All articles starting with S
44,216 articles
Sperm Count
Sperm count, also called semen analysis, measures the number of sperm in an ejaculate; WHO 6th edition (2021) 5th centile is 16 million/ml concentration, 39 million total, not a fertile-infertile cutoff.
Sperm cryopreservation
Sperm cryopreservation is a reproductive medicine technique that freezes and stores sperm at −196 °C in liquid nitrogen for later insemination, IVF, or ICSI, preserving fertility before cancer treatment.
Sperm donation
Sperm donation, also called donor insemination via sperm banks, provides semen for women or couples needing third-party conception. Distinguished by FDA/ASRM screening, 6-month quarantine, family-size limits, and varying anonymity laws.
Sperm mitochondrial-associated cysteine-rich protein
SMCP (sperm mitochondrial-associated cysteine-rich protein, gene SMCP, UniProt P49901) is a cysteine- and proline-rich structural protein of the sperm mitochondrial capsule supporting sperm motility and zona pellucida penetration; not the selenoprotein once assumed.
Sperm Motility
Sperm motility, the movement characteristics of spermatozoa in fresh semen, is graded by WHO as progressive, non-progressive, or immotile, with a 30% progressive reference limit, measured manually or by CASA.
Sperm retrieval
Sperm retrieval, also called testicular sperm retrieval, is a group of surgical procedures collecting sperm from the epididymis or testis for ICSI in azoospermia, used routinely since 1992.
Sperm whale
The sperm whale (Physeter macrocephalus) is the largest toothed whale, a deep-diving oceanic predator named for the spermaceti oil in its oversized head, diving about 800 meters to hunt giant squid.
Sperm-associated antigen 5
Sperm-associated antigen 5 (SPAG5), also called astrin or MAP126, is a human 17q11.2 mitotic spindle protein regulating sister chromatid separation, kinetochore attachments, and an overexpressed oncogenic prognostic biomarker in many cancers.
Spermaceti
Spermaceti (cetaceum, spermaceti wax, CAS 8002-23-1) is the cetyl palmitate-rich wax from the sperm whale's head, once prized for clean-burning candles and replaced by jojoba oil after the whaling moratorium.
Spermacoce alata
Spermacoce alata Aubl. (syn. Borreria alata, S. latifolia), broadleaf buttonweed, a Rubiaceae herb native from Colombia to northern South America and W. Brazil, naturalized weed and medicinal plant in Asia, Africa, and Oceania.
Spermadhesin
Spermadhesins are 12–16 kDa CUB-domain secretory proteins of ungulate seminal plasma (pig, cattle, horse), major sperm-surface ligand-binding proteins with five porcine genes (AQN-1, AQN-3, AWN, PSP-I, PSP-II) involved in fertilization.
Spermatic cord
The spermatic cord (funiculus spermaticus) is either of a pair of tubular structures in males that suspends the testis in the scrotum and carries the ductus deferens, blood vessels, and nerves.
Spermatid
Spermatid (nematoblast, spermatoblast): haploid male germ cell (CL:0000018) formed from secondary spermatocytes by meiosis II; without dividing again it transforms via spermiogenesis, about 23 days in humans, into a spermatozoon.
Spermatocyte
Spermatocyte: male germ cell arising from spermatogonia; primary spermatocytes (diploid, largest germ cells) undergo a 24-day meiosis I in humans to form haploid secondary spermatocytes, which complete meiosis II in about 8 hours to yield four spermatids each.
Spermatocytic seminoma
Spermatocytic seminoma, now called spermatocytic tumour, is a rare testicular germ cell tumor of older men, unrelated to seminoma, lacking GCNIS, rarely metastasizing, cured by orchiectomy, with rare aggressive sarcomatous transformation.
Spermatogenesis
Spermatogenesis: production of haploid spermatozoa from spermatogonia via mitosis, meiosis, and spermiogenesis; 64–74 days in humans, FSH/testosterone-regulated, 150–275 million sperm daily.
Spermatogonium
Spermatogonium (Spermatogonia) is a diploid male germ cell at the earliest stage of spermatogenesis, residing on the basement membrane of the seminiferous tubules, where it maintains the stem cell pool.
Spermicide
Spermicide: chemical contraceptive, usually nonoxynol-9, in foams, gels, films, or suppositories; kills sperm, low effectiveness alone (18-28% annual failure), no STI protection, can irritate tissue.
Spermidine
Spermidine is a naturally occurring polyamine synthesized from putrescine in nearly all living cells, essential for protein synthesis, an inducer of autophagy, and a focus of longevity research.
Spermidine synthase
Spermidine synthase (SpdS, putrescine aminopropyltransferase, EC 2.5.1.16, human gene SRM) transfers an aminopropyl group from dcAdoMet to putrescine, making spermidine and MTA; structures, mechanism, and inhibitors known across species.
Spermine
Spermine is a naturally occurring polyamine required for eukaryotic growth, first observed as crystals in human semen by van Leeuwenhoek in 1678 and named for that source.
Spermophilus
Spermophilus (old world ground squirrels, sousliks) is a Eurasian ground squirrel genus in tribe Marmotini, reduced from a Holarctic genus of 41 species by the 2009 Helgen revision; a 2024 study recognizes 18 species including S. vorontsovi.
Spermworld
Spermworld is a 2024 FX/Hulu documentary directed by Lance Oppenheim, produced by The New York Times and Edgeline Films, inspired by Nellie Bowles' article on unregulated Facebook sperm-donation groups; it follows donors Ari Nagel, Tyree Kelly, and Steve Walker.
Sperner property of partially ordered sets
The Sperner property of partially ordered sets, or Sperner posets, holds when no antichain is larger than the largest rank level; Sperner proved it for subset lattices in 1928.
Sperner's lemma
Sperner's lemma, published by Emanuel Sperner in 1928, states that any Sperner-labeled triangulation of a simplex contains at least one fully labeled subsimplex, an odd number of them.
Speroach Beatz
Speroach Beatz, born Prosper Obi, is a Nigerian record producer from Gboko, Benue State, known for producing Davido's 'Assurance' and 'Risky' as a DMW in-house producer.
Sperry Chalet
Sperry Chalet is a 1913 stone backcountry hotel in Glacier National Park, Montana, built by the Great Northern Railway's Hill family, one of two surviving backcountry chalets, destroyed by the 2017 Sprague Fire and rebuilt by 2020.
Sperry Corporation
Sperry Corporation was an American electronics company, founded in 1910 as the Sperry Gyroscope Company, that owned the UNIVAC computer line and merged with Burroughs in 1986 to form Unisys.
Spesolimab
Spesolimab (brand name Spevigo, research code BI 655130) is a monoclonal antibody blocking the interleukin-36 receptor, approved in 2022 to treat generalized pustular psoriasis flares in adults.
Spessartine
Spessartine is a manganese aluminum silicate mineral of the garnet group, the manganese end-member of the garnet series, occurring in granite pegmatites and cut as an orange to red-orange gemstone.