| macula communicans | <cell biology> A junction between two cells consisting of many pores that allow the passage of molecules up to about 900D. Each pore is formed by an hexagonal array (connexon) of six transmembrane proteins (connexins) in each plasma membrane: when mated together the pores open, allowing communication and the interchange of metabolites between cells. Electrical synapses are gap junctions and metabolic cooperation depends upon the formation of gap junctions. (18 Nov 1997) |
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| macula communis | The thickened area in the medial wall of the auditory vesicle that later subdivides to form the maculae of the sacculus and utriculus as well as the cristae of the ampullae of the saemicircular ducts. (05 Mar 2000) |
| macula corneae | A moderately dense opacity of the cornea. Synonym: corneal spot. (05 Mar 2000) |
| macula cribrosa | One of three areas on the wall of the vestibule of the labyrinth, marked by numerous foramina giving passage to nerve filaments supplying portions of the membranous labyrinth, macula cribrosa inferior, located in the posterior bony ampulla for passage of posterior ampullary nerve fibres, macula cribrosa media, area near the base of the cochlea through which the saccular nerve fibres pass, macula cribrosa superior, perforated area above the elliptical recess for passage of the utriculoampullary nerve fibres, macula cribrosa quarta, a name sometimes applied to the opening for the cochlear nerve. (05 Mar 2000) |
| macula densa | A closely packed group of densely staining cells in the distal tubular epithelium of a nephron, in direct apposition to the juxtaglomerular cells; they may function as either chemoreceptors or as baroreceptors feeding information to the juxtaglomerular cells. (05 Mar 2000) |
| macula flava | A yellowish spot at the anterior extremity of the rima glottidis where the two vocal folds join. (05 Mar 2000) |
| macula germinativa | Archaic term for the nucleolus in the nucleus of an ovum; also refers to any germinal area. (05 Mar 2000) |
| macula gonorrhoica | A spot of red brighter than the surrounding membrane, at the congested orifice of the duct of Bartholin's gland, sometimes seen in gonorrhoea. Synonym: Saenger's macula. (05 Mar 2000) |
| macula lactea | Gray-white or white, rounded or irregularly shaped, slightly opaque patches or spots that are sometimes observed postmortem in the epicardium, especially in middle-aged or older persons; they result from fibrous thickening, and sometimes hyalinization, of the epicardium; similar lesions may also occur in the visceral layer of the peritoneum. Synonym: macula lactea, macula tendinea, tache blanche, tache laiteuse, tendinous spot, white spot. (05 Mar 2000) |
| macula lutea | An oval area in the retina, 3 to 5 mm in diameter, usually located temporal to the posterior pole of the eye and slightly below the level of the optic disk. It is characterised by the presence of a yellow pigment diffusely permeating the inner layers, contains the fovea centralis in its centre, and provides the best phototopic visual acuity. It is devoid of retinal blood vessels, except in its periphery, and receives nourishment from the choriocapillaris of the choroid. (12 Dec 1998) |
| macula of saccule | The oval neuroepithelial sensory receptor in the anterior wall of the saccule; hair cells of the neuroepithelium support the statoconial membrane and have terminal arborizations of vestibular nerve fibres around their bodies. Synonym: macula sacculi, saccular spot. (05 Mar 2000) |
| macula of utricle | The neuroepithelial sensory receptor in the inferolateral wall of the utricle; hair cells of the neuroepithelium support the statoconial membrane and have terminal arborizations of vestibular nerve fibres around their bodies; sensitive to linear acceleration in the longitudinal axis of the body and to gravitational influences. Synonym: macula utriculi, utricular spot. (05 Mar 2000) |
| macula pellucida | <gynaecology, physiology> The point where the graafian follicle is about to rupture on the surface of the ovary. Synonym: macula pellucida, stigma. (05 Mar 2000) |
| macula retinae | An oval area of the sensory retina, 3 by 5 mm, temporal to the optic disk corresponding to the posterior pole of the eye; at its centre is the central fovea, which contains only retinal cones. Synonym: area centralis, macula lutea, macular area, punctum luteum, Soemmerring's spot, yellow spot. (05 Mar 2000) |
| macula sacculi | The oval neuroepithelial sensory receptor in the anterior wall of the saccule; hair cells of the neuroepithelium support the statoconial membrane and have terminal arborizations of vestibular nerve fibres around their bodies. Synonym: macula sacculi, saccular spot. (05 Mar 2000) |