Ovarian follicles of sterlets (Acipenser ruthenus) are composed of a single oocyte surrounded by follicular cells (FCs), basal lamina, and thecal cells. Previtellogenic oocytes are polarized. Homogeneous ooplasm (contains ribosomes) and granular ooplasm (comprises nuage aggregations of nuclear origin, rough endoplasmic reticulum (RER), Golgi complexes, ribosomes, and mitochondria) are distinguished. Granular ooplasm is initially located near the nucleus, contacts the plasma membrane of the oocyte (oolemma) and forms a thin layer underneath its entire perimeter. Next, a ring that surrounds the nucleus is formed and sends strands directed toward the oolemma. The lipid body composed of lipid droplets forms adjacent to this ring. Later, the granular ooplasm and strands enlarge toward the oolemma, lipid body disperses, and homogeneous ooplasm is no longer present. A thin cortical ooplasm is formed underneath the oolemma and does not contain any organelles. The oocyte nucleus moves to the center. The nucleoplasm contains lampbrush chromosomes, nuclear bodies, and multiple nucleoli. Early vitellogenic oocytes are polarized, too. Three regions in the ooplasm are distinguished: the perinuclear (contains lipid droplets near the nuclear envelope), the endoplasm (contains yolk platelets and lipid droplets), and the periplasm (contains yolk spheres, pigment granules, and microtubules). In all these regions the RER, Golgi complexes, nuage, and mitochondria are present. Micropinocytotic vesicles, Golgi vesicles and precursors of the internal layer of the egg envelope are in the cortical ooplasm. Some FCs delaminate from the follicular epithelium, degenerate and vesicles are released into the perioocytic space. They may contain precursors of egg envelope and may be involved in "cell-cell" communication. The egg envelope (zona radiata, zona pellucida) is made up of three layers: the vitelline envelope (inner layer), the middle layer, and the outer layer. In its deposition, both the oocyte and FCs are engaged.
- MeSH
- Cytoplasm MeSH
- Oocytes * MeSH
- Ovarian Follicle * ultrastructure MeSH
- Fishes MeSH
- Vitellogenesis MeSH
- Animals MeSH
- Check Tag
- Female MeSH
- Animals MeSH
- Publication type
- Journal Article MeSH
- Research Support, Non-U.S. Gov't MeSH
Female fertility relies on successful egg development. Besides chromosome segregation, complex structural and biochemical changes in the cytoplasmic compartment are necessary to confer the female gamete the capacity to undergo normal fertilization and sustain embryonic development. Despite the profound impact on egg quality, morphological bases of cytoplasmic maturation remain largely unknown. Here, we report our findings from the ultrastructural analysis of 69 unfertilized human oocytes from 34 young and healthy egg donors. By comparison of samples fixed at three consecutive developmental stages, we explored how ooplasmic architecture changes during meiotic maturation in vitro. The morphometric image analysis supported observation that the major reorganization of cytoplasm occurs before polar body extrusion. The organelles initially concentrated around prophase nucleus were repositioned toward the periphery and evenly distributed throughout the ooplasm. As maturation progressed, distinct secretory apparatus appeared to transform into cortical granules that clustered underneath the oocyte's surface. The most prominent feature was the gradual formation of heterologous complexes composed of variable elements of endoplasmic reticulum and multiple mitochondria with primitive morphology. Based on the generated image dataset, we proposed a morphological map of cytoplasmic maturation, which may serve as a reference for future comparative studies. In conclusion, this work improves our understanding of human oocyte morphology, cytoplasmic maturation, and intracellular factors defining human egg quality. Although this analysis involved spare oocytes completing development in vitro, it provides essential insight into the enigmatic process by which human egg progenitors prepare for fertilization.
- MeSH
- Cytoplasm drug effects ultrastructure MeSH
- Adult MeSH
- Endoplasmic Reticulum drug effects ultrastructure MeSH
- Follicle Stimulating Hormone pharmacology MeSH
- Ovulation Induction MeSH
- Humans MeSH
- Mitochondria drug effects ultrastructure MeSH
- Young Adult MeSH
- Oocytes drug effects ultrastructure MeSH
- Oogenesis drug effects physiology MeSH
- Chromosome Segregation MeSH
- Check Tag
- Adult MeSH
- Humans MeSH
- Young Adult MeSH
- Female MeSH
- Publication type
- Journal Article MeSH
- Research Support, Non-U.S. Gov't MeSH
In oocytes, RNA localization has critical implications, as assembly of proteins in particular subcellular domains is crucial to embryo development. The distribution of mRNA molecules can identify and characterize localized transcripts. The goal of this study was to clarify the origin of primordial germ cells in the oocyte body plan and to reveal the generation of cell lineages by localized RNAs. The distribution of 12 selected mRNAs in sterlet Acipenser ruthenus oocytes was investigated by qPCR tomography and compared with known patterns of mRNA localization in Xenopus laevis. We investigated the distribution of two gene clusters in the ooplasm along the animal-vegetal axis of the sturgeon oocyte, both of which showed clearly defined intracellular gradient pattern remarkably similar to their distribution in the frog oocyte. We elucidated the localization of sturgeon egg germplasm markers belonging to the vegetal group of mRNAs. The mRNAs coding otx1, wnt11, and veg1 found to be localized in the sturgeon animal hemisphere are, in contrast, distributed in the vegetal hemisphere in amphibian. Actinopterygii and Sarcopterygii, two major lineages of osteichthyan vertebrates, split about 476 Ma (Blair & Hedges, ), albeit basal lineages share conserved biological features. Acipenseriformes is one the most basal living lineages of Actinopterygii, having evolved about 200 Ma (Bemis, Birstein, & Waldman, ), contemporaneous with modern amphibians (Roelants et al., ).
An ultrastructural study of the ovarian follicles and their associated oviducts of the cestode Gyrocotyle urna Grube et Wagener, 1852, a parasite from the spiral valve of the rabbit fish, Chimaera monstrosa L., was undertaken. Each follicle gives rise to follicular oviduct, which opens into one of the five collecting ducts, through which pass mature oocytes. These collecting ducts open into an ovarian receptacle which, in turn, opens via a muscular sphincter (the oocapt) to the main oviduct. The maturation of oocytes surrounded by the syncytial interstitial cells within the ovarian follicles of G. urna follows a pattern similar to that in Eucestoda. The ooplasm of mature oocytes contain lipid droplets (2.0 x 1.8 microm) and cortical granules (0.26 x 0.19 microm). The cytoplasm of primary and secondary oocytes contains centrioles, indicating the presence of the so-called "centriole cycle" during oocyte divisions. A morphological variation between different oviducts was observed. The luminal surface of the follicular and the collecting oviducts is smooth. The zones of the septate junctions are present within the distal portion of the net-like epithelial wall of the collecting ducts close to the ovarian receptacle. The syncytial epithelial lining of the ovarian receptacle, oocapt and main oviduct is covered with lamellae and cilia. Cortical granules secreted from mature oocytes occur freely within the lumen of the main oviduct that functions as a fertilisation canal. A division of the ovary into separated parts with their own collecting ducts as that typical of Gyrocotyle has been observed in neodermates, basal monogenean family Chimaericolidae, and Neoophora (some Proseriata and Fecampiidae). Ultrastructural data thus reveal several unique morphological characteristics of gyrocotylideans, the most basal taxon of tapeworms (Cestoda).
The effect of extracellular sperm ubiquitination was examined from many aspects and the majority of existing studies negatively correlated the amount of highly ubiquitinated sperm cells in the sample with the ejaculate quality and the fertilization success rate. In the present study, we compared an early embryonic development up to blastocyst stage in the pig using two defined sperm cell populations sorted by flow cytometry (FACS) based on the rate of the extracellular ubiquitination. This novel approach allows studying the direct effect of extracellular ubiquitin (eUb), which is a marker for epididymal recognition and degradation of defective sperm cells. We further examined the hypothesis that eUb could be recognized directly in the ooplasm. In the porcine model, the significance of results might be seriously affected by a high variability among sperm cell doses from individual boars as well as by the variability among separate sample collections. To overcome this obstacle, we used cryopreserved sperm cells from a single dose. Comparison of an early embryonic development employing intracytoplasmic sperm cell injection (ICSI) with cryopreserved (frozen/thawed, F/T) and fresh sperm cells did not reveal significant difference regarding blastocyst formation rate. We also observed no difference in the male and female pronuclei formation and the first zygote cleavage after fertilization of oocytes with high or non-ubiquitinated sperm cells sorted by FACS. However, results of the early embryonic development to the blastocyst stage showed the difference between both experimental groups (16.67% of blastocysts in non-ubiquitinated group vs. 6.20% of blastocyst in the high-ubiquitinated group, P < 0.001). We further confirmed the negative effect of eUb by the masking of Ub epitopes with the appropriate primary antibody in fresh sperm cells prior to ICSI. This procedure improved the blastocyst formation rate from 14.19% in the untreated group to 24.03% concerning antibody masked sperms (P < 0.01). We conclude our results support a generally accepted hypothesis concerning the negative correlation of the presence of eUb on the sperm cell membrane and developmental competence of fertilized oocytes. However, experiments with masking Ub antibody indicate the direct negative effect of the membrane ubiquitin rather than sperm cell quality on the early embryonic development to the blastocyst stage, at least in the porcine model.
- MeSH
- Blastocyst physiology MeSH
- Sperm Injections, Intracytoplasmic veterinary MeSH
- Cryopreservation veterinary MeSH
- Embryo Culture Techniques veterinary MeSH
- Oocytes physiology MeSH
- Swine * MeSH
- Flow Cytometry MeSH
- Spermatozoa physiology MeSH
- Ubiquitination physiology MeSH
- Semen Preservation veterinary MeSH
- Animals MeSH
- Check Tag
- Male MeSH
- Female MeSH
- Animals MeSH
- Publication type
- Journal Article MeSH
Závěrečná zpráva o řešení grantu Interní grantové agentury MZ ČR
Přeruš. str. : il. ; 32 cm
Studium protilátek proti ooplasma,zona pellucida,membrana granulosa,theca foliculi interna a corpus luteum,stanovení tříd a submikroskopické lokalizace.U pozitivních nálezů diagnostika dalších autoprotilátek.Histologické hodnocení biopsie ovárií.
- Conspectus
- Lékařské vědy. Lékařství
- NML Fields
- reprodukční lékařství
- endokrinologie
- alergologie a imunologie
- NML Publication type
- závěrečné zprávy o řešení grantu IGA MZ ČR
The egg plays a pivotal role in the reproduction of our species. Nevertheless, its fundamental biology remains elusive. Transmission electron microscopy is traditionally used to inspect the ultrastructure of female gametes. However, two-dimensional micrographs contain only fragmentary information about the spatial organization of the complex oocyte cytoplasm. Here, we employed the Focused Ion Beam Scanning Electron Microscopy (FIB-SEM) to explore human oocyte intracellular morphology in three dimensions (3D). Volume reconstruction of generated image stacks provided an unprecedented view of ooplasmic architecture. Organelle distribution patterns observed in nine donor oocytes, representing three maturational stages, documented structural changes underlying the process by which the egg acquires developmental competence. 3D image segmentation was performed to extract information about distinct organelle populations, and the following quantitative analysis revealed that the mitochondrion occupies ∼ 4.26% of the maturing oocyte cytoplasm. In summary, this proof-of-concept study demonstrates the potential of large volume electron microscopy to study rare samples of delicate female gametes and paves the way for applying the FIB-SEM technique in human oocyte research.
- Publication type
- Journal Article MeSH
... ngenital conditions 262 ilmonary infections 262 enerative conditions 263 iscular conditions 266 ooplasms ...
1st ed. xviii, 478 s., obr.
- MeSH
- Paleopathology MeSH
- Publication type
- Encyclopedia MeSH
- Conspectus
- Antropologie
- NML Fields
- patologie
- antropologie
- přírodní vědy
