Study the T.S of Blastula through Permanent Slides

You might be knowing that after 7-9 days of fertilisation, zygote implants in the uterus. The zygote undergoes repeated divisions called cleavage. Cleavage includes a series of successive mitotic divisions that transform the zygote into an embryo. In this experiment, we will observe many characteristics of the human blastula stage. Blastula formed after 5-6 days of fertilisation. And it implants in a uterine wall process known as implantation. In this article, we will also describe the structure of the blastula.

Table of Content

• Aim

• Articles Required

• Theory

• Procedure

• Observations

• Results

• Precautions

• Lab Manual Questions

• Viva Questions

• Practical Based Questions

• Conclusion

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.

Blastula Diagram

Results

Different parts of the blastula such as the trophoblast and inner cell mass are seen in T.S of the blastula slide. 

Precautions

• Always first focus slides under a low power microscope and then after under a high power microscope.

• And use fine adjustment while focusing slides under the microscope.

• Always clean slides before doing an experiment. 

• Handle slides very carefully.

Lab Manual Questions

Q1. What is morula?

Ans: It is a stage of embryogenesis in which a solid mass is formed of about 16 cells.

Q2. What is implantation?

Ans: Implantation is the attachment of the blastocyst to the uterine wall.

Q3. When does implantation occur in human beings?

Ans: Implantation occurs in human beings after 7 days of fertilisation.

Viva Questions

Q1. Is morula a 16-celled stage?

Ans: Yes, morula is a 16-celled stage. Zygote undergoes cleavage to form a morula. It is mulberry shaped and divides further to form blastula.

Q2. What is cleavage in Biology?

Ans: Cleavage is a kind of mitotic division in which a cell is divided into a large number of cells and overall volume remains the same but per cell volume decreases. 

Q3. What is the difference between division and cleavage?

Ans: The main difference between division and cleavage is that in cleavage size/volume of cell is reduced after division but in division size of progeny cell remains same as parent cell.

Q4. What is blastula used for?

Ans: Blastula formed by division in zygote, it later develops into blastocyst which further undergoes development to form embryos.

Q5. What are the types of blastula?

Ans: There are many types of the blastula. Some types are- coeloblastula, periblastula, discoblastula, amphiblastula, and stereoblastula. 

Q6. What is LH surge?

Ans: Sudden increase level of LH hormone is known as an LH surge. It is important for ovulation. Ovum is released after 36-40 hours of blood level of luteinising hormone.

Q7. Which hormone is released from Graafian follicles?

Ans: Graafian follicles mature into Graafian follicles. During development, it releases oestrogen hormone, which helps in the further development of follicles.

Q8. What is embryogenesis? 

Ans: Embryogenesis is the process of the formation of an embryo from zygote. It is a process by which an embryo matures into a foetus. This process occurs after fertilisation. 

Q9. What are the different stages of embryogenesis?

Ans: The different stages of embryogenesis are- fertilisation, blastocyst formation, blastocyst implantation, embryo development, and foetus development. 

Practical Based Questions

Q1. What cell stage is blastula?

1. First stage

2. Second stage

3. Third stage

4. Fourth stage

Ans: 2. Second stage

Q2. How many-celled stages is a  blastula?

1. 32-64 celled stage

2. 128 celled stage

3. 12-16 celled stage

4. None of the above

Ans: 1. 32-64 celled stage

Q3. Which is the part of the blastula?

1. Trophoblast

2. Ectoderm

3. All of the above

4. None of the above

Ans: 1. Trophoblast

Q4. Which cavity is present in the blastula?

1. Gastrocoel

2. Gastrula

3. Blastocoel 

4. None of the above

Ans: 3. Blastocoel

Q5. What is the fate of blastula?

1. Formation of gastrula

2. Formation of morula

3. Formation of zygote

4. None of the above

Ans: 1. Formation of gastrula

Q6. How many cells are in the morula stage?

1. 8-16 cells

2. 12-14 cells

3. 32-64 cells

4. None of the above

Ans: 1 . 8-16 cells.

Q7. Is blastula bigger than zygote?

1. Yes

2. No 

3. Of the same size

4. None of the above

Ans: 3. Of the same size

Q8. Which kingdom has a blastula stage?

1. Plantae

2. Mineral

3. Animalia

4. None of the above

Ans: 3. Animalia 

Conclusion

In this article, we have studied an experiment on the ts of blastula under a microscope. The blastula is a 64-celled stage divided into two parts. The inner part is known as the inner cell mass consists of a large number of cells, whereas the outer layer is known as the trophoblast. Blastocysts undergo implantation in the uterus. There are various types of blastula depending on many factors. Blastula undergoes further development to form gastrula process known as gastrulation.