Tetrasporic embryo sacs, Biology

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.

Posted Date: 1/23/2013 1:47:34 AM | Location : United States

Related Discussions:- Tetrasporic embryo sacs, Assignment Help, Ask Question on Tetrasporic embryo sacs, Get Answer, Expert's Help, Tetrasporic embryo sacs Discussions

Write discussion on Tetrasporic embryo sacs
Your posts are moderated
Related Questions
Health Stroke Scale: Stroke is a leading cause of death, hospitalization, disability and health care expenditure in U.S. (Fonarow G. et al., 2012).  Stroke is a medical condit

Exchange of oxygen, nutrients, carbon dioxide and waste products from mother to fetus takes place through diffusion across the: a) Chorionic villi (pron: core-e-on-ick villi)

Explain Objectives of Root-End Resection Apicoectomy a) Removal of untreated apical portion of the root, b) Enable the obturator to determine the cause of failure,  c) To

Carbohydrate characteristic chemical features include: Select one: a. the potential to form multiple hydrogen bonds. b. the existence of one or more asymmetric centers.

Symptoms: The E. coli gastroenteritis syndrome is caused by the ingestion of 10 6 -10 10 viable cells/g that must colonize the small intestine and produce  enterotoxin. The syndr

what SOAP is: Subjective - The data includes information obtained from the patient or the patient's family regarding the problem. Objective dat a - the data is gathered  f

Subsequently many such fossils were known from France, Italy and middle East. All such fossils exhibited reduced brow ridges, steep forehead, high rounded cranial vault, short face

Q. Use of Sulphur dioxide and sulphites in microorganisms? Sulphur dioxide as a preservative in wine preparation has been in use since ancient times. It is also used in other f

diagram of phyllum protozoa

Relationship of Ecology with Other Disciplines of Biology In order to understand the scope and relevance of ecology let us consider its position in relation to other biological