Smooth muscles Consists of fusiform or spindle shaped cell 15 to 500 microns in length with abundant cytoplasm in whose central thickest position the nucleus lies. The nucleus is oval elongated or rod-shaped. The nuclei of contracted muscle cells usually have a folded outline. The cytoplasm contains the usual organoids and appears more or less […]

Three types of muscle viz., smooth, skeletal and cardiac are distinguishable histologically- Smooth or non-striated muscle lacks the cross striations seen in other two muscles. The smooth muscle is involuntary, being especially associated with viscera which are not under the voluntary control. Skeletal muscle is striated and voluntary making up the bulky muscles of the body. Cardiac or heart muscle is striated

Red marrow (Myeloid tissue) is composed of stroma of reticular cells and fibres with free cells located in the meshwork. The stroma also shows varying number of fat cells. Majority of free cells in bone marrow are the developmental stages of the granulocytes and a few lymphocytes, monocytes and plasma cells. Sinusoids are numerous and

Leucocytes (White blood cells) are nucleated, (true cells) and may be divided into non-granular  (agranulocytes) and granular (granulocytes) varieties. The cytoplasm of granular leucocytes shows numerous granules. In many, these granules are fine and slightly refractive but in others they are coarse and highly refractive. Chicken 19.8 Cat 17.2 Swine 14.9 Goat and guinea pig 12 Dog 11.3 Sheep 9.2

Erythrocyte (Red blood corpuscles) are highly differentiated and specialized for the function of transporting oxygen. In the lower vertebrates, the erythrocyte is nucleated but in mammals, it loses it nucleus, Golgi apparatus, mitochondria and centroiles before entering blood stream. The erythrocytes are acidophilic biconcave discs and round in all mammals except in camel and llama

Blood is the connective tissue consisting of free cells and a fluid intercellular substance or plasma. The structural elements of Mammalian blood include red blood corpuscles (erythrocytes), white blood corpuscles (leucocytes) and blood platelets.

Bone is richly supplied with blood vessels and nerves which pass into it form the periosteum. An artery, the medullary artery runs through the nutrient canal, through the nutrient foramen into the marrow cavity. In its course through compact bone, the branches of the medullary artery communicate with the vessels of the Haversian canal. The

Bone marrow is a soft tissue which occupies the medullary cavity of the long bones and the space between trabeculae of spongy bone. It consists of a delicate reticular connective tissue in the meshes of which are many kinds of cells. Two varieties of marrow are seen, red and yellow. Red marrow: It is the

Periosteum is a fibrous membrane investing the bones except at their articular surfaces. It consists of two layers, the outer of which is composed of course fibrous connective tissue containing few cells but numerous blood vessels and nerves. The inner layer is more cellular and less vascular and contains many elastic fibres. In the growing

Cancellated bone consists of a network of columns of lamellae enclosing spaces which contain bone marrow. There are no Haversian systems.