITION, Issue 4 2009H. RODRÍGUEZ-GONZÁLEZ Abstract The effect of five experimental diets with different crude protein content (220, 270, 330, 390 and 450 g kg,1) on gonad development of female Cherax quadricarinatus was tested under laboratory conditions. After 70 days, a significant linear relationship indicated that higher concentrations of protein and carbohydrates in the hepatopancreas were produced as the dietary crude protein increased (P < 0.05). There were significant responses of the gonadosomatic index, hepatosomatic index, biochemical composition of the gonad (protein, lipids, carbohydrates and energy) and frequency of secondary vitellogenic oocytes to dietary protein level, as indicated by significant fits of the quadratic equation to the observed experimental data. The optimal response of the criteria parameters corresponded to levels of crude protein in the range 284,355 g kg,1. Overall, 330 g kg,1 crude protein with a protein : energy ratio of 15.6 mg kJ,1 was considered the most adequate concentration of dietary protein for gonad development and biochemical composition in female redclaw crayfish. [source] Comparison of continuous and batch feeding systems on maturation, biochemical composition and immune variables of the oyster Crassostrea corteziensis (Hertlein 1951)AQUACULTURE RESEARCH, Issue 4 2009Miguel A Hurtado Abstract Two feeding systems for maturing oysters were compared, one a continuous feeding system and the other a batch system in which the whole microalgal ration was supplied once daily. The maturation diet consisted in Isochrysis galbana (T-ISO) complemented with an enriched lipid emulsion. Survival and growth did not differ between the feeding systems after 3 weeks of conditioning. Maturation, biochemical composition, fatty acids in membranes and reserves, digestive enzymes activities and immune parameters in Crassostrea corteziensis were analysed. Only oysters fed using the once-daily system had vitellogenic oocytes, whereas the gonad of oysters fed using a continuous-drip system remained immature. Total and differential haemocyte counts were similar between both the systems, but respiratory burst was significantly higher in oysters fed using the once-daily system. Amylase, lipase and trypsin activities in oyster's digestive gland were similar between both the feeding systems. Total lipids, however, differed significantly in oyster tissue in relation to feeding system, with highest level in those fed using the once-daily system, but fatty acid composition in reserves and membrane were similar. No differences were found for biochemical parameters in haemolymph. These results suggest that feeding oysters using a batch, once-daily system allows more rapid initial gonad maturation without affecting general physiological condition and growth. [source] | |||||||||||||