Tetrasporic embryo sacs, Biology

Assignment Help:

Tetrasporic Embryo Sacs

In this group neither of the meiotic divisions is accompanied by wall formation so that at the end of meiosis all the four haploid nuclei remain in a common cytoplasm forming what is termed a coenomegaspore. A tetrasporic embryo sac is more heterogeneous than a bisporic embryo sac because the four products of meiosis involved in its formation are genetically different. The nuclear behavior in tetrasporic embryo sacs is quite variable. The arrangement of the four nuclei in the coenomegaspore before the beginning of post-meiotic mitosis is of three types:

(A) 2+2 arrangement; two nuclei at the micropylar ad and two of the chalazal end

 (B) 1+1+1+1 arrangement; one nucleus at the micropylar end, one at the chalazal end, and two placed laterally, one in each side, and

(C) 1+3 arrangement; one nucleus at the micropylar end and three at the chalazal end. Depending on whether nuclear fusion occurs or not, the number of the post-meiotic mitosis in the coenomegaspore and final organisation of the embryo sac, tetrasporic embryo sacs are of many types.


Related Discussions:- Tetrasporic embryo sacs

What is the incubation period of an infection, What is the incubation perio...

What is the incubation period of an infection? Incubation period is the time interval among the infection by an agent that causes disease and the first signs or symptoms of th

Congenital aortic stenosis-types of aortic stenosis, Congenital Aortic Sten...

Congenital Aortic Stenosis :  The valve may be unicuspid, bicuspid or tricuspid. Rarely it is a dome shaped diaphragm. Uni commissural aortic stenosis produces significant sy

Cell coat, what is the job of the cell coat?

what is the job of the cell coat?

Microbiology, Applications of microbiology in different fields

Applications of microbiology in different fields

Nucleolus, NUCLEOLUS Discovered by Fontana and name given by Bowm...

NUCLEOLUS Discovered by Fontana and name given by Bowman. It is naked structure that is attached to chromatin at specific point called nucleolar organiser region or

Explain preoperative antibiotics, Preoperative antibiotics Preoperativ...

Preoperative antibiotics Preoperative antibiotics can decrease the incidence of infection after colorectal surgery; for elective operations, an oral regimen of neomycin (not a

Explain the transcription and the replication processes, What are similarit...

What are similarities and differences among the transcription process and the replication processes? A DNA polynucleotide chain serves as a template in replication (DNA duplica

Prevention of overloading the sterilizer, Prevention of overloading the ste...

Prevention of overloading the sterilizer Most sterilizers have a system to notify the operator of mechanical malfunction, but sterilizers cannot notify the operator whether the

Protein percentage in lowry method, How to calculate protein percentage in ...

How to calculate protein percentage in Lowry method? Ans) By verification of optical density by coloimetric method

Explain risk factors and their role in cad, Explain risk factors and their ...

Explain risk factors and their role in cad ? The concept of risk factors constitutes a major advance for developing strategies to prevent CVD. The Framingham Heat Study played

Write Your Message!

Captcha
Free Assignment Quote

Assured A++ Grade

Get guaranteed satisfaction & time on delivery in every assignment order you paid with us! We ensure premium quality solution document along with free turntin report!

All rights reserved! Copyrights ©2019-2020 ExpertsMind IT Educational Pvt Ltd