In a bisexual flower, the stamen (male part) includes the anther and filament.
\begin{itemize}
\item (a) Anther: This part of the stamen generates pollen grains, which carry the male gametes.
\item (b) Ovary: The ovary, part of the pistil (female part), holds ovules containing the female gamete (egg cell).
\item (c) Stigma: The stigma is the pistil's tip, where pollen is received.
\item (d) Filament: The filament is the anther's supporting stalk.
\end{itemize}
Male gametes develop inside pollen grains, produced in the anther.
\[ \boxed{\text{anther}} \]