Human health and medicine

Microneedling

Microneedling, also known as collagen induction therapy, is a minimally invasive dermatologic procedure that uses fine needles to trigger new collagen for treating scars and wrinkles.

Microneurography is an electrophysiological method recording action potentials from sensory and sympathetic nerve fibers in conscious humans, introduced by Karl-Erik Hagbarth and Åke Vallbo in Uppsala in 1966.

Microneutralization assay

The microneutralization assay is a serological test measuring whether serum antibodies, primarily against hemagglutinin, neutralize live virus in cultured cells, used chiefly for influenza and pandemic virology.

Micronutrient

Micronutrient: vitamins and minerals (about 30, including 13 vitamins and 16 minerals) needed in tiny amounts for enzymes, hormones, and growth. Key facts: iron, vitamin A, iodine deficiencies most common; 42% of under-fives anaemic; prevented by fortification, supplementation, diverse diets.

Micropenis

Micropenis: a structurally normal penis with stretched penile length over 2.5 SD below the age-matched mean; under 2 cm at birth, under 4 cm after age 5. Causes include hypogonadism; treated with early testosterone or DHT.

Microperimetry

Microperimetry is a psychophysical eye test measuring retinal light sensitivity at defined points while infrared fundus tracking assigns each stimulus to a known retinal location.

Microphthalmia with limb anomalies

Microphthalmia with limb anomalies (ophthalmo-acromelic syndrome, Waardenburg anophthalmia syndrome, OMIM 206920) is a rare autosomal recessive disorder of absent or small eyes with hand and foot malformations, mostly caused by biallelic SMOC1 mutations.

Microphthalmia with linear skin defects syndrome

Microphthalmia with linear skin defects syndrome (MLS, MIDAS, Gazali-Temple syndrome) is a rare X-linked dominant, male-lethal disorder of HCCS, COX7B, or NDUFB11 causing microphthalmia and linear facial skin defects in females.

Microphthalmia-retinitis pigmentosa-foveoschisis-optic disc drusen syndrome

Microphthalmia-retinitis pigmentosa-foveoschisis-optic disc drusen syndrome, also called nanophthalmos-RP-foveoschisis-optic disc drusen syndrome or MCOP5, is a rare autosomal recessive MFRP-related eye disorder with posterior microphthalmia, retinal dystrophy, foveal schisis, and optic disc drusen.

Microphthalmia, Lenz type

Microphthalmia, Lenz type (Lenz microphthalmia syndrome, OMIM 309800) is a rare X-linked recessive syndromic microphthalmia affecting males, with small or absent eyes, coloboma, ear, dental, skeletal, and urogenital anomalies, and intellectual disability, linked to BCOR and NAA10.

Microphthalmos

Microphthalmos (microphthalmia), abnormally small eye with axial length 2 SD below age mean, part of the MAC spectrum with anophthalmia and coloboma; about 1 in 7,000, often bilateral, SOX2-related, poor vision with corneal diameter under 6 mm.

Microplastics and human health

Microplastics and human health concerns the effects of microscopic plastic particles, which humans ingest and inhale and which have been detected in blood, lungs, placenta, and arterial plaque.

Micropore Filters

Micropore filters (microporous membrane filters) are 0.01-to-several-micrometer pore membranes of MCE, PVDF, PES, or PTFE that retain bacteria by sieve retention and adsorption; sterilizing grades retain 10^7 Pseudomonas diminuta per cm², though Acholeplasma and Leptospira can penetrate.

Microscopic colitis

Microscopic colitis (collagenous colitis, lymphocytic colitis) is a chronic inflammatory bowel disease causing watery diarrhea with normal colonoscopy, diagnosed by biopsy histology; budesonide is first-line therapy.

Microscopic haematuria

Microscopic haematuria, or microhematuria, is 3 or more red blood cells per high-power field on urine microscopy with normal-appearing urine. Guided by AUA/SUFU risk stratification (low, intermediate, high) for cystoscopy and imaging.

Microscopic polyangiitis

Microscopic polyangiitis (MPA), also called micropolyangiitis, is a rare pauci-immune ANCA-associated small-vessel vasculitis, usually MPO-ANCA positive, causing crescentic glomerulonephritis and alveolar hemorrhage, distinct from GPA, EGPA, and polyarteritis nodosa.

Microsleep

Microsleep: brief involuntary sleep episode (a few seconds to about 30 s) during wakefulness, caused by sleep deprivation, undetectable to the sufferer, EEG-detectable, and a major factor in drowsy-driving crashes.

Oct 20, 2026

Microspheres

Microspheres: spherical particles from ~20 nm to 1000 μm made of polymers, glass, ceramics, or hydrogels; fabricated by emulsion, spray drying, electrospraying, or microfluidics; used for drug delivery, embolization, diagnostics, and tissue engineering.

Oct 20, 2026

Microsporidiosis

Microsporidiosis is a rare parasitic disease caused by microsporidia, spore-forming parasites related to fungi, causing chronic diarrhea and weight loss that can be severe in immunodeficient people.

Microstomia

Microstomia: congenital or acquired abnormal reduction of the oral aperture (narrow mouth), coded ICD-10 Q18.5 and ICD-11 LA31.4. Main causes are burns, caustic ingestion, scleroderma, and lip cancer surgery; treated with splints or commissuroplasty.

Microsurgery

Microsurgery is a surgical technique that uses an operating microscope and fine instruments to join blood vessels, nerves, and lymphatic vessels below about 3 mm in diameter.

Microsurgical reconstruction

Microsurgical reconstruction uses an operating microscope to reattach or transplant blood vessels with lumens under 3 mm, so a transferred flap or amputated part regains a blood supply; it underpins microsurgical breast reconstruction.

Microtia

Microtia is a congenital underdevelopment of the external ear, ranging from a small malformed auricle to anotia; about 1 in 3,800 US births, usually unilateral, treated by rib cartilage or porous polyethylene reconstruction and bone conduction hearing devices.

Microtia reconstruction

Microtia reconstruction is a surgical procedure that builds an external ear for patients with microtia, using rib cartilage or a porous polyethylene implant, typically around age 8.

Microtomy

Microtomy is the laboratory technique of cutting tissue, usually embedded in paraffin wax, into thin slices with a microtome for examination under a light or electron microscope.

Microtransplantation

Microtransplantation (MST) is a transplantation technique, born in China, that infuses small amounts of HLA-mismatched donor stem cells after chemotherapy to fight acute myeloid leukemia with low graft-versus-host disease.

Microvascular anastomosis

Microvascular anastomosis is the surgical connection of blood vessels under 3 mm wide, done under magnification to restore blood flow in free flap and replantation surgery.

Microvascular decompression

Microvascular decompression is a neurosurgical operation that moves an offending blood vessel away from a compressed cranial nerve, most often to relieve trigeminal neuralgia, hemifacial spasm, or glossopharyngeal neuralgia.

Microvascular Density

Microvascular density (MVD, microvessel density) is the measured density of microvessels in a tissue field, a surrogate biomarker of angiogenesis. Developed by Weidner et al. in 1991, it is assessed by endothelial immunohistochemistry (factor VIII, CD31, CD34, CD105) and studied as a prognostic marker in solid tumors.