Answer to Case 550

Answer toParasite Case of the Week 550:Ascaris lumbricoideseggs, decorticatedKudos to everyone who took the time to write in with their answer. All responses were correct! And I really enjoyed hearing about the different layers of of nematode eggs from Old One and Blaine. Here is some of the information they shared in their comments, along with some definitions:Decorticated - To remove the bark, rind, or husk from; i.e., to remove the outer mammillated layerMammillated - Having relatively small protrusions from the exterior, most commonly the surfaceThis case happened to have both mammillated and decorticated eggs, with a large number of the latter:When only decorticated eggs are seen, they can be confused for other helminth eggs such as hookworm andSchistosoma japonicum.Fortunately the size and thick shell can be used to reliably differentiate them.So what are the layers of a nematode egg?  There are several (from outer to inner), as described by Old One and Blaine, with a few comments from my own research:Mucopolysaccharide/protein coat - not present in all nematode eggs; this is an exogenous product of the nematode uterus and what is referred to as the ' mammillated ' albuminous layer. It is unique to each species and often stained by the bile salts of its host (yellow, orange, to brown). It is often uniquely textured during its creation. This layer may be friable, hence the decortication seen in this week ' s specimen. Vitelline layer - derived from the vit...
Source: Creepy Dreadful Wonderful Parasites - Category: Parasitology Source Type: blogs