The pig is only an example, just an animal. Leydig cells have protein inclusions (Reinke crystals) that are mostly made of crystallised lipofuscin. They are secretory inclusions i.e. cells formed in secreting cells.
An example of Leydig cell in pig's testicle:
My teacher told me that there is a difference in the existence of some cells between humans and animals. However, I cannot find such a difference. I have not been provided a slide of human Leydig cell so I have not been able to compare.
What is the morphological difference between Leydig cell in human and pig?