Your eye.
To mount a Canon lens on a Nikon body, you will need an adapter ring that is compatible with both the Canon lens mount and the Nikon body mount. This adapter ring allows you to physically connect the Canon lens to the Nikon body, enabling you to use the Canon lens on the Nikon camera.
The eyepiece lens, also known as the ocular lens, is located on the superior end of the body tube on a microscope. This lens is where you look through to observe the specimen on the slide.
No, an EF lens will not fit an EF-S camera body.
The Body Tube
convex lens
To remove a camera lens, first locate the release button or switch on the camera body near the lens. Press or slide this button to release the lens. Then, gently twist the lens counterclockwise to unscrew it from the camera body. Be careful not to force it, as this could damage the lens or camera.
In a camera with a removable lens system, the camera body is all of the camera except the lens mechanism. Many more-sophisticated cameras employ a system of removable/ exchangeable lenses. The "camera body" and the "lens" are often sold separately. What is called simply the "lens," though, is really a lens tube with multiple lenses and multiple adjustment mechanisms. It will have a standard connection point that mates to the lens mount on the camera body.
Eye
To remove a Nikon lens, first locate the lens release button on the camera body. Press and hold this button while simultaneously rotating the lens counterclockwise. Once the lens is loose, carefully lift it away from the camera body. Be sure to store the lens in a safe place when not in use.
body tube - for microscope
Yes; the ciliary body is a mass of smooth muscle from which the lens is suspended.
To use a Canon lens on a Nikon body with an adapter, you will need to purchase a lens adapter that is specifically designed to connect Canon lenses to Nikon cameras. Make sure the adapter is compatible with both the lens mount of the Canon lens and the Nikon camera body. Attach the adapter to the Canon lens first, then mount the lens onto the Nikon camera body as you would with a regular lens. Keep in mind that some functionalities may be limited when using a lens adapter, so it's important to test the setup and adjust settings accordingly.