Answer to Case 712

 Answer to the Parasite Case of the Week 712: Schistosoma sp. egg within an eosinophilic granuloma.

As nicely described by Idzi (with minor edits from me), "When the eggs are deposited by the female worm in the arterial plexus of intestines/bladder, many of these eggs will flow back to the liver. In the picture, I can’t see the egg’s spine, so the exact species remains unknown, but we can see the refractive egg shell with miracidium inside. At the miracidium’s terebratorium (upper left), we can see one of the two lateral secretory glands (staining basophilic). Right behind this gland, we see part of a ring of nerve cells (surrounding the cephalic gland), creating some of the typical “bulls-eye” aspect. The dark staining round structures everywhere would be germ cells."

It's hard to appreciate the full ring of germ cells ("bulls-eye") in this image, but here is a photo of a different case that nicely shows the ring.