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Search Results: 1 - 10 of 32 matches for " vitellogenesis "
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Ovary Development and Maturation in Nezara viridula (L.) (Hemiptera: Pentatomidae)
Fortes, P;Salvador, G;C?nsoli, FL;
Neotropical Entomology , 2011, DOI: 10.1590/S1519-566X2011000100013
Abstract: ovary development and maturation of nezara viridula (l.) were evaluated by examining ovariole morphology and the alterations in the biochemical (protein synthesis related to reproduction) composition of the hemolymph. quantitative and qualitative protein analyses were performed and ovary structural alterations for the pre-reproductive and reproductive stages were recorded. total concentration of proteins in female hemolymph gradually increased until the end of the pre-mating stage, remaining unaltered thereafter. proteins linked to reproduction (vitellogenins) appeared in the hemolymph 10 days after adult emergence and indicated the end of the pre-mating stage. after mating, total protein concentration in the hemolymph was lower compared to virgin females; vitellogenin levels were similar during most of the observation period. oocyte development and maturation were gradual and age dependent. ten-day-old females had chorionated oocytes ready for fertilization. mating did not stimulate oocyte development in n. viridula, but the lack of mating activity appeared to have stimulated oocyte resorption in 17-day-old females.
Nuclear activity in Apis mellifera L. (Hymenoptera, Apidae) queen ovary cells demonstrated by silver nitrate impregnation and ultrastructure
Cruz-Landim, C.;Patrício, K.;
Brazilian Journal of Biology , 2010, DOI: 10.1590/S1519-69842010000500023
Abstract: the present paper shows through conventional light microscopy, silver nitrate impregnation and transmission electron microscopy, the changes in nuclear activity that occurs in the ovary cells during vitellogenesis of apis mellifera (linnaeus, 1758). the material impregnated by silver nitrate was detected in nurse cells, oocyte germinal vesicle and follicular cells, whose amounts are greater in phases corresponding to ovarian cells more intense activity. the silver impregnation permitted to demonstrate that the oocyte germinal vesicle synthezises ribonucleoproteins (rnp) during the beginning of the vitellogenesis. the ultrastructure show nucleolar-like material corresponding to nuclear sites impregnated by silver.
Desenvolvimento ovariano de Plagioscion squamosissimus (Heckel, 1840) (Actinopterygii, Perciformes), no reservatório de Pedra, Rio de Contas, Bahia
Félix, Renata Triane da Silva;Severi, William;Santos, Athiê Jorge Guerra;El-Deir, Ana Carla Asfora;Soares, Maria Goretti;Evêncio Neto, Joaquim;
Biota Neotropica , 2009, DOI: 10.1590/S1676-06032009000300012
Abstract: this study aimed to characterize oocyte organization and maturation stages of plagioscion squamosissimus ovary. samples were collected bimonthly in pedra reservoir, contas river (ba), between november 2004 and september 2006. microscopic analyses were made on histological cuts stained with hematoxylin - eosin - phloxine and gomori trichromic mixture. five maturation stages were identified through macro and microscopic analysis. gonad coloration varied according to maturation stages. six phases of oocyte development were identified: oogonia and perinucleolar, vitellogenic and early lipidic, vitellogenic and intermediate lipidic, vitellogenic and advanced lipidic, and pre-ovulation. cell structures were similar to those found among marine species, such as oil droplets fusion at later developmental stages and pre-ovulatory hydration. such features may be explained by the marine origin of sciaenidae, thus suggesting the need of more detailed studies for understanding the origin, development and function of these structures along oocyte developmental stages.
Histological characterization of cellular types during Scinax fuscovarius oogenesis (Lutz) (Anura, Hylidae)
Oliveira, Classius de;Santos, Lia Raquel de Souza;
Revista Brasileira de Zoologia , 2004, DOI: 10.1590/S0101-81752004000400029
Abstract: this paper describes morphological characteristics of the ovarian germinative cells of the scinax fuscovarius (lutz, 1925). the ovary is organized in primordial germinative cells (oogonia) and follicular structures (ovarian follicle) - oocytes surrounded by follicular cells. oogonia: their nests are peripherically localized, containing cells with large and oval nucleus. oocytes i: basophilic cytoplasm; the spherical nucleus presents few nucleoli, one or two; the follicular cells (one tenuous layer) surround these previtellogenic cells. oocytes ii: the cell is larger and the cytoplasm becomes more basophilic; the nucleus presents few nucleoli and contains many chromosomes in the periphery (beginning the perinucleolar stage). oocytes iii: the cytoplasm acquires an intense acidophilia; the peripherical region of cytoplasm is filled with yolk and the internal region has no yolk at all; pigment synthesis begins; the follicular envelope presents three tenuous layers: an inner acellular (vitelline envelope) and two cellular layers (follicle cells). oocytes iv: a characteristic of this stage is the differentiation between the animal and the vegetal poles; the nucleus in the animal hemisphere and the pigments give the oocyte a color dark brown; the vitellogenesis is intense and the yolk occupies the whole cytoplasm.
Annual reproductive cycle in two free living populations of three-spined stickleback (Gasterosteus aculeatus L.): patterns of ovarian and testicular development
Ewa Soko?owska,Ewa Kulczykowska
Oceanologia , 2006,
Abstract: The annual reproductive cycle in two wild populations of three-spinedstickleback was studied. Sticklebacks from the Dead Vistula River(Martwa Wis a) (brackish water) and the Oliva Stream (Potok Oliwski)(freshwater) were exposed to annual environmental changes in their naturalhabitats. Ovaries and livers (females), and testes and kidneys (males) werecollected during 1-2 years. The gonadosomatic IG, hepatosomaticIH, nephrosomatic IN indices, kidney epithelium height(KEH) and size of oocytes were calculated.The number of mature oocytes andpercentage of ovulating females were determined during the spawning season.Histological changes in the ovaries and testes were described throughouta year. Annual reproductive cycles were similar in both populations ofsticklebacks. This is the first histological and morphological study carriedout throughout a year, simultaneously in two wild populations of three-spinedsticklebacks inhabiting different environments. An improved scale of gonadaldevelopment in conjunction with the determined indices and fecundity givea comprehensive description of the reproductive cycle. These new observations,in combination with previously reported features, provide a universal scalethat can be successfully used to distinguish all phases of gametogenesis insticklebacks in different habitats.
Oogenesis and egg development in triatomines: a biochemical approach
Atella, Georgia C.;Gondim, Katia C.;Machado, Ednildo A.;Medeiros, Marcelo N.;Silva-Neto, Mário A.C.;Masuda, Hatisaburo;
Anais da Academia Brasileira de Ciências , 2005, DOI: 10.1590/S0001-37652005000300005
Abstract: in triatomines, as well as in other insects, accumulation of yolk is a process in which an extra-ovarian tissue, the fat body, produces yolk proteins that are packed in the egg. the main protein, synthesized by the fat body, which is accumulated inside the oocyte, is vitellogenin. this process is also known as vitellogenesis. there are growing evidences in triatomines that besides fat body the ovary also produces yolk proteins. the way these yolk proteins enter the oocyte will be discussed. yolk is a complex material composed of proteins, lipids, carbohydrates and other minor components which are packed inside the oocyte in an organized manner. fertilization triggers embryogenesis, a process where an embryo will develop. during embryogenesis the yolk will be used for the construction of a new individual, the first instar nymph. the challenge for the next decade is to understand how and where these egg proteins are used up together with their non-protein components, in pace with the genetic program of the embryo, which enables cell differentiation (early phase of embryogenesis) and embryo differentiation (late phase) inside the egg.
Annual changes in serum calcium and inorganic phosphate levels and correlation with gonadal status of a freshwater murrel, Channa punctatus (Bloch)
Srivastav, S.K.;Srivastav, A.K.;
Brazilian Journal of Medical and Biological Research , 1998, DOI: 10.1590/S0100-879X1998000800006
Abstract: adult channa punctatus murrels of both sexes (60-80 g) were collected locally from ramgarh lake during the second week of every month (10 individuals of each sex/month) throughout the year. blood samples were collected and analyzed for serum calcium and phosphate levels by the methods of trinder (1960) and fiske and subbarow (1925), respectively. gonads were fixed to judge the state of maturation of the fish. males exhibited no change in serum calcium levels throughout the year in correlation with testicular maturation. however, serum phosphate levels exhibited a rise in correlation with the increased gonadosomatic index. females showed marked seasonal changes in serum calcium and phosphate levels which were associated with ovarian maturation (vitellogenesis).
Oogenesis,Vitellogenesis and Cocoon Secretion in Two Freshwater Leeches from Assiut, Egypt
Research in Zoology , 2012, DOI: 10.5923/j.zoology.20120205.02
Abstract: The organization of the ovisacs, fine structure of the oogenesis, vitellogenesis and formation of cocoons were studied in two freshwater leeches; Alboglossiphonia levis (Glossiphoniidae) and Barbronia assiuti (Barbronidae). Each of them was composed of two elongated ovisacs of germ cells' clusters. The ovisacs, in the studied species, were meroistic (nutrimental), without regionalization and mitotically dividing oogonia, germ cells entering the meiosis prophase as well as trophocytes, prominent cytophores and growing oocytes were occurred. During late previtellogenesis/early vitellogenesis, the oocytes detached from the cytophore and floated in the coelom; they are usually enveloped by the peritoneal epithelium and associated with blood vessels. Meantime, the activity of clitellar gland cells in both studied leeches could be distinguished. Both light and electron microscopy revealed two types of clitellar gland cells. These exocrine gland cells were responsible for the formation of cocoons which enclosed the fertilized ova. The organization of ovisacs and the course of oogenesis in the two genera were studied ultrastructurally and compared with other related leeches.
Oogenesis and egg development in triatomines: a biochemical approach
Atella Georgia C.,Gondim Katia C.,Machado Ednildo A.,Medeiros Marcelo N.
Anais da Academia Brasileira de Ciências , 2005,
Abstract: In triatomines, as well as in other insects, accumulation of yolk is a process in which an extra-ovarian tissue, the fat body, produces yolk proteins that are packed in the egg. The main protein, synthesized by the fat body, which is accumulated inside the oocyte, is vitellogenin. This process is also known as vitellogenesis. There are growing evidences in triatomines that besides fat body the ovary also produces yolk proteins. The way these yolk proteins enter the oocyte will be discussed. Yolk is a complex material composed of proteins, lipids, carbohydrates and other minor components which are packed inside the oocyte in an organized manner. Fertilization triggers embryogenesis, a process where an embryo will develop. During embryogenesis the yolk will be used for the construction of a new individual, the first instar nymph. The challenge for the next decade is to understand how and where these egg proteins are used up together with their non-protein components, in pace with the genetic program of the embryo, which enables cell differentiation (early phase of embryogenesis) and embryo differentiation (late phase) inside the egg.
Ecdysteroids, juvenile hormone and vitellogenesis in the cockroach Leucophaea maderae
Franz Engelmann
Journal of Insect Science , 2002,
Abstract: Topical application of 400μg of the juvenile hormone analog, methoprene, to females of the penultimate instar of Leucophaea maderae failed to induce vitellogenin synthesis. However, last instar females showed an increasing response level in making vitellogenin as they aged during the first half of the instar. In the second half of the last instar the response to methoprene declined to nearly zero when the prothoracic glands have become highly active. Then, a few days before the metamorphic molt the responsiveness reached maximal levels, i.e., comparable to adult females. These data suggest that the fat body develops competency to produce vitellogenin during the last nymphal instar, but increasing titers of ecdysone then interfere with the action of methoprene and consequently production of vitellogenin is curtailed.
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