mesaxon

Portion of the ensheathing process (either myelin or non-myelin) where the enveloping lips of the ensheathing cell come together so that their apposed plasma membranes run parallel to each other, separated by a cleft 12 nm wide.

tricellular tight junction

An specialized occluding junction where three epithelial cells meet. It is composed of a branching network of sealing strands that run perpendicularly to the bicellular tight junction at the point of contact between three epithelial cells in an epithelial sheet.

intermediate filament cytoskeleton

Cytoskeletal structure made from intermediate filaments, typically organized in the cytosol as an extended system that stretches from the nuclear envelope to the plasma membrane. Some intermediate filaments run parallel to the cell surface, while others traverse the cytosol; together they form an internal framework that helps support the shape and resilience of the cell.

alae of collagen and cuticulin-based cuticle extracellular matrix

Raised, thickened cuticular ridges that run longitudinally, and in parallel, along the left and right sides of the animal. The alae lie above the hypodermal cells known as the lateral seam cells. In C. elegans, alae are produced in L1 larvae, dauer larvae and adult stage animals, where they consist of three, five, and three ridges of distinct morphology, respectively.

synaptic vesicle recycling

The trafficking of synaptic vesicles from the pre-synaptic membrane so the vesicle can dock and prime for another round of exocytosis and neurotransmitter release. Recycling occurs after synaptic vesicle exocytosis, and is necessary to replenish presynaptic vesicle pools, sustain transmitter release and preserve the structural integrity of the presynaptic membrane. Recycling can occur following transient fusion with the presynaptic membrane (kiss and run), or via endocytosis of presynaptic membrane.

general adaptation syndrome

General adaptation syndrome is the set of changes in various organ systems of the body, especially the pituitary-endocrine system, in response to a wide range of strong external stimuli, both physiological and psychological. It is described as having three stages: alarm reaction, where the body detects the external stimulus; adaptation, where the body engages defensive countermeasures against the stressor; and exhaustion, where the body begins to run out of defenses.

septin band

A diffuse ring composed of a series of septin bars that run parallel to the long axis of the cell. This type of septin structure has been observed in a number of locations associated with polarized grown and/or deposition of new membrane, but not with cytokinesis, such as at the shmoo (mating projection) neck, at the junction between the mother cell and the germ tube (hypha) of a fungal cell growing filamentously.

paramesonephric duct development

The process whose specific outcome is the progression of the paramesonephric duct over time, from its formation to the mature structure. Mullerian ducts (or paramesonephric ducts) are paired ducts of the embryo that run down the lateral sides of the urogenital ridge and terminate at the mullerian eminence in the primitive urogenital sinus. In the female, they will develop to form the fallopian tubes, uterus, cervix, and the upper portion of the vagina; in the male, they are lost. These ducts are made of tissue of mesodermal origin.

sperm principal piece

The segment of the sperm flagellum where the mitochondrial sheath ends, and the outer dense fibers (ODFs) associated with outer axonemal doublets 3 and 8 are replaced by the 2 longitudinal columns of the fibrous sheath (FS) which run the length of the principal piece and are stabilized by circumferential ribs. The principal piece makes up ~2/3 of the length of the sperm flagellum and is defined by the presence of the FS and of only 7 (rather than 9) ODFs which taper and then terminate near the distal end of the principal piece.

exocytosis

A process of secretion by a cell that results in the release of intracellular molecules (e.g. hormones, matrix proteins) contained within a membrane-bounded vesicle. Exocytosis can occur either by full fusion, when the vesicle collapses into the plasma membrane, or by a kiss-and-run mechanism that involves the formation of a transient contact, a pore, between a granule (for example of chromaffin cells) and the plasma membrane. The latter process most of the time leads to only partial secretion of the granule content. Exocytosis begins with steps that prepare vesicles for fusion with the membrane (tethering and docking) and ends when molecules are secreted from the cell.