question_answer 28)

  Acrosomal reaction of the sperm occurs due to (a) its contact with zona pellucida of the ova (b) reactions within the uterine environment of the female (c) reactions within the epididymal environment of the male (d) androgens produced in the uterus

Answer:

                  (c) One of the three glycol proteins (ZP3), functions as a sperm receptor and binds to a complementary molecule on the surface of the sperm head. Binding of the sperm head to the receptor molecule ZP3 induces the acrosome of the sperm to release its hydrolytic enzymes (sperm lysins). The sperm lysins include (i) Hyaluronidase, that hydrolyses hyaluronic acid of the follicular cells. (ii) Corona penetrating enzyme dissolves corona radiata portion around these condary oocyte by hydrolyzing their ground substances. (iii) Zona lysine or across in that helps to digest zona pellucida. All these enzymes dissolve the corona radiata and zona pellucida and enable the sperm to reach the plasma membrane of the egg. The above changes in the head of sperm are called acrosome reaction.