Angiogenesis is a fundamental process of microvascular growth and expansion implicated in different physiological and pathological processes. It can occur by two main mechanisms: sprouting and intussusception. Although both mechanisms lead to creation of new vascular segments, they involve different morphogenic mechanisms and probably are regulated by different factors.
Sprouting angiogenesis is characterized by local vasodi-lation, followed by increased vascular permeability. After proteolytic degradation of the basement membrane, the endothelial cells migrate into the extracellular matrix and proliferate. After internal reorganization, the sprouts form a vascular lumen and get connected to other capillary segments. Sprouting is a relatively sluggish process. At least three to five days are needed before the newly formed capillary loop is perfused and integrated into the vascular system.
In intussusceptive angiogenesis, the capillary system expands and grows by the insertion of new capillary meshes into the existing network.
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This ebook provides an introductory explanation of the workings of the human body, with an effort to draw connections between the body systems and explain their interdependencies. A framework for the book is homeostasis and how the body maintains balance within each system. This is intended as a first introduction to physiology for a college-level course.