$(1)$  Location : As soon as head and middle part of a sperm enters into secondary oocyte, nucleus present in head is know as spermatid.

– Function : Spermatid unites with oocyte and form a zygote.

$(2)$ Location : It is an enzyme located in acrosome of sperm cell.

– Function : Hyleuronidase makes the entry of sperm in ovum possible in making hole in the wall of ovarian layer.