Where does fertilisation take place in human beings? What changes occur in the egg cell (ovum) during fertilisation?

(N/A) In humans,fertilisation takes place at the ampullary-isthmic junction of the fallopian tube.
During copulation,semen is released into the vagina. The motile sperm swim rapidly through the cervix and uterus to reach the ampullary-isthmic junction.
The ovum released by the ovary is also transported to the same junction. Fertilisation can only occur if the ovum and sperms are transported simultaneously to this site.
During fertilisation,the following changes occur in the ovum:
$1$. When a sperm comes in contact with the zona pellucida layer of the ovum,it induces changes in the membrane that block the entry of additional sperms,ensuring that only one sperm fertilises the ovum.
$2$. The secretions of the acrosome help the sperm enter the cytoplasm of the ovum through the zona pellucida and the plasma membrane.
$3$. This entry induces the completion of the second meiotic division of the secondary oocyte,which is an unequal division resulting in the formation of a second polar body and a haploid ovum (ootid).
$4$. Finally,the haploid nucleus of the sperm and the haploid nucleus of the ovum fuse together to form a diploid zygote.