The ovule initially consists of a stalked, integumented "megasporangium" (also called the "nucellus"). It is structurally and functionally equivalent to the megasporangium. A megasporocyte inside a megasporangium or ovule undergoes meiosis, producing four megaspores. The ovule appears to be a megasporangium with integuments surrounding it. The megaspore mother cell arises within the megasporangium tissue. Anthers typically consist of four microsporangia and an ovule is an integumented megasporangium. The remnants of the megasporangium tissue (the nucellus) surround the megagametophyte. Seeds consist of an endosporic megasporangium surrounded by one or two sheathing layers (integuments). "Runcaria", small and radially symmetrical, is an integumented megasporangium surrounded by a cupule. A megasporangium enclosed in a protective layer called an integument is known as an ovule. Typically, one cell in the megasporangium undergoes meiosis resulting in one to four megaspores. One kind, the megasporangium, produces only a single large spore (a megaspore). The megasporangium bears an unopened distal extension protruding above the multilobed integument. The megasporangium bears an unopened distal extension protruding above the mutlilobed integument.