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Mesoderm

Mesoderm is one of the three germ layers, groups of cells that interact early during the embryonic life of animals and from which organs and tissues form. As organs form, a process called organogenesis, mesoderm interacts with endoderm and ectoderm to give rise to the digestive tract, the heart and skeletal muscles, red blood cells, and the tubules of the kidneys, as well as a type of connective tissue called mesenchyme. All animals that have only one plane of symmetry through the body, called bilateral symmetry, form three germ layers.

Format: Articles

Subject: Processes

The Germ-Plasm: a Theory of Heredity (1893), by August Weismann

Friedrich Leopold August Weismann published Das
Keimplasma: eine Theorie der Vererbung (The Germ-Plasm: a
Theory of Heredity, hereafter The Germ-Plasm) while
working at the University of Freiburg in Freiburg, Germany in 1892.
William N. Parker, a professor in the University College of South
Wales and Monmouthshire in Cardiff, UK, translated The
Germ-Plasm into English in 1893. In The Germ-Plasm,
Weismann proposed a theory of heredity based on the concept of the

Format: Articles

Subject: Publications, Theories

David Michael Rorvik (1944–)

David Michael Rorvik is a science journalist who publicized advancements in the field of reproductive medicine during the late twentieth century. Rorvik wrote magazine articles and books in which he discussed emerging methods and technologies that contributed to the progression of reproductive health, including sex determination, in vitro fertilization, and human cloning. During that time, those topics were controversial and researchers often questioned Rorvik’s work for accuracy.

Format: Articles

Subject: People

The Shettles Method of Sex Selection

In the 1960s in the United States Landrum B. Shettles developed the Shettles method, which is a procedure for couples to use prior to and during an intercourse to increase their chances of conceiving a fetus of their desired sex. Shettles, a physician, who specialized in obstetrics and gynecology, found a difference in the size and shape of male sperm cells that he correlated with the different sex chromosomes they carry.

Format: Articles

Subject: Technologies, Reproduction

Alfred Day Hershey (1908–1997)

During the twentieth century in the United States, Alfred Day Hershey studied phages, or viruses that infect bacteria, and experimentally verified that genes were made of deoxyribonucleic acid, or DNA. Genes are molecular, heritable instructions for how an organism develops. When Hershey started to study phages, scientists did not know if phages contained genes, or whether genes were made of DNA or protein. In 1952, Hershey and his research assistant, Martha Chase, conducted phage experiments that convinced scientists that genes were made of DNA.

Format: Articles

Subject: People

The Hershey-Chase Experiments (1952), by Alfred Hershey and Martha Chase

In 1951 and 1952, Alfred Hershey and Martha Chase conducted a series of experiments at the Carnegie Institute of Washington in Cold Spring Harbor, New York, that verified genes were made of deoxyribonucleic acid, or DNA. Hershey and Chase performed their experiments, later named the Hershey-Chase experiments, on viruses that infect bacteria, also called bacteriophages. The experiments followed decades of scientists’ skepticism about whether genetic material was composed of protein or DNA.

Format: Articles

Subject: Experiments

Stephen Jay Gould (1941-2002)

Stephen Jay Gould studied snail fossils and worked at Harvard University in Cambridge, Massachusetts during the latter half of the twentieth century. He contributed to philosophical, historical, and scientific ideas in paleontology, evolutionary theory, and developmental biology. Gould, with Niles Eldredge, proposed the theory of punctuated equilibrium, a view of evolution by which species undergo long periods of stasis followed by rapid changes over relatively short periods instead of continually accumulating slow changes over millions of years.

Format: Articles

Subject: People

Your Baby’s Sex: Now You Can Choose (1970), by David M. Rorvik and Landrum B. Shettles

In the book Your Baby’s Sex: Now You Can Choose, David Michael Rorvik and Landrum Brewer Shettles describe methods that couples can use prior to and during conception that will increase the chances of producing a child of their desired sex. Rorvik, a science writer, and Shettles, an obstetrics and gynecology researcher and physician, co-wrote the book. Shettles developed the methods detailed in the book during the 1960s. Although the authors claim a high success rate, some researchers have contested the validity of the methods proposed in Your Baby’s Sex: Now You Can Choose.

Format: Articles

Subject: Publications

Medical Vibrators for Treatment of Female Hysteria

During the late 1800s through the early 1900s, physicians administered pelvic massages involving clitoral stimulation by early electronic vibrators as treatments for what was called female hysteria. Until the early 1900s, physicians used female hysteria as a diagnosis for women who reported a wide range of complaints and symptoms unexplainable by any other diagnosis at the time. According to historian Rachel Maines, physicians provided pelvic massages for thousands of years to female patients without it being considered erotic or sexually stimulating.

Format: Articles

Subject: Reproduction, Technologies, Ethics

“Perspectives on the Properties of Stem Cells” (2005), by Ernest McCulloch and James Till

In 2005, Ernest McCulloch and James Till published the article “Perspectives on the Properties of Stem Cells,” which discusses the various properties and future possibilities for the use of stem cells. Stem cells are unspecialized cells that can develop into several different cell types. In the article published in the journal Nature on 1 October 2005, the authors say they wrote the article to dispel misconceptions about what stem cells are, what they do, address some controversies surrounding stem cells, and discuss potential uses of stem cells.

Format: Articles

Subject: Publications

“Epidemiology of Surgically Managed Pelvic Organ Prolapse and Urinary Incontinence” (1997), by Ambre L. Olsen, Virginia J. Smith, John O. Bergstrom, Joyce C. Colling, and Amanda L. Clark

In 1997, physicians and researchers Ambre Olsen, Virginia Smith, John Bergstrom, Joyce Colling, and Amanda Clark published, “Epidemiology of Surgically Managed Pelvic Organ Prolapse and Urinary Incontinence,” in the journal Obstetrics and Gynecology. In their article, the authors retrospectively analyzed data from patients who underwent surgery for pelvic organ prolapse or urinary incontinence two years prior in 1995. Often due to a weakening of or damage to their pelvic muscles, women with pelvic organ prolapse can experience a descent of pelvic organs into the lower pelvis and vagina.

Format: Articles

Subject: Publications, Disorders

“Survival of Mouse Embryos Frozen to -196 ° and -269 °C” (1972), by David Whittingham, Stanley Leibo, and Peter Mazur

In 1972, David Whittingham, Stanley Leibo, and Peter Mazur published the paper, “Survival of Mouse Embryos Frozen to -196 ° and -269 °C,” hereafter, “Survival of Mouse Embryos,” in the journal Science. The study marked one of the first times that researchers had successfully cryopreserved, or preserved and stored by freezing, a mammalian embryo and later transferred that embryo to a live mouse who gave birth to viable offspring. Previously, scientists had only been successful cryopreserving single cells, like red blood cells.

Format: Articles

Subject: Experiments, Publications

Victor Jollos (1887-1941)

Victor Jollos studied fruit flies and microorganisms in Europe and the US, and he introduced the concept of Dauermodifikationen in the early 1900s. The concept of Dauermodifikationen refers to environmentally-induced traits that are heritable for only a limited number of generations. Some scientists interpreted the results of Jollos's work on Paramecium and Drosophila as

Format: Articles

Subject: People

Human Papillomavirus (HPV) Strains 16 and 18

The Human Papillomavirus (HPV) strains 16 and 18 are the two most common HPV strains that lead to cases of genital cancer. HPV is the most commonly sexually transmitted disease, resulting in more than fourteen million cases per year in the United States alone. When left untreated, HPV leads to high risks of cervical, vaginal, vulvar, anal, and penile cancers. In 1983 and 1984 in Germany, physician Harald zur Hausen found that two HPV strains, HPV-16 and HPV-18, caused cervical cancer in women. In the early twenty first century, pharmaceutical companies Merck & Co.

Format: Articles

Subject: Theories

“Mesenchymal and Induced Pluripotent Stem Cells: General Insights and Clinical Perspectives” (2015), by Helena D. Zomer, Antanásio S. Vidane, Natalia G. Gonçalves, and Carlos E. Ambrósio

In 2015, biologist Helena D. Zomer and colleagues published the review article “Mesenchymal and Induced Pluripotent Stem Cells: General Insights and Clinical Perspectives” or “Mesenchymal and Induced Pluripotent Stem Cells” in Stem Cells and Cloning: Advances and Applications. The authors reviewed the biology of three types of pluripotent stem cells, embryonic stem cells, or ESCs, mesenchymal stem cells, or MSCs, and induced pluripotent stem cells, or iPS cells. Pluripotent stem cells are a special cell type that can give rise to other types of cells and are essential for development.

Format: Articles

Subject: Publications

“HPV in the Etiology of Human Cancer” (2006) by Nubia Muñoz, Xavier Castellsagué, Amy Berrington de González, and Lutz Gissmann

In 2006, the article “HPV in the Etiology of Human Cancer,” hereafter “HPV and Etiology,” by Nubia Muñoz, Xavier Castellsagué, Amy Berrington de González, and Lutz Gissmann, appeared as the first chapter in the twenty-fourth volume of the journal Vaccine. Muñoz and colleagues discuss the role of the Human Papillomavirus, or HPV, in uterine cervical cancers. The authors introduce the mechanisms of HPV infection that lead to genital and non-genital cancers, establishing a link between HPV and multiple human cancers.

Format: Articles

Subject: Disorders, Processes, Technologies

No-scalpel Vasectomy

No-scalpel vasectomy, or NSV or keyhole vasectomy, is a surgical method of sterilization that involves puncturing the skin of the scrotum to access the vas deferens, a tube that carries spermatozoa, or sperm, from the testes to the penis. The surgeon performing the procedure blocks the flow of sperm through the vas deferens, sterilizing the patient. NSV is a less invasive procedure, as it does not use a scalpel to make a deep cut on sensitive scrotal tissue.

Format: Articles

Subject: Technologies, People, Organizations, Places, Reproduction

Stump v. Sparkman (1978)

On March 28, 1978, in Stump v. Sparkman, hereafter Stump, the United States Supreme Court held, in a five-to-three decision, that judges have absolute immunity from lawsuits involving any harm their judicial decisions cause. Linda Sparkman, who was unknowingly sterilized when she was fifteen years old in 1971, sued Harold Stump, the county circuit court judge who signed the petition to allow Sparkman’s mother to have her sterilized. Sparkman’s mother stated to Stump that she wanted her daughter sterilized because of Sparkman’s alleged mental deficiencies and sexual promiscuity.

Format: Articles

Subject: Legal, Ethics, Reproduction

NuvaRing

The NuvaRing is a self-administered hormonal contraceptive device in the form of a flexible plastic ring that is inserted into the vagina. It releases the hormones etonogestrel and ethinylestradiol, which are synthetic forms of the female reproductive hormones progesterone and estrogen, respectively. The pharmaceutical company Organon first made NuvaRing in the Netherlands in 1980s. The Netherlands first approved it for use in February of 2001, and the United States did the same in October of that year.

Format: Articles

Subject: Technologies, Reproduction, Legal

Emil von Behring (1854–1917)

Emil von Behring researched treatments for the common childhood disease diphtheria in Germany in the 1890s and early 1900s. Diphtheria is a lethal disease that infected approximately 40,000 people in Germany between 1886 and 1888 with a general mortality rate of twenty-five percent. Behring investigated treatment of diphtheria using serum therapy, which is an alternative to vaccination that uses protective agents from other people’s blood to defend a patient against disease. Behring termed those protective agents antitoxins.

Format: Articles

Subject: People, Theories

Aristotle (384-322 BCE)

Aristotle studied developing organisms, among other things, in ancient Greece, and his writings shaped Western philosophy and natural science for greater than two thousand years. He spent much of his life in Greece and studied with Plato at Plato's Academy in Athens, where he later established his own school called the Lyceum. Aristotle wrote greater than 150 treatises on subjects ranging from aesthetics, politics, ethics, and natural philosophy, which include physics and biology. Less than fifty of Aristotle's treatises persisted into the twenty-first century.

Format: Articles

Subject: People

Max Ludwig Henning Delbruck (1906–1981)

Max Ludwig Henning Delbrick applied his knowledge of theoretical physics to biological systems such as bacterial viruses called bacteriophages, or phages, and gene replication during the twentieth century in Germany and the US. Delbrück demonstrated that bacteria undergo random genetic mutations to resist phage infections. Those findings linked bacterial genetics to the genetics of higher organisms. In the mid-twentieth century, Delbrück helped start the Phage Group and Phage Course in the US, which further organized phage research.

Format: Articles

Subject: People

Petr Alekseevich Kropotkin (1842-1921)

Petr Kropotkin proposed the theory of Pleistocene ice age, alternative theories of evolution based on embryology, and he advocated anarchist and communist social doctrines in Europe during the nineteenth and twentieth centuries. He traveled in eastern Siberia and Manchuria from 1863 until 1867, and his subsequent publications about that area's geography became authoritative until the middle of the twentieth century.

Format: Articles

Subject: People

Stazione Zoologica Anton Dohrn, Naples, Italy

The Stazione Zoologica Anton Dohrn (Anton Dohrn Zoological Station) is a public research institute focusing on biology and biodiversity. Hereafter called the Station, it was founded in Naples, Italy, in 1872 by Anton Dohrn. The type of research conducted at the Station has varied since it was created, though initial research focused on embryology. At the turn of the twentieth century, researchers at the Station established the sea urchin (Echinoidea) as a model organism for embryological research.

Format: Articles

Subject: Organizations, People, Places