There are several types of PhD - one which is, in effect, a book, one which is, in effect, a series of papers, and one which is, in effect, a single giant paper.
The first form is common in arts and social sciences here in Ireland, and many of theses end up being published as books.
The third format was the usual format here, both in physical and biological sciences, and was often laid out as 'Introduction', 'Materials and Methods', 'Results' (usually more than one chapter), and 'Discussion'. This is falling out of favour, because it is too hard to produce papers from it.
We are moving, slowly, to the second form, which is the norm in the Netherlands, Sweden, and Finland ( and may be in other places too). This is a short introduction, a series of papers, or chapters in paper format, some of which have been published, possibly a linking narrative between chapters, and a final discussion section.
I've supervised one person, whose PhD was ten papers, eight published, and two or so, in draft. He was (and is) a capable and prolific researcher, who had just never got around to a PhD, and was applying for a chair. Needless to add, he got the PhD and the chair :-)