Thyroid gland blood vessels. Coloured scanning electron micrograph (SEM) of a resin cast of blood vessels in the thyroid gland. The smallest blood vessels, capillaries, are coiled around individual secretory areas known as lobes (rounded structures). Larger blood vessels bring blood to and from the capillaries. This network of vessels exchanges gases, hormones and nutrients with the gland tissue through the permeable walls of the capillaries. The thyroid gland, part of the endocrine system, lies at the base of the neck. The hormones it secretes into the bloodstream control metabolism and growth. The cast was made by injecting resin into the blood vessels. The surrounding tissues were then chemically digested.
Science Photo Library was founded in 1981 by Michael Marten, one of the authors of "Worlds Within Worlds", a book exploring different ways to observe the universe - from electron micrographs, to images of earthrise taken from the Apollo spacecraft. When Marten started receiving requests for the beautiful images in the book, he had an idea of setting up Science Photo Library.
Since then, Science Photo Library has continued to work alongside world acclaimed photographers and the leading science and medical experts to provide a central source of the best science and specialist imagery available. Although the collection started with scientific images, it has grown to encompass all aspects of science and their impact on everyday life.
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