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Category Archives: Histology

Urinary Concentration – The Medullary Osmotic Gradient


The kidneys can produce a range of urine osmolalities depending on the levels of ADH. The production of hypo-osmotic urine is an understandable process: The tubules (particularly the thick ascending limb of Henle's loop) reabsorb relatively more solute than water, and the dilute fluid that remains in the lumen is excreted. The production of hyperosmotic […]

[Histology] The Blood Tissue


Major Componments of Blood Blood is a specialized connective tissue in which cells are suspended in fluid extracellular material called plasma (ECM/extracellular matrix). When blood leaves the circulatory system, either in a test tube or in the ECM surrounding blood vessels, plasma proteins (coagulation factors) react with one another to produce a clot, which includes […]

[Histology] Basic Four Types of Tissues – Connective Tissues


The different types of connective tissue maintain the form of organs throughout the body. Differences in composition and amount of the cells, fibers, and ground substance make up variety of connective tissue types. Connective tissues provide a matrix that supports and physically connects other tissues and cells together in organs. The interstitial fluid of connective […]

[Histology] Basic Four Types of Tissues – Epithelia Tissues


Cells and ECM Tissues have two interacting components: cells and extracellular matrix (ECM). The ECM consists of many kinds of macromolecules, most of which form complex structures, such as collagen fibrils and basement membranes. The ECM supports the cells and the fluid that transports nutrients to the cells, and carries away their catabolites and secretory […]

Functions of the Skin


Histology of Skin Epidermis The epidermis consists mainly of a stratified squamous keratinized epithelium composed of cells called keratinocytes. There are also other three much less abundant epidermal cell types: pigment-producing melanocytes, antigen-presenting Langerhans cells, and epithelial cells called Merkel cells. From the dermis, the epidermis consists of four layers of keratinocytes (or five layers […]