- acroplaxome - structure forms the acrosome plate with intermediate filament bundles of the marginal ring at the leading edge of the acrosome. The sub-acrosomal layer located in the developing spermatozoa head perinuclear region, located between the inner acrosomal membrane and the nuclear envelope. The other part of the perinuclear region is the post-acrosomal sheath (PAS) at the post-acrosomal region.
- acrosome - Cap-shaped cellular structure formed from the golgi apparatus and contains enzymes to dissolve the oocyte (egg) zona pellucida for fertilisation.
- acrosome compaction - Acrosome reshaping process in final stages of spermatogenesis (spermatid to spermatozoa).
- acrosome reaction - Chemical change within the spermatozoa following binding to the zona pellucida, only acrosome reacted spermatozoa have an ability to fuse with oocytes.
- annulus - Cytoskeletal (septin) structure located between the midpiece and principal piece regions of the tail, thought to form a diffusion barrier between these two domains. PMID 20042538
- asthenozoospermia - (asthenospermia) Term for reduced sperm motility and can be the cause of male infertility.
- axoneme - (axonema) The basic structure in cilia and eukaryotic flagella and in the spermatozoa tail, consisting of parallel microtubules in a characteristic "9 + 2" pattern. This pattern describes 9 outer microtubule doublets (pairs) surrounding 2 central singlet microtubules, in humans 50 μm long. The motor protein dynenin move the outer microtubules with respect to the central pair, bending the cilia and generating motility. Note that prokaryotic bacteria have a similar process (flagellum) that uses an entirely different mechanism for motility.
- blood-testis barrier - (BTB) Formed by tight junctions, basal ectoplasmic specializations, desmosome-like junctions and gap junctions between adjacent sertoli cells near the basement membrane of the seminiferous epithelium. image - BTB | image - tight junction
- capacitation - term describing the process by which spermaozoa become capable of fertilizing an oocyte, requires membrane changes, removal of surface glycoproteins and increased motility.
- caput - proximal head of the epididymis, epithelium with stereocilia, involved in absorbing fluid to concentrate spermatozoa. Underlying smooth muscle aids movement. Epididymis three main parts : caput (head), corpus (body), cauda (tail).
- CatSper - cationic (Ca2+) channel of spermatozoa, progesterone activated involved in hyperactivation, acrosome reaction, and possibly chemotaxis.
- cauda - distal tail of the epididymis, region with a thin epithelium and the greatest quantity of smooth muscle. Epididymis three main parts : caput (head), corpus (body), cauda (tail).
- centriole - a microtubule organising centre. First required for axoneme formation (distal centriole) that is lost and a second for pronuclei formation (proximal) following fertilisation. Rodents loose both and only have maternal centrioles.
- connecting piece - linkage between the spermatozoa head and the midpiece of the tail. PMID 22767409
- corpus - elongated body of the epididymis, This has an intermediate thickness of epithelium and thicker smooth muscle layer than caput. Epididymis three main parts : caput (head), corpus (body), cauda (tail).
- cytoplasmic bridges - Transient cytoplasm connections between spermatids arising from one spermatogonium due to incomplete cytokinesis.
- diploid - (Greek, di = double + ploion = vessel) Having two sets of chromosomes, the normal state for all cells other than the gametes.
- end piece - Last portion of the spermatozoa tail region.
- epididymis - testis tubular structure connecting the efferent ducts to the ductus deferent and functions for the storage and maturation of spermatozoa. Epididymis three main parts : caput (head), corpus (body), cauda (tail). PMID27307387
- fibrous sheath - cytoskeletal structure surrounding the axoneme and outer dense fibers, defining the extent of the principal piece region.
- haploid - (Greek, haploos = single) Having a single set of chromosomes as in mature germ/sex cells (oocyte, spermatozoa) following reductive cell division by meiosis. Normally cells are diploid, containing 2 sets of chromosomes.
- interstitial cell - (Leydig cell) Male gonad (testis) cell which secrete the androgen testosterone, beginning in the fetus.
- interstitium - testis developmental region (space between testis cords) that generates Leydig cells and other less well characterized cell types.
- Johnsen score - a clinical score (1-10) for assessing spermatogenesis in a human testicular biopsy. Named after the author of the original article. PMID 5527187
- Leydig cell - (interstitial cell) Male gonad (testis) cell that secrete the androgen testosterone, beginning in the fetus. Fetal Leydig cells develop from coelomic epithelium and undifferentiated perivascular cells in the gonad–mesonephros border region. Adult Leydig cells appear after birth from stem/progenitor cells among peritubular and peri-vascular cells. Leydig cells were first histologically identified in 1850 by Franz von Leydig (1821 - 1908) a German scientist.
- meiosis - The cell division that occurs only in production of germ cells where there is a reduction in the number of chromosomes (diploid to haploid) which is the basis of sexual reproduction. All other non-germ cells in the body divide by mitosis.
- midpiece - (middle piece) spermatozoa tail initial segment of axoneme surrounded outer dense fibres then by mitochondria. Next in the tail is the principal piece then finally the end piece.
- mitosis - The normal division of all cells, except germ cells, where chromosome number is maintained (diploid). In germ cell division (oocyte, spermatozoa) meiosis is a modified form of this division resulting in reduction in genetic content (haploid). Mitosis, division of the nucleus, is followed by cytokinesis the division of the cell cytoplasm and the cytoplasmic contents. cytokinesis overlaps with telophase.
- outer dense fibres - (ODF, outer dense fibers) cytoskeletal structures that surround the axoneme in the middle piece and principal piece of the spermatozoa tail.
- primary spermatocyte - arranged in the seminiferous tubule wall deep (luminal) to the spermatogonia. These large cells enter the prophase of the first meiotic division. (More? meiosis)
- principal piece - Spermatozoa tail segment containing the plasma membrane calcium channels (CatSper1 and CatSper2) required for hyperactivation of motility. Region is partially separated from the midpiece by a barrier called the annulus.
- sertoli cells - (sustentacular cell) These cells are the spermatozoa supporting cells, nutritional and mechanical, as well as forming a blood-testis barrier. The cell cytoplasm spans all layers of the seminiferous tubule. The cells are named after Enrico Sertoli (1842 - 1910), and italian physiologist and histologist.
- sperm annulus - (Jensen's ring; Latin, annulus = ring) A region of the mammalian sperm flagellum connecting the midpiece and the principal piece. The annulus is a septin-based structure formed from SEPT1, 4, 6, 7 and 12. Septins are polymerizing GTPases that can act as a scaffold forming hetero-oligomeric filaments required for cytokinesis and other cell cycle roles.
- spermatogenesis - (Greek, genesis = origin, creation, generation) The term used to describe the process of diploid spermatagonia division and differentiation to form haploid spermatazoa within the testis (male gonad). The process includes the following cellular changes: meiosis, reoorganization of DNA, reduction in DNA content, reorganization of cellular organelles, morphological changes (cell shape). The final process of change in cell shape is also called spermiogenesis.
- spermatogenesis - (Greek, genesis = origin, creation, generation) The maturation process of the already haploid spermatazoa into the mature sperm shape and organization. This process involves reorganization of cellular organelles (endoplasmic reticulum, golgi apparatus, mitochondria), cytoskeletal changes (microtubule organization) and morphological changes (cell shape, acrosome and tail formation).
- spermatogonia - The cells located in the seminiferous tubule adjacent to the basal membrane that either divide and separate to renew the stem cell population, or they divide and stay together as a pair (Apr spermatogonia) connected by an intercellular cytoplasmic bridge to differentiate and eventually form spermatazoa.
- spermatozoa head - Following spermiogenesis, the first region of the spermatozoa containing the haploid nucleus and acrosome. In humans, it is a flattened structure (5 µm long by 3 µm wide) with the posterior part of nuclear membrane forming the basal plate region. The human spermatozoa is about 60 µm long, actively motile and divided into 3 main regions (head, neck and spermatozoa tail).
- spermatozoa neck - Following spermiogenesis, the second region of the spermatozoa attached to basal plate, transverse oriented centriole, contains nine segmented columns of fibrous material, continue as outer dense fibres in tail. In humans, it forms a short structure (1 µm). The human spermatozoa is about 60 µm long, actively motile and divided into 3 main regions (head, neck and tail).
- spermatozoa tail - Following spermiogenesis, the third region of the spermatozoa that has a head, neck and tail). The tail is also divided into 3 structural regions a middle piece, a principal piece and an end piece. In humans: the middle piece (5 µm long) is formed by axonema and dense fibres surrounded by mitochondria; the principal piece (45 µm long) fibrous sheath interconnected by regularly spaced circumferential hoops; the final end piece (5 µm long) has an axonema surrounded by small amount of cytoplasm and plasma membrane.
- spermatogonial stem cells - (SSCs) The spermatagonia cells located beside the seminiferous tubule basal membrane that either divide and separate to renew the stem cell population, or they divide and stay together as a pair (|Apr spermatogonia) connected by an intercellular cytoplasmic bridge to differentiate and eventually form spermatazoa.
- spermatozoon - singular form of of spermatozoa.
- sperm protein 56 - A component of the spermatozoa acrosomal matrix released to the sperm surface during capacitation.
- teratospermia - Clinical term for a spermatozoa with abnormal morphology (small, large, defects in the head, tail, and/or mid-piece) present in the semen or ejaculate.
- testis cords - developmental structure that give rise to the adult seminiferous tubules, the other developmental region is the interstitium.
- vasectomy - Clinical term for ligation of the scrotal portion of the ductus deferens.
See also: Spermatozoa Terms collapse table
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