I do notice that only the mucus membrane, blood, hair, sweat gland, and hair follicle slides specifically say they're from a human, the others could be from a p

I do notice that only the mucus membrane, blood, hair, sweat gland, and hair follicle slides specifically say they're from a human, the others could be from a pig or any other large mammal and it would be very hard to tell the difference. Were I buying an assortment of electronics and a few items were labeled with a brand name and others were unlabeled, I'd assume the unlabeled ones were generic. Also, one cadaver can generate an awful lot of slides. Each slide requires on the order of a microliter (1/1000 of a milliliter) of material, and a good microtome can cut samples with a thickness of a few micrometers (1/1000 millimeters). Essentially all medical students go through an anatomy class involving the dissection of a cadaver, and Google says there are 3.8 million doctors in China, so even with a generous assumption of 20 students per cadaver and a static field (it's not) with 50-year careers, that's still several thousand cadavers per year.