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Egg Activation
Oocyte (or ovum/egg) activation is a series of processes that occur in the oocyte during fertilization. Sperm entry causes calcium release into the oocyte. In mammals, this is caused by the introduction of phospholipase C isoform zeta (PLCζ) from the sperm cytoplasm. Activation of the ovum includes the following events: * Cortical reaction to block against other sperm cells * Activation of egg metabolism * Reactivation of meiosis * DNA synthesis Sperm trigger of egg activation The sperm may trigger egg activation via the interaction between a sperm protein and an egg surface receptor. Izumo is the sperm cell signal, that will trigger the egg receptor Juno. This receptor is activated by the sperm binding and a possible signaling pathway could be the activation of a tyrosine kinase which then activates phospholipase C (PLC). The inositol signaling system has been implicated as the pathway involved with egg activation. IP3 and DAG are produced from the cleavage of PIP2 by phospholi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Oocyte
An oocyte (, oöcyte, or ovocyte) is a female gametocyte or germ cell involved in reproduction. In other words, it is an immature ovum, or egg cell. An oocyte is produced in a female fetus in the ovary during female gametogenesis. The female germ cells produce a primordial germ cell (PGC), which then undergoes mitosis, forming oogonia. During oogenesis, the oogonia become primary oocytes. An oocyte is a form of genetic material that can be collected for cryoconservation. Formation The formation of an oocyte is called oocytogenesis, which is a part of oogenesis. Oogenesis results in the formation of both primary oocytes during fetal period, and of secondary oocytes after it as part of ovulation. Characteristics Cytoplasm Oocytes are rich in cytoplasm, which contains yolk granules to nourish the cell early in development. Nucleus During the primary oocyte stage of oogenesis, the nucleus is called a germinal vesicle. The only normal human type of secondary oocyte has the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hyalin
Hyalin is a protein released from the cortical granules of a fertilized Fertilisation or fertilization (see spelling differences), also known as generative fertilisation, syngamy and impregnation, is the fusion of gametes to give rise to a zygote and initiate its development into a new individual organism or off ... animal Egg (biology), egg. The released hyalin modifies the extracellular matrix of the fertilized egg to block other sperm from binding to the egg, and is known as the slow-block to polyspermy. All animals have this slow-block mechanism. Hyalin is a large, acidic protein which aids in embryonic development. The protein has strong adhesive properties which can help with cell differentiation and as a polyspermy prevention component. It forms the hyaline layer which covers the surface of the egg after insemination. Structure Its physical structure has a major and minor component. One is filamentous, having flexible molecules containing a globular domain he ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Globozoospermic
Teratospermia or teratozoospermia is a condition characterized by the presence of sperm with abnormal morphology that affects fertility in males. Causes The causes of teratozoospermia are unknown in most cases. However, Hodgkin's disease, coeliac disease, and Crohn's disease may contribute in some instances. Lifestyle and habits (smoking, toxin exposure, etc.) can also cause poor morphology. Varicocele is another condition that is often associated with decreased normal forms (morphology). In cases of globozoospermia (sperm with round heads), the Golgi apparatus is not transformed into the acrosome that is needed for fertilization. Symptoms and treatment The presence of abnormally-shaped sperm can negatively affect fertility by preventing transport through the cervix and/or preventing sperm from adhering to the ovum. Achieving a pregnancy may be difficult. In testing for teratozoospermia, sperm are collected, stained and analyzed under a microscope to detect abnormalities. These a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Oligoasthenoteratozoospermia
Male infertility refers to a sexually mature male's inability to impregnate a fertile female. Male infertility can wholly or partially account for 40% of infertility among couples who are trying to have children. "A problem with the male is the sole cause, or a contributing cause, of infertility in about 40 percent of infertile couples. It affects approximately 7% of all men. Male infertility is commonly due to deficiencies in the semen, and semen quality is used as a surrogate measure of male fecundity. More recently, advance sperm analyses that examine intracellular sperm components are being developed. Age considerations Sperm motility increases from puberty through one's mid-thirties. Research shows that from the age of 36 onwards, sperm motility decreases from 40% Grade A & B to 31% in one's 50s. The effects of aging on semen quality is summarized below based on a study of 1,219 subjects: 90% of seminiferous tubules in men in their 20s and 30s contain spermatids, whereas men ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Teratozoospermia
Teratospermia or teratozoospermia is a condition characterized by the presence of sperm with abnormal morphology that affects fertility in males. Causes The causes of teratozoospermia are unknown in most cases. However, Hodgkin's disease, coeliac disease, and Crohn's disease may contribute in some instances. Lifestyle and habits (smoking, toxin exposure, etc.) can also cause poor morphology. Varicocele is another condition that is often associated with decreased normal forms (morphology). In cases of globozoospermia (sperm with round heads), the Golgi apparatus is not transformed into the acrosome that is needed for fertilization. Symptoms and treatment The presence of abnormally-shaped sperm can negatively affect fertility by preventing transport through the cervix and/or preventing sperm from adhering to the ovum. Achieving a pregnancy may be difficult. In testing for teratozoospermia, sperm are collected, stained and analyzed under a microscope to detect abnormalities. These ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
In Vitro Maturation
In vitro maturation (IVM) is the technique of letting the contents of ovarian follicles and the oocytes inside mature ''in vitro''. It can be offered to women with infertility problems, combined with in vitro fertilization (IVF), offering women pregnancy without ovarian stimulation. History In 1935, Pincus & Enzmann did the first experiment on immature rabbit oocyte, showing ''in vitro'' spontaneous maturation and fertilization. They showed maturation occurs in isolation from normal follicular environment. In 1965 Edwards then continued IVM studies in mouse, sheep, cow, pig, rhesus monkey and human. By 1991, the first human pregnancy was recorded using IVM followed by IVF, and in 1994 the first birth using IVM oocytes from polycystic ovarian syndrome (PCOS) patients was recorded, confirming that their oocytes are capable of maturation. Background Oogenesis takes place during fetal life, in which primordial germ cells undergo mitosis until a few weeks prior to birth, forming ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Intracytoplasmic Sperm Injection
Intracytoplasmic sperm injection (ICSI ) is an in vitro fertilization (IVF) procedure in which a single sperm cell is injected directly into the cytoplasm of an egg. This technique is used in order to prepare the gametes for the obtention of embryos that may be transferred to a maternal uterus. With this method, the acrosome reaction is skipped. There are several differences between classic IVF and ICSI. However, the steps to be followed before and after insemination are the same. In terms of insemination, ICSI needs only one sperm cell per oocyte, while IVF needs 50,000–100,000. This is because the acrosome reaction has to take place and thousands of sperm cells have to be involved in IVF. Once fertilized, the egg is transformed into a pre-embryo and it has to be transferred to the uterus to continue its development. The first human pregnancy generated by ICSI was carried out in 1991 by Gianpiero Palermo and his team. Round spermatid injection (ROSI) Round spermatid injecti ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ionophore
In chemistry, an ionophore () is a chemical species that reversibly binds ions. Many ionophores are lipid-soluble entities that transport ions across the cell membrane. Ionophores catalyze ion transport across hydrophobic membranes, such as liquid polymeric membranes (carrier-based ion selective electrodes) or lipid bilayers found in the living cells or synthetic vesicles ( liposomes). Structurally, an ionophore contains a hydrophilic center and a hydrophobic portion that interacts with the membrane. Some ionophores are synthesized by microorganisms to import ions into their cells. Synthetic ion carriers have also been prepared. Ionophores selective for cations and anions have found many applications in analysis. These compounds have also shown to have various biological effects and a synergistic effect when combined with the ion they bind. Classification Biological activities of metal ion-binding compounds can be changed in response to the increment of the metal concentr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Reactive Oxygen Species
In chemistry and biology, reactive oxygen species (ROS) are highly Reactivity (chemistry), reactive chemicals formed from diatomic oxygen (), water, and hydrogen peroxide. Some prominent ROS are hydroperoxide (H2O2), superoxide (O2−), hydroxyl radical (OH.), and singlet oxygen(1O2). ROS are pervasive because they are readily produced from O2, which is abundant. ROS are important in many ways, both beneficial and otherwise. ROS function as signals, that turn on and off biological functions. They are intermediates in the redox behavior of O2, which is central to fuel cells. ROS are central to the photodegradation of organic pollutants in the atmosphere. Most often however, ROS are discussed in a biological context, ranging from their effects on aging and their role in causing dangerous genetic mutations. Inventory of ROS ROS are not uniformly defined. All sources include superoxide, singlet oxygen, and hydroxyl radical. Hydrogen peroxide is not nearly as reactive as these s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Centriole
In cell biology a centriole is a cylindrical organelle composed mainly of a protein called tubulin. Centrioles are found in most eukaryotic cells, but are not present in conifers ( Pinophyta), flowering plants ( angiosperms) and most fungi, and are only present in the male gametes of charophytes, bryophytes, seedless vascular plants, cycads, and ''Ginkgo''. A bound pair of centrioles, surrounded by a highly ordered mass of dense material, called the pericentriolar material (PCM), makes up a structure called a centrosome. Centrioles are typically made up of nine sets of short microtubule triplets, arranged in a cylinder. Deviations from this structure include crabs and ''Drosophila melanogaster'' embryos, with nine doublets, and '' Caenorhabditis elegans'' sperm cells and early embryos, with nine singlets. Additional proteins include centrin, cenexin and tektin. The main function of centrioles is to produce cilia during interphase and the aster and the spindle durin ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pronucleus
A pronucleus (: pronuclei) denotes the nucleus found in either a sperm or egg cell during the process of fertilization. The sperm cell undergoes a transformation into a pronucleus after entering the egg cell but prior to the fusion of the genetic material of both the sperm and egg. In contrast, the egg cell possesses a pronucleus once it becomes haploid, not upon the arrival of the sperm cell. Haploid cells, such as sperm and egg cells in humans, carry half the number of chromosomes present in somatic cells, with 23 chromosomes compared to the 46 found in somatic cells. It is noteworthy that the male and female pronuclei do not physically merge, although their genetic material does. Instead, their membranes dissolve, eliminating any barriers between the male and female chromosomes, facilitating the combination of their chromosomes into a single diploid nucleus in the resulting embryo, which contains a complete set of 46 chromosomes. The presence of two pronuclei serves as the in ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Protamines
Protamines are small, arginine-rich, nuclear proteins that replace histones late in the haploid phase of spermatogenesis and are believed essential for sperm head condensation and DNA stabilization. They may allow for denser packaging of DNA in the spermatozoon than histones, but they must be decompressed before the genetic data can be used for protein synthesis. However, part of the sperm's genome is packaged by histones (10-15% in humans and other primates) thought to bind genes that are essential for early embryonic development. Protamine and protamine-like (PL) proteins are collectively known as the sperm-specific nuclear basic proteins (SNBPs). The PL proteins are intermediate in structure between protamine and Histone H1. The C-terminal domain of PL could be the precursor of vertebrate protamine. Spermatogenesis During the formation of sperm, protamine binds to the phosphate backbone of DNA using the arginine-rich domain as an anchor. DNA is then folded into a toroid, an ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
