This is a dermoid cyst of the ovary. These are tumors that arise from the cells that could have become eggs instead. Like most of these tumors, this one is mostly skin, only it is turned inside, so that skin debris accumulates and makes it grow.
Opened, you can see hair, and the greasy yellowish fatty oils and keratin of the skin.
The second picture is a photomicrograph shows stratified squamous epithelium, just like in skin.
The third picture shows some sebaceous (skin oil) glands.
We also found thyroid tissue and the stellate reticulum of a beginning tooth. Many ovarian dermoids have a wealth of other tissues.
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