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 skeleton in the different classes of coelentrata known

what is the skeleton in the different classes of coelentrata known

Atp, what is atp explain in detail?

what is atp explain in detail?

Calculate the amount of oxygen - microbial survival, Calculate the Amount o...

Calculate the Amount of Oxygen - Microbial Survival and Growth? The amount of oxygen in the environment influences the microbial growth. Depending on the oxygen requirement, yo

Myocardial ischemia, In patients with coronary artery disease an acute coro...

In patients with coronary artery disease an acute coronary syndrome event can precipitate heart failure. Mitral regurgitation occurring as a result of papillary muscle ischemia con

Diestrus- estrous cycle, Diestrus- Estrous cycle This lasts 60 to 70 h...

Diestrus- Estrous cycle This lasts 60 to 70 hours during which functional regression of the corpora lutea occurs. The uteri are small, anaemic, and only slightly contractile.

Discuss about dengue and aids, Why is it difficult to produce efficient vac...

Why is it difficult to produce efficient vaccines against a viral infection like dengue and AIDS? It is complex to make vaccines against dengue because there are four dissimila

How bone implant interface can be evaluated, How bone implant interface can...

How bone implant interface can be evaluated 1) Evaluation of the bone - implant interface can be done by following: i) Implant mobility and discomfort a)  Clinical implan

Ventilation of tracheal system - diffusion, Ventilation of Tracheal System ...

Ventilation of Tracheal System - Diffusion Gaseous exchange due to diffusion generally takes care of the oxygen needs of most small insects. Similarly fairly large but inactiv

What is the procedure of examining foot, Procedure of Examining Foot Le...

Procedure of Examining Foot Let us learn the steps of examining the foot and identify foot at risk. Steps to follow: 1. Make the patient comfortable. 2. Provide priv

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