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Ovarian Reserve
Ovarian reserve is a term that is used to determine the capacity of the ovary to provide egg cells that are capable of fertilization resulting in a healthy and successful pregnancy. With advanced maternal age, the number of egg cell that can be successfully recruited for a possible pregnancy declines, constituting a major factor in the inverse correlation between age and female fertility. While there is no known method for assessing the ovarian reserve of individual women, indirect determination of ovarian reserve is important in the treatment of infertility. Establishment The ovary is generally thought of as an egg bank from which the woman draws during her reproductive life. The human ovary contains a population of primordial follicles. At 18–22 weeks post-conception, the female ovary contains its peak number of follicles (about 300,000 in the average case, but individual peak populations range from 35,000 to 2.5 million). The size of the initial ovarian reserve is strongly i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
BRCA1
Breast cancer type 1 susceptibility protein is a protein that in humans is encoded by the ''BRCA1'' () gene. Orthologs are common in other vertebrate species, whereas invertebrate genomes may encode a more distantly related gene. ''BRCA1'' is a human tumor suppressor gene (also known as a caretaker gene) and is responsible for repairing DNA. ''BRCA1'' and ''BRCA2'' are unrelated proteins, but both are normally expressed in the cells of breast and other tissues, where they help repair damaged DNA, or destroy cells if DNA cannot be repaired. They are involved in the repair of chromosomal damage with an important role in the error-free repair of DNA double-strand breaks. If ''BRCA1'' or ''BRCA2'' itself is damaged by a BRCA mutation, damaged DNA is not repaired properly, and this increases the risk for breast cancer. ''BRCA1'' and ''BRCA2'' have been described as "breast cancer susceptibility genes" and "breast cancer susceptibility proteins". The predominant allele has a no ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
International Unit
In pharmacology, the international unit (IU) is a unit of measurement for the effect or biological activity of a substance, for the purpose of easier comparison across similar ''forms'' of substances. International units are used to quantify vitamins and biologics (hormones, some medications, vaccines, blood products and similar biologically active substances). International units as used in pharmacology are not part of the International System of Units (SI). For biologic preparations Biologics are medications and other products made from biological sources. Depending on the form (powder vs solution), production method, or just batch-to-batch differences, there is often some variation in their relative potencies, so that a simple measure of mass would not suffice. The ''international unit'' allows one to compare the relative potency of all these forms, so that different forms or preparations with the same biological effect will contain the same number of IUs. To do so, th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Estradiol
Estradiol (E2), also called oestrogen, oestradiol, is an estrogen steroid hormone and the major female sex hormone. It is involved in the regulation of female reproductive cycles such as estrous and menstrual cycles. Estradiol is responsible for the development of female secondary sexual characteristics such as the breasts, widening of the hips and a female pattern of fat distribution. It is also important in the development and maintenance of female reproductive tissues such as the mammary glands, uterus and vagina during puberty, adulthood and pregnancy. It also has important effects in many other tissues including bone, fat, skin, liver, and the brain. Though estradiol levels in males are much lower than in females, estradiol has important roles in males as well. Apart from humans and other mammals, estradiol is also found in most vertebrates and crustaceans, insects, fish, and other animal species. Estradiol is produced within the follicles of the ovaries and in oth ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Negative Feedback
Negative feedback (or balancing feedback) occurs when some function (Mathematics), function of the output of a system, process, or mechanism is feedback, fed back in a manner that tends to reduce the fluctuations in the output, whether caused by changes in the input or by other disturbances. Whereas positive feedback tends to instability via exponential growth, oscillation or chaos theory, chaotic behavior, negative feedback generally promotes stability. Negative feedback tends to promote a settling to List of types of equilibrium, equilibrium, and reduces the effects of perturbations. Negative feedback loops in which just the right amount of correction is applied with optimum timing, can be very stable, accurate, and responsive. Negative feedback is widely used in Mechanical engineering, mechanical and electronic engineering, and it is observed in many other fields including biology, chemistry and economics. General negative feedback systems are studied in Control engin ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Estrogen
Estrogen (also spelled oestrogen in British English; see spelling differences) is a category of sex hormone responsible for the development and regulation of the female reproductive system and secondary sex characteristics. There are three major endogenous estrogens that have estrogenic hormonal activity: estrone (E1), estradiol (E2), and estriol (E3). Estradiol, an estrane, is the most potent and prevalent. Another estrogen called estetrol (E4) is produced only during pregnancy. Estrogens are synthesized in all vertebrates and some insects. Quantitatively, estrogens circulate at lower levels than androgens in both men and women. While estrogen levels are significantly lower in males than in females, estrogens nevertheless have important physiological roles in males. Like all steroid hormones, estrogens readily diffuse across the cell membrane. Once inside the cell, they bind to and activate estrogen receptors (ERs) which in turn modulate the expression of many ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Follicle-stimulating Hormone
Follicle-stimulating hormone (FSH) is a gonadotropin, a glycoprotein polypeptide hormone. FSH is synthesized and secreted by the gonadotropic cells of the anterior pituitary gland and regulates the development, growth, puberty, pubertal maturation, and reproductive processes of the body. FSH and luteinizing hormone (LH) work together in the reproductive system. Structure FSH is a 35.5 kDa glycoprotein protein dimer, heterodimer, consisting of two polypeptide units, alpha and beta. Its structure is similar to those of luteinizing hormone (LH), thyroid-stimulating hormone (TSH), and human chorionic gonadotropin (hCG). The chorionic gonadotropin alpha, alpha subunits of the glycoproteins LH, FSH, TSH, and hCG are identical and consist of 96 amino acids, while the beta subunits vary. Both subunits are required for biological activity. FSH has a beta subunit of 111 amino acids (FSH β), which confers its specific biologic action, and is responsible for interaction with the follicl ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Menopause
Menopause, also known as the climacteric, is the time when Menstruation, menstrual periods permanently stop, marking the end of the Human reproduction, reproductive stage for the female human. It typically occurs between the ages of 45 and 55, although the exact timing can vary. Menopause is usually a natural change related to a decrease in circulating blood estrogen levels. It can occur earlier in those who smoke tobacco. Other causes include surgery that removes both ovaries, some types of chemotherapy, or anything that leads to a decrease in hormone levels. At the physiological level, menopause happens because of a decrease in the ovaries' production of the hormones estrogen and progesterone. While typically not needed, measuring hormone levels in the blood or urine can confirm a diagnosis. Menopause is the opposite of menarche, the time when periods start. In the years before menopause, a woman's periods typically become irregular, which means that periods may be longer ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mutation
In biology, a mutation is an alteration in the nucleic acid sequence of the genome of an organism, virus, or extrachromosomal DNA. Viral genomes contain either DNA or RNA. Mutations result from errors during DNA or viral replication, mitosis, or meiosis or other types of damage to DNA (such as pyrimidine dimers caused by exposure to ultraviolet radiation), which then may undergo error-prone repair (especially microhomology-mediated end joining), cause an error during other forms of repair, or cause an error during replication ( translesion synthesis). Mutations may also result from substitution, insertion or deletion of segments of DNA due to mobile genetic elements. Mutations may or may not produce detectable changes in the observable characteristics ( phenotype) of an organism. Mutations play a part in both normal and abnormal biological processes including: evolution, cancer, and the development of the immune system, including junctional diversity. Mutati ... [...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] |
ATM Serine/threonine Kinase
ATM serine/threonine kinase or Ataxia-telangiectasia mutated, symbol ATM, is a serine/threonine protein kinase that is recruited and activated by DNA double-strand breaks (canonical pathway), oxidative stress, topoisomerase cleavage complexes, splicing intermediates, R-loops and in some cases by single-strand DNA breaks. It phosphorylates several key proteins that initiate activation of the DNA damage checkpoint, leading to cell cycle arrest, DNA repair or apoptosis. Several of these targets, including p53, CHK2, BRCA1, NBS1 and H2AX are tumor suppressors. In 1995, the gene was discovered by Yosef Shiloh who named its product ATM since he found that its mutations are responsible for the disorder ataxia–telangiectasia. In 1998, the Shiloh and Kastan laboratories independently showed that ATM is a protein kinase whose activity is enhanced by DNA damage. Throughout the cell cycle DNA is monitored for damage. Damages result from errors during replication, by-products of met ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Homologous Recombination
Homologous recombination is a type of genetic recombination in which genetic information is exchanged between two similar or identical molecules of double-stranded or single-stranded nucleic acids (usually DNA as in Cell (biology), cellular organisms but may be also RNA in viruses). Homologous recombination is widely used by cells to accurately DNA repair, repair harmful DNA breaks that occur on both strands of DNA, known as double-strand breaks (DSB), in a process called homologous recombinational repair (HRR). Homologous recombination also produces new combinations of DNA sequences during meiosis, the process by which eukaryotes make gamete cells, like sperm and ovum, egg cells in animals. These new combinations of DNA represent genetic variation in offspring, which in turn enables populations to Adaptation, adapt during the course of evolution. Homologous recombination is also used in horizontal gene transfer to exchange genetic material between different strains and species ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
