Ovarian nests in cultured females of the Siberian sturgeon Acipenser baerii (Chondrostei, Acipenseriformes)

The dynamics of cellular development and homeostasis of the ovary depend on the balance between proliferation and cell death throughout the reproductive cycle.Millerichthys robustus is an annual fish whose ovarian follicles develop asynchronously, allowing daily reproduction from sexual maturity until death. The objective of this research is to describe, histologically, the processes of follicular atresia and regression of postovulatory follicular complexes (POC) throughout a reproductive cycle of M. robustus. Patterns of cell death were documented by apoptosis in atretic follicles and POC, and necrosis in the POC after ovulation with an associated inflammatory response. Atretic follicles were seen from the onset of sexual maturity, duringweek three post-hatching (PH), both in primary growth (from the Cortical alveoli step, with folliculogenesis completed) and secondary growth Stages, with a higher prevalence in the latter. POCs were observed in different stages of regression from week four PH until the death of the fish. The apoptotic characteristics found were:(i) fragmentation of the nuclear membrane and zona pellucida, and liquefaction of the cortical alveoli and yolk; (ii) follicular cells becoming phagocytic, increasing their size, and migrating within the oocyte; and (iii) formation of an intrafollicular lumen, a product of phagocytosis of the oocyte constituents and dispersed pigments that remain after the digestion of yolk and cortical alveoli. The morphological changes of the follicular cells of the POC, from a squamous morphology after ovulation to columnar during its regression with PAS+ contents, was documented, suggesting a secretory activity.

Section: Discussioncontrasting

confidence: 99%

Morphological patterns of cell death in ovarian follicles of primary and secondary growth and postovulatory follicle complex of the annual killifish Millerichthys robustus (Cyprinodontiformes: Cynolebiidae)

Domínguez-Castanedo

Uribe

Muñoz-Campos

2019

“…In the latter species, numerous nucleoli arise due to the extrachromosomal amplification of cistrons of ribosomal deoxyribonucleic acid (rDNA) which takes place in nucleoplasm during the pachytene stage (Thiry & Poncin, 2005). This process has also been described in the nucleoplasm of oocytes of other vertebrates including sturgeons and paddlefish, and amphibians (Coimbra & Azevedo, 1984;Raikova, 1976;Raikova, Steinert, & Thomas, 1979;Żelazowska & Fopp-Bayat, 2017b;Żelazowska et al, 2015). Such multiplied nucleoli synthetize ribosomes subunits that are then transported to the ooplasm and are stored until the cleavage in embryogenesis.…”

Section: Discussionmentioning

confidence: 99%

“…In many cases, the cystoblasts continue mitotic division (karyokineses), however, cytokinesis is not complete, and the female germline cysts composed of cystocytes are formed. In the ovaries of teleost fish, and also of other vertebrates and of invertebrates, some cystocytes are eliminated by cell death, the remaining begin meiosis and continue the development as the oocytes (Bilinski, Kloc, & Tworzydlo, ; Elkouby, ; Elkouby, Jamieson‐Lucy, & Mullins, ; Elkouby & Mullins, ; Ikami, Nuzhat, & Lei, ; Kloc, Bilinski, Dougherty, Brey, & Etkin, ; Lei & Spradling, ; Marlow & Mullins, ; Mazzoni, Grier, & Quagio‐Grassiotto, ; Nakamura et al, ; Żelazowska & Fopp‐Bayat, ). The karyokineses of cystoblasts that lead to the formation of cysts are sometimes stopped in the ovaries and the cystoblasts enter meiosis without producing the cysts (Grier, Porak, Carroll, & Parenti, ).…”

Section: Introductionmentioning

confidence: 99%

“…It has also been investigated in teleost fish, for example, in zebrafish Danio rerio (Elkouby, ; Elkouby et al, ; Elkouby & Mullins, ; Lyman‐Gingerich & Pelegri, ; Marlow & Mullins, ), rainbow trout Salmo gairdneri (Beams & Kessel, ), golden grey mullet Mugil (Liza) auratus (Bruslé, ), medaka Oryzias latipes (Iwamatsu & Nakashima, ; Kobayashi & Iwamatsu, ; Nakamura et al, ), and in the Atlantic salmon Salmo salar (Škugor, Tveiten, Johnsen, & Andersen, ). It is also present in oocytes of several species of sturgeons and paddlefish (Chondrostei, Acipenseriformes); for example, in the Russian sturgeon, Acipenser gueldenstaedtii (Zelazowska et al, ; Żelazowska, Jankowska, Plewniak, & Rajek, ), Siberian sturgeon, A. baerii (Żelazowska & Fopp‐Bayat, , ), Chinese, A. sinensis , Dabry's, A. dabryanus sturgeons (Yang, Yue, Ye, Li, & Wei, ; Ye et al, ; Ye, Li, Yue, Yang, & Wei, ; Ye, Yue, Yang, Li, & Wei, ; Yue et al, ), the North American paddlefish, Polyodon spathula (Żelazowska et al, ; Żelazowska & Kilarski, ) as well as in numerous species of invertebrates (e.g., Bilinski et al, ; Kloc, Jedrzejowska, Tworzydlo, & Bilinski, ). In all species investigated, the Balbiani body is involved in the development of ooplasm polarity and marks the future vegetal region or vegetal pole in the oocytes.…”

Section: Introductionmentioning

confidence: 99%

“…remaining begin meiosis and continue the development as the oocytes (Bilinski, Kloc, & Tworzydlo, 2017;Elkouby, 2017;Elkouby, Jamieson-Lucy, & Mullins, 2016;Elkouby & Mullins, 2017;Ikami, Nuzhat, & Lei, 2017;Kloc, Bilinski, Dougherty, Brey, & Etkin, 2004;Lei & Spradling, 2016;Marlow & Mullins, 2008;Mazzoni, Grier, & Quagio-Grassiotto, 2010;Nakamura et al, 2011;Żelazowska & Fopp-Bayat, 2017b). The karyokineses of cystoblasts that lead to the formation of cysts are sometimes stopped in the ovaries and the cystoblasts enter meiosis without producing the cysts (Grier, Porak, Carroll, & Parenti, 2018).…”

mentioning

confidence: 99%

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Previtellogenic oocytes of South African largemouth bass Micropterus salmoides Lacépède 1802 (Actinopterygii, Perciformes) ‐ the Balbiani body, cortical alveoli and developing eggshell

Żelazowska

Halajian

2019

Self Cite

The ovaries of the largemouth bass Micropterus salmoides, an alien and invasive species in South Africa, contain a germinal epithelium which consists of germline and somatic cells, as well as previtellogenic and late vitellogenic ovarian follicles. The ovarian follicle consists of an oocyte surrounded by follicular cells and a basal lamina; thecal cells adjacent to this lamina are covered by an extracellular matrix. In this article, we describe the Balbiani body and the polarization and ultrastructure of the cytoplasm (ooplasm) in previtellogenic oocytes. The nucleoplasm in all examined oocytes contains lampbrush chromosomes, nuclear bodies and several nucleoli near the nuclear envelope. The ultrastructure of the nucleoli is described. Numerous nuage aggregations are present in the perinuclear cytoplasm in germline cells as well as in the ooplasm. Possible roles of these aggregations are discussed. The ooplasm contains the Balbiani body, which defines the future vegetal region in early previtellogenic oocytes. It is comprised of nuage aggregations, rough endoplasmic reticulum, Golgi apparatus, mitochondria, complexes of mitochondria with nuage‐like material, and lysosome‐like organelles. In mid‐previtellogenic oocytes, the Balbiani body surrounds the nucleus and later disperses in the ooplasm. The lysosome‐like organelles fuse and transform into vesicles containing material which is highly electron dense. As a result of the fusion of the vesicles of Golgi and rough endoplasmic reticulum, the cortical alveoli arise and distribute uniformly throughout the ooplasm of late previtellogenic oocytes. During this stage, the deposition of the eggshell (zona radiata) begins. The eggshell is penetrated by canals containing microvilli and consists of the following: the internal and the external egg envelope. In the external envelope three sublayers can be distinguished.

Description of ovary organization and oogenesis in a phreodrilid clitellate

Świątek

Pinder²,

Gajda

2019

Phreodrilidae is a small family uniting about 50 species of minute freshwater clitellate annelids inhabiting mainly the Southern hemisphere. Other than the male and spermathecal genitalia, their internal organization is poorly known. Here, we present results of our study of the ovaries and oogenesis in Insulodrilus bifidus, a phreodrilid from Western Australia using light and electron microscopy. The ovaries are paired and located in segment XII. They are inconspicuous and composed of several (10–12) spherical germ‐line cysts loosely interconnected by flattened somatic cells. The cysts usually comprise 32 germ cells and each cell is connected via a cytoplasmic bridge (ring canal) to the central cytoplasmic mass (the cytophore). In ovaries, germ cells in a given cyst develop in full synchrony. However, there is no synchrony among cysts, so there is a developmental gradient of cysts (from oogonial to early meiotic) along the longitudinal ovary axis. Within the cysts that are located in the distal end of the ovary the synchrony is finally lost and interconnected cells diversify into two morphologically distinct categories: an oocyte and 31 nurse cells. Such cysts detach from the ovaries and further development occurs within the body cavity. The oocyte gathers nutrients, mainly in form of yolk spheres, whereas nurse cells grow slightly and do not gather yolk. Organelles such as ribosomes, mitochondria and endoplasmic reticulum pass freely through the ring canals and are present within the cytophore, which suggests cytoplasmic transfer towards the oocyte. The formation of female germ‐line cysts equipped with cytophore and cells differentiated into oocyte and nurse cells matches the general pattern of oogenesis found in clitellates. In details, the ovary organization and oogenesis found in I. bifidus resembles the situation described in some representatives of Naidinae and Enchytraeidae.