Human Reproduction Test - 12

The inner foetal membrane invests the embryo and forms a space called amniotic cavity. It is filled with fluid called amniotic fluid. It is useful for studying chromosomal abnormalities of foetus.

Haploid nucleus of sperms and a haploid ovum fuse together to form diploid zygote. Zygote undergoes mitotic division to form embryo and fetus.

Zygote undergoes mitotic division as it moves through the isthmus of oviduct by cleavage to form 2, 4,8,16 blastomeres.

After implantation of blastocysts, finger-like projections appear on the trophoblast called chronic villi which is surrounded by the uterine tissue and maternal blood.

The inner cell mass contain certain cells that contain cells called stem cells which have potency to give rise all the tissues and organs. Now a day’s stem cells are preserved for future use.

The heart is formed first in foetus after one month of pregnancy. Limbs and digits after second months, limbs and external genital organs after three months and eye lids and hair after six months.

Human chorionic gonadotropin (hCG), human placental lactogens (hCL) and relaxin are produced in human females only during pregnancy.

Oxytocin hormone is released by foetal ejection reflex from maternal pituitary gland that causes stronger and stronger uterine contraction that leads to ejection of baby through birth canal.

During growth of embryo limbs and external genital organs is formed by the ends of 12 weeks (3 months). Ultrosonography can be used to know the sex of foetus after this period as genital organs are formed.

After implantation, embryo differentiates into outer layer called ectoderm, middle layer mesoderm and inner layer endoderm. These three layers forms the all tissues or organs of human beings.