What does reverse transcriptase use to form dna apex?

Reverse transcriptase use mRNA to form DNA apex

Reverse transcriptase is a broad family of enzymes that play a unique role in the flow of genetic information. The synthesis of DNA from an RNA template through reverse transcription produces complementary DNA. Reverse transcriptase use an RNA template and a short primer complementary to the 3' end of the RNA to direct the synthesis of the first strand complementary DNA, which can be used directly as a template for the Polymerase Chain Reaction.

To make DNA from mRNA

Explanation:( Apex )

the unequal cytoplasmic division that  results  in  one egg  and three polar bodies ensures that a fertilized  egg has  ample nutrients  forits journey  to  the uterus.