<Grid>
  <Grid.RowDefinitions>
   <RowDefinition Height="25"></RowDefinition>
   <RowDefinition></RowDefinition>
  </Grid.RowDefinitions>
  <Button Height="23" Click="Button_Click" Content="Click" Grid.Row="0"></Button>
  <DataGrid Name="dgStudent" AutoGenerateColumns="False" IsEnabled="True" Grid.Row="1"
     EnableColumnVirtualization="True" EnableRowVirtualization="True">
   <DataGrid.Columns>
    <DataGridTextColumn Header="Name" Binding="{Binding Name}" Width="80"></DataGridTextColumn>
    <DataGridTemplateColumn Header="Age" Width="70">
     <DataGridTemplateColumn.CellTemplate>
      <DataTemplate>
       <TextBox Margin="5" Text="{Binding Age, Mode=TwoWay, UpdateSourceTrigger=PropertyChanged}"></TextBox>
      </DataTemplate>
     </DataGridTemplateColumn.CellTemplate>
    </DataGridTemplateColumn>
    <DataGridTemplateColumn Header="Course" Width="100">
     <DataGridTemplateColumn.CellTemplate>
      <DataTemplate>
       <ComboBox Margin="5" ItemsSource="{Binding CourseSource}" Text="{Binding Course, Mode=TwoWay, UpdateSourceTrigger=PropertyChanged}"></ComboBox>
      </DataTemplate>
     </DataGridTemplateColumn.CellTemplate>
    </DataGridTemplateColumn>
   </DataGrid.Columns>
  </DataGrid>
 </Grid>

 public class Student
 {
  public string Name { get; set; }
  public string Age { get; set; }
  public List<string> CourseSource { get; set; } = new List<string>() { "C", "C++", "C#" };
  public string Course { get; set; }
 }

 private void Button_Click(object sender, RoutedEventArgs e)
  {
   var students = new List<Student>();
   for (int i = 1; i <= 50; i++)
   {
    var student = new Student()
    {
     Name = $"student{i}"
    };
    students.Add(student);
   }
   this.dgStudent.ItemsSource = null;
   this.dgStudent.ItemsSource = students;
  }