Fill in the blanks:
a. Zygote divides to form ….1…. which is implanted to uterus.
b. The structure which provides vascular connection between foetus and uterus is called …2…
c. Inner cell mass contains certain cells called …3…. which have the potency to give rise to all the tissues and organs.
d. By the end of ...4...., most of the major organ systems are formed, for example, the limbs and external genital organs are well-developed.
e. Immediately after implantation, the ...5...defferentiates into an outer layer called ectoderm and an inner layer called endoderm.
A. 1-morula, 2-umbilical cord, 3-trophoblast, 4-second trimester, 5-stem cells
B. 1-blastocyst, 2-placenta, 3-stem cells, 4-first trimester, 5-trophoblast
C. 1-blastocyst, 2-umbilical cord, 3-stem cells, 4-seond trimesters, 5-inner cell mass
D. 1-blastocyst, 2-placenta, 3-stem cells, 4-first trimester, 5-inner cell mass.