Balbiani body of basal insects is potentially involved in multiplication and selective elimination of mitochondria.

Oocytes of both vertebrates and invertebrates often contain an intricate organelle assemblage, termed the Balbiani body (Bb). It has previously been suggested that this assemblage is involved in the delivery of organelles and macromolecules to the germ plasm, formation of oocyte reserve materials, and transfer of mitochondria to the next generation. To gain further insight into the function of the Bb, we performed a series of analyses and experiments, including computer-aided 3-dimensional reconstructions, detection of DNA (mtDNA) synthesis as well as immunolocalization studies.

Morphology and ultrastructure of the Balbiani body in the oocytes of closely related bush cricket species. Shared features reveal important aspect of functioning.

Balbiani bodies (Bbs) are female germline-specific organelle assemblages usually composed of mitochondria, Golgi complexes, elements of endoplasmic reticulum and accumulations of fine granular material, termed the nuage. Here we present results of morphological and ultrastructural analysis of the Bb of four bush crickets nested in four subfamilies of the family Tettigonidae. This study has revealed that Bbs of closely related species (belonging to the defined evolutionary line) are morphologically rather different.

Flutamide treatment reveals a relationship between steroidogenic activity of Leydig cells and ultrastructure of their mitochondria.

Our present knowledge on interrelation between morphology/ultrastructure of mitochondria of the Leydig cell and its steroidogenic function is far from satisfactory and needs additional studies. Here, we analyzed the effects of blockade of androgen receptor, triggered by exposure to flutamide, on the expression of steroidogenic proteins (1) and ultrastructure of Leydig cells' constituents (2). We demonstrated that increase in the expression level of steroidogenic (StAR, CYP11A1, 3β-HSD, and CYP19A1) proteins (and respective mRNAs) in rat testicular tissue as well as elevation of intratesticular sex steroid hormone (testosterone and estradiol) levels observed in treated animals correspond well to morphological alterations of the Leydig cell ultrastructure.

Morphogenesis of the Balbiani body in developing oocytes of an orthopteran, Metrioptera brachyptera, and multiplication of female germline mitochondria.

Balbiani body (Bb) is a female germline specific organelle complex. Although the morphology and morphogenesis of the Bb have been analyzed in numerous vertebrate and invertebrate species, the role and ultimate fate of this organelle assemblage are still under debate. As a result, various functions have been attributed to the Bb in given animal lineages or even species.

Transmission of Functional, Wild-Type Mitochondria and the Fittest mtDNA to the Next Generation: Bottleneck Phenomenon, Balbiani Body, and Mitophagy.

The most important role of mitochondria is to supply cells with metabolic energy in the form of adenosine triphosphate (ATP). As synthesis of ATP molecules is accompanied by the generation of reactive oxygen species (ROS), mitochondrial DNA (mtDNA) is highly vulnerable to impairment and, consequently, accumulation of deleterious mutations. In most animals, mitochondria are transmitted to the next generation maternally, i.

Morphogenesis of the ovarian follicular epithelium during initial stages of embryogenesis of the viviparous earwig, Hemimerus talpoides.

Representatives of the highly specialized earwig family Hemimeridae are epizoic and viviparous. Their embryos develop inside terminal ovarian follicles (termed also embryonic follicles) and rely solely on nutrients transferred from mother tissues. In this report, we present results of ultrastructural and histochemical studies of the initial stage of Hemimerus talpoides development.

Evolutionary origin and functioning of pregenital abdominal outgrowths in a viviparous insect, Arixenia esau.

Although pregenital abdominal outgrowths occur only rarely in pterygote insects, they are interesting from the evolutionary viewpoint because of their potential homology to wings. Our previous studies of early development of an epizoic dermapteran, Arixenia esau revealed that abdominal segments of the advanced embryos and larvae, growing inside a mother's uterus, are equipped with paired serial outgrowths. Here, we focus on the origin and functioning of these outgrowths.

Viviparity in Two Closely Related Epizoic Dermapterans Relies on Disparate Modifications of Reproductive Systems and Embryogenesis.

Nutritional modes operating during embryonic/larval development of viviparous species range from "pure" lecitothrophy in which embryos rely solely on reserve materials (yolk spheres, lipid droplets, and glycogen particles) accumulated in the egg cytoplasm to matrotrophy in which embryos are continuously supplied with nutrients from a parental organism. Interestingly, a wide spectrum of diverse "mixed" modes employed in the embryo nourishment have also been described among viviparous species. Here, we summarize results of histochemical, ultrastructural, and biochemical analyses of reproductive systems as well as developing embryos of two closely related viviparous species of earwigs (Dermaptera), Hemimerus talpoides and Arixenia esau.

Viviparity in the dermapteran Arixenia esau: respiration inside mother's body requires both maternal and larval contribution.

Earwigs (Dermaptera) use different strategies to increase their reproductive success. Most species lay eggs; however, viviparity of the matrotrophic type has been reported in two groups: Hemimeridae and Arixeniidae. In Arixeniidae, offspring develop in two separate places: inside an ovary (the intraovarian phase) and within a uterus (the intrauterine phase).

Organelle assemblages implicated in the transfer of oocyte components to the embryo: an insect perspective.

Besides reserve materials (yolk spheres, lipid droplets), ribosomes and various mRNA species, insect oocytes contain large easily morphologically recognizable organelle assemblages: the Balbiani body and the oosome (pole plasm). These assemblages are implicated in the transfer of oocyte components (mitochondria, polar granules) to the embryo that is to offspring. Here, we review present knowledge of morphology, morphogenesis, molecular composition and function/s of these assemblages.

Morphogenesis of serial abdominal outgrowths during development of the viviparous dermapteran, Arixenia esau (Insecta, Dermaptera).

The embryos and first instar larvae of the epizoic earwig, Arixenia esau, develop sequentially in two different compartments of the female reproductive system, that is ovarian follicles and the lateral oviducts (the uterus). Here we show that the second (intrauterine) phase of development consists of three physiologically disparate stages: early embryos (before dorsal closure, surrounded by an egg envelope), late embryos (after dorsal closure, surrounded by an egg envelope) and the first instar larvae (after "hatching" from an egg envelope). Early and late embryos float in the fluid filling the uterus, whereas the first instar larvae develop attached to the uterus wall.

Excretion in the mother's body: modifications of the larval excretory system in the viviparous dermapteran, Arixenia esau.

The vast majority of Dermaptera are free-living and oviparous, i.e., females lay eggs within which embryonic development occurs until the larva hatches.

Unusual morphological adaptations and processes associated with viviparity in an epizoic dermapteran.

Matrotrophic viviparity is a reproductive pattern in which offspring develop inside a female's body which provides gas exchange and nutrients necessary for development. Besides placental mammals, structural and physiological aspects of matrotrophic viviparity are poorly characterized. In insects, the majority of species is oviparous, i.

Ovaries and oogenesis in an epizoic dermapteran, Hemimerus talpoides (Dermaptera, Hemimeridae): Structural and functional adaptations to viviparity and matrotrophy.

The Dermaptera are traditionally classified in three taxa: the free living Forficulina and two viviparous (matrotrophic) groups, the Hemimerina and Arixeniina. Recent molecular and histological analyses suggest that both matrotrophic groups should be nested among the most derived taxon of the Forficulina, the Eudermaptera. We present results of ultrastructural analyses of ovary/ovariole morphology and oogenesis in a representative of the Hemimerina, Hemimerus talpoides (Walker, 1871).

The Pole (Germ) Plasm in Insect Oocytes.

Animal germline cells are specified either through zygotic induction or cytoplasmic inheritance. Zygotic induction takes place in mid- or late embryogenesis and requires cell-to-cell signaling leading to the acquisition of germline fate de novo. In contrast, cytoplasmic inheritance involves formation of a specific, asymmetrically localized oocyte region, termed the germ (pole) plasm.

Selection of mitochondria in female germline cells: is Balbiani body implicated in this process?

Early oocytes of nearly all animal species contain a transient organelle assemblage termed the Balbiani body. Structure and composition of this assemblage may vary even between closely related species. Despite this variability, the Balbiani body always comprises of numerous tightly clustered mitochondria and accumulations of nuage material.

Asymmetric Divisions in Oogenesis.

In the majority of animals, the oocyte/egg is structurally, molecularly, and functionally asymmetric. Such asymmetry is a prerequisite for a flawless fertilization and faithful segregation of maternal determinants during subsequent embryonic development. The oocyte asymmetry develops during oogenesis and must be maintained during consecutive and obligatorily asymmetric oogonial divisions, which depending on the species lead to the formation of either oocyte alone or oocyte and nurse cell complex.

Gametic synapses, nanotubes and sperm RNAs - Redefining the origin of maternal determinants.

The female germline cells, i.e., the oocytes/eggs, contain a subpopulation of unique organelles and molecules (RNA and proteins) collectively called "the maternal determinants" that are indispensable for the determination of cell fate in the developing embryo.

Meiosis, Balbiani body and early asymmetry of Thermobia oocyte.

The meiotic division guarantees maintenance of a genetic diversity; it consists of several stages, with prophase I being the longest and the most complex. We decided to follow the course of initial stages of meiotic division in ovaries of Thermobia domestica using modified techniques of squash preparations, semithin sections, and electron microscopy. We show that germaria contain numerous germline cells that can be classified into three categories: cystoblasts, meiotic oocytes, and growing previtellogenic oocytes.

Exclusion of dysfunctional mitochondria from Balbiani body during early oogenesis of Thermobia.

Oocytes of many invertebrate and vertebrate species contain a characteristic organelle complex known as the Balbiani body (Bb). Until now, three principal functions have been ascribed to this complex: delivery of germ cell determinants and localized RNAs to the vegetal cortex/posterior pole of the oocyte, transport of the mitochondria towards the germ plasm, and participation in the formation of lipid droplets. Here, we present the results of a computer-aided 3D reconstruction of the Bb in the growing oocytes of an insect, Thermobia domestica.

The ovary structure and oogenesis in the basal crustaceans and hexapods. Possible phylogenetic significance.

Recent large-scale phylogenetic analyses of exclusively molecular or combined molecular and morphological characters support a close relationship between Crustacea and Hexapoda. The growing consensus on this phylogenetic link is reflected in uniting both taxa under the name Pancrustacea or Tetraconata. Several recent molecular phylogenies have also indicated that the monophyletic hexapods should be nested within paraphyletic crustaceans.

Morphology and ultrastructure of the germarium in panoistic ovarioles of a basal "apterygotous" insect, Thermobia domestica.

It has been shown that in Drosophila the germline stem cells (GSCs), similar to the germline and non-germline stem cells of other species, develop and function in specialized microenvironments formed by somatic cells, referred to as the niches. In the fruit fly ovaries, the female GSCs divide asymmetrically to produce new GSCs and the progenitor cells, the cystoblasts (Cbs). Each Cb then divides to generate the cyst composed of 16 interconnected sibling cells, the cystocytes.

Ultrastructural analysis of the ovary and oogenesis in Spinicaudata and Laevicaudata (Branchiopoda) and its phylogenetic implications.

Recent molecular studies have indicated a close relationship between Crustacea and Hexapoda and postulated their unification into the Pancrustacea/Tetraconata clade. Certain molecular analyses have also suggested that the crustacean lineage, which includes the Branchiopoda, might be the sister group of Hexapoda. We test this hypothesis by analyzing the structure of the ovary and the ultrastructural features of oogenesis in two branchiopod species, Cyzicus tetracerus and Lynceus brachyurus, representing two separate orders, Spinicaudata and Laevicaudata, respectively.

Balbiani body, nuage and sponge bodies--term plasm pathway players.

In many animal species, germ cells are specified by maternally provided, often asymmetrically localized germ cell determinant, termed the germ plasm. It has been shown that in model organisms such as Xenopus laevis, Danio rerio and Drosophila melanogaster germ plasm components (various proteins, mRNAs and mitochondria) are delivered to the proper position within the egg cell by germline specific organelles, i.e.