SPI Interfacing circuit between two microcontrollers

Hi sir ,

I'm communicating two microcontrollers (pic8722) using SPI communication .One microcontroller as a Master and one as a Slave.But here my doubt is on the  communication lines pull up and pull down resistors are required or not.
               
                          ON SDI
                                SDO
                                 SCLK
                                  SS
On these four pins pull up & down resistors required or not .If required please tell me the values of that resistors . 

    

Thanks  for giving reply

     Actually i use pull up resistors on SDI SDO & SS Lines. 
                         PULL down resistor ON SCLK line. It's correct or not i don't know.But in one Analog devices slave circuit i saw like this .

  In which situation pull up and pull down resistors are required and which situation they are not required.
      pls  give me brief explanation.

And tell me the calculation of pull up and pull down resistors mathematical calculation for Communication  lines and I/O Lines separately.