primitive node

node (nōd) a small mass of tissue in the form of a swelling, knot, or protuberance, either normal or pathological.no´dal

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atrioventricular node , AV node (AVN) a collection of Purkinje fibers beneath the endocardium of the right atrium, continuous with the atrial muscle fibers and atrioventricular bundle; it receives the cardiac impulses from the sinoatrial node and passes them on to the ventricles.

Bouchard's nodes  cartilaginous and bony enlargements of the proximal interphalangeal joints of the fingers in degenerative joint disease.

Dürck's nodes  granulomatous perivascular infiltrations in the cerebral cortex in trypanosomiasis.

Flack's node  sinoatrial n.

Heberden's nodes  small hard nodules, usually at the distal interphalangeal joints of the fingers, formed by calcific spurs of the articular cartilage and associated with osteoarthritis.

Hensen's node  primitive node.

Keith's node , Keith-Flack node sinoatrial n.

lymph node  any of the accumulations of lymphoid tissue organized as definite lymphoid organs along the course of lymphatic vessels, consisting of an outer cortical and an inner medullary part; they are the main source of lymphocytes of the peripheral blood and, as part of the reticuloendothelial system, serve as a defense mechanism by removing noxious agents, e.g., bacteria and toxins, and probably play a role in antibody formation.

Lymph node (nodus lymphoideus).

Osler's nodes  small, raised, swollen, tender areas, bluish or sometimes pink or red, occurring commonly in the pads of the fingers or toes, in the thenar or hypothenar eminences, or the soles of the feet; they are practically pathognomonic of subacute bacterial endocarditis.

primitive node  a mass of cells at the cranial end of the primitive streak in the early embryo.

nodes of Ranvier  constrictions of myelinated nerve fibers at regular intervals at which the myelin sheath is absent and the axon is enclosed only by Schwann cell processes.

Schmorl's node  an irregular or hemispherical bone defect in the upper or lower margin of the body of a vertebra.

sentinel node 

1. the first lymph node to receive drainage from a tumor; used to determine whether there is lymphatic metastasis in certain types of cancer.

2. signal n.

signal node  an enlarged supraclavicular lymph node; often the first sign of a malignant abdominal tumor.

singer's nodes  vocal cord nodules.

sinoatrial node , sinuatrial node, sinus node a microscopic collection of atypical cardiac muscle fibers (Purkinje fibers) at the junction of the superior vena cava and right atrium, in which the cardiac rhythm normally originates and which is therefore called the cardiac pacemaker.

teacher's nodes  vocal cord nodules.

Troisier's node , Virchow's node signal n.

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primitive node

n.

A knotlike thickening at the anterior end of the primitive streak of the blastoderm at the point of origin of the embryonic head. Also called Hensen's node, primitive knot.

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primitive node,

a knoblike accumulation of cells at the cephalic end of the primitive streak in the early stages of embryonic development in humans and higher animals. It consists of mesoderm cells that give rise to the notochord, and it corresponds to the dorsal lip of the blastopore in lower animals. Also called Hensen's knot, Hensen's node.

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primitive

first in point of time; existing in a simple or early form; showing little evolution.

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primitive groove

longitudinal furrow in the primitive streak of the embryo.

primitive knot

see hensen's node.

primitive node

enlarged cranial end of the primitive streak.

primitive streak

the thickened median area of the epiblast which sets out the future longitudinal axis of the early embryo.