1. HISTOLOGY 1.6.: CONNECTIVE AND SUPPORTIVE TISSUES CLASSIFICATION OF CONNECTIVE AND SUPPORTIVE TISSUES I.Embryonic connective and supportive tissue MesenchymeMesenchyme Gelatinous connective tissueGelatinous connective tissue Chordoid tissueChordoid tissue II. Adult connective and supportive tissues Adult connective tissues 1. Loose connective tissue 2. Dense irregular connective tissue 3. Dense regular connective tissues CollagenElastic 4. Reticular connective tissue 5. Adipose tissue White adipose tissue Brown adipose tissue Adult supportive tissues (see later)

2. Embryonic connective tissues Mesenhyme Three-dimesional network of irregular-shaped cells + abundant ground substance (no fibers). Function: gives rise to various types of adult connective tissue Occurrence: Body of embryo In the adult around blood vessels

3. Embryonic connective tissues Gelatinous connective tissue Cross-section of the umbilical cord Occurrence in adult: Omasal laminae Bovine glans penis Core of rooster comb Tissue components: Stellate fibroblasts, amorphous ground substance collagen fibrils

4. Embryonic supportive tissue Chordoid tissue 1 2 3 1.Cross-section fo an embryo. The arrow points at the notochord 2.Cross-section of the notochord 3.The chordoid tissue in a young notochord composed of large polygonal cells

5. ADULT CONNECTIVE TISSUES: Loose connective tissue The most widely distributed type of CT Present around blood vessels and nerves, between muscle bundles, beneath epithelia, in pia mater and arachnoidea Functions:support, dampening tissue repair, defence activities Tissue components:free and fixed cells (dominating, see before) collagen, elastic and reticular fibers ground substance

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

7. ADULT CONNECTIVE TISSUES: Dense regular connective tissue The fibers are arranged in the same plane and direction Occurs in collagen tendons and elastic ligaments Collagen tendon longitudinal section. Arrows point at elongated nuclei of tendocytes. H.E. staining

8. Elastic ligament longitudinal section. Resorcin-fuchsin staining Elastic ligaments: Ligamentum flavum (see above) Ligamentum nuchae Elastic fasciae of abdominal musculature of herbivores

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

10. ADULT CONNECTIVE TISSUES Adipose tissues: Specialized to multiple functions White adipose tissue: unilocular adipocytes + collagen and reticular fibers Functions:thermal and mechanical insulation, dampening (digital pads) stored energy source hormone-production (leptin)

11. ADULT CONNECTIVE TISSUES Brown adipose tissue: multilocular adipocytes (lot of mitochondria) + collagen and reticular fibers Function: non-shivering thermogenesis Occurrence: in newborns, rodents and hibernating animals (axillary and neck region, interscapular fat, thoracic aorta, mediastinum, mesenteries, vena cava dorsal to kidney)