HISTOLOGY 1.6.: CONNECTIVE AND SUPPORTIVE TISSUESHISTOLOGY 1.6.: CONNECTIVE AND SUPPORTIVE TISSUES

CLASSIFICATION OF CONNECTIVE AND SUPPORTIVE TISSUESCLASSIFICATION OF CONNECTIVE AND SUPPORTIVE TISSUESI.I. Embryonic connective and supportive tissueEmbryonic connective and supportive tissue• MesenchymeMesenchyme• Gelatinous connective tissueGelatinous connective tissue• Chordoid tissueChordoid tissueII. Adult connective and supportive tissuesII. Adult connective and supportive tissues

Adult connective tissuesAdult connective tissues1. Loose connective tissue1. Loose connective tissue2. Dense irregular connective tissue2. Dense irregular connective tissue3. Dense regular connective tissues3. Dense regular connective tissues

CollagenCollagenElasticElastic

4. Reticular connective tissue4. Reticular connective tissue5. Adipose tissue5. Adipose tissue

White adipose tissueWhite adipose tissueBrown adipose tissueBrown adipose tissue

Adult supportive tissues (see later)Adult supportive tissues (see later)

Embryonic connective tissuesEmbryonic connective tissuesMesenhymeMesenhymeThree-dimesional network ofThree-dimesional network of irregular-shaped cells + abundant ground irregular-shaped cells + abundant ground substance (no fibers). substance (no fibers). Function: gives rise to various types of adult connective tissueFunction: gives rise to various types of adult connective tissue

Occurrence:

• Body of embryo• In the adult around blood vessels

Embryonic connective tissuesEmbryonic connective tissuesGelatinous connective tissueGelatinous connective tissue

Cross-section of theCross-section of theumbilical cordumbilical cord

Occurrence in adult:Occurrence in adult:Omasal laminaeOmasal laminaeBovine glans penisBovine glans penisCore of rooster combCore of rooster comb

Tissue components:Tissue components:Stellate fibroblasts,Stellate fibroblasts,amorphous ground substanceamorphous ground substancecollagen fibrilscollagen fibrils

Embryonic supportive tissueEmbryonic supportive tissueChordoid tissueChordoid tissue

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1. Cross-section fo an embryo. The arrow points at the notochord2. Cross-section of the notochord3. The chordoid tissue in a young notochord composed of large polygonal cells

ADULT CONNECTIVE TISSUES:ADULT CONNECTIVE TISSUES:Loose connective tissueLoose connective tissueThe most widely distributed type of CTThe most widely distributed type of CTPresent around blood vessels and nerves, between muscle bundles, Present around blood vessels and nerves, between muscle bundles, beneath epithelia, in pia mater and arachnoideabeneath epithelia, in pia mater and arachnoideaFunctions:Functions: support, dampeningsupport, dampening

tissue repair, defence activitiestissue repair, defence activitiesTissue components:Tissue components: free and fixed cells (dominating, see before)free and fixed cells (dominating, see before)

collagen, elastic and reticular fiberscollagen, elastic and reticular fibersground substanceground substance

ADULT CONNECTIVE TISSUESADULT CONNECTIVE TISSUESDense irregular connective tissueDense irregular connective tissueCollagen fibers are the most abundant tissue components arranged Collagen fibers are the most abundant tissue components arranged in bundles crossing each other at various angles. in bundles crossing each other at various angles. From among cell types fibroblasts and fibrocytes predominate.From among cell types fibroblasts and fibrocytes predominate.Occurrence: Occurrence: aponeuroses, muscular fascia, capsules of organs,aponeuroses, muscular fascia, capsules of organs,

dermis, pericardium.dermis, pericardium.

ADULT CONNECTIVE TISSUES:ADULT CONNECTIVE TISSUES:Dense regular connective tissueThe fibers are arranged in the same plane and directionOccurs in collagen tendons and elastic ligaments

Collagen tendon longitudinal section. Arrows point atCollagen tendon longitudinal section. Arrows point atelongated nuclei of tendocytes. H.E. stainingelongated nuclei of tendocytes. H.E. staining

Elastic ligament longitudinalElastic ligament longitudinalsection. Resorcin-fuchsin section. Resorcin-fuchsin stainingstaining

Elastic ligaments:Ligamentum flavum (see above)Ligamentum nuchaeElastic fasciae of abdominalmusculature of herbivores

ADULT CONNECTIVE TISSUEADULT CONNECTIVE TISSUEReticular connective tissue: Reticular connective tissue: forms the stroma fo all lymphatic organs (spleen,lymph node,forms the stroma fo all lymphatic organs (spleen,lymph node,hemal node, tonsils, etc.)hemal node, tonsils, etc.)Tissue components:Tissue components:Stellate reticular cells + complex three-dimensional network Stellate reticular cells + complex three-dimensional network

of reticular fibersof reticular fibers

ADULT CONNECTIVE TISSUESADULT CONNECTIVE TISSUESAdipose tissues:Adipose tissues:Specialized to multiple functionsSpecialized to multiple functionsWhite adipose tissue:White adipose tissue: unilocular adipocytes + collagen and reticular fibersunilocular adipocytes + collagen and reticular fibersFunctions:Functions: thermal and mechanical insulation,thermal and mechanical insulation,

dampening (digital pads)dampening (digital pads)stored energy sourcestored energy sourcehormone-production (leptin)hormone-production (leptin)

ADULT CONNECTIVE TISSUESADULT CONNECTIVE TISSUESBrown adipose tissue:Brown adipose tissue: multilocular adipocytes (lot of multilocular adipocytes (lot of mitochondria) + collagen and reticular fibersmitochondria) + collagen and reticular fibersFunction: non-shivering thermogenesisFunction: non-shivering thermogenesis

Occurrence: in newborns, Occurrence: in newborns, rodents and hibernating animalsrodents and hibernating animals(axillary and neck region, (axillary and neck region, interscapular fat, thoracic aorta,interscapular fat, thoracic aorta,mediastinum, mesenteries,mediastinum, mesenteries,vena cava dorsal to kidney)vena cava dorsal to kidney)