Connective Tissue Types
Loose connective tissue and dense connective tissues
These two tissues are distinguished according to the relative amounts of fibres they contain. Dense connective tissues are completely dominated by fibres. They are subdivided according to the spatial arrangement of the fibres in the tissue.
In dense irregularconnective tissue the fibres do not show a clear orientation within the tissue but instead form a densely woven three-dimensional network. A good example is the dermis of the skin.
We talk about regulardense connective tissue if the fibres run parallel to each other. Good examples of regular dense connective tissue are tendons, ligaments and the fasciae and aponeuroses of muscles.
Loose connective tissueis relatively cell rich, soft and compliant. It is also rich in vessels and nerves. It is best understood as a kind of generalised connective tissue in which all connective tissue cell types may occur. Loose connective tissue may occur in some special variants: mucous connective tissue, reticular connective tissue and adipose tissue.
sections of tendons or ligaments - van Gieson, H&E
| Muscle-Tendon Junction, rat - van Gieson In van Gieson stained preparations collagen stains dark red while other tissue components appear in varying shades of grey (nuclei) and yellow (cytoplasm). Areas of dense regular connective tissue are usually easy to identify in these preparations. Coarse collagen fibres are aligned with each other with only very narrow opens spaces between them. Like in most other connective tissues, there will be only a few cells between the fibres. Their cytoplasm is difficult to identify but the nuclei can be seen scattered among the collagen fibres. Nuclei are often elongated, and their long axis runs parallel to the course of the collagen fibres Sketch part of the regular dense connective tissue. |
sections of skin or non-lactating mammary gland - H&E, van Gieson, trichrome
| Non-lactating Breast - H&E Dense irregular connective tissue forms the dermis of the skin, i.e. the layer of connective tissue immediately below the epithelium lining the surface of the skin. Beneath the skin forming the mammae (nipples), dense connective tissue areas are very extensive. This tissue surrounds the resting mammary gland. Both the high density of collagen fibres and the their irregular distribution are easily visible. Again, only a very small fraction of the tissue is taken up by cells. Like in van Gieson stained preparations, their cytoplasm is often not visible in H&E stained sections. Dark spots scattered between the collagen fibres represent the nuclei of the cells. Draw part of the connective tissue including some fibrocytes. The excretory ducts of the mammary glands are called lactiferous ducts. They are lined by a quite nice stratified columnar epithelium. If you are working with a section of non-lactating breast look for the lactiferous ducts in the connective tissue. |
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