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The EMBO Journal May 2023Human in vitro oogenesis provides a framework for clarifying the mechanism of human oogenesis. To create its benchmark, it is vital to promote in vitro oogenesis using a...
Human in vitro oogenesis provides a framework for clarifying the mechanism of human oogenesis. To create its benchmark, it is vital to promote in vitro oogenesis using a model physiologically close to humans. Here, we establish a foundation for in vitro oogenesis in cynomolgus (cy) monkeys (Macaca fascicularis): cy female embryonic stem cells harboring one active and one inactive X chromosome (Xa and Xi, respectively) differentiate robustly into primordial germ cell-like cells, which in xenogeneic reconstituted ovaries develop efficiently into oogonia and, remarkably, further into meiotic oocytes at the zygotene stage. This differentiation entails comprehensive epigenetic reprogramming, including Xi reprogramming, yet Xa and Xi remain epigenetically asymmetric with, as partly observed in vivo, incomplete Xi reactivation. In humans and monkeys, the Xi epigenome in pluripotent stem cells functions as an Xi-reprogramming determinant. We further show that developmental pathway over-activations with suboptimal up-regulation of relevant meiotic genes impede in vitro meiotic progression. Cy in vitro oogenesis exhibits critical homology with the human system, including with respect to bottlenecks, providing a salient model for advancing human in vitro oogenesis.
Topics: Animals; Female; Humans; Macaca fascicularis; Oocytes; Oogenesis; Ovary; Embryonic Stem Cells
PubMed: 36929479
DOI: 10.15252/embj.2022112962 -
Sexual Development : Genetics,... 2022Whether to produce sperm or eggs is the most basic and important choice from the perspective of germ cell development and differentiation. However, the induction... (Review)
Review
BACKGROUND
Whether to produce sperm or eggs is the most basic and important choice from the perspective of germ cell development and differentiation. However, the induction mechanism has not received much attention until relatively recently. This is because the issue of sexual differentiation has generally been considered a theme of somatic cells to make a testis or ovary. Basically, the sex of individual somatic cells and germ cells matches. Therefore, the sex of germ cells is thought to follow the sex of somatic cells once determined. However, researchers realized that a big, open question remained: What somatic cell signals actually induce the sexual differentiation of germ cells and what is the sex determinant in germ cells?
SUMMARY
In vitro experiments demonstrated that 2 somatic signals (BMP and RA) act directly on germ cells to induce oogonia. Therefore, these 2 signals may be referred to as oogonia inducers. From the viewpoint of germ cells, an independent experiment identified SMAD4 and STRA8, which are directly downstream of BMP and RA, respectively, acting in germ cells as female determinants. However, what about male? If these factors are female determinants, their absence may result in the induction of spermatogonia. This may be true in vivo because germ cells enter a male pathway if they do not receive these signals even in the ovary. However, this has not been confirmed in an in vitro culture system. There should be signals required for germ cells to enter a male pathway.
KEY MESSAGES
The important message is that although testis-specific factors secreted from the testis are considered to include male-inducing factors for germ cells, this may not be the case, and the male-inducing factor, if it exists, also exists in the ovary.
PubMed: 35263749
DOI: 10.1159/000520976 -
Plant Disease May 2022Sanqi (Panax notoginseng (Burk.) F. H. Chen) is a precious traditional Chinese herbal medicine. During April of 2021, a root rot disease with approximate 15% incidence...
Sanqi (Panax notoginseng (Burk.) F. H. Chen) is a precious traditional Chinese herbal medicine. During April of 2021, a root rot disease with approximate 15% incidence was observed on 2-year-old Sanqi plants in a field of Zhouning (27º12' N, 119°33' E), Fujian Province of China. The disease symptoms included severe stunting, leaf chlorosis, root rotting and necrosis, as the disease progressed, the whole plant gradually wilted and died. To recover the causal agent, symptomatic roots were excised, surface sterilized in 75% alcohol for 1.5 min, rinsed in sterilized water three times, dried, and placed on PARP selective medium (Jeffers and Martin 1986), and incubated at 20°C in dark. After 5 days, total of 26 Pythium-like isolates were obtained, and one representative isolate Py21-6 (available from the Institute of Plant Protection, Fujian Academy of Agricultural Sciences) was selected for further identification. Colonies of Py21-6 on PARP plate were white with dense, cottony, aerial, and transparent mycelia. Sporangia were terminal or intercalary, non-papillate, spherical, pyriform or ovoid, measuring 21.7 ± 2.8 × 19.3 ± 2.3 μm (n = 30). Zoospores were saucer-like, released out of sporangium after maturation, and dispersed quickly by swimming. Oogonia were spherical, terminal or occasionally intercalary. Oospores were globose, smooth and aplerotic. The dimensions of zoospores, oogonia, and oospores were 6.8 ± 0.7 μm, 21.6 ± 2.2 μm and 18.2 ± 2.7 μm (n = 30), respectively. Antheridia were bell-shaped or irregular, terminal, monoclinous, and usually one per oogonium. According to the morphological characteristics the isolate was initially identified as Pythium spp. (Van der Plaats-Niterink 1981, Yong et al. 2016). For further identification, DNA extracted from Py21-6, the cytochrome c oxidase subunit I (COI) gene and internal transcribed spacer (ITS) region were amplified and sequenced with primers FM55/FM52R (Long et al. 2012) and ITS1 /ITS4 (White et al. 1990), respectively. BLAST analysis of 680-bp COI (OM688194) and 728-bp ITS (OM663703) sequences revealed 99.86% and 99.99% similarity to Pythium vexans in GenBank (HQ708995 [COI], GU133572 [ITS]). Therefore, the pathogen was identified as P. vexans. In order to fulfill Koch's postulates, isolate Py21-6 was grown on Martin's liquid medium (Martin 1992) for 72 h to produce a spore suspensions of 106 oospores/ml, and the pathogenicity test was conducted by root-dip method. Three groups of 2-year-old Sanqi (15 plants per group) with root soaked for 20 min in oospore suspension were used for pathogenicity, and the other three groups (15 plants per group) with root dipped in sterilized water as control. All treated plants were replanted in (15-cm-diameter) pots (2 plants/pot) filled with mixture of sterilized soil: vermiculite: pearlite (2:1:1, v/v), maintained in greenhouse under 60% black shade cloth at 20 to 26°C with 80% relative humidity, and watered once every three days. After 21days, all inoculated plants showed the same symptoms observed on the original diseased plants in the field, whereas, the control plants remained symptomless. The same pathogen was successfully re-isolated from the inoculated plants, and identical to those of the originals based on morphological and sequence data. To our knowledge, this is the first report of P. vexans causing root rot on Sanqi in China (Farr and Rossman 2022). Root rot is one of the destructive diseases in Sanqi production, identification of the pathogen will be useful to develop effective field management strategies to control this disease.
PubMed: 35581918
DOI: 10.1094/PDIS-04-22-0781-PDN -
General and Comparative Endocrinology Oct 2014Although present at relatively low number in the testis, spermatogonial stem cells (SSCs) are crucial for the establishment and maintenance of spermatogenesis in... (Comparative Study)
Comparative Study Review
Although present at relatively low number in the testis, spermatogonial stem cells (SSCs) are crucial for the establishment and maintenance of spermatogenesis in eukaryotes and, until recently, those cells were investigated in fish using morphological criteria. The isolation and characterization of these cells in fish have been so far limited by the lack of specific molecular markers, hampering the high SSCs biotechnological potential for aquaculture. However, some highly conserved vertebrate molecular markers, such as Gfra1 and Pou5f1/Oct4, are now available representing important candidates for studies evaluating the regulation of SSCs in fish and even functional investigations using germ cells transplantation. A technique already used to demonstrate that, different from mammals, fish germ stem cells (spermatogonia and oogonia) present high sexual plasticity that is determined by the somatic microenvironment. As relatively well established in mammals, and demonstrated in zebrafish and dogfish, this somatic environment is very important for the preferential location and regulation of SSCs. Importantly, a long-term in vitro culture system for SSCs has been now established for some fish species. Therefore, besides the aforementioned possibilities, such culture system would allow the development of strategies to in vitro investigate key regulatory and functional aspects of germline stem cells (ex: self-renewal and/or differentiation) or to amplify SSCs of rare, endangered, or commercially valuable fish species, representing an important tool for transgenesis and the development of new biotechnologies in fish production.
Topics: Animals; Biomarkers; Cell Differentiation; Fishes; Male; Mammals; Spermatogenesis; Spermatogonia; Stem Cells; Testis
PubMed: 24967950
DOI: 10.1016/j.ygcen.2014.06.018 -
Stem Cells International 2021Germ cells are capable of maintaining species continuity through passing genetic and epigenetic information across generations. Female germ cells mainly develop during... (Review)
Review
Germ cells are capable of maintaining species continuity through passing genetic and epigenetic information across generations. Female germ cells mainly develop during the embryonic stage and pass through subsequent developmental stages including primordial germ cells, oogonia, and oocyte. However, due to the limitation of using early human embryos as research model, research models are needed to reveal the early developmental process and related mechanisms of female germ cells. After birth, the number of follicles gradually decreases with age. Various conditions which damage ovarian functions would cause premature ovarian failure. Alternative treatments to solve these problems need to be investigated. Germ cell differentiation from pluripotent stem cells can simulate early embryonic development of female germ cells and clarify unresolved issues during the development process. In addition, pluripotent stem cells could potentially provide promising applications for female fertility preservation after proper differentiation. Mouse female germ cells have been successfully reconstructed and delivered to live offspring. However, the derivation of functional human female germ cells has not been fully achieved due to technical limitations and ethical issues. To provide an updated and comprehensive information, this review centers on the major studies on the differentiation of mouse and human female germ cells from pluripotent stem cells and provides references to further studies of developmental mechanisms and potential therapeutic applications of female germ cells.
PubMed: 33510796
DOI: 10.1155/2021/8849230 -
International Journal of Molecular... Apr 2023It is a well-known fact that the reproductive organs in women, especially oocytes, are exposed to numerous regulatory pathways and environmental stimuli. The maternal... (Review)
Review
It is a well-known fact that the reproductive organs in women, especially oocytes, are exposed to numerous regulatory pathways and environmental stimuli. The maternal age is one cornerstone that influences the process of oocyte fertilization. More precisely, the longer a given oocyte is in the waiting-line to be ovulated from menarche to menopause, the longer the duration from oogenesis to fertilization, and therefore, the lower the chances of success to form a viable embryo. The age of menarche in girls ranges from 10 to 16 years, and the age of menopause in women ranges from approximately 45 to 55 years. Researchers are paying attention to the regulatory pathways that are impacting the oocyte at the very beginning during oogenesis in fetal life to discover genes and proteins that could be crucial for the oocyte's lifespan. Due to the general trend in industrialized countries in the last three decades, women are giving birth to their first child in their thirties. Therefore, maternal age has become an important factor impacting oocytes developmental competence, since the higher a woman's age, the higher the chances of miscarriage due to several causes, such as aneuploidy. Meiotic failures during oogenesis, such as, for instance, chromosome segregation failures or chromosomal non-disjunction, are influencing the latter-mentioned aging-related phenomenon too. These errors early in life of women can lead to sub- or infertility. It cannot be neglected that oogenesis is a precisely orchestrated process, during which the oogonia and primary oocytes are formed, and RNA synthesis takes place. These RNAs are crucial for oocyte growth and maturation. In this review, we intend to describe the relevance of regulatory pathways during the oogenesis in women. Furthermore, we focus on molecular pathways of oocyte developmental competence with regard to maternal effects during embryogenesis. On the background of transcriptional mechanisms that enable the transition from a silenced oocyte to a transcriptionally active embryo, we will briefly discuss the potential of induced pluripotent stem cells.
Topics: Pregnancy; Female; Humans; Maternal Age; Oogenesis; Oocytes; Ovulation; Stem Cells
PubMed: 37047809
DOI: 10.3390/ijms24076837 -
Reproductive Biology and Endocrinology... Aug 2014Preantral follicles are the majority of the ovarian follicle population and their use as a source of homogeneous oocytes for bovine reproductive biotechnologies could... (Review)
Review
Preantral follicles are the majority of the ovarian follicle population and their use as a source of homogeneous oocytes for bovine reproductive biotechnologies could result in a substantial advance in this field. However, while in other species embryos and offspring have been produced, in bovine species the results have been limited to the follicular activation of small (primordial) preantral follicles and formation of early antral follicles from large (secondary) preantral follicles after in vitro culture. Therefore, this review will highlight the basic aspects of bovine folliculogenesis by focusing on preantral follicles, the methods of harvesting preantral follicles, the main results from in vitro follicular culture during the last 20 years, and the potential candidate substances (basic supplements, growth factors, and hormones) for improving the efficiency of in vitro follicle growth.
Topics: Animals; Cattle; Female; In Vitro Oocyte Maturation Techniques; Oogenesis; Oogonia; Ovarian Follicle; Reproductive Techniques, Assisted; Tissue Culture Techniques
PubMed: 25117631
DOI: 10.1186/1477-7827-12-78 -
Cellular and Molecular Life Sciences :... Jul 2017In fetal females, oogonia proliferate immediately after sex determination. The progress of mitosis in oogonia proceeds so rapidly that the incompletely divided cytoplasm... (Review)
Review
In fetal females, oogonia proliferate immediately after sex determination. The progress of mitosis in oogonia proceeds so rapidly that the incompletely divided cytoplasm of the sister cells forms cysts. The oogonia will then initiate meiosis and arrest at the diplotene stage of meiosis I, becoming oocytes. Within each germline cyst, oocytes with Balbiani bodies will survive after cyst breakdown (CBD). After CBD, each oocyte is enclosed by pre-granulosa cells to form a primordial follicle (PF). Notably, the PF pool formed perinatally will be the sole lifelong oocyte source of a female. Thus, elucidating the mechanisms of CBD and PF formation is not only meaningful for solving mysteries related to ovarian development but also contributes to the preservation of reproduction. However, the mechanisms that regulate these phenomena are largely unknown. This review summarizes the progress of cellular and molecular research on these processes in mice and humans.
Topics: Animals; Cell Adhesion; Cell Differentiation; Female; Germ Cells; Humans; Meiosis; Oocytes; Ovarian Follicle
PubMed: 28197668
DOI: 10.1007/s00018-017-2480-6 -
The International Journal of... 2015In a number of mammalian species, the main events of development of the primordial germ cells (PGCs), the embryonic precursors of the oocytes and spermatozoa, were... (Review)
Review
In a number of mammalian species, the main events of development of the primordial germ cells (PGCs), the embryonic precursors of the oocytes and spermatozoa, were described during the early twentieth century. Actually, the concept of the origin of germ cells in extragonadal sites before the formation of the gonadal anlagen, was put forward for the human embryo around the first decade of the 1900s (for a review, see De Felici, 2013). PGC development is characterized by two major cellular processes, a movement from the wall of the yolk sac, where the germline is determined, to the gonadal anlagen and an increase in number due to active proliferation. As far as we know, the notion that programmed cell death (PCD) might physiologically occur in mammalian PGCs was for the first time put forward by us in 1993 in the case of the mouse. How we arrived to such a concept and the progress made up to now in the characterization of this process in our and other laboratories mainly in the mouse are the topics of the present review.
Topics: Animals; Apoptosis; Embryo, Mammalian; Embryonic Development; Male; Mice; Oogonia; Spermatogonia
PubMed: 26374524
DOI: 10.1387/ijdb.150064md