Question

Draw the following diagrams related to human reproduction and label them.
a) The zygote after the first cleavage division
b) Morula stage
c) Blastocyst state(sectional view)

Answer 1

Hint: The zygote, morula and blastocyst are the stages of embryonic development. Embryonic development is the development of embryo from fertilized ovum and its subsequent development into a young organism.

Complete answer:
Let’s get familiar with the terms mentioned in the question to get an idea of the structure and to get ease in labelling them on the diagram.

Zygote is formed upon fusion of the haploid nucleus of the sperm and that of the ovum resulting in a unique genotype. It is formed around 12-14 hours after evolution. The cleavage takes place around 30 hours to 3 days. The principal events associated here are that the meiotic divisions increase the number of cells and do not increase.

Morula stage is achieved on the third or fourth day. Number of cells produced are 8. A solid ball is formed which consists of an outer layer with small cells and inner mass of large cells. The morula then reaches the uterus on day 5 or 6.

Endometrial glands secretes glycogen rich secretion which passes into the uterus and then into the morula to provide nutrition. Blastocyst is formed during day 5 to the end of the second week. During this stage 32 cells are formed. It is basically a hollow ball which comprises trophoblast, embryonic cavity and embryonic knob. During this stage, implantation occurs, various embryonic discs and primary germ layers are established.

Let’s now see the above mentioned terms in the following diagrams.
a)

b)

c)

Note: In developmental biology, the development of an animal or plant embryo is embryonic development, also known as embryogenesis. Embryonic growth begins with a sperm cell fertilizing an egg cell (ovum) (spermatozoon).