In humans, both of these organs are outside the abdominal cavity. This is why the testes are carried in an external pouch viz. The female reproductive system likewise contains two main divisions: the vagina and the Ovum.
The ovum meets with sperm cell , a sperm may penetrate and merge with the egg, fertilizing it with the help of certain hydrolytic enzymes present in the acrosome. The fertilization usually occurs in the oviducts , but can happen in the uterus itself. The zygote then becomes implanted in the lining of the uterus, where it begins the processes of embryogenesis and morphogenesis. When the fetus is developed enough to survive outside of the uterus , the cervix dilates and contractions of the uterus propel it through the birth canal, which is the vagina.
The ova, which are the female sex cells, are much larger than the spermatozoon and are normally formed within the ovaries of the female fetus before its birth.
They are mostly fixed in location within the ovary until their transit to the uterus, and contain nutrients for the later zygote and embryo. Over a, usually, regular interval known as the menstrual cycle , in response to hormonal signals, a process of oogenesis matures one ovum which is released and sent down the Fallopian tube.
Human Reproductive and Prenatal Genetics - 1st Edition
If not fertilized, this egg is flushed out of the system through menstruation. Human reproduction normally begins with copulation, followed by nine months of pregnancy before childbirth, though it may be achieved through artificial insemination. Many years of parental care are required before a human child becomes independent, typically between twelve and eighteen or more.
Pregnancy can be avoided with the use of contraceptives such as condoms and Intrauterine devices. Human reproduction naturally takes place as internal fertilization by sexual intercourse. During this process, the male inserts his penis, which needs to be erect , into the female's vagina , and then either partner initiates rhythmic pelvic thrusts until the male ejaculates semen, which contains sperm, into the vaginal canal.
This process is also known as "coitus", "mating", "having sex", or, euphemistically , "making love".
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The sperm and the ovum are known as gametes each containing half the genetic information of the parent, created through meiosis. The sperm being one of approximately million sperm in a typical male ejaculation travels through the vagina and cervix into the uterus or Fallopian tubes. Only 1 in 14 million of the ejaculated sperm will reach the Fallopian tube. The egg simultaneously moves through the Fallopian tube away from the ovary.
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One of the sperm encounters, penetrates and fertilizes the ovum, creating a zygote. Upon fertilization and implantation , gestation of the fetus then occurs within the female's uterus. Pregnancy rates for sexual intercourse are highest during the menstrual cycle time from some 5 days before until 1 to 2 days after ovulation. As an alternative to natural sexual intercourse, there are many methods of assisted reproductive technology , such as artificial insemination where sperm is introduced into the female reproductive system without sexual intercourse.
Another method of assisted reproductive technology is in vitro fertilization , where one or more egg cells are retrieved from a woman's ovaries and co-incubated with sperm outside the body. The resulting embryo can then be reinserted into the woman's womb. Pregnancy is the period of time during which the fetus develops, dividing via mitosis inside the female. During this time, the fetus receives all of its nutrition and oxygenated blood from the female, filtered through the placenta , which is attached to the fetus' abdomen via an umbilical cord.
This drain of nutrients can be quite taxing on the female, who is required to ingest slightly higher levels of calories. In addition, certain vitamins and other nutrients are required in greater quantities than normal, often creating abnormal eating habits.
Gestation period is about days in humans. While in the uterus, the baby first endures a very brief zygote stage, then the embryonic stage, which is marked by the development of major organs and lasts for approximately eight weeks, then the fetal stage, which revolves around the development of bone cells while the fetus continues to grow in size.
Once the fetus is sufficiently developed, chemical signals begin the process of birth, which begins with the fetus being pushed out of the birthing canal. The newborn, which is called an infant in humans, should typically begin respiration on its own shortly after birth. Not long after, the placenta eventually falls off on its own. The person assisting the birth may also sever the umbilical cord. A human baby is nearly helpless and the growing child requires high levels of parental care for many years.
One important type of early parental care is lactation , feeding the baby milk from the mother's mammary glands in her breasts.
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From Wikipedia, the free encyclopedia. Further information: Human reproductive system. Further information: Human male reproductive system. Further information: Female reproductive system. Main article: Sexual intercourse. Main article: Pregnancy. Main article: Childbirth. Main article: Parenting. Heat mutagenesis in bacteriophage T4: The transition pathway. USA 73 4 : Retrieved May 8, The Regents of The University of California. Complete Fertility Centre Southampton. Human Genetics and Assisted Reproduction in Endometriosis Uterine Transplantation. Part IV. Epidemiology and Genetics of Human Aneuploidy Noninvasive Prenatal Testing for Genetic Diseases Prenatal diagnosis and treatment of genetic steroid disorders Leung received his PhD from Western University.
After post-doctoral training at the University of California at Los Angeles and the Laval University, he joined the University of British Columbia in as a faculty member. His publication record to date includes papers, abstracts, 22 book chapters and 7 monographs. Since his appointment at UBC, Dr.
Leung has served as the research supervisor for more than graduate students, postdoctoral fellows and visiting scientists. She has been engaged in reproductive health-related clinical and basic research throughout her career, including as a visiting scholar at the University of Hong Kong and as a post-doctoral researcher at Stanford University. Her research has focused on gametes fertilization, infertility and embryo implantation mechanisms, and polycystic ovary syndrome pathogenesis among other topics. Jie Qiao has published more than paper publications in peer reviewed journals on topics related to reproductive health.
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View on ScienceDirect. Editors: Peter Leung Jie Qiao. Paperback ISBN: Imprint: Academic Press. Published Date: 29th August Page Count: For regional delivery times, please check When will I receive my book? Sorry, this product is currently out of stock. Flexible - Read on multiple operating systems and devices.
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Institutional Subscription. Free Shipping Free global shipping No minimum order. Features chapter contributions from leading international scientists and clinicians Provides in-depth coverage of key topics in human reproductive and prenatal genetics, including genetic controls, fertilization and implantation, in vitro culture of the human embryo for the study of post-implantation development, and more Identifies how researchers and clinicians can implement the latest genetic, epigenetic, and —omics based approaches.
Uterine Transplantation Part IV.
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