CYCLIC CHANGES IN THE GONAD OF THE AMERICAN OYSTER, CRASSOSTREA VIRGINICA (GMELIN)

1964 ◽  
Vol 42 (2) ◽  
pp. 305-321 ◽  
Author(s):  
Austina V. Kennedy ◽  
Helen I. Battle
Keyword(s):  
Crassostrea Virginica ◽  
Gonadal Development ◽  
Germinal Epithelium ◽  
Nuclear Area ◽  
Seasonal Growth ◽  
Body Width ◽  
Visceral Mass ◽  
Current Season ◽  
Primary Oocyte ◽  
Cyclic Changes

Cyclic changes in the gonad of Crassostrea virginica (Gmelin), a dioecious, oviparous lamellibranch, are described as they occurred toward the most northerly limit of the range, Malpeque Bay, P.E.I., Canada, during 1961 and 1962. The gonad, composed of right and left gonadal lobes lying immediately beneath the mantle, consists of extensively branched follicles comprising the outer margin of the visceral mass. The follicles open into peripherally located ducts which lead into paired gonoducts terminating in the suprabranchial chamber. During the fall and winter the germinal epithelium is in an indifferent or inactive state. The sex for the current season is distinguishable when proliferation commences in May. Maximum gonadal development occurs in late June or early July as determined by comparison of gonadal width to body width in mid-transverse sections. Primary oocytes are initially distinguishable from oogonia by the presence of a distinct nucleolus, and later by an amphinucleolus consisting of a plasmosome and a karyosome. Seasonal growth of the primary oocyte was followed by a planimetry method using measurements of total area and nuclear area from prepared sections. The spindle for the first meiotic division is established immediately on rupture of the oocyte from the follicular wall. Spermatogenesis and spermiogenesis are completed within the follicle. Following spawning, amoebocytes infiltrate the follicles and interfollicular connective tissue to phagocytize unspawned gametes. By late October the follicles of both male and female consist of a low germinal epithelium and a few unresorbed gametes, and remain inactive until proliferation the following spring.

scholarly journals The c-kit receptor protein in the testis of green frog Rana esculenta: seasonal changes in relationship to testosterone titres and spermatogonial proliferation

Reproduction ◽  
2007 ◽  
Vol 133 (1) ◽  
pp. 51-60 ◽  
Author(s):  
Franca Raucci ◽  
Maria Maddalena Di Fiore
Keyword(s):  
Germ Cell ◽  
Mitotic Activity ◽  
Rana Esculenta ◽  
Reproductive Period ◽  
Receptor Protein ◽  
Germinal Epithelium ◽  
Positive Staining ◽  
Green Frog ◽  
Cyclic Changes ◽  
Spermatogonial Proliferation

The green frogRana esculentais a seasonal breeder. The cyclic changes between almost arrested and highly activated spermatogenesis offer an ideal model to study basic mechanisms of spermatogenesis. In this study, we demonstrated, to our knowledge for the first time,c-kitreceptor positive cells in the testis of this amphibian. The presence ofc-kitreceptor protein was confirmed by western blotting (Wb) analyses carried out in the testis during all the three main phases of the sexual cycle. The antibody recognized a band of about 150 kDa that was correlated with the positive staining in the germinal epithelium. The immunolabelling forc-kitreceptor, evaluated by immunohistochemistry (IHC), was localized in I and II spermatogonia (SPG), in I and II spermatocytes, in both elongating spermatids and spermatozoa and in the Leydig cells. Furthermore,c-kitexpression showed a seasonal pattern connected with both testicular and plasma profiles of testosterone during the reproductive cycle. The highest expression ofc-kitreceptor occurred during the reproductive period, when the testis exhibited the maximum concentration of testosterone. In this period, the mitotic activity of germ cell, assessed by both Wb and IHC analyses for proliferating cell nuclear antigen (PCNA), was intensive. Indeed, during the post-reproductive period, testosterone titres were the lowest and the expression of both PCNA andc-kitreceptor protein in the testis, although present, is minor when compared with the reproductive phase. This evidence suggests that cell division can continue sufficiently to accumulate SPG for the next spring, when new germinal cells undergo multiplication. Finally, during the pre-reproductive period, testosterone levels begin to increase and mitotic activity of germinal epithelium is comparably enhanced. These events seem to precede the period of maximum stimulated spermatogonial proliferation, i.e. the reproductive period. These results suggest that thec-kitreceptor may play a role in germ cell proliferation and provide a basis for future detailed investigation of regulatory factors of the proliferation of SPG.

scholarly journals Effect of temperature and salinity on the reproductive cycle of males and females of Crassostrea virginica (Bivalvia: Ostreidae).

2016 ◽  
Vol 64 (2) ◽  
pp. 449 ◽  
Author(s):  
Luis Alfonso Ascencio Aguirre ◽  
Martha Enríquez D. ◽  
Imelda Martínez M. ◽  
Dalila Aldana A.
Keyword(s):  
Crassostrea Virginica ◽  
Reproductive Cycle ◽  
Management Strategies ◽  
Gonadal Development ◽  
Effect Of Temperature ◽  
American Oyster ◽  
Additional Information ◽  
Standard Procedures ◽  
Size Groups ◽  
Reproductive Cycles

<p>The American oyster, <em>Crassostrea virginica,</em> is one of the most important economic coastal fishery activities in Mexico. As for other bivalve molluscs, its sustainability is based on healthy populations, and additional information on current reproductive cycles, will reinforce local management strategies. The objective of this study was to evaluate the effect of temperature and salinity on the gonadal development stages in both sexes and in two size groups (40-60 mm and ≥ 61 mm) of <em>C. virginica</em> from Tamiahua Lagoon, Gulf of Mexico. Monthly surveys of 90 organisms were undertaken, for a yearly total of 1 080 oysters sampled from the lagoon in 2011. Both field and laboratory work used standard procedures. Our results showed that reproduction was continuous in both sexes, but some peaks of the reproductive cycle were observed along the year. Peaks registered from January to July were for gametogenesis; those of June and September were for mature individuals; and in January, February, and from September to December, for spawning/spent oysters. Maturity of females of both range sizes was positively correlated with temperature, but not for males. For spawning, spent individuals, males of sizes ≥ 61 mm were positively correlated with salinity, whereas smaller males (40-60 mm) and females of both sizes, did not show any correlation. In this study, we observed that temperature and salinity had a different effect in the reproduction of the American oyster of different sizes and sexes of Tamiahua lagoon.</p>

scholarly journals Specific miRNA-GPCR networks regulate Sox9a/Sox9b activities to promote gonadal renewal in zebrafish

2018 ◽  
Author(s):  
Xinlu Du ◽  
Huiping Guo ◽  
Ying Zhang ◽  
Jiacheng Wu ◽  
Minyou Li ◽  
...  
Keyword(s):  
Regulatory Networks ◽  
Sex Differentiation ◽  
Gonadal Development ◽  
Endocrine Function ◽  
Mechanistic Insight ◽  
Regulatory Circuits ◽  
Primary Oocyte ◽  
G Protein Coupled ◽  
Insight Into

AbstractFertility and endocrine function rely on a tightly regulated synchronicity within the hypothalamic-pituitary gonadal (HPG) axis. FSH/cAMP/MAPK/ Sox9 axis signaling and its regulated specific miRNAs are thought to regulate vertebrate gonadal development and sex differentiation, and yet the regulatory networks are largely unknown. Here we construct small RNA and mRNA libraries from sexually matured ovary and testis of zebrafish to identify specific miRNA-target pairs. Integration of Targetscan prediction and in vivo induced gene expression highlight four specific miRNAs that conditionally target three G protein–coupled receptor (GPCR) x-Sox9 signaling genes, and implicate two regulatory circuits of miR430a-Sox9a in the testis and miR218a-Sox9b in the ovary. Co-injected Sox9a-miR430a mixture increases the proportion of spermatogonia but degenerates primary oocyte, while Sox9b-miR218a mixture induces renewal of ovarian follicles. Co-immunoprecipitation and mass-spectrometry analyses further reveal that miR430a and Sox9a synergistically activate testicular PKC/Rock1 signals while miR218a and Sox9b constrict ovary PKC/PI3K/Rock1 signaling. These results clarify specific miRNAs-GPCR regulatory networks of Sox9a/Sox9b switch, and also provide mechanistic insight into gonadal rejuvenation and plasticity.

Cellular development of the germinal epithelium during the female and male gametogenesis of Chaetodon striatus (Perciformes: Chaetodontidae)

Zygote ◽  
2020 ◽  
Vol 28 (4) ◽  
pp. 291-299
Author(s):  
Isabelle Leite Bayona Perez ◽  
Talita Sarah Mazzoni ◽  
Irani Quagio-Grassiotto
Keyword(s):  
Reproductive Activity ◽  
Gonadal Development ◽  
Reproductive Period ◽  
Morphological Data ◽  
Germinal Epithelium ◽  
Cellular Dynamics ◽  
Spawning Period ◽  
Reproductive Life ◽  
Early Primary ◽  
Reproductive Phases

SummaryButterflyfish Chaetodon striatus is highly sought after in the marine ornamental aquarium, although studies about its reproductive biology are scarce. Therefore, to contribute to a better understanding of the reproductive aspects of C. striatus, we describe in detail with the use of high resolution histology the cellular dynamics of the germinal epithelium during the reproductive life history of this species. Based on the activity of the germinal epithelium, this study describes different stages of the gonadal development, similar to the reproductive phases found in other fish, to determine the reproductive period of C. striatus. In characterization of gonadal development, the following germ cells are described for males: spermatogonia, spermatocytes, spermatids and spermatozoa. Oogonia, early, primary, secondary, full-grown and maturing oocytes are described for females. Female germinal epithelium of C. striatus showed substantial changes over the study period, indicating that there was an active spawning period. Male germinal epithelium also presented relevant alterations, indicating reproductive activity in the testicular lobules. Morphological data confirm how informative was the cellular dynamics of the germinal epithelium for understanding gonadal development during adult reproductive life of fish in general. Although Chaetodon are a popular species, previous studies have only produced superficial and rough histological analyses. Therefore, this study demonstrates important information on germinal epithelium of Chaetodon. This knowledge could be a fundamental tool for development of new strategies for breeding of several species in captivity, especially butterflyfishes.

Spherulitic crystal growth in the prodissoconch larval of Crassostrea virginica

1983 ◽  
Vol 41 ◽  
pp. 518-519
Author(s):  
George G. Cocks ◽  
Louis Leibovitz ◽  
DoSuk D. Lee
Keyword(s):  
Crystal Structure ◽  
Crassostrea Virginica ◽  
Crystal Orientation ◽  
Developmental Changes ◽  
Gastrula Stage ◽  
Orthorhombic Crystal ◽  
Orthorhombic Crystal Structure ◽  
Stages Of Growth ◽  
Early Stages ◽  
Initial Deposition

Our understanding of the structure and the formation of inorganic minerals in the bivalve shells has been considerably advanced by the use of electron microscope. However, very little is known about the ultrastructure of valves in the larval stage of the oysters. The present study examines the developmental changes which occur between the time of conception to the early stages of Dissoconch in the Crassostrea virginica(Gmelin), focusing on the initial deposition of inorganic crystals by the oysters.The spawning was induced by elevating the temperature of the seawater where the adult oysters were conditioned. The eggs and sperm were collected separately, then immediately mixed for the fertilizations to occur. Fertilized animals were kept in the incubator where various stages of development were stopped and observed. The detailed analysis of the early stages of growth showed that CaCO3 crystals(aragonite), with orthorhombic crystal structure, are deposited as early as gastrula stage(Figuresla-b). The next stage in development, the prodissoconch, revealed that the crystal orientation is in the form of spherulites.

Binucleate Spermiogenesis in the Mouse

1972 ◽  
Vol 30 ◽  
pp. 112-113
Author(s):  
John J. Wolosewick
Keyword(s):  
Electron Microscopy ◽  
Phosphate Buffer ◽  
Seminiferous Epithelium ◽  
Mouse Testis ◽  
Germinal Epithelium ◽  
Intercellular Bridges ◽  
Adult Mice ◽  
Cervical Dislocation ◽  
Human And Mouse

Classically, the male germinal epithelium is depicted as synchronously developing uninucleate spermatids conjoined by intercellular bridges. Recently, binucleate and multinucleate spermatids from human and mouse testis have been reported. The present paper describes certain developmental events in one type of binucleate spermatid in the seminiferous epithelium of the mouse.Testes of adult mice (ABP Jax) were removed from the animals after cervical dislocation and placed into 2.5% glutaraldehyde/Millonig's phosphate buffer (pH 7.2). Testicular capsules were gently split and separated, exposing the tubules. After 15 minutes the tissue was carefully cut into cubes (approx. 1mm), fixed for an additional 45 minutes and processed for electron microscopy.

Ultrastructural Study of Human Testicular Biopsies in Infertility

1976 ◽  
Vol 34 ◽  
pp. 156-157
Author(s):  
Shirley Siew ◽  
Philip Troen ◽  
Howard R. Nankin
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Basement Membrane ◽  
Leydig Cells ◽  
Clinical Evidence ◽  
Young Male ◽  
Germinal Epithelium ◽  
Transmission Electron ◽  
Age Range ◽  
Male Subjects

Testicular biopsies were obtained from six young male subjects (age range 24-33) who complained of infertility and who had clinical evidence of oligospermia. This was confirmed on histological examination which showed a broad spectrum from profound hypospermatogenesis to relatively normal appearing germinal epithelium. Thickening of the tubular walls was noted in half of the cases and slight peritubular fibrosis in one. The Leydig cells were reported as normal or unremarkable.Transmission electron microscopy showed that the thickening of the supporting tissue of the germinal epithelium was caused more by an increase in the thickness of the layers of the lamina propria than of the tubular wall itself. The changes in the basement membrane of the tubular wall consisted mostly of a greater degree of infolding into the tubule and some reduplication which gave rise to a multilayered appearance.

HISTOMORPHOLOGICAL CHANGES IN THE BRAIN IN RELATION TO OVARIAN CYCLE OF FRESHWATER CRAB, BARYTELPHUSA CUNICULARIS

2017 ◽  
Vol 23 (1) ◽  
Author(s):  
C.A. JAWALE
Keyword(s):  
Staining Intensity ◽  
Neurosecretory Cells ◽  
Ovarian Cycle ◽  
Secretory Product ◽  
Freshwater Crab ◽  
Intensity Index ◽  
Cytoplasmic Material ◽  
Histomorphological Changes ◽  
Cyclic Changes ◽  
The Brain

Ovarian maturation by neurosecretory cells in the brain of freshwater crab, Barytelphusa cunicularis have been examined. The histological scrutiny of the brain of Barytelphusa cunicularis related with three types (A, B and C) of neurosecretory cells, which are classified on the basis of size, shape and tinctorial characters. All these types of cells marked annual cyclic changes of cytoplasmic material in association with ovarian cycle. The activity of these cells has been correlated with the ovarian cycle. They are distinguishable by their size, nature locations, shape, nucleus position, cell measure and the secretory product in the cytoplasm. The result indicates that the neurosecretory A, B and C cells of the brain seen involved in the process of mating ovulation. The neurosecretory materials staining intensity index of these cells is described.

Effects of resuspension of eastern oyster Crassostrea virginica biodeposits on phytoplankton community structure

2020 ◽  
Vol 640 ◽  
pp. 79-105
Author(s):  
ET Porter ◽  
E Robins ◽  
S Davis ◽  
R Lacouture ◽  
JC Cornwell
Keyword(s):  
Water Quality ◽  
Community Structure ◽  
Crassostrea Virginica ◽  
Skeletonema Costatum ◽  
Eastern Oyster ◽  
Energy Dissipation Rate ◽  
Negative Effects ◽  
Cell Densities ◽  
Sediment Bottom ◽  
Nitrite Nitrate

Anthropogenic disturbances in the Chesapeake Bay (USA) have depleted eastern oyster Crassostrea virginica abundance and altered the estuary’s environment and water quality. Efforts to rehabilitate oyster populations are underway; however, the effect of oyster biodeposits on water quality and plankton community structure are not clear. In July 2017, we used 6 shear turbulence resuspension mesocosms (STURMs) to determine differences in plankton composition with and without the daily addition of oyster biodeposits to a muddy sediment bottom. STURM systems had a volume-weighted root mean square turbulent velocity of 1.08 cm s-1, energy dissipation rate of ~0.08 cm2 s-3, and bottom shear stress of ~0.36-0.51 Pa during mixing-on periods during 4 wk of tidal resuspension. Phytoplankton increased their chlorophyll a content in their cells in response to low light in tanks with biodeposits. The diatom Skeletonema costatum bloomed and had significantly longer chains in tanks without biodeposits. These tanks also had significantly lower concentrations of total suspended solids, zooplankton carbon, and nitrite +nitrate, and higher phytoplankton carbon concentrations. Results suggest that the absence of biodeposit resuspension initiates nitrogen uptake for diatom reproduction, increasing the cell densities of S. costatum. The low abundance of the zooplankton population in non-biodeposit tanks suggests an inability of zooplankton to graze on S. costatum and negative effects of S. costatum on zooplankton. A high abundance of the copepod Acartia tonsa in biodeposit tanks may have reduced S. costatum chain length. Oyster biodeposit addition and resuspension efficiently transferred phytoplankton carbon to zooplankton carbon, thus supporting the food web in the estuary.

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