Close Up with Human Skin

What am I looking at?

This is a fluorescently labeled section of embryonic human skin. The dark, diagonal slash through the center of the image is a hair follicle (1). The pink areas are stem cells in the hair follicles that will eventually grow hair (2). The developing bud of a sweat gland can be seen as a bulb of blue and green near the top of the image (3). The nuclei of all the cells are shown in blue (4). And the green line is the basement membrane of the epithelium – the supporting structure that skin grows on (5).

Biology in the background

Our skin protects us from the external environment and is considered to be the largest organ in the human body. The hairs on our skin grow from hair follicles, which are tiny tubes in the skin with cells that produce hair lining their bottom. These cells are constantly working to produce hair, which is why most of us are in need of a haircut regularly.

Sweat glands produce sweat on our skin. Humans are born with between two million and four million sweat glands. The primary function of sweat is to cool us off, via evaporative cooling, when our body temperature rises. In addition, sweat contains antimicrobial compounds that help control the growth of bacteria on our skin.

A human hair follicle can vary in size, with the largest being about 100 micrometers across, or slightly larger than the width of the strand of hair that grows out of it. A sweat gland has an inner diameter of up to about 80 micrometers, or roughly the same size as the width of a human hair.

Technique

This image was created using confocal microscopy.