1. Don’t sweat it: the answer is at your fingertips!

    Investigation

    Goal

    To ascertain whether there are variations in the number of sweat glands in residents of different climates.

    Research question

    Do the number of sweat glands in residents of differing climates vary?

    Equipment

    • A Digital Blue QX7 digital microscope or any digital school microscope that takes pictures.
    • PVA (polyvinyl acetate) glue or medical “skin” glue BF-6.

    Why use data from multiple participants?

    Data from a large number of project participants from different regions is necessary in order to determine whether there are variations in the amount of sweat glands in residents of different climates.

    Investigation Protocol

    1. Apply a thin layer of glue to the pad of the index finger. This creates an accurate mold of one’s skin surface. On this cast the ducts of sweat glands appear as holes and are fairly evenly distributed throughout the area.
    2. After 5-10 minutes, when the glue is completely dry, remove the resulting film.
    3. Place the glue cast of your finger on the glass slide.
    4. Look at the slide under the microscope at a magnification strength of10x and then at 60x. Magnified 10x the excretory ducts look like points; increasing the strength to 60x will give you an even clearer picture of the holes.
    5. If you are using a Digital Blue QX7 microscope, count the number of sweat glands per 1 mm ² at 60x magnification according to the procedure below. If you are using any other digital microscope please refer to the manual.
      - Select the "Line" tool in the Microscope menu and use it to select an area of 1 mm².
      - Choose the "Grid" tool from the menu and apply a grid on the selected area.
      - At the 60x magnification each square of the grid is 0.5 mm x 0.5 mm. That means that an area of 1 mm² consists of four small squares.
      - Count the glands inside the four small squares. To avoid accidentally counting the glands that are on the lines between the squares twice, stick to counting glands only inside each square and on the left and top border of the same square.
    6. Take a picture of the slide at 60x magnification.
    7. Browse the data obtained by other participants, compare and analyze findings using charts and maps. Did you find an answer to the Research Question?

    Safety tips

    If you have sensitive skin or are prone to allergic reactions, instead of PVA glue, you can use medical glue BF-6. This “skin” glue (BF-6) bonds tightly with the skin, making its removal from the finger slightly harder than that of PVA glue.

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    • Project was published on:October 10, 2013
    Report Form Before filling in the Report Form, please read the Investigation Protocol