Vertebrates
Tendon cells, or tenocytes, are elongated
fibroblast
A fibroblast is a type of biological cell that synthesizes the extracellular matrix and collagen, produces the structural framework ( stroma) for animal tissues, and plays a critical role in wound healing. Fibroblasts are the most common cells of ...
type cells. The cytoplasm is stretched between the
collagen fibres of the tendon. They have a central
cell nucleus with a prominent
nucleolus
The nucleolus (, plural: nucleoli ) is the largest structure in the nucleus of eukaryotic cells. It is best known as the site of ribosome biogenesis, which is the synthesis of ribosomes. The nucleolus also participates in the formation of s ...
. Tendon cells have a well-developed
rough endoplasmic reticulum and they are responsible for synthesis and turnover of tendon fibres and
ground substance.
Invertebrates
Tendon cells form a connecting
epithelial
Epithelium or epithelial tissue is one of the four basic types of animal tissue, along with connective tissue, muscle tissue and nervous tissue. It is a thin, continuous, protective layer of compactly packed cells with a little intercellu ...
layer between the
muscle
Skeletal muscles (commonly referred to as muscles) are Organ (biology), organs of the vertebrate muscular system and typically are attached by tendons to bones of a skeleton. The muscle cells of skeletal muscles are much longer than in the other ...
and shell in
molluscs
Mollusca is the second-largest phylum of invertebrate animals after the Arthropoda, the members of which are known as molluscs or mollusks (). Around 85,000 extant species of molluscs are recognized. The number of fossil species is esti ...
. In
gastropods
The gastropods (), commonly known as snails and slugs, belong to a large taxonomic class of invertebrates within the phylum Mollusca called Gastropoda ().
This class comprises snails and slugs from saltwater, from freshwater, and from land. ...
, for example, the retractor muscles connect to the shell via tendon cells. Muscle cells are attached to the collagenous myo-tendon space via
hemidesmosomes. The myo-tendon space is then attached to the base of the tendon cells via basal hemidesmosomes, while apical hemidesmosomes, which sit atop
microvilli, attach the tendon cells to a thin layer of
collagen. This is in turn attached to the shell via organic fibres which insert into the shell. Molluscan tendon cells appear columnar and contain a large basal
cell nucleus. The
cytoplasm
In cell biology, the cytoplasm is all of the material within a eukaryotic cell, enclosed by the cell membrane, except for the cell nucleus. The material inside the nucleus and contained within the nuclear membrane is termed the nucleoplasm. ...
is filled with granular
endoplasmic reticulum
The endoplasmic reticulum (ER) is, in essence, the transportation system of the eukaryotic cell, and has many other important functions such as protein folding. It is a type of organelle made up of two subunits – rough endoplasmic reticulum ( ...
and sparse
golgi. Dense bundles of
microfilaments
Microfilaments, also called actin filaments, are protein filaments in the cytoplasm of eukaryotic cells that form part of the cytoskeleton. They are primarily composed of polymers of actin, but are modified by and interact with numerous other p ...
run the length of the cell connecting the basal to the apical hemidesmosomes.
See also
*
List of human cell types derived from the germ layers
References
*
*
Human cells
Connective tissue cells
GAG secreting cells
{{Cell-biology-stub