Advances in Anatomy Embryology and Cell Biology最新文献

Extracellular vesicles (EVs), including exosomes and microvesicles, have emerged as pivotal mediators of intercellular communication. Embryo implantation is a critical process in early pregnancy and requires communication between the embryo and maternal uterus. EVs are important in coordinating the communication between the embryo and maternal uterus. This review explores EV biogenesis, molecular composition, and functional roles during implantation. It emphasizes the dynamic role of EVs in modulating the maternal-embryo dialogue, which is critical for establishing a receptive endometrium and facilitating successful implantation. EVs secreted by the embryo and endometrial cells have been shown to carry a diverse cargo of proteins, lipids, and miRNAs, which collectively influence key physiological processes, including immune tolerance, endometrial receptivity, and trophoblast invasion. EVs can be potential candidates as non-invasive biomarkers to assess the quality of embryos and uterine receptivity to enhance reproductive success. By providing a comprehensive overview of the current understanding of EVs in implantation, this chapter aims to highlight the significance of EVs in reproductive biology and their potential applications in improving fertility rates.

Life relies on redox reactions to sustain; however, imbalanced redox exerts stress on living beings. This is particularly pivotal as mammalian gamete sperm cells undergo functional maturation in the epididymis, preparing themselves for the long and challenging journey to begin a new life by successfully fertilizing an oocyte. Defects in epididymal sperm maturation are closely related to male infertility and reproductive health. In the epididymis, the halted translational machinery in spermatozoa while maturing in a quiescent state prompts them to immensely depend on epithelial cells for nutritional supports and information exchange. Extensive intercellular communication is therefore required between sperm and epithelial cells, and extracellular vesicles (EVs) play a crucial role as intercellular carriers. Epididymal luminal microenvironment is spatially specialized to be an acidic, decalcitonic, and pro-reductive protective milieu to prevent premature sperm dysfunction. The uniqueness of epididymal microenvironment also requires the EVs to have adaptive characteristics. Although the biogenesis and compositions of EVs in the epididymis have been reviewed elsewhere, this chapter discusses the potential role of EVs from the perspective of cellular nutrient balance of vitamins and minerals, redox metabolism, and intercellular interplay during sperm maturation to better understand the biology of epididymis in male reproduction.

The seminal vesicle contributes to a large extent of the semen volume and composition. Removal of seminal vesicle or lack of seminal vesicle proteins leads to decreased fertility. Seminal plasma proteome revealed that seminal fluid contained a wide diversity of proteins. Many of them are known to modulate sperm capacitation and serve as capacitation inhibitors or decapacitation factors. Despite identifying secretory vesicles from the male reproductive tract, such as epididymosomes or prostasomes, isolation, identification, and characterization of seminal vesicle-derived exosomes are still unknown. This chapter aims to review the current understanding of the function of seminal vesicles on sperm physiology and male reproduction and provide ultracentrifugation-based isolation protocols for the isolation of seminal vesicle exosomes. Moreover, via proteomic analysis and functional categorization, a total of 726 proteins IDs were identified in the purified seminal vesicle exosomes fraction. Preliminary data showed seminal vesicle-derived exosomes inhibited sperm capacitation; however, more studies will be needed to reveal other functional involvements of seminal vesicle-derived exosomes on the sperm physiology and, more importantly, how these exosomes interact with sperm membrane to achieve their biological effects.

This article provides an overview of literature pertaining to epididymosome origin, composition and their functional significance. Broadly, epididymosomes are defined as extracellular vesicles that are secreted by the epididymal epithelium and thereafter facilitate intercellular communication within the male reproductive tract. Epididymosomes fulfil this communication role via their encapsulation and delivery of a diverse macromolecular payload to recipient cells. This complex cargo includes proteins, lipids, and nucleic acids, which are delivered to maturing spermatozoa, thereby influencing their viability and function. Additionally, epididymosomes have been implicated in the post-translational modification of intrinsic sperm proteins, protection of sperm from oxidative stress and immune surveillance, and in the transmission of epigenetic information capable of mediating intergenerational effects. Hence, continued research into the biogenesis, cargo composition, and functional significance of epididymosomes holds promise for advancing male reproductive health and fertility treatments.

In this chapter, we explore the multifaceted roles of extracellular vesicles (EVs) in ovarian biology, focusing on their contributions to folliculogenesis, oocyte competence, corpus luteum function, and immune response regulation. EVs, particularly those derived from follicular fluid (ffEVs), are crucial mediators of cell-to-cell communication within the ovarian follicle, influencing processes such as meiotic progression, stress response, and hormonal regulation. We review preexisting literature, highlighting key findings on the molecular cargo of EVs, such as miRNAs and proteins, and their involvement in regulating the function of the follicle cells. Additionally, the influence of EVs on the immune responses within the ovary was also addressed. Some attention is given to the potential of EVs as non-invasive biomarkers and therapeutic tools, particularly in addressing conditions like premature ovarian insufficiency and polycystic ovary syndrome. By discussing the existing challenges and emerging research, we hope that this chapter will provide a deeper understanding of EVs' therapeutic potential and offer insights or suggestions for advancing assisted reproductive technologies.

The intent of this chapter is to provide a morphological foundation in the normal cellular process of bovine gamete development so that abnormalities occurring are recognizable. The knowledge gained here is essential to begin to understand the significance of many of the common bull sperm abnormalities encountered in the clinics. Spermatogenesis is divided into three phases (i. e., Mitosis, Meiosis and Spermiogenesis) all happening in the seminiferous epithelium. The 'Cycle of the Bovine Seminiferous Epithelium' is explained in relation to these phases. Information is provided as to how to identify the stages of the bovine cycle and the steps of spermiogenesis at the histological and ultrastructural levels in preparation to recognize where and when in the cycle a spermatid abnormality arises. Spermiogenesis, the last phase of spermatogenesis, is the most revealing phase to recognize gamete abnormalities as this is where spermatid head and tail differentiation take place and spermatid compartments materialize. The formation of the nucleus, acrosome, manchette, perinuclear theca, axoneme, outer dense fibers, fibrous sheath, connecting piece and mitochondrial sheath occur during this phase and are evaluated. The origins and assembly of a number of essential proteins compartmentalizing the sperm head and tail as well as defects arising during spermiogenesis are reviewed.

The intention of this chapter is to provide insights on the possible causes and disruptive mechanisms in play of some commonly occurring bull sperm abnormalities. Consideration is given to mutations of genes, inhibition of enzymes, deficiencies of trace elements, toxins, simulated stress, hormonal changes, hypoosmolarity and cold shock that cause similar disruptive phenotypes in development and structure seen in commonly occurring bull sperm abnormalities. The possible causes and disruptive mechanisms of the following bull sperm defects, arising from the above research, are evaluated: Tail stump, Decapitations, Dag, Dag-like, Short tail, Pseudodoplet, Segmental aplasia of the mitochondrial sheath, Coiled tails, Knobbed and Nuclear vacuolation. In addition, the idea arising from murid research, that mutations affecting sperm head shape most always affect motility, while mutations affecting sperm tail formation rarely affect sperm head shape is considered. Examples of mutations in genes or inhibition of enzymes involved with the early stages of acrosome formation are given that lead to a variety of 'globozoospermic-like' sperm head phenotypes all of which are associated with various degrees of aberrant sperm tail morphologies.

Research has determined that the percentage morphologically normal sperm in bulls is highly repeatable and strongly correlated with days to conception and calf output in both dairy and beef herds. Currently, however, standardization of the assessment of morphology between laboratories is lacking, leading to inability of the practitioner to gain meaningful evaluations that relate to bull fertility.Here we outline protocols that permit a standardized approach among laboratories that has been successfully used for 20 years. The scheme includes skill updates and training of laboratory personnel along with annual examination of their work. This results in a reliable analysis and report which is easily interpreted by practitioners and used as part of the standard BBSE.This model has enabled increased accuracy of prognosis for practitioners and is well regarded both in Australia and overseas.

This chapter is intended to provide an accurate visual description of normal and abnormal bovine sperm morphology as seen under the light microscope. The photographs were taken × 1000 magnification and enlarged × 1.6, unless specified otherwise, using either a) differential interference microscopy (DIC), b) phase contrast microscopy, c) eosin-nigrosin-stained sperm smears, or d) Feulgen stained smears as indicated in the legends.When viewed with a critical eye, there is an extremely wide variation in form and structure within the various categories of sperm cell abnormalities. It would be an impossible and fruitless task to attempt to show every minor variation in appearance of each type. Therefore, a series of photographs has been put together showing the main features of each type of abnormality so that any other deviation observed can easily be recognized as to the category in which it belongs.The nomenclature applied to the various abnormalities is that preferred by us, although generally accepted by other workers. Synonymous nomenclature used by other workers is included in the discussion on interpretation of sperm cell abnormalities in Chapter 5 .

In this chapter we discuss spermatozoal abnormalities which are associated with reduced bull fertility in practice as assessed by published case studies or research experiments. Each abnormality follows the standardized form found in Chap. 9 . An initial summary of the abnormality is given including the suggested tolerated threshold for the abnormality in an ejaculate. This is followed by detail of research into the abnormality and its associated affect upon fertility in the bull. Images of the abnormalities are presented and the reader is further directed to photomicrographs of Chap. 4 where appropriate.