The queen ant in my young Camponotus chromaiodes colony has started "Physogastriming." This is when the ovaries of a queen ant kick into high gear and start producing eggs at a much higher rate than typical in the year. Normally when queen ants do this it's done in phases to produce large batches of eggs. This helps the colony hit a sudden population burst early in the year for probably a whole lot of different reasons. It makes up for not laying over the winter, the added workers will make the colony more competitive with other colonies, they can steak out their territory better, and if they need to find a better location or additional satellite locations to extend the nest then they're better able to do that and populate them with defenders.
Workers do something similar but not exactly. Even though they're sterile, they can still have ovaries and in some species it's common for workers to even lay eggs of their own. That is not the case here (I don't think.) Usually these tropic eggs are offered as food to the queen or her larva. In the rare case that they do develop they will only ever become a male because they're not fertilized. In a different genus, Formica, it's common the majority of the males in the colony to have been born from the workers.
More commonly though, workers will become repletes. The food is simply stored in a social stomach and as it expands we see a similar effect with the white membrane showing through.