垂直椭圆节点

Question

我怎样才能使这个椭圆节点垂直（高度 > 宽度）。我尝试使用 `` 似乎不起作用。

\documentclass{amsart}
\usepackage{tikz}
\usetikzlibrary{shapes}

\begin{document}
\begin{tikzpicture}[scale=1.5]
\fill[gray!20!white] (-0.5,-0.4)rectangle(0.5,0.4);
\node at (0,0) [ellipse, minimum height =2,draw] (V) {\makebox[1.4\width][c]{x}}; 
\draw(V) to coordinate[pos=0.9](D1)  (-0.5,0.4);
\draw (V) -- (-0.5,-0.4);
\draw (V) to coordinate[pos=0.9](D2) (-0.5, -0.15);
\node at  (-0.4,0.13) {\vdots};
\draw (V) -- (0.5,-0.4);
\draw (V) -- (0.5, -0.15);
\draw (V) -- (0.5,0.4);
\node at (0.4,0.13) {\vdots};
\end{tikzpicture}
\end{document}