^^A small bundle of fiber-optic cables attached to the camera, a microscope and a common fluorescent dye allowed doctors to easily distinguish cancerous cells from healthy cells by viewing the LCD monitor on the back of the camera.
How is this sentence constructed?
I am seeing it as "a microscope" is used to explain this particular camera is a microscope.
A camera and a microscope are two different devices. I don't think there's a need to call one the other name. Even if a camera is indeed a microscope here, then the punctuation is wrong. I would write it: "A small bundle of fiber-optic cables attached to the camera (a microscope) and a common..."
If the fiber-optic is attached to both of the camera and the microscope then the sentence should be:
"...attached to the camera and the microscope and a common..." right? Yes, I agree. It would be so.
Another possibility is there are 3 objects.
fiber-optic cables attached to the camera as one subject
a microscope as second
and fluorescent dye as third.
Yes, I think you're right here. The way the sentence is written suggests to me that there are indeed 3 objects.
However there's no comma before the and which makes me think there are only two objects:
cables attached to the camera and a fluorescent dye.
The absence of comma doesn't say anything. A serial comma is a moot point in English punctuation; some people use it, others prefer to leave it out - you never know.
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