Definitions beginning with M

megestrol - permalink - collapse

All > Medicine > Cancer

A drug used to block estrogen and suppress the effects of estrogen and androgens. It is used to treat breast and endometrial cancer, and is being studied in the treatment of other types of cancer. It is also used to improve appetite in patients with cancer. Megestrol belongs to the group of hormones called progestins. Also called Megace.
National Cancer Institute - Cite This Source - This Definition
Browse Related Terms: antiandrogen, danazol, ketoconazole, Megace, nilutamide

A special form of cell division in which each daughter cell receives half the amount of DNA as the parent cell. Meiosis occurs during formation of egg and sperm cells in mammals.
National Cancer Institute - Cite This Source - This Definition
Browse Related Terms: conception, germ cell (jurm sel), germline DNA, germline mutation, hereditary mutation, reproductive cell, sperm count (spurm kownt), sperm (spurm)

All > Science > Biotechnology and Genetics > Food Biotechnology

The two-stage process in sexual reproduction by which the chromosome number is reduced from the somatic to the haploid number. The first division, in which homologous chromosomes pair and exchange genetic material, is followed by amitotic division. The nucleus divides twice, but the chromosomes only once, generating haploid nuclei, which develop into the gametes (egg and sperm in animals; egg and s in plants).
UN Food and Agriculture Organization - Cite This Source - This Definition
The reduction division process by which haploid gametes and spores are formed, consisting of a single duplication of the genetic material followed by two mitotic divisions.
Susan Allender-Hagedorn and Charles Hagedorn - Cite This Source - This Definition
Browse Related Terms: amphimixis, Gamete, gametogenesis, isogamy, life cycle, maturation, meiotic product, zygospore

All > Science > Biotechnology and Genetics > Human Genome

The process of two consecutive cell divisions in the diploid progenitors of sex cells. Meiosis results in four rather than two daughter cells, each with a haploid set of chromosomes. See also: mitosis
Human Genome Project - Cite This Source - This Definition
Browse Related Terms: flow cytometry, independent assortment, interphase, segregation

All > Science > Biotechnology and Genetics > Stem Cell

A process where two successive cells divide and produce cells, eggs, or sperm that contain half the number of chromosomes in the somatic cells. During fertilization, the nuclei of the sperm and ovum fuse and produce a zygote with the full chromosome complements.
DHHS - Cite This Source - This Definition
A special process of cell division comprising two nuclear divisions in rapid succession that result in four cells (that will become gametes) with the haploid number of chromosomes. (Based on SMD)
The President's Council on Bioethics - Cite This Source - This Definition
Cell division of a gamete to reduce the chromosomes within it to half the normal number. This is to ensure that fertilization restores the full number of chromosomes rather than causing aneuploidy, or an abnormal number of chromosomes.
NIH - Cite This Source - This Definition
Browse Related Terms: Egg cylinder, Haploid human cell, in vitro fertilization, In vitro fertilization (IVF), oocyte, parthenogenesis, Polar Body, syngamy, zygote

meiotic analysis - permalink - collapse

All > Science > Biotechnology and Genetics > Food Biotechnology

The use of patterns of chromosome pairing at meiotic prophase and metaphase to detect relationships between chromosomes, from which can be deduced the relationship between the parents of the organism studied..
UN Food and Agriculture Organization - Cite This Source - This Definition
Browse Related Terms: asynapsis, autopolyploid, bivalent, chiasma, pairing, quadrivalent, recombination, Synapsis, synaptonemal complex, terminalization, unequal crossing over, zygonema

meiotic drive - permalink - collapse

All > Science > Biotechnology and Genetics > Food Biotechnology

Any mechanism that causes a particular allele or chromosome to be over-represented in a population of gametes.
UN Food and Agriculture Organization - Cite This Source - This Definition
Browse Related Terms: ecotype, Feral, founder principle, Hardy-Weinberg equilibrium, Introgression, panmictic population, panmixis, Population, population genetics, subspecies, variant, Variation

meiotic product - permalink - collapse

All > Science > Biotechnology and Genetics > Food Biotechnology

See: gamete.
UN Food and Agriculture Organization - Cite This Source - This Definition
Browse Related Terms: amphimixis, Gamete, gametogenesis, isogamy, life cycle, maturation, Meiosis, zygospore

MEK inhibitor AZD6244 - permalink - collapse

All > Medicine > Cancer

(... in-HIH-bih-ter...) A substance being studied in the treatment of several types of cancer. MEK inhibitor AZD6244 blocks proteins needed for cell growth and may kill cancer cells. It is a type of protein kinase inhibitor. Also called AZD6244.
National Cancer Institute - Cite This Source - This Definition
Browse Related Terms: AT7519M, AZD6244, bryostatin 1, CDK inhibitor AT7519M, CYC116, KX2-391, ON 01910.Na, PHA-739358

MEL - permalink - collapse

All > Technology > Defense

(1) Maintenance Expenditure Limit. (2) Mobile Erector Launcher.
DoD Missile Defense Agency - Cite This Source - This Definition
Browse Related Terms: LAA, LPS, LUP, MPS, TPS

Melan-A protein - permalink - collapse

All > Medicine > Cancer

A substance found on the surface of melanoma cells. It is being used to develop cancer vaccines that may help the immune system kill cancer cells. Vaccines made using the Melan-A protein are being studied in the treatment of advanced melanoma. Also called MART-1 antigen.
National Cancer Institute - Cite This Source - This Definition
Browse Related Terms: antigen-presenting cell vaccine, APC vaccine, dendritic cell, dendritic cell vaccine, glycoprotein 100, gp100, gp209-2M, MART-1 antigen, tumor antigen vaccine

melanin - permalink - collapse

All > Medicine > Cancer

(MEH-luh-nin) A pigment that gives color to skin and eyes and helps protect it from damage by ultraviolet light.
National Cancer Institute - Cite This Source - This Definition
Browse Related Terms: albinism, iris, jaundice, MC1R, melanocortin 1 receptor, melanocyte, melanotropin receptor, mole, nevus, ophthalmic, pigment, pupil

All > Science > Biotechnology and Genetics > Food Biotechnology

Dark pigment, produced by specialized epidermal cells called melanocytes.
UN Food and Agriculture Organization - Cite This Source - This Definition
Browse Related Terms: anthocyanin, cell sap, cytochrome, guard cell, sap, stomatal complex

melanocortin 1 receptor - permalink - collapse

All > Medicine > Cancer

(meh-LA-nuh-KOR-tin 1 reh-SEP-ter) A protein found in skin and eye cells that make melanin (a pigment that gives color to the skin and helps protect it from damage by ultraviolet light). People with certain changes in the gene for melanocortin 1 receptor have a higher risk of developing melanoma (skin cancer that begins in melanocytes). Also called MC1R and melanotropin receptor.
National Cancer Institute - Cite This Source - This Definition
Browse Related Terms: albinism, iris, jaundice, MC1R, melanin, melanocyte, melanotropin receptor, mole, nevus, ophthalmic, pigment, pupil

melanocyte - permalink - collapse

All > Medicine > Cancer

(mel-AN-o-site) A cell in the skin and eyes that produces and contains the pigment called melanin.
National Cancer Institute - Cite This Source - This Definition
Browse Related Terms: albinism, iris, jaundice, MC1R, melanin, melanocortin 1 receptor, melanotropin receptor, mole, nevus, ophthalmic, pigment, pupil

All > Science > Biotechnology and Genetics > Stem Cell

A cell that produces the dark pigment melanin; responsible for the pigmentation of skin and hair.
DHHS - Cite This Source - This Definition
Browse Related Terms: epithelium, Keratin, Keratinocytes, microtubule, Osteocalcin (OC), Signal transduction pathways, Tenocyte, Transaminase

Melanoma - permalink - collapse

All > Medicine > Cancer

(MEH-luh-NOH-muh) A form of cancer that begins in melanocytes (cells that make the pigment melanin). It may begin in a mole (skin melanoma), but can also begin in other pigmented tissues, such as in the eye or in the intestines.
National Cancer Institute - Cite This Source - This Definition
A malignant form of skin cancer that arises in melanocytes, the cells that produce pigment. Melanoma usually begins in a mole.
ATSDR: Agency for Toxic Substances & Disease Registry - Cite This Source - This Definition
Browse Related Terms: basal cell, microstaging, non-melanoma skin cancer, nonmelanoma skin cancer, skin cancer, stage I nonmelanoma skin cancer, stage IV nonmelanoma skin cancer

All > Science > Biotechnology and Genetics > Human Genome

Cancer of the cells in the skin that produce melanin, a brown pigment. Melanoma often begins in a mole. See also cancer, cell
National Human Genome Research Institute - Cite This Source - This Definition
Browse Related Terms: apoptosis, Embryonic stem (ES) cells, hematopoietic stem cell, Niemann-Pick disease, type C (NPC), Pluripotency, Somatic cell, Somatic cells

melanoma in situ - permalink - collapse

All > Medicine > Cancer

(MEH-luh-NOH-muh in SY-too) Abnormal melanocytes (cells that make melanin, the pigment that gives skin its color) are found in the epidermis (outer layer of the skin). These abnormal melanocytes may become cancer and spread into nearby normal tissue. Also called stage 0 melanoma.
National Cancer Institute - Cite This Source - This Definition
Browse Related Terms: Abnormal, abnormality, carcinoma in situ, CIN 3, nonmelanoma carcinoma in situ, stage 0 anal carcinoma in situ, stage 0 bladder carcinoma in situ, stage 0 cervical carcinoma in situ, stage 0 colorectal carcinoma in situ, stage 0 esophageal carcinoma in situ, stage 0 extrahepatic bile duct carcinoma in situ, stage 0 gallbladder carcinoma in situ, stage 0 gastric carcinoma in situ, stage 0 hypopharyngeal carcinoma in situ, stage 0 laryngeal carcinoma in situ, stage 0 lip and oral cavity carcinoma in situ, stage 0 maxillary sinus carcinoma in situ, stage 0 medullary thyroid carcinoma in situ, stage 0 melanoma, stage 0 nasal cavity and ethmoid sinus carcinoma in situ, stage 0 nasopharyngeal carcinoma in situ, stage 0 non-small cell lung carcinoma in situ, stage 0 nonmelanoma skin carcinoma in situ, stage 0 oropharyngeal carcinoma in situ, stage 0 pancreatic carcinoma in situ, stage 0 penile carcinoma in situ, stage 0 testicular carcinoma in situ, stage 0 transitional cell carcinoma in situ of the renal pelvis and ureter, stage 0 urethral carcinoma in situ, stage 0 vaginal carcinoma in situ, stage 0 vulvar carcinoma in situ

melanoma vaccine - permalink - collapse

All > Medicine > Cancer

A cancer vaccine prepared from human melanoma cancer cells. It can be used alone or with other therapy in treating melanoma.
National Cancer Institute - Cite This Source - This Definition
Browse Related Terms: anti-idiotype vaccine, attenuated, booster, cancer vaccine, GM2-KLH vaccine, hepatitis A vaccine, HPV vaccine, human papillomavirus vaccine, immunity, keyhole limpet hemocyanin, KLH, mercury, Montanide ISA-51, QS21, resiquimod, tetanus toxoid, tyrosinase peptide, vaccinated, vaccination, Vaccine, vaccine adjuvant, vaccine therapy, whole cell vaccine

melanotropin receptor - permalink - collapse

All > Medicine > Cancer

(meh-LA-nuh-TROH-pin reh-SEP-ter) A protein found in skin and eye cells that make melanin (a pigment that gives color to the skin and helps protect it from damage by ultraviolet light). People with certain changes in the gene for melanotropin receptor have a higher risk of developing melanoma (skin cancer that begins in melanocytes). Also called MC1R and melanocortin 1 receptor.
National Cancer Institute - Cite This Source - This Definition
Browse Related Terms: albinism, iris, jaundice, MC1R, melanin, melanocortin 1 receptor, melanocyte, mole, nevus, ophthalmic, pigment, pupil

melatonin - permalink - collapse

All > Medicine > Cancer

(MEH-luh-TOH-nun) A hormone made by the pineal gland (tiny organ near the center of the brain). Melatonin helps control the body's sleep cycle, and is an antioxidant. It is also made in the laboratory and sold as a supplement.
National Cancer Institute - Cite This Source - This Definition
Browse Related Terms: endogenous, pineal body, pineal gland, pineal organ