Question regarding infant 'leaky gut'

[Heyanonynonymous]

Does anyone have any well researched articles regarding the open gut in infants? I've just read this article: health-e-learning.com/artic..., and I'm a bit annoyed to see that nearly all of it has sources cited, but there is no source for this statement: "Tight junctions of the GI mucosa take many weeks to mature and close the gut to whole proteins and pathogens." And I would like to learn some more of the specifics, as I've heard supplementing with any formula could prevent the gut from ever closing, linking to adult 'leaky gut,' which isn't even a proven condition at all, and I'm just sceptical about it in general. Open gut in infants appears to be a different thing, but I would like some evidence backed information about how long it takes for the gut to mature and what exact harm is caused by the ph difference brought on by any formula supplementation.

Thanks!