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tunica
tu·ni·ca T0413100 (to͞o′nĭ-kə, tyo͞o′-)n. pl. tu·ni·cae (-kē′, -sē′) An enclosing membrane or layer of tissue.
[Latin, tunic; see tunic.]tunica (ˈtjuːnɪkə) n1. (Anatomy) anatomy tissue forming a layer or covering of an organ or part, such as any of the tissue layers of a blood vessel wall2. (Botany) botany the outer layer or layers of cells of the meristem at a shoot tip, which produces the epidermis and cells beneath it. Compare corpus4[C17: from Latin tunica tunic]tu•nic (ˈtu nɪk, ˈtyu-)
n. 1. a coat worn as part of a military or other uniform. 2. a gownlike outer garment worn by the ancient Greeks and Romans. 3. a. a woman's straight, usu. sleeveless upper garment, loose or fitted, extending to the hips or below. b. Also called tu′nic dress`. any of various dresses styled like this or incorporating this as one element. 4. tunicle. 5. a covering membrane, layer, or integument over an organ or part. [1600–10; (< French tunique) < Latin tunica] Thesaurus| Noun | 1. |  tunica - an enveloping or covering membrane or layer of body tissueadventitia, tunictissue layer, membrane - a pliable sheet of tissue that covers or lines or connects the organs or cells of animals or plantsalbuginea - whitish tunic |
Tunica
tunica[′tü·nə·kə] (biology) A membrane or layer of tissue that covers or envelops an organ or other anatomical structure. Tunica (1) In animals, the peripheral layer of skin coverings of ascidians, salpids, and other animals of the subphylum Tunicata, phylum Chordata. The tunica is a thickened cuticle of cutaneous epithelium that is colonized by cells, a unique phenomenon in the animal kingdom. It serves to protect the internal organs. The tunica is composed of tunicin, a carbohydrate closely related to cellulose. This substance has a gelatinous consistency, which makes possible the implantation in the tunica of cells that migrate from the cutaneous epithelium. In histological structure, the tunica resembles connective tissue with a gelatinous basal substance. Blood vessels may grow into the tunica. In appendicu-larians, the tunica separates from the body as the result of a process that resembles molting, forming a transparent gelatinous or chitinoid membrane, which serves as an outer covering of the animal or which is appended to the animal externally. This structure is adapted to filtering food particles out of seawater. (2) In plants, one or more external layers of cells of formative tissue (meristem) covering the corpus of the growing point (apex) in the form of a vault. Dicotyledons have as many as five tunicae, while monocotyledons have as many as three. Cell division in the tunica predominantly occurs anticlinally, or perpendicular to the surface of the organ; hence the surface of the tunica enlarges without change in the number of cell layers. The epidermis is usually formed from the outer layer of the tunica, which corresponds to the dermatogen according to the histogen theory of the German botanist J. von Hanstein; the primary cortex or part of it is formed from the inner layer of the tunica. The tunica-corpus theory was proposed by the German scientist A. Schmidt in 1924. Sometimes only the layers of cells located higher than the rudimentary leaves are called the tunica. The number of layers of the tunica sometimes increases gradually, but always remains a characteristic taxonomical feature of the plant. tunica
tunica [too´nĭ-kah] (L.) a tunic or coat; used in anatomic nomenclature to designate a membranous covering of an organ or a distinct layer of the wall of a hollow structure, as a blood vessel.tunica adventi´tia the outer coat of various tubular structures.tunica albugi´nea a dense white fibrous sheath that encloses a part or organ, such as the testicle or ovary.tunica conjuncti´va the conjunctiva.tunica dar´tos dartos.tunica exter´na an outer coat, such as the fibroelastic coat of a blood vessel.tunica inter´na an inner coat or layer.tunica in´tima the innermost coat of a blood vessel; called also Bichat's tunic.tunica me´dia the muscular middle coat of a blood vessel.tunica muco´sa the mucous membrane lining of various tubular structures.tunica muscula´ris the muscular coat or layer surrounding the tela submucosa in most portions of the digestive, respiratory, urinary, and genital tracts.tunica pro´pria the proper coat or layer of a part, as distinguished from an investing membrane.tunica sero´sa the membrane lining the external walls of the body cavities and reflected over the surfaces of protruding organs; it secretes a watery exudate.tunica vagina´lis tes´tis the serous membrane covering the front and sides of the testis and epididymis.tunica vasculo´sa a vascular coat, or a layer well supplied with blood vessels.tu·nic (tū'nik), Coat or covering; one of the enveloping layers of a part, especially one of the coats of a blood vessel or other tubular structure.
See also: layer. Synonym(s): tunica [L. tunica] tunica (to͞o′nĭ-kə, tyo͞o′-)n. pl. tuni·cae (-kē′, -sē′) An enclosing membrane or layer of tissue.tu·nic (tū'nik) Coat or covering; one of the enveloping layers of a part, especially one of the coats of a blood vessel or other tubular structure.
Synonym(s): tunica. [L. tunica]tunica A covering or investing membrane or layer of tissue.tunica any layer of tissue or membrane that encloses a structure or organ in either an animal or plant.tunica
Related to tunica: tunica intima, tunica adventitia, tunica externa, tunica media, tunica albugineaSynonyms for tunicanoun an enveloping or covering membrane or layer of body tissueSynonymsRelated Words- tissue layer
- membrane
- albuginea
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