Okazaki fragments formed during formation of replication fork are structurally:

DNA polymerases only synthesize DNA in the 5'-3' direction, and only one of the several different types of polymerases is involved at the replication fork. Because the DNA strands are antiparallel, the polymerase functions asymmetrically. On the leading (forward) strand, the DNA is synthesized continuously. On the lagging (retro-grade) strand, the DNA is synthesized in sho fragments, the so-called Okazaki fragments. The enzyme DNA ligase joins the Okazaki fragments together as lagging strand replication proceeds. Ref: Weil P. (2011). Chapter 35. DNA Organization, Replication, & Repair. In D.A. Bender, K.M. Botham, P.A. Weil, P.J. Kennelly, R.K. Murray, V.W. Rodwell (Eds), Harper's Illustrated Biochemistry, 29e.