Given below are the names of certain stages/substances related to reproduction and found in human body. Answer the questions related to them.

(a) Foetus

• Where is it contained?
• How does it differ from embryo?

(b) Hyaluronidase

• Is it an enzyme or simply a protein?
• What is its function?

(c) Morula

• What is this stage?
• Name the stage which comes next to it.

(d) Amniotic fluid

• Where is it found?
• What are its functions?

(e) Placenta

• What are the two sources that form placenta?
• Name any two main substances which pass from foetus to mother through placenta.
• Name any two hormones it produces.

(f) Implantation

• The development stage that undergoes this process.
• The approximate time after fertilization, when it occurs.

(a) Foetus —

• It is contained in the uterus.
• In foetus, limbs have appeared and resembles the humans unlike the embryo which is a growing or dividing zygote.

(b) Hyaluronidase —

• Enzyme
• It is an enzyme secreted by the sperm that allows the sperm to penetrate the egg.

(c) Morula —

• It is the stage in the development of human embryo which consists of a spherical mass of cells.
• Blastocyst

(d) Amniotic fluid —

• Between amnion and embryo
• The functions of Amniotic fluid are:
  1. It protects the embryo from physical damage by jerks or mechanical shocks.
  2. Keeps an even pressure all around the embryo.
  3. Allows the foetus some restricted movement.
  4. Prevents sticking of the foetus to the amnion.

(e) Placenta —

• Placenta is formed by two sets of minute finger like processes called the villi. One set of villi is from the uterine wall and the other set is from the allantois.
• Carbon dioxide and Urea pass from foetus to mother through placenta.
• Two hormones produced by Placenta are Progesterone and Oestrogens.

(f) Implantation —

• Blastocyst
• It occurs in about 5-7 days after fertilisation.