A fluorescent photo of a turtle embryo took first place. The photographers stacked and stitched together hundreds of images to fully capture every detail.
A trippy image of three stentors, a type of single-celled protozoa that lives in freshwater and feeds on algae, snagged second place.
A photo showing a fluorescent alligator embryo came in third. The picture was taken just 20 days into the creature's development, as nerves and a skeleton formed.
Here are the rest of the top 20 selections, followed by 20 of our personal favorites:
4. The bushy antennae of a male mosquito.
5. A crystal-clear snowflake.
6. The soul-piercing eyes of a small spider covered in white hair.
7. The pollen-releasing stamen of a Chinese red carnation.
8. A frozen water droplet magnified eight times.
9. A tulip bud, sliced open to show the petals and stamen curled inside.
10. Cells from the pulmonary artery of a young cow undergo the telophase stage of mitosis, in which they form two nuclei before dividing into two new cells.
11. The ovaries of a fruit fly. The protein filament F-actin is stained yellow, nuclei are green, and follicle cells are magenta.
12. A squirming mosquito larva.
13. Cuprite, a mineral composed of copper oxide.
14. A female lynx spider.
15. A pregnant freshwater crustacean called Daphnia magna.
16. A housefly's eye, magnified 50 times.
17. A crystal of ascorbic acid, also known as vitamin C, reveals fascinating structures under a microscope.
18. A crystal of cristobalite suspended in quartz.
19. A California two-spot octopus embryo.
20. Blood vessels in a mouse heart after it suffered a heart attack.
In addition to those winners, 15 photos got honorable mentions. Here are the best ones, starting with this image of a moth wing.
Mold grows on a plum seed.
A blend of vitamin C crystals and sugar.
A fossilized ammonite: a sea creature that went extinct around 66 million years ago.
Amino acids, the building blocks of proteins and life, crystallized under a microscope.
Dozens more fantastic photos received recognition from the judges as "images of distinction." This one show eggs inside a brine shrimp.
A cereal rye leaf curls around its stem.
A tiny daphnia, a crustacean also known as a water flea.
Karlsbad Sprudelstein, a type of sedimentary rock.
A single-celled organism called Paramecium caudatum, which had been fed yeast cells stained with red dye.
The deer-like antennae of a Haplomalachius flabellatus insect.
A mouse's mammary gland, which was grown in a lab.
The threads of a striated muscle cell in heart tissue, which was developed from a human stem cell.
The magnified surface of a seed.
The sporangia structures that produce spores, tucked inside the leaf of a lady fern.
A bearing from a mechanical watch.
Myoepithelial cells wrapped around milk-producing sacs in a mouse's mammary gland.
A single-celled algae called Triceratium morlandii.
An ornate crystal of methylsulphonal, an organic sulfur compound.
