Which of the following are secretions produced by the spermatozoa at the time of fertilization?
Fertilizin and anti-fertilizin
Anti-fertilizin and sperm lysin
Fertilizin and sperm lysin
Only sperm lysin
Which of the following depicts the site of impantation of blastocyst under normal condition?
The mammalian primitive streak gives rise to
The first sign of the growing foetus may be noticed by listening to the heart sound carefully through the stethoscope. Embryo's heart is formed _________.
Animal $\quad$ Gestation period
Which of the following is ‘immortal’
In mammalian sperm, spirally arranged mitochondria are present in