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A band of fibrous or muscular tissue extending from the capsule or wall into the interior of an organ.



(1) In reference to vertebrates, including man, the word “trabecula” has several meanings. The trabeculae cra-nii, in the cranium of the embryo, are two cartilaginous bars anterior to the notochord, under the base of the forebrain. The part of the cranium that develops from the trabeculae is called prechordal, as distinct from the parachordal part of the cranium, which lies behind the end of the notochord and which bears traces of segmentation. The trabeculae occupy the orbital region of the cranium and lie horizontally or in flexed position, depending on the flexure of the rudimentary brain. As the cranium develops, the trabeculae fuse with each other and with the parachordal part of the cranium, forming its base. Anterior to the developing trabeculae are attached the cartilaginous nasal capsules. On the sides are the auditory vesicles.

The word “trabeculae” is also used to denote the septa that depart from the external capsule of connective tissue and project into the lymph nodes and spleen, forming the stroma of those organs; blood vessels pass through the trabeculae.

The word also denotes supporting structures in the spongy substance of the bone.

(2) In reference to invertebrates, the word is also used in several senses. In ascidians, the trabeculae are slender cords that unite the outer wall of the peribranchial cavity with the pharynx and provide support. In gastropods, they are folds that project into the kidneys. In arachnids, they are bands of connective tissue between the leaflike folds of the lung book; they prevent the leaves from collapsing and thus facilitate blood circulation.

(3) In plants, the trabeculae are incomplete transverse septa in the sporangia of certain plants, for example, the genera Pleuromeia, Lepidodendron, and Isoetes. The word is used to denote the elongated cells of the endoderm in the trunks of Selaginella; the trabeculae suspend the stele in the air cavity. In addition, trabeculae are transverse thickenings on the peristome teeth along the margins of the spore-bearing capsule of certain mosses.

References in periodicals archive ?
Numerical density "NV (cells/bone)" refers to the number of cells per unit volume of the trabeculae and was evaluated by using the disector method.
This cavity increase can be due to: a thinning of the separating walls (trabeculae) which will only give a slight increase in the marrow space or b) the increase can be caused by disappearance or perforation of some separating walls with or without changes of the thickness of the walls (trabeculae).
Caption: Figure 3: (a) Sagittal reconstructed computed tomography image showed a lobulated osteolytic lesion with well-defined margins, few internal trabeculae, and surrounding sclerosis in the proximal metaphysis of the ulna.
Thus, the studied combination of drugs, three months after the modeling of osteoporosis in rats, has a protective effect, which is slowing down the thinning of the trabeculae in the trochanteric region of the femur.
(B) The marrow and the air spaces of the entire rostral portion of the skull are diffusely infiltrated by an unencapsulated, poorly demarcated, highly cellular neoplasm composed of islands and trabeculae of polygonal neoplastic cells embedded in a loose fibrovascular stroma (solid arrows), with evidence of invasion into adjacent muscle tissue (open arrow) (hematoxylin and eosin; X0.5).
In particular, data indicated that whereas the viscosity of native bone was similar between 4 and 12 weeks, the viscosity of newly formed bone trabeculae significantly increased (+34%) during bone healing, till achieving a similar value to that of preexisting bone.
Bone vessel quantification, analysis of spatial relationships between vessels and bone trabeculae, and calculation of blood flow are nontrivial.
An incisional biopsy was performed which microscopically revealed irregularly shaped trabeculae of immature woven bone in a cellular, loosely arranged fibrous stroma.
The epithelial architectural pattern was studied with respect to the ducts, trabeculae, solid nests while mesenchymal component was divided into myxoid, chondroid and chondromyxoid elements.
Compact osteomas consist of dense, compact bone with a few marrow spaces, while cancellous osteoma is characterized by bony trabeculae and a fibrofatty marrow enclosing osteoblasts which resembles mature bone.
Cortical bone density, cortical thickness, cortical porosity, trabecular bone density, bone volume fraction (bone volume/trabecular volume), number of trabeculae, trabecular thickness and trabecular separation can be evaluated with HR-pQCT.
Characteristic histopathological features of ON were defined as a diffuse presence of lacunae or pyknotic nuclei of osteocytes in the trabeculae accompanied by surrounding necrotic bone marrow, adipocyte hypertrophy, and vascular thrombosis.