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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.
Developmental biology is the study of the process by which animals and plants grow and develop. Developmental biology also encompasses the biology of regeneration, asexual reproduction, metamorphosis, and the growth and differentiation of stem cells in the adult organism.
Human cloning is the creation of a genetically identical copy of a human. The term is generally used to refer to artificial human cloning, which is the reproduction of human cells and tissue. It does not refer to the natural conception and delivery of identical twins. The possibilities of human cloning have raised controversies. These ethical concerns have prompted several nations to pass laws regarding human cloning.
Fertilisation or fertilization, also known as generative fertilisation, syngamy and impregnation, is the fusion of gametes to give rise to a new individual organism or offspring and initiate its development. While processes such as insemination or pollination which happen before the fusion of gametes are also sometimes informally referred to as fertilisation, these are technically separate processes. The cycle of fertilisation and development of new individuals is called sexual reproduction. During double fertilisation in angiosperms the haploid male gamete combines with two haploid polar nuclei to form a triploid primary endosperm nucleus by the process of vegetative fertilisation.
In cell biology, the centrosome is an organelle that serves as the main microtubule organizing center (MTOC) of the animal cell, as well as a regulator of cell-cycle progression. The centrosome provides structure for the cell. The centrosome is thought to have evolved only in the metazoan lineage of eukaryotic cells. Fungi and plants lack centrosomes and therefore use other structures to organize their microtubules. Although the centrosome has a key role in efficient mitosis in animal cells, it is not essential in certain fly and flatworm species.
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.
The zona pellucida is a specialized extracellular matrix that surrounds the plasma membrane of mammalian oocytes. It is a vital constitutive part of the oocyte. The zona pellucida first appears in unilaminar primary oocytes. It is secreted by both the oocyte and the ovarian follicles. The zona pellucida is surrounded by the corona radiata. The corona is composed of cells that care for the egg when it is emitted from the ovary.
James Alexander Thomson is an American developmental biologist best known for deriving the first human embryonic stem cell line in 1998 and for deriving human induced pluripotent stem cells (iPS) in 2007.
Regenerative medicine deals with the "process of replacing, engineering or regenerating human or animal cells, tissues or organs to restore or establish normal function". This field holds the promise of engineering damaged tissues and organs by stimulating the body's own repair mechanisms to functionally heal previously irreparable tissues or organs.
Sperm is the male reproductive cell, or gamete, in anisogamous forms of sexual reproduction. Animals produce motile sperm with a tail known as a flagellum, which are known as spermatozoa, while some red algae and fungi produce non-motile sperm cells, known as spermatia. Flowering plants contain non-motile sperm inside pollen, while some more basal plants like ferns and some gymnosperms have motile sperm.
An oogonium is a small diploid cell which, upon maturation, forms a primordial follicle in a female fetus or the female gametangium of certain thallophytes.
Human fertilization is the union of a human egg and sperm, occurring primarily in the ampulla of the fallopian tube. The result of this union leads to the production of a fertilized egg called a zygote, initiating embryonic development. Scientists discovered the dynamics of human fertilization in the nineteenth century.
Ralph Lawrence Brinster is an American geneticist, National Medal of Science laureate, and Richard King Mellon Professor of Reproductive Physiology at the School of Veterinary Medicine, University of Pennsylvania.
Stem cell laws are the law rules, and policy governance concerning the sources, research, and uses in treatment of stem cells in humans. These laws have been the source of much controversy and vary significantly by country. In the European Union, stem cell research using the human embryo is permitted in Sweden, Spain, Finland, Belgium, Greece, Britain, Denmark and the Netherlands; however, it is illegal in Germany, Austria, Ireland, Italy, and Portugal. The issue has similarly divided the United States, with several states enforcing a complete ban and others giving support. Elsewhere, Japan, India, Iran, Israel, South Korea, China, and Australia are supportive. However, New Zealand, most of Africa, and most of South America are restrictive.
Cell potency is a cell's ability to differentiate into other cell types. The more cell types a cell can differentiate into, the greater its potency. Potency is also described as the gene activation potential within a cell, which like a continuum, begins with totipotency to designate a cell with the most differentiation potential, pluripotency, multipotency, oligopotency, and finally unipotency.
Laura Charlotte Hewitson is a British-born primate researcher noted for her work in the fields of reproductive biology and behavior. She is an affiliate scientist at the Washington National Primate Research Center (WaNPRC) and adjunct associate professor of psychiatry at the University of Texas Southwestern Medical Center. Additionally, she is Research Director of The Johnson Center for Child Health and Development in Austin, Texas. Hewitson was a staff scientist at Oregon Health Sciences University from 1997 to 2001. From 2002 to 2010 she was an associate professor of obstetrics, gynecology and reproductive sciences at the University of Pittsburgh School of Medicine and member of Magee-Women's Research Institute and Foundation (MWRI&F) in Pittsburgh, Pennsylvania.
Juan Carlos Izpisua Belmonte is a Spanish biochemist and developmental biologist. He is a professor in the Gene Expression Laboratories at the Salk Institute for Biological Studies in La Jolla, California since 1993.
A spermatogonial stem cell (SSC), also known as a type A spermatogonium, is a spermatogonium that does not differentiate into a spermatocyte, a precursor of sperm cells. Instead, they continue dividing into other spermatogonia or remain dormant to maintain a reserve of spermatogonia. Type B spermatogonia, on the other hand, differentiate into spermatocytes, which in turn undergo meiosis to eventually form mature sperm cells.
Mohamadreza Baghaban Eslaminejad is the director of the Adult Stem Cell Lab and histology/embryology Professor at the Royan Institute where he held a multi-departmental professorship in bioengineering, tissue engineering, regenerative medicine, and stem cell therapy. Eslaminejad studies have been cited over 4000 times. He is best known for Hard Tissue Engineering and utilizing Mesenchymal stem cells for treatment of orthopedic diseases.
The Hwang affair, or Hwang scandal, or Hwanggate, is a case of scientific misconduct and ethical issues surrounding a South Korean biologist, Hwang Woo-suk, who claimed to have created the first human embryonic stem cells by cloning in 2004. Hwang and his research team at the Seoul National University reported in the journal Science that they successfully developed a somatic cell nuclear transfer method with which they made the stem cells. In 2005, they published again in Science the successful cloning of 11 person-specific stem cells using 185 human eggs. The research was hailed as "a ground-breaking paper" in science. Hwang was elevated as "the pride of Korea", "national hero" [of Korea], and a "supreme scientist", to international praise and fame. Recognitions and honours immediately followed, including South Korea's Presidential Award in Science and Technology, and Time magazine listing him among the "People Who Mattered 2004" and the most influential people "The 2004 Time 100".
References
- ↑ "Magee-Womens Research Institute". institute.mwrif.org. Archived from the original on 10 April 2009. Retrieved 14 January 2022.
- ↑ "Home". pdc.magee.edu.
- 1 2 3 4 5 6 7 8 9 10 11 Gerald P. Schatten, PhD, Pittsburgh Development Center.
- ↑ Schatten, G. in PubMed.
- 1 2 3 4 Guterman, Lila. "Silent Scientist Under Fire: the American Collaborator of a Disgraced South Korean Is Keeping Mum", The Chronicle of Higher Education .
- ↑ Levine, Arthur S., ed. (2006-02-08). Summary investigative report on allegations of possible scientific misconduct on the part of Gerald P. Schatten, Ph.D. (PDF). Pittsburgh, PA: University of Pittsburgh. p. 9. hdl:1813/11589. Archived from the original (PDF) on 2006-05-06.
- ↑ Executive Committee, UNESCO International Cell Research Organization.
- ↑ "September 25, 2002 Hearings. 107th Congress Hearings" Archived June 2, 2009, at the Wayback Machine , Office of Legislative Policy.
- ↑ "Congressional Hearings Held on Stem Cell Research" Archived 2009-08-10 at the Wayback Machine , American Association for the Advancement of Science.
- ↑ "Assisted Reproductive Technologies in the Genomics Era" Archived 2009-05-20 at the Wayback Machine The President's Council on Bioethics. December 13, 2002.
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