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Topic Review
Primordial Germ Cells
Primordial germ cells (PGCs) are precursor cells of sperm and eggs. The fate decisions of chicken PGCs in terms of their development, integrity, and sex determination have unique features, thereby providing insights into evolutionary developmental biology.
  • 784
  • 21 Mar 2023
Topic Review
Roles of Interferons in Human Endometrial Function
Endometriosis is an estrogen-dependent inflammatory disease that develops in reproductive-aged women who experience pelvic pain and infertility. Even though endometriosis is not a new disease, its molecular etiology has not been clearly elucidated. Defects in the immune system might be one of the factors that promote endometriosis progression. For example, elevated levels of proinflammatory cytokines are associated with endometriosis. Interferon is one of the cytokines that is elevated in endometriotic tissues compared with normal endometrium. 
  • 748
  • 18 Nov 2022
Topic Review
Spermatogenesis and Male Fertility
Spermatogenesis is an extremely complex developmental process and involves the orderly differentiation of multiple types of spermatogenic cells, including mitotically proliferating spermatogonial cells, meiotically dividing spermatocytes, and spermatids that eventually mature into spermatozoa.
  • 713
  • 17 Feb 2022
Topic Review
Early Fetal Growth Restriction
Early fetal growth restriction (FGR) is a complex and multifactorial disorder affecting fetal development. Most cases are related to uteroplacental dysfunction, while non-placental etiologies include chromosomal/genetic anomalies, congenital infections and inborn errors of metabolism.
  • 711
  • 27 May 2021
Topic Review
Stem Cells and the Endometrium
Adult stem cells (ASCs) were long suspected to exist in the endometrium. Indeed, several types of endometrial ASCs were identified in rodents and humans through diverse isolation and characterization techniques. Putative stromal and epithelial stem cell niches were identified in murine models using label-retention techniques. In humans, functional methods (clonogenicity, long-term culture, and multi-lineage differentiation assays) and stem cell markers (CD146, SUSD2/W5C5, LGR5, NTPDase2, SSEA-1, or N-cadherin) facilitated the identification of three main types of endogenous endometrial ASCs: stromal, epithelial progenitor, and endothelial stem cells. Further, exogenous populations of stem cells derived from bone marrow may act as key effectors of the endometrial ASC niche.
  • 674
  • 29 Apr 2021
Topic Review
SARS-CoV-2 Infection and the Testis
Many studies have suggested that SARS-CoV-2, directly or indirectly, can affect the male reproductive system, although the underlined mechanisms have not been completely elucidated yet. The main data regarding the morphological alterations in the testes emerged from autoptic studies that revealed interstitial congestion, micro thrombosis, reduction of Sertoli, Leydig, and germinal cells, infiltrated immune cells, and atrophic seminiferous tubules consistent with orchitis. Furthermore, men with severe infection exhibit sperm parameter alterations, together with abnormalities of the hypothalamic–pituitary–testis axis, strongly suggesting that SARS-CoV-2 could increase the risk of male infertility.
  • 667
  • 09 Mar 2023
Topic Review
Placental Dysfunction in Assisted Reproductive Pregnancies
Obstetric and newborn outcomes of assisted reproductive technology (ART) pregnancies are associated with significative prevalence of maternal and neonatal adverse health conditions, such as cardiovascular and metabolic diseases. These data are interpreted as anomalies in placentation involving a dysregulation of several molecular factors and pathways. It is not clear which extent of the observed placental alterations are the result of ART and which originate from infertility itself. These two aspects probably act synergically for the final obstetric risk. Data show that mechanisms of inappropriate trophoblast invasion and consequent altered vascular remodeling sustain several clinical conditions, leading to obstetric and perinatal risks often found in ART pregnancies, such as preeclampsia, fetal growth restriction and placenta previa or accreta. 
  • 658
  • 28 Jan 2022
Topic Review
Melatonin Application in Assisted Reproductive Techniques
Infertility is an increasing global public health issue that affects up to 16% of couples of reproductive age. According to the World Health Organization (WHO), infertility is a disease of the reproductive system defined by the failure to achieve a clinical pregnancy after 12 months of regular, unprotected sexual intercourse. Half of infertility cases are due to female factors, which are generally attributed to hormonal, functional or anatomical dysfunction of the organs of the reproductive tract. Moreover, the age of the female is of great importance because of its physiological and genetic influence on conception, which includes a reduced ovarian follicular pool, perturbations in ovulation and increased meiotic errors within the oocyte. As for male factors, these are responsible for 20–30% of infertility cases. The most important factors are hormonal deficits, physical causes, sexually transmitted problems, and genetic factors. Nevertheless, the origin of about 40% of male infertility is unknown. Many studies have investigated the potential use of melatonin in assisted reproductive techniques (ART) to improve success rates. These techniques include oocyte manipulation, artificial insemination, in vitro fertilization (IVF), and embryo culture and transfer.
  • 648
  • 16 Jan 2023
Topic Review
Gene Therapy for Malignant and Benign Gynaecological Disorders
Gene therapy aims to introduce or modify genetic material into target cells, thus altering their function, usually by either restoring a lost function or initiating a new one. Although it was initially employed for the treatment of inherited genetic diseases, gene therapy was soon identified as an effective approach for the treatment of both gynaecological malignancies such as ovarian, cervical, and endometrial cancer and certain benign gynaecological abnormalities, such as leiomyomas, endometriosis, placental, and embryo implantation disorders.  There are two main strategies for specific and efficient gene delivery to cancer and non-cancer cells, and these involve either viral or non-viral systems.
  • 642
  • 22 Aug 2022
Topic Review
Melatonin in Embryogenesis
Embryogenesis is a complex multi-stage process regulated by various signaling molecules including pineal and extrapineal melatonin (MT). Extrapineal MT is found in the placenta and ovaries, where it carries out local hormonal regulation. MT is necessary for normal development of oocytes, fertilization and subsequent development of human, animal and avian embryos.
  • 637
  • 29 Jun 2021
Topic Review
Beginning of Meiosis in Mammalian Female Germ Cells
Meiosis is the unique division of germ cells resulting in the recombination of the maternal and paternal genomes and the production of haploid gametes. In mammals, it begins during the fetal life in females and during puberty in males. In both cases, entering meiosis requires a timely switch from the mitotic to the meiotic cell cycle and the transition from a potential pluripotent status to meiotic differentiation. Revealing the molecular mechanisms underlying these interrelated processes represents the essence in understanding the beginning of meiosis. Meiosis facilitates diversity across individuals and acts as a fundamental driver of evolution. Major differences between sexes and among species complicate the understanding of how meiosis begins.
  • 634
  • 30 Oct 2022
Topic Review
Medically Assisted Reproduction
Since the birth of Louise Joy Brown, the first baby conceived via in vitro fertilization, more than 9 million children have been born worldwide using assisted reproductive technologies (ART). In vivo fertilization takes place in the maternal oviduct, where the unique physiological conditions guarantee the healthy development of the embryo. During early embryogenesis, a major wave of epigenetic reprogramming takes place that is crucial for the correct development of the embryo.
  • 619
  • 27 Apr 2022
Topic Review
Human Sperm as Model and Relationship with ROS
Spermatozoa are highly differentiated cells that produce reactive oxygen species (ROS) due to aerobic metabolism. Below a certain threshold, ROS are important in signal transduction pathways and cellular physiological processes, whereas ROS overproduction damages spermatozoa. Sperm manipulation and preparation protocols during assisted reproductive procedures—for example, cryopreservation—can result in excessive ROS production, exposing these cells to oxidative damage. Human spermatozoa represent an ideal cell model to test numerous compounds in vitro, including antioxidants that can be used as supplements to improve the outcome of these procedures.
  • 610
  • 24 May 2023
Topic Review
Maternal Obesity and Gut Microbiota
Obesity in pregnancy induces metabolic syndrome, low-grade inflammation, altered endocrine factors, placental function, and the maternal gut microbiome. All these factors impact fetal growth and development, including brain development. The lipid metabolic transporters of the maternal-fetal-placental unit are dysregulated in obesity. Consequently, the transport of essential long-chain PUFAs for fetal brain development is disturbed. The mother’s gut microbiota is vital in maintaining postnatal energy homeostasis and maternal-fetal immune competence. Obesity during pregnancy changes the gut microbiota, affecting fetal brain development. Obesity in pregnancy can induce placental and intrauterine inflammation and thus influence the neurodevelopmental outcomes of the offspring.
  • 608
  • 03 Nov 2022
Topic Review
Podarcis siculus Spermatogenesis
Spermatogenesis is a genetically driven differentiation process that occurs in the testis and leads to the formation of spermatozoa. This process is extensively studied in several experimental models, particularly in vertebrates that share the morphological structure and functionality of the mammalian testis. Reptiles are not generally considered biological models, the lizard Podarcis siculus has represented a suitable organism for the study of spermatogenesis. In this lizard, the process of spermatogenesis is regulated by the interaction between systemic factors such as gonadotropins and local factors, i.e., molecules produced by the somatic and germinal cells of the testis.
  • 601
  • 20 Dec 2022
Topic Review
Contemporary Use of Intracytoplasmic Sperm Injection
Intracytoplasmic sperm injection (ICSI) has been used for severe male factor infertility and non-male factors, such as unexplained infertility or advanced maternal age, without robust scientific evidence. However, applying ICSI blindly is not free of potential detrimental consequences since novel studies report possible health consequences to offspring. DNA methylation and epigenetic alterations in sperm cells of infertile men might help explain some of the adverse effects reported in ICSI studies on reproductive health in future generations. 
  • 595
  • 17 May 2022
Topic Review
Epigenetic Modifications in Plant Development and Reproduction
Plants are exposed to highly fluctuating effects of light, temperature, weather conditions, and many other environmental factors throughout their life. As sessile organisms, unlike animals, they are unable to escape, hide, or even change their position. Therefore, the growth and development of plants are largely determined by interaction with the external environment. The success of this interaction depends on the ability of the phenotype plasticity, which is largely determined by epigenetic regulation. In addition to how environmental factors can change the patterns of genes expression, epigenetic regulation determines how genetic expression changes during the differentiation of one cell type into another and how patterns of gene expression are passed from one cell to its descendants. Thus, one genome can generate many ‘epigenomes’. Epigenetic modifications acquire special significance during the formation of gametes and plant reproduction when epigenetic marks are eliminated during meiosis and early embryogenesis and later reappear. However, during asexual plant reproduction, when meiosis is absent or suspended, epigenetic modifications that have arisen in the parental sporophyte can be transmitted to the next clonal generation practically unchanged. In plants that reproduce sexually and asexually, epigenetic variability has different adaptive significance.
  • 583
  • 22 Dec 2021
Topic Review
Protective Agents for Male Fertility
The male reproductive system is highly susceptible to noxious influences, that can induce germ cell damage, alterations in spermatogenesis and male fertility. For this reason, it is of major importance to investigate possible ways to protect the male reproductive system. For centuries, natural products have been used by humans in folk medicine as therapeutic agents, and because of their beneficial properties for human health, plenty of them have been introduced to the pharmaceutical market as supplementary therapies.
  • 576
  • 08 Nov 2021
Topic Review
Application of Single-Cell RNA Sequencing in Ovarian Development
The ovary is a female reproductive organ that plays a key role in fertility and the maintenance of endocrine homeostasis, which is of great importance to women’s health. It is characterized by a high heterogeneity, with different cellular subpopulations primarily containing oocytes, granulosa cells, stromal cells, endothelial cells, vascular smooth muscle cells, and diverse immune cell types. Each has unique and important functions. From the fetal period to old age, the ovary experiences continuous structural and functional changes, with the gene expression of each cell type undergoing dramatic changes. In addition, ovarian development strongly relies on the communication between germ and somatic cells. Compared to traditional bulk RNA sequencing techniques, the single-cell RNA sequencing (scRNA-seq) approach has substantial advantages in analyzing individual cells within an ever-changing and complicated tissue, classifying them into cell types, characterizing single cells, delineating the cellular developmental trajectory, and studying cell-to-cell interactions. 
  • 572
  • 06 Jan 2023
Topic Review
Relevance of Aquaporins for Gamete Function and Cryopreservation
Aquaporins (AQPs) are a family of transmembrane channels that allow the transport of water and small solutes across cell membranes. Different members of this family have been identified in gametes. In sperm, they are relevant to osmoadaptation after entering the female reproductive tract, which is crucial for sperm motility activation and capacitation and, thus, for their fertilizing ability. In addition, they are relevant during the cryopreservation process, since some members of this family are also permeable to glycerol, one of the most frequently used cryoprotective agents in livestock. Regarding oocytes, AQPs are very important in their maturation but also during cryopreservation. 
  • 570
  • 29 Jun 2022
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