diff --git a/Doc/c-api/init.rst b/Doc/c-api/init.rst
index d3a2a3b..ab4734f 100644
--- a/Doc/c-api/init.rst
+++ b/Doc/c-api/init.rst
@@ -489,13 +489,13 @@
 global variable). Conversely, when acquiring the lock and restoring the thread
 state, the lock must be acquired before storing the thread state pointer.
 
-Why am I going on with so much detail about this?  Because when threads are
-created from C, they don't have the global interpreter lock, nor is there a
-thread state data structure for them.  Such threads must bootstrap themselves
-into existence, by first creating a thread state data structure, then acquiring
-the lock, and finally storing their thread state pointer, before they can start
-using the Python/C API.  When they are done, they should reset the thread state
-pointer, release the lock, and finally free their thread state data structure.
+It is important to note that when threads are created from C, they don't have
+the global interpreter lock, nor is there a thread state data structure for
+them.  Such threads must bootstrap themselves into existence, by first
+creating a thread state data structure, then acquiring the lock, and finally
+storing their thread state pointer, before they can start using the Python/C
+API.  When they are done, they should reset the thread state pointer, release
+the lock, and finally free their thread state data structure.
 
 Threads can take advantage of the :cfunc:`PyGILState_\*` functions to do all of
 the above automatically.  The typical idiom for calling into Python from a C
diff --git a/Doc/c-api/structures.rst b/Doc/c-api/structures.rst
index b654eb7..7048968 100644
--- a/Doc/c-api/structures.rst
+++ b/Doc/c-api/structures.rst
@@ -69,7 +69,24 @@
    Note that :cmacro:`PyObject_HEAD` is part of the expansion, and that its own
    expansion varies depending on the definition of :cmacro:`Py_TRACE_REFS`.
 
-.. cmacro:: PyObject_HEAD_INIT
+
+.. cmacro:: PyObject_HEAD_INIT(type)
+
+   This is a macro which expands to initialization values for a new
+   :ctype:`PyObject` type.  This macro expands to::
+
+      _PyObject_EXTRA_INIT
+      1, type,
+
+
+.. cmacro:: PyVarObject_HEAD_INIT(type, size)
+
+   This is a macro which expands to initialization values for a new
+   :ctype:`PyVarObject` type, including the :attr:`ob_size` field.
+   This macro expands to::
+
+      _PyObject_EXTRA_INIT
+      1, type, size,
 
 
 .. ctype:: PyCFunction