The heterochromatin-euchromatin pattern of a carcinoid tends to be coarse, as you can see here. But you see the nuclear membranes are intact, so these are not mitotic figures. There is a conspicuous lack of anaplasia. This tumor has a fairly dense fibrous stroma. Carcinoid cells are fastened together by desmosomes.
Carcinoid tumors come from cells related to nerve cells.
Often they produce serotonin. This and other substances produced by these tumors can have a variety of effects systemically.