List of abbreviations
of micros-
specialist terms
explained in
English +

Every attempt was made to provide correct information and labelling, however any liability for eventual errors or incompleteness is rejected!

dieser Seite

Dr. med.
H. Jastrow

of use
Overview bones (Ossa) and ossification (Ossificatio):
Pages with explanations are linked to the text below the images if available!
hardly active
osteoblasts (monkey)
organells of an
osteoblast 1 (monkey)
organells of an
osteoblast 2 (monkey)
opening zone in chondral
crystallisation centre
overview thereof
fresh osteoid (monkey)
osteoid formation 1
fresh osteoid
detail (monkey) 
osteoid formation 2
osteoid formation
3 (monkey)

In humans the usually altogether 210 Bones (Terminologia histologica: Ossa) consist of bone tissue (Terminologia histologica: Textus osseus). Two main types of bones can be distinguished: flat bones with a massive, i.e. hard outer and inner layer and the elongate long bones with large central cavities.
cells of bones:
all bone tissues consist of bone cells and the ossified matrix around them. These bone cells are:
Osteoblasts (Terminologia histologica: Osteoblasti) with a high metabolic activity. These cells build up bone tissue as long as they are activated and not present as inactive lining cells in the end- or periosteum.
Osteocytes (Terminologia histologica: Osteocyti), the immured bone cells with low metabolic activity form dozens of up to 200 µm long, 150 nm thin osteocyte processes (Terminologia histologica: Processus osteocyti) and on the latter connexin 43-containing gap junctions establish connections in between the cells and to endothelial cells of Haversian canalsThe processes are located in tiny bone canaliculi (Terminologia histologica: Canalculi ossis) with diameters up to 400 nm which interrupt the bone matrix.
Osteoclasts (Terminologia histologica: Osteoclasti) belong to the mononuclear phagocyte system despite the fact that they always have many (up to 25) nuclei. They are giant cells with diameters of 30 - 100 µm arising from fusing monocytes from blood which are true mononuclear cells. Numerous Golgi apparatuses produce numerous vesicles most of which are lysosomes. The latter release their content by exocytosis in the area of the ruffled border. Together with the hydrochloric acid these substances destroy the bone matrix.
Bone lining cells (Terminologia histologica: Cellulae vestientes osseorum) mainly comprise inactive osteoblasts resting in the endosteum and periosteum which are interconnected by gap-junctions forming a flat epithelium since hardly any intercellular substance is present in between them.

Kinds of bone tissue:
1. Woven bone (Terminologia histologica: Textus osseus reticulofibrosus) is the primary kind of newly formed bone.
2. Trabecular bone (spongy bone, cancellous bone; Terminologia histologica: Textus osseus spongiosus, Textus osseus trabecularis) appears as a spongy framework with many holes consisting of bone trabecula and depending on long-time pressure forces is constantly remodelled.
3. Bundle bone (Terminologia histologica: Textus osseus fasciculatus) forms the transition area from trabecular bone to lamellar bone showing larger bundles of still lamellated bone which then terminate into the trabecula trabecular bone nearly devoid of Haversian systems.
4. Compact bone (Terminologia histologica: Textus osseus compactus) lies as massive compact bone tissue on and directly under the surface of long bones as well as Substantia or Pars compacta on the bone shaft (diaphysis), or as Substantia corticalis on the ends of bones. Further, the inner and the outer surface of skull bones (Tabula interna and - externa) consist of stable Substantia corticalis. In the temporal bone (Os temporale) compact bone tissue protects the structures of the inner ear. Only in this area it is organised as woven bone otherwise it is present in form of
Lamellar bone (Terminologia histologica: Textus osseus lamellaris). The latter consists of 2-4 mm strongbone lamellas (Terminologia histologica: Lamellae osseae). Hereby in most cases lamellas of concurrent (aniostropic) collagen fibrils alternate with lamellas containing collagen fibrils running in opposite direction which can be observed in a polarisation microscope as texture with light and dark bands. The lamellas are usually oriented longitudinally to the bone shaft.
Much more information and many more images are available in the professional version of this atlas.

--> hyaline-, elastic cartilage, connective tissue, resident connective tissue cells, bone marrow
--> Electron microscopic atlas Overview
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Most images were kindly provided by Prof. H. Wartenberg; other images, page & copyright H. Jastrow.