Aim
This experiment aims to study the T.S of Blastula through permanent slides.
Articles Required
Permanent slides
Compound microscope
Theory
The blastula is an important stage of embryonic development. Zygote forms after male and female gamete
fertilisation. Then zygotes undergo further cleavages to form embryos. Cleavage occurs in the upper part
of the fallopian tube. After some cleavages, a solid mass of about 8-16 cells formed; this mass is called a
morula. Then the morula undergoes further cleavages to form a blastula. The blastula contains about 64
cells. There are six types of blastula.
The outer layer of the blastula is called the blastoderm, and the inner cavity is called the blastula,
undergoes further division or development and forms a gastrula. The process of formation of a gastrula
from blastula is known as gastrulation. The T.S. of the gastrula of the frog will be discussed in further
experiments
Procedure
Fix the slides under the microscope properly. Then observe the slide under a low-power microscope and
then observe it under a high-power microscope.
Observations
In a microscope, we can see a large spherical mass of 64 cells. This mass is the blastula stage of the
embryo of mammals.
The outer layer of this mass is trophoblast or trophectoderm and inside this inner cell, mass is
present. After these inner cell masses convert into three different germ layers which will make a
complete organism.
Blastocoel is the fluid-filled cavity present within the envelope. The embryonic pole is the pole of
the trophoblast through which inner cell mass is attached, while the embryonic is the opposite
pole.
The inner cell mass is the precursor of the embryo.
