General Histology Lecture 2 PDF - 26/9/2024 - Al-Iraqia University

Lecture 2 General Histology Prof. Dr. Ammar Ismail 26/9/2024 Al-Iraqia University College of Dentistry Second Class General Histology Lec: 2 Prof. Dr. Ammar Ismail Jabbar  Lecture 2 General Histology Prof...

Lecture 2 General Histology Prof. Dr. Ammar Ismail 26/9/2024 Al-Iraqia University College of Dentistry Second Class General Histology Lec: 2 Prof. Dr. Ammar Ismail Jabbar  Lecture 2 General Histology Prof. Dr. Ammar Ismail 26/9/2024 Connective Tissue: serves a connecting function. It supports and binds other tissues in the body. General Features of Connective Tissue 2 basic parts: ∙ Cells and Matrix ∙ Matrix – material between widely spaced cells ∙ Consists of protein fibers and ground substance ∙ Ground substance – material between cells and fibers secreted by the cells and determine the tissue qualities Note: the matrix of connective is invaded by blood and enervated by nerves Ground Substance: It is a complex of highly hydrophilic, viscous, amorphous, gel-like material composed of mucopolysaccharide especially hyaluronic acid which fills the space between the cells. The ground substance formed from macro molecules of an ionic material can bind large quantities of water without changing its viscosity. The function of ground substance are to act as a barrier against viruses and foreign protein, also form a medium through which nutrients and metabolic wastes are exchanged between cells and their blood supply. Fibers : The connective tissue fibers are formed by proteins that polymerize into elongated structures. there are three main types of connective tissue fibers collagen, reticular, and elastic. 1– Collagen fibers : (White fibers ) -a bundle of fibrils ,  Lecture 2 General Histology Prof. Dr. Ammar Ismail 26/9/2024 -The bundle have a wave form and are branched and units. The fibroblast produce protein molecules ( tropo collagen ) which consider as a fine unit of collagen fiber. In fresh case it appears white color ;therefore,called white fibers. It is inelastic and possess great tensile strength , it is found in the tendon. 2 – Elastic fibers : yellow fibers : Elastic fibers are always single , very thin , branch and re unite frequently. They consist of elastin ( Tropo elastin ) which is a very resistant material. 3 – Reticular fibers : -These fibers branch and unite to form a fine reticulum -very thin. -stained especially by silver, called argyrophilic fibers. Connective Tissue Cells Free cells Fixed cells 1 – Plasma cells. 1 – Fibroblasts. 2 – Lymphocytes 2 – Adipose cells 3 – Neutrophiles 3 – Pericytes. 4 – Eosenophils. 4 – Mast cells 5 – Basophiles. 5 – Macrophage. 6 – Monocytes 6 – Pigmented cells 7 –Macrophages  Lecture 2 General Histology Prof. Dr. Ammar Ismail 26/9/2024 Fibroblast : Its responsible for producing and secretion the ground substance and fibers. It is derived from undifferentiated mesenchymal cells. The fibroblast is an elongated oval or spindle shape has long cytoplasmic processes, with spherical nucleus. Pericyte: Pericyte is smaller than fibroblast except have long processes. Its surrounds the endothelial cells of capillaries and small venules. Adipose cells : Are fully differentiated cells that function in the synthesis, storage and release of fat. Adipocytes are large spherical cells, when filled with the fat the nucleus and cytoplasm are displaced to the peripherally thus giving these cells a ring shape. Mast cell It’s a largest of fixed cells of connective tissue. they are avoid and possess a centrally placed, spherical nucleus. The characteristic feature of this cells is the presence of numerous granules in the cytoplasm which contain heparin, histamine. Pigmental cells : The cells are oval , large , have process and there cytoplasm have melanin granules , its found in the cornea & retina of eye  Lecture 2 General Histology Prof. Dr. Ammar Ismail 26/9/2024 Classification of connective tissue Types of connective tissue Embryonic connective tissue 1 – Mesenchymal c.t. : Is present only in the embryo, consist of mesenchymal cells in semi fluid amorphous ground substance containing a fine scattered immature fibers. The mesenchymal cell present an oval nucleus and its cytoplasm have a small processes in several directions. The mesenchymal cell characterized by undifferentiated. 2-connective tissue. Mucoid – Is a loose amorphous c.t. exhibiting a jelly – like matrix, considered as a temporal c.t containing cells similar to the mesenchymal cell, this type has fiber. This  Lecture 2 General Histology Prof. Dr. Ammar Ismail 26/9/2024 tissue also known as Warton jelly which found only in the Umbilical cord. Connective tissue proper( adult ) : A-Loose c.t. 1 – Areolar connective tissue: Its wide spread throughout the body, surrounding vessels, and nerves and is found in the serous membrane. This type of connective tissue contains all types of connective tissue cells and fibers. 2 – Reticular tissue : The type III collagen is the major fibre forming network interspersed with fibroblasts and macrophages. Reticular tissue forms the architectural framework of liver sinusoid, adipose tissue, bone marrow, lymph node, and spleen. 3-Adipose tissue: It is believed that adipose cells are derived from undifferentiated embryonic stem cells which enrich with blood vessels. also become enlarged after loss of cytoplasmic processes and accumulation of fat droplets. B-Dense connective tissue : Contain most of the same components found in loose c.t. ,except that it has many more fibers and few cells. the orientation and the arrangements of bundles of fibers in this tissue make it resistant to stress. Include :  Lecture 2 General Histology Prof. Dr. Ammar Ismail 26/9/2024 -Dense regular collagenous c. t.: the bundles of collagen fibers may be arranged in row to provide tensile strength in tendons and ligaments. -Dense regular elastic c.t. : the bundles of elastic fibers instead of collagen fibers.nuchal lig. - Dense irregular c. t. : the fibers are arranged in different planes to allow stretching without tearing of the surface membrane as in the dermis and vagina.