Connective tissue & mesenchymal tissue Prepared by: Ms. BR Tsauses Anatomical Pathology 2A (ANP611S) April 2020
Learning objectives • Understand connective and mesenchymal tissues in order to describe and apply appropriate staining techniques in Histology.
Pre-learning Quiz • Please take the pre-learning quiz before proceeding with the presentation.
Introduction • Connective tissue (CT) is of the four tissue types • Derived fom latin word connectere meaning to bind. • Is to connect together and provide support
Introduction cont … • During embryonic development: ectoderm + endoderm = mesoderm • This germ layer is known as mesenchymal • Mesos means middle • Enchyma means infusion
Connective tissue CT are divided into: 1. Connective tissue proper (dense, areolar, regular,adipose regular and reticular 2. Cartilage (hyaline elastic, fibrocartilage) 3. Bone( spongy or cancellous and dense or cortical) 4. Blood 5. Blood-forming (hematopoietic)
Connective tissue cell types • Fibroblast • Mast cells • Histocytes • Adipose cells • Reticulor cells • Osteoblast and osteocytes • Chondroblast and chondrocytes • Blood cells and blood forming cells
Intercellular substance • Intercellular substance (ICS) is composed of both amorphous(sulfated and non sulfated mucopolysaccharides) and formed elements (collagen, reticular fibers and elastic fibers) • The nature of these substance varies according its function (hard or dense or soft.) • Classified into: formed or fibrous type : gel or amorphous type
Formed or fibrous intercellular substances Collagenenic fibers • Most common ICS found in large quantities in most sites • Appear as individual fibers as in loose areolar tissues e. g tendon • Collagenic fibers do not branch • Collagen types: Type (i) up to (vi)
Reticular fibers • Provide bulk of supporting network of more cellular organs e. g spleen, lymph nodes, liver. • To support individual cell within the tissue.
Elastic fibers • Elastic fibers are associated with respiratory system, circulatory system and integumentary system • Oxytalan fibers • Elaunin fibers • Lack structure or functional significance.
Basement membrane • Found throughout the body as resilient matrix separating connective tissue from epithelial • Support epithelial cells • Support epithelial cells lining blood vessels etc • Divided into three zones or layers: - lamina- rara (or lamina lucida) - lamina densa (basal lamina) - lamina reticularis
Connective tissue
Connective Tissue cont.
Connective tissue cont (examples)…
Connective tissue cont …
Connective tissue…
References 1. John D. Bancroft, Christopher Layton and S.Kim Suvarna, (2013),Bancroft’s Theory and Practice of Histological Techniques,7thEdition, Elsevier, China 2. J.A.Kiernan,(2015)Histological and Histochemical Methods, 5thEdition, Scion, UK
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