Background: It has long been thought that the factors affecting embryo and foetal development were exclusively maternally derived; hence, if issues regarding fertility and embryo development were to arise, the blame has traditionally been placed solely on the mother. An escalating interest in how paternal factors influence embryo development, however, has begun to prove otherwise. Evidence suggests that both seminal plasma (SP) and sperm contribute multiple factors that shape embryogenesis. This review thus focuses on the role that semen has in driving early embryonic development, and describes how paternal factors, such as SP, sperm centriole, sperm proteins, sperm RNA, sperm DNA, and its integrity, together with epigenetics, may influence the female reproductive tract and post-fertilization events. The important contributions of paternal factors to embryo development highlight the imperative need for further research in this area, which is sure to bring forth breakthroughs leading to improvements in infertility diagnosis and ART as well as reducing the risk of miscarriage.
Objective and rationale: This review provides a comprehensive overview of the role of human semen in development of the early embryo, with the aim of providing a better understanding of the influence of SP and sperm on early embryonic divisions, gene and protein expression, miscarriage, and congenital diseases.
Search methods: PubMed searches were performed using the terms 'sperm structure', 'capacitation', 'acrosome reaction', 'fertilization', 'oocyte activation', 'PLCζ', 'PAWP', 'sperm-borne oocyte activation factor', 'oocyte activation deficiency', 'sperm centriole', 'sperm transport', 'sperm mitochondria', 'seminal plasma', 'sperm epigenetics', 'sperm histone modifications', 'sperm DNA methylation', 'sperm-derived transcripts', 'sperm-derived proteins', 'sperm DNA fragmentation', 'sperm mRNA', 'sperm miRNAs', 'sperm piRNAs', and 'sperm-derived aneuploidy'. The reviewed articles were restricted to those published in English between 1980 and 2022.
Outcomes: The data suggest that male-derived factors contribute much more than just the male haploid genome to the early embryo. Evidence indicates that semen contributes multiple factors that help shape the fate of embryogenesis. These male-derived factors include contributions from SP, the paternal centriole, RNA and proteins, and DNA integrity. In addition, epigenetic changes have an impact on the female reproductive tract, fertilization, and early stages of embryo development. For example, recent proteomic and transcriptomic studies have identified several sperm-borne markers that play important roles in oocyte fertilization and embryogenesis.
Wider implications: This review highlights that several male-derived factors are required to work in tandem with female counterparts to allow for correct fertilization and deve
Background: Regulated cell death is a fundamental component of numerous physiological processes; spanning from organogenesis in utero, to normal cell turnover during adulthood, as well as the elimination of infected or damaged cells throughout life. Quality control through regulation of cell death pathways is particularly important in the germline, which is responsible for the generation of offspring. Women are born with their entire supply of germ cells, housed in functional units known as follicles. Follicles contain an oocyte, as well as specialized somatic granulosa cells essential for oocyte survival. Follicle loss-via regulated cell death-occurs throughout follicle development and life, and can be accelerated following exposure to various environmental and lifestyle factors. It is thought that the elimination of damaged follicles is necessary to ensure that only the best quality oocytes are available for reproduction.
Objective and rationale: Understanding the precise factors involved in triggering and executing follicle death is crucial to uncovering how follicle endowment is initially determined, as well as how follicle number is maintained throughout puberty, reproductive life, and ovarian ageing in women. Apoptosis is established as essential for ovarian homeostasis at all stages of development and life. However, involvement of other cell death pathways in the ovary is less established. This review aims to summarize the most recent literature on cell death regulators in the ovary, with a particular focus on non-apoptotic pathways and their functions throughout the discrete stages of ovarian development and reproductive life.
Search methods: Comprehensive literature searches were carried out using PubMed and Google Scholar for human, animal, and cellular studies published until August 2022 using the following search terms: oogenesis, follicle formation, follicle atresia, oocyte loss, oocyte apoptosis, regulated cell death in the ovary, non-apoptotic cell death in the ovary, premature ovarian insufficiency, primordial follicles, oocyte quality control, granulosa cell death, autophagy in the ovary, autophagy in oocytes, necroptosis in the ovary, necroptosis in oocytes, pyroptosis in the ovary, pyroptosis in oocytes, parthanatos in the ovary, and parthanatos in oocytes.
Outcomes: Numerous regulated cell death pathways operate in mammalian cells, including apoptosis, autophagic cell death, necroptosis, and pyroptosis. However, our understanding of the distinct cell death mediators in each ovarian cell type and follicle class across the different stages of life remains the source of ongoing investigation. Here, we highlight recent evidence for the contribution of non-apoptotic pathways to ovarian development and function. In particular, we discuss the involvement of autophagy during follicle formation and the role of autophagic cell death, necroptosis, py
Background: Primary ciliary dyskinesia (PCD) is a genetic condition affecting the structure and function of sperm flagellum and motile cilia including those in the male and female reproductive tracts. Infertility is a commonly reported feature of PCD, but there is uncertainty as to how best to counsel patients on their fertility prognosis.
Objective and rationale: This review aimed to summarize the prevalence of subfertility, possible underlying mechanisms, and the success of ART in men and women with PCD. The efficacy of ART in this patient group is relatively unknown and, hence, the management of infertility in PCD patients remains a challenge. There are no previous published or registered systematic reviews of fertility outcomes in PCD.
Search methods: Systematic literature searches were performed in Medline, Embase, Cochrane Library, and PubMed electronic databases to identify publications between 1964 and 2022 reporting fertility outcomes in men and women with PCD. Publications were excluded if they reported only animal studies, where gender was not specified or where subjects had a medical co-morbidity also known to impact fertility. Quality of evidence was assessed by critical appraisal and application of an appraisal tool for cross-sectional studies. The primary outcomes were natural conception in men and women with PCD, and conception following ART in men and women with PCD.
Outcomes: A total of 1565 publications were identified, and 108 publications were included after screening by two independent researchers. The quality of available evidence was low. The exact prevalence of subfertility in PCD is unclear but appears to be higher in men (up to 83% affected) compared to women (up to 61% affected). Variation in the prevalence of subfertility was observed between geographic populations which may be explained by differences in underlying genotype and cilia function. Limited evidence suggests subfertility in affected individuals is likely caused by abnormal cilia motion in the fallopian tubes, endometrium and efferent ductules, and dysmotile sperm. Some men and women with PCD benefited from ART, which suggests its use should be considered in the management of subfertility in this patient group. Further epidemiological and controlled studies are needed to determine the predictors of fertility and optimal management in this patient group.
Wider implications: It is important that patients with PCD receive evidence-based counselling about the potential impact of their condition on their fertility prognosis and what management options may be available to them if affected. Understanding the pathophysiology and optimal management of subfertility in PCD will increase our understanding of the role of cilia and the impact of wider secondary ciliopathies on reproduction.
Background: Several GnRH antagonist protocols are currently used during COS in the context of ART treatments; however, questions remain regarding whether these protocols are comparable in terms of efficacy and safety.
Objective and rationale: A systematic review followed by a pairwise and network meta-analyses were performed. The systematic review and pairwise meta-analysis of direct comparative data according to the PRISMA guidelines evaluated the effectiveness of different GnRH antagonist protocols (fixed Day 5/6 versus flexible, ganirelix versus cetrorelix, with or without hormonal pretreatment) on the probability of live birth and ongoing pregnancy after COS during ART treatment. A frequentist network meta-analysis combining direct and indirect comparisons (using the long GnRH agonist protocol as the comparator) was also performed to enhance the precision of the estimates.
Search methods: The systematic literature search was performed using Embase (Ovid), MEDLINE (Ovid), Cochrane Central Register of Trials (CENTRAL), SCOPUS and Web of Science (WOS), from inception until 23 November 2021. The search terms comprised three different MeSH terms that should be present in the identified studies: GnRH antagonist; assisted reproduction treatment; randomized controlled trial (RCT). Only studies published in English were included.
Outcomes: The search strategy resulted in 6738 individual publications, of which 102 were included in the systematic review (corresponding to 75 unique studies) and 73 were included in the meta-analysis. Most studies were of low quality. One study compared a flexible protocol with a fixed Day 5 protocol and the remaining RCTs with a fixed Day 6 protocol. There was a lack of data regarding live birth when comparing the flexible and fixed GnRH antagonist protocols or cetrorelix and ganirelix. No significant difference in live birth rate was observed between the different pretreatment regimens versus no pretreatment or between the different pretreatment protocols. A flexible GnRH antagonist protocol resulted in a significantly lower OPR compared with a fixed Day 5/6 protocol (relative risk (RR) 0.76, 95% CI 0.62 to 0.94, I2 = 0%; 6 RCTs; n = 907 participants; low certainty evidence). There were insufficient data for a comparison of cetrorelix and ganirelix for OPR. OCP pretreatment was associated with a lower OPR compared with no pretreatment intervention (RR 0.79, 95% CI 0.69 to 0.92; I2 = 0%; 5 RCTs, n = 1318 participants; low certainty evidence). Furthermore, in the network meta-analysis, a fixed protocol with OCP resulted in a significantly lower OPR than a fixed protocol with no pretreatment (RR 0.84, 95% CI 0.71 to 0.99; moderate quality evidence). The surface under the cumulative ranking (SUCRA) scores suggested that the fixed protocol with no pretreatment is the antagonist protocol most likely (84%) to result in the highest OPR. Ther

