Regenerative Medicine in Gynecology.

The female reproductive tract undergoes dynamic changes across the life span. Congenital abnormalities, life events, and medical interventions can negatively affect the structure and function of reproductive tract organs, resulting in lifelong sequelae. The objective of regenerative gynecology is to discover and promote endogenous mechanisms by which a healthy tissue maintains overall tissue integrity after injury, after disease, or with age. In this review, we discuss some of the key state-of-the-art cell-based and scaffolding therapies that have been applied to regenerate gynecologic tissues and organs primarily in animal and tissue culture models. We further discuss the limitations of current technologies, problems of implementation and scalability, and future outlook of the field.

Three-dimensional correlative microscopy of the Drosophila female reproductive tract reveals modes of communication in seminal receptacle sperm storage.

In many taxa, females store sperm in specialized storage organs. Most insect sperm storage organs have a tubular structure, typically consisting of a central lumen surrounded by epithelial cells. These specialized tubules perform the essential tasks of transporting sperm through the female reproductive tract and supporting long-term sperm survival and function. Little is known about the way in which female sperm storage organs provide an environment conducive to sperm survival. We address this using a combined light microscopy, micro computed tomography (microCT), and Focused Ion Beam Scanning Electron Microscopy (FIB-SEM) approach for high-resolution correlative three-dimensional imaging to advance our understanding of sperm-female interactions in Drosophila melanogaster. Using this multimodal approach, we were able to scan the lower female reproductive tract and distal portion of the seminal receptacle at low magnification, and to subsequently zoom in for further analysis on an ultrastructural level. Our findings highlight aspects of the way in which the seminal receptacle keeps sperm viable in the lumen, and set the stage for further studies. The methods developed are suitable not only for Drosophila but also for other organisms with soft, delicate tissues.

N6-Methyladenosine Modifications in the Female Reproductive System: Roles in Gonad Development and Diseases.

N6-methyladenosine (m6A) is the most prevalent chemical modification in eukaryotic messenger RNAs. By participating in various RNA-related bioprocesses including RNA decay, splicing, transport and translation, m6A serves as a pivotal regulator of RNA fate and plays an irreplaceable role in cellular activities. The m6A modifications of transcripts are coordinately regulated by methyltransferase "writers" and demethylase "erasers", and produce variable effects via different m6A reading protein "readers". There is emerging evidence that m6A modifications play a critical role in a variety of physiological and pathological processes in the female reproductive system, subsequently affecting female fertility. Here, we introduce recent advances in research on m6A regulators and their functions, then highlight the role of m6A in gonad development and female reproductive diseases, as well as the underlying mechanisms driving these processes.

The influence of the female reproductive tract and sperm features on the design of microfluidic sperm-sorting devices.

Although medical advancements have successfully helped a lot of couples with their infertility by assisted reproductive technologies (ART), sperm selection, a crucial stage in ART, has remained challenging. Therefore, we aimed to investigate novel sperm separation methods, specifically microfluidic systems, as they do sperm selection based on sperm and/or the female reproductive tract (FRT) features without inflicting any damage to the selected sperm during the process. In this review, after an exhaustive studying of FRT features, which can implement by microfluidics devices, the focus was centered on sperm selection and investigation devices. During this study, we tried not to only point to the deficiencies of these systems, but to put forth suggestions for their improvement as well.

The Potential Relationship Between Different Human Female Reproductive Disorders and Sperm Quality in Female Genital Tract.

Spermatozoa should travel throughout the female reproductive tract to reach its ultimate goal, fertilization of the oocyte. At the ejaculation moment, millions of sperm within a few milliliters of the ejaculate are deposited at the cranial segment of vagina and make their journey to the fertilization site. This is done by means of various factors, such as sperm motility, the uterine and fallopian tubes contractility, and the ciliary movement of the lining cells. During this migration, spermatozoa interact with the female microenvironment both physically and molecularly. In this regard, the quality of the environmental conditions may affect this interaction. Therefore, some alterations in women's genital tract microenvironment, such as conditions that occur in female reproductive disorders, may have detrimental effects on sperm reproductive function. In this review, human sperm migration through the female tract is described, and the potential effects of different reproductive disorders at reproductive organs, such as vagina, uterine cervix, uterus, fallopian tubes, and ovary on sperm survival and quality, are also argued. The understanding of those conditions that may impair sperm fertility in the female genital tract can provide a more accurate diagnosis of the causes of infertility in couples. This can ultimately lead to the discovery of effective treatment approaches.

The damage effect of heat stress and psychological stress combined exposure on uterus in female rats.

AIMS: Explore the effects of heat stress and psychological stress combined exposure on the uterus and its underlying mechanisms. MAIN METHODS: Sixty female Sprague-Dawley rats were randomly assigned to four groups: control group, psychological stress group, high ambient temperature group, and high ambient temperature combined with psychological stress group. All treatments were administered for two weeks. During this period, the estrous cycle, body weights and rectal temperature were measured regularly. Then, ovarian weight coefficient, serum estradiol (E2) and progesterone (P) concentration, uterine histomorphological alterations, levels of tumor necrosis factor alpha (TNF-α), malondialdehyde (MDA) and superoxide dismutase (SOD), and the expressions of ovarian hormone receptors, leukemia inhibitory factor (LIF) and its receptor, homeobox gene A10 (HoxA10), Wnt5a, Wnt7a, ß-catenin, and P-ß-cateninY142 in the uterus and endometrium were detected. KEY FINDINGS: High temperature combined with psychological stress lead to body weight, body temperature, ovarian hormones and estrus cycle disorder, uterine gland ducts expansion and endometrial thickness reduction, and the decreased expression of endometrial receptivity markers (LIF and HoxA10). Further, disturbed expression of E2 and P receptors in endometrium, elevated MDA and TNF-α levels, and decreased Wnt5a, Wnt7a and P-ß-cateninY142 content were found. Our data suggested that co-exposure to high temperature and psychological stress could aggravate uterine damage probably by inducing ovarian hormonal disorder and the subsequent oxidative stress and inflammation, and reduce the endometrial function through suppressing Wnt signaling. SIGNIFICANCE: This will provide the scientific basis for improving female reproductive health, and preventing and treating reproductive disorders.

Sperm Accumulation Induced by the Female Reproductive Fluid: Putative Evidence of Chemoattraction Using a New Tool.

There is considerable evidence that female reproductive fluid (FRF) interacts intimately with sperm, affecting several sperm traits, including sperm motility and longevity, and ultimately fertilization success. One of the first documented interactions between FRF and sperm is the ability of FRF to attract and guide sperm towards the eggs. However, most of the evidence of FRF's chemoattraction proprieties comes from a limited number of taxa, specifically mammals and invertebrate broadcasting spawners. In other species, small FRF volumes and/or short sperm longevity often impose methodological difficulties resulting in this gap in chemoattraction studies in non-model species. One of the outcomes of sperm chemotaxis is sperm accumulation towards high chemoattractant concentrations, which can be easily quantified by measuring sperm concentration. Here, we tested sperm accumulation towards FRF in the zebrafish, Danio rerio, using an ad hoc developed, 3D printed, device ('sperm selection chamber'). This easy-to-use tool allows to select and collect the sperm that swim towards a chemical gradient, and accumulate in a chemoattractant-filled well thus providing putative evidence for chemoattraction. We found that sperm accumulate in FRF in zebrafish. We also found that none of the sperm quality traits we measured (sperm swimming velocity and trajectory, sperm motility, and longevity) were correlated with this response. Together with the 3D printable project, we provide a detailed protocol for using the selection chamber. The chamber is optimized for the zebrafish, but it can be easily adapted for other species. Our device lays the foundation for a standardized way to measure sperm accumulation and in general chemoattraction, stimulating future research aimed at understanding the role and the mechanisms of sperm chemoattraction by FRF.

Individual and community-level determinants of knowledge of ovulatory cycle among women of childbearing age in Ethiopia: A multilevel analysis based on 2016 Ethiopian Demographic and Health Survey.

BACKGROUND: Knowledge of the ovulatory cycle (KOC) aids women to refrain and engage in sexual intercourse to avoid and to get pregnancy, respectively. The effect of community-level factors on KOC was not yet known in Ethiopia. Therefore, we aimed to investigate the community- and individual-level determinants of KOC among women of childbearing age. METHODS: We used the 2016 Ethiopian Demographic and Health Survey, and total weighted samples of 15,683 women were included. Intra-class correlation, median odds ratio, and deviance were executed for model comparison in which a model with the lowest deviance was the best model i.e. model III in this case. A multivariable multilevel logistic regression model was employed to identify community- and individual-level factors of correct KOC. In the ultimate model, an adjusted odds ratio (AOR) with a 95% confidence interval was reported and variables with a p<0.05 were considered as statistically significant. RESULTS: In this study, 3,698 [23.58% (95% CI; 22.92-24.25)] participants had correct KOC. Women's age in years, i.e. 20-24 (AOR = 1.46;1.28-1.68) 25-29 (AOR = 1.72; 1.49-1.99), 30-34 (AOR = 2.21; 1.89-2.58), 35-39 (AOR = 1.78; 1.51-2.09), 40-44 (AOR = 1.97; 1.65-2.37), and 45-49 (AOR = 1.78; 1.44-2.19), knowledge of contraceptive methods (AOR = 3.08; 2.07-4.58), increased women's educational level, i.e. higher (AOR = 4.24; 3.54-5.07), secondary (AOR = 2.89; 2.48-3.36), and primary (AOR = 1.57; 1.39-1.78), higher household's wealth index, i.e. richest (AOR = 1.71; 1.35-2.16), richer (AOR = 1.42; 1.16-1.72), middle (AOR = 1.29; 1.07-1.56), and poorer (AOR = 1.24; 1.03-1.48), current contraceptive use (AOR = 1.26; 1.13-1.39), menstruating in the last six weeks (AOR = 1.13; 1.03-1.24), women's media exposure (AOR = 1.20; 1.07-1.35), and being in the community with a high level of media exposure (AOR = 1.53; 1.24-1.88) were statistically significant with KOC. CONCLUSIONS: Knowledge of the ovulatory cycle was low in this study, which demands health education for women of childbearing age. Special attention should be given to teenagers, those with lower educational, and lower economic status. Besides, the strengthening of media campaigns could increase women's KOC, which is crucial for preventing unintended pregnancy.

The human memory T cell compartment changes across tissues of the female reproductive tract.

Memory CD4 T cells in tissues fulfill numerous functions that are critical for local immune homeostasis and protection against pathogens. Previous studies have highlighted the phenotypic and functional heterogeneity of circulating and tissue-resident memory CD4 T cells across different human tissues such as skin, lung, liver, and colon. Comparatively little is known in regard to memory CD4 T cells across tissues of the female reproductive tract (FRT). We examined CD4 T cells in donor-matched vaginal, ecto- and endocervical tissues, which differ in mucosal structure and exposure to external environmental stimuli. We hypothesized that this could be reflected by tissue-specific differences in the memory CD4 T cell compartment. We found differences in CD4 subset distribution across these tissues. Specifically, CD69+CD103+ CD4 T cells were significantly more abundant in vaginal than cervical tissues. In contrast, the transcriptional profiles of CD4 subsets were fairly conserved across FRT tissues. CD69+CD103+ CD4 T cells showed a TH17 bias independent of tissue niche. Our data suggest that FRT tissues affect T cell subset distribution but have limited effects on the transcriptome of each subset. We discuss the implications for barrier immunity in the FRT.

The impact of aging on innate and adaptive immunity in the human female genital tract.

Mucosal tissues in the human female reproductive tract (FRT) are primary sites for both gynecological cancers and infections by a spectrum of sexually transmitted pathogens, including human immunodeficiency virus (HIV), that compromise women's health. While the regulation of innate and adaptive immune protection in the FRT by hormonal cyclic changes across the menstrual cycle and pregnancy are being intensely studied, little to nothing is known about the alterations in mucosal immune protection that occur throughout the FRT as women age following menopause. The immune system in the FRT has two key functions: defense against pathogens and reproduction. After menopause, natural reproductive function ends, and therefore, two overlapping processes contribute to alterations in immune protection in aging women: menopause and immunosenescence. The goal of this review is to summarize the multiple immune changes that occur in the FRT with aging, including the impact on the function of epithelial cells, immune cells, and stromal fibroblasts. These studies indicate that major aspects of innate and adaptive immunity in the FRT are compromised in a site-specific manner in the FRT as women age. Further, at some FRT sites, immunological compensation occurs. Overall, alterations in mucosal immune protection contribute to the increased risk of sexually transmitted infections (STI), urogenital infections, and gynecological cancers. Further studies are essential to provide a foundation for the development of novel therapeutic interventions to restore immune protection and reverse conditions that threaten women's lives as they age.

Recent Advancements in Engineered Biomaterials for the Regeneration of Female Reproductive Organs.

Various gynecologic diseases and chemoradiation or surgery for the management of gynecologic malignancies may damage the uterus and ovaries, leading to clinical problems such as infertility or early menopause. Embryo or oocyte cryopreservation-the standard method for fertility preservation-is not a feasible option for patients who require urgent treatment because the procedure requires ovarian stimulation for at least several days. Hormone replacement therapy (HRT) for patients diagnosed with premature menopause is contraindicated for patients with estrogen-dependent tumors or a history of thrombosis. Furthermore, these methods cannot restore the function of the uterus and ovaries. Although autologous transplantation of cryopreserved ovarian tissue is being attempted, it may re-introduce malignant cells after cancer treatment. With the recent development in regenerative medicine, research on engineered biomaterials for the restoration of female reproductive organs is being actively conducted. The use of engineered biomaterials is a promising option in the field of reproductive medicine because it can overcome the limitations of current therapies. Here, we review the ideal properties of biomaterials for reproductive tissue engineering and the recent advancements in engineered biomaterials for the regeneration of female reproductive organs.

Penetration mechanics of elongated female and male genitalia of earwigs.

We unveiled the penile penetration mechanics of two earwig species, Echinosoma horridum, whose intromittent organ, termed virga, is extraordinarily long, and E. denticulatum, whose virga is conversely short. We characterised configuration, geometry, material and bending stiffness for both virga and spermatheca. The short virga of E. denticulatum has a material gradient with the stiffer base, whereas the long virga of E. horridum and the spermathecae of both species are homogeneously sclerotised. The long virga of E. horridum has a lower bending stiffness than the spermatheca. The virga of E. denticulatum is overall less flexible than the spermatheca. We compared our results to a previous study on the penetration mechanics of elongated beetle genitalia. Based on the comparison, we hypothesised that the lower stiffness of the male intromittent organ comparing to the corresponding female structure is a universal prerequisite for the penetration mechanics of the elongated intromittent organ in insects.

Advancements in Microfluidic Systems for the Study of Female Reproductive Biology.

The female reproductive tract is a highly complex physiological system that consists of the ovaries, fallopian tubes, uterus, cervix, and vagina. An enhanced understanding of the molecular, cellular, and genetic mechanisms of the tract will allow for the development of more effective assisted reproductive technologies, therapeutics, and screening strategies for female specific disorders. Traditional 2-dimensional and 3-dimensional static culture systems may not always reflect the cellular and physical contexts or physicochemical microenvironment necessary to understand the dynamic exchange that is crucial for the functioning of the reproductive system. Microfluidic systems present a unique opportunity to study the female reproductive tract, as these systems recapitulate the multicellular architecture, contacts between different tissues, and microenvironmental cues that largely influence cell structure, function, behavior, and growth. This review discusses examples, challenges, and benefits of using microfluidic systems to model ovaries, fallopian tubes, endometrium, and placenta. Additionally, this review also briefly discusses the use of these systems in studying the effects of endocrine disrupting chemicals and diseases such as ovarian cancer, preeclampsia, and polycystic ovarian syndrome.

The impact of the gut microbiota on the reproductive and metabolic endocrine system.

As the gut microbiota exerts various effects on the intestinal milieu which influences distant organs and pathways, it is considered to be a full-fledged endocrine organ. The microbiota plays a major role in the reproductive endocrine system throughout a woman's lifetime by interacting with estrogen, androgens, insulin, and other hormones. Imbalance of the gut microbiota composition can lead to several diseases and conditions, such as pregnancy complications, adverse pregnancy outcomes, polycystic ovary syndrome (PCOS), endometriosis, and cancer; however, research on the mechanisms is limited. More effort should be concentrated on exploring the potential causes and underlying the mechanisms of microbiota-hormone-mediated disease, and providing novel therapeutic and preventive strategies.As the gut microbiota exerts various effects on the intestinal milieu which influences distant organs and pathways, it is considered to be a full-fledged endocrine organ. The microbiota plays a major role in the reproductive endocrine system throughout a woman's lifetime by interacting with estrogen, androgens, insulin, and other hormones. Imbalance of the gut microbiota composition can lead to several diseases and conditions, such as pregnancy complications, adverse pregnancy outcomes, polycystic ovary syndrome (PCOS), endometriosis, and cancer; however, research on the mechanisms is limited. More effort should be concentrated on exploring the potential causes and underlying the mechanisms of microbiota-hormone-mediated disease, and providing novel therapeutic and preventive strategies.

Role of Zinc (Zn) in Human Reproduction: A Journey from Initial Spermatogenesis to Childbirth.

Zinc (Zn), the second-most necessary trace element, is abundant in the human body. The human body lacks the capacity to store Zn; hence, the dietary intake of Zn is essential for various functions and metabolism. The uptake of Zn during its transport through the body is important for proper development of the three major accessory sex glands: the testis, epididymis, and prostate. It plays key roles in the initial stages of germ cell development and spermatogenesis, sperm cell development and maturation, ejaculation, liquefaction, the binding of spermatozoa and prostasomes, capacitation, and fertilization. The prostate releases more Zn into the seminal plasma during ejaculation, and it plays a significant role in sperm release and motility. During the maternal, labor, perinatal, and neonatal periods, the part of Zn is vital. The average dietary intake of Zn is in the range of 8-12 mg/day in developing countries during the maternal period. Globally, the dietary intake of Zn varies for pregnant and lactating mothers, but the average Zn intake is in the range of 9.6-11.2 mg/day. The absence of Zn and the consequences of this have been discussed using critical evidence. The events and functions of Zn related to successful fertilization have been summarized in detail. Briefly, our current review emphasizes the role of Zn at each stage of human reproduction, from the spermatogenesis process to childbirth. The role of Zn and its supplementation in in vitro fertilization (IVF) opens opportunities for future studies on reproductive biology.

Organoids of the female reproductive tract.

Healthy functioning of the female reproductive tract (FRT) depends on balanced and dynamic regulation by hormones during the menstrual cycle, pregnancy and childbirth. The mucosal epithelial lining of different regions of the FRT-ovaries, fallopian tubes, uterus, cervix and vagina-facilitates the selective transport of gametes and successful transfer of the zygote to the uterus where it implants and pregnancy takes place. It also prevents pathogen entry. Recent developments in three-dimensional (3D) organoid systems from the FRT now provide crucial experimental models that recapitulate the cellular heterogeneity and physiological, anatomical and functional properties of the organ in vitro. In this review, we summarise the state of the art on organoids generated from different regions of the FRT. We discuss the potential applications of these powerful in vitro models to study normal physiology, fertility, infections, diseases, drug discovery and personalised medicine.

Lessons Learned from Hereditary 1,25-Dihydroxyvitamin D-Resistant Rickets Patients on Vitamin D Functions.

We summarize here lessons learned from studies on skeletal and extra-skeletal functions of vitamin D in hereditary 1,25-dihydroxyvitamin D-resistant rickets (HVDRR) patients with a mutant, nonfunctioning vitamin D receptor (VDR). During childhood, HVDRR patients are dependent on intestinal VDR, demonstrate low intestinal fraction calcium absorption, and have a bone calcium accretion rate that leads to hypocalcemia and rickets. After puberty, there is recovery in intestinal calcium absorption and in bone calcium accretion and structure. HVDRR monocytes and lymphocytes show impairment in the expression of antimicrobial proteins and demonstrate a proinflammatory cytokine profile. However, HVDRR patients do not exhibit increased rates of infections or inflammatory diseases. Vitamin D deficiency is associated with asthmatic exacerbations. Surprisingly, HVDRR patients do not usually develop asthma. They have normal allergic tests and lung functions and are protected against provoked bronchial hyperactivity. HVDRR patients have decreased IL-5 levels in their exhaled breath condensate. Given that IL-5 is a key cytokine in the development of airway inflammation and hyperactivity and that VDR is important for IL-5 generation, it is plausible that low lung IL-5 protects HVDRR patients from asthma. Vitamin D metabolites have suppressive effects on the renin angiotensin system. However, no HVDRR patient showed hypertension or echocardiographic pathology, and their renin angiotensin metabolites were normal. The VDR is expressed throughout the reproductive system, suggesting a role in reproduction. However, the reproductive history of HVDRR patients is normal despite the lack of a normal VDR. HVDRR patients provide a unique opportunity to study the role of the VDR and the role of vitamin D in various human systems.

Role of nuclear and membrane estrogen signaling pathways in the male and female reproductive tract.

Estrogen signaling through the main estrogen receptor, estrogen receptor 1 (ESR1; also known as ERα), is essential for normal female and male reproductive function. Historically, studies of estrogen action have focused on the classical genomic pathway. Although this is clearly the major pathway for steroid hormone actions, these hormones also signal through rapid non-classical effects involving cell membrane actions. Reports of rapid effects of estrogens extend for more than half a century, but recent results have expanded understanding of the identity, structure, function and overall importance of membrane receptors in estrogen responses. Key findings in this field were the immunohistochemical detection of ESR1 in cell membranes and demonstration that a portion of newly synthesized ESR1 is routed to the membrane by palmitoylation. These receptors in the membrane can then signal through protein kinases and other mechanisms following ligand binding to alter cell function. Another crucial advance in the field was development of transgenic mice expressing normal amounts of functional nuclear ESR1 (nESR1) but lacking membrane ESR1 (mESR1). Both male and female transgenic mice lacking mESR1 were infertile as adults, and both sexes had extensive reproductive abnormalities. Transgenic mice lacking mESR1 were highly protected from deleterious effects of neonatal estrogen administration, and estrogen effects on the histone methyltransferase Enhancer of Zeste homolog 2 that are mediated through mESR1 could have significant effects on epigenetic imprinting. In summary, signaling through mESR1 is essential for normal male and female reproductive function and fertility, and is a critical enabler of normal estrogen responses in vivo. Although the precise role of mESR1 in estrogen responses remains to be established, future research in this area should clarify its mechanism of action and lead to a better understanding of how mESR1 signaling works with classical genomic signaling through nESR1 to promote full estrogenic responses.

Female ejaculation: An update on anatomy, history, and controversies.

Female ejaculation is a contentious topic. From a review of the literature, history indicates that it is not a modern concept; some females were aware of it in times past without understanding the role of the fluid or composition of the ejaculate. Over time, scholars experimented, mainly with anatomical studies, in an attempt to identify the source of the ejaculate and explore its physiological and anatomical benefits for the female sexual experience. Despite these studies, views about female ejaculation remain controversial and inconsistent, with no clear conclusion as to its function. This review discusses the history of studies of female ejaculation and presents various hypotheses from an anatomical and physiological perspective. After reviewing 44 publications from 1889 to 2019, it became apparent that clinical and anatomical studies conducted during recent decades provide substantial evidence in support of the female ejaculatory phenomenon. Anatomical studies have shown that the ejaculate originates in the paraurethral (Skene's) glands, but its composition has been debated. Female ejaculate differs from urine in its creatinine and urea concentrations. The fluid also contains prostate specific antigen (PSA) and could have antibacterial properties that serve to protect the urethra. While the specific function of female ejaculation remains a topic of debate, there is sufficient evidence to support the existence of the phenomenon.