Question

Draw and label early AND later stage blastulae, and answer the following questions. Blastulae (Label blastocoel, blastomeres) j) How does the size of the blastula compare with the size of the morula?

Answer 1

Draw early and late blastula

Zona Pellucida 2 cells A cens oblast 8cells Trophoblast -Embryobia mbryoblast Morula blastocoel Early Late blastula blastula

J) How does the size of blastula compare with size of morula?

Morula is the 16- cell structure after 3–4 days after fertilization with highly totipotent cells with dimensions of 60-85 micrometers. The blastula is relatively bigger than morula with 200-300 cells and diameter of about 0.1-0.2 mm which undergo rapid cleavage.

K) how has the position of cells change?

Zygote transformed to morula which is a ball of 16 compact cells lined inside the zona pellucida. Blastula is a spherical layer of cells which contains fluid filled cavity called blastocoel.

L) Why does the centre appear to be lighter?

The blastula arrange themselves in two layers as outer trophoblast and inner cell mass (embryoblast). The inner fluid-filled cavity called the blastocoele surrounded by blastomere which appears lighter under microscope.