Types of embryogeny, Biology

Assignment Help:

Types of Embryogeny

On the basis of the plane of division of the zygote and of the cells of the 2-celled proembryo, and also taking into account the relative contributions of the cells of the 4-celled proembryo to the mature embryo, six chief types of Embryogeny have been recognized.

A. Division of the zygote is vertical - Piperade type (e.g. Loranthaceae, Piperaceae).

AA. Division of the zygote is transverse.

B. Apical cell of the 2-celled proembryo divides vertically to form a T-shaped, 4-celled proembryo.

C. Basal cell plays no role at all or only an insignificant role in subsequent development of the proembryo-(Crucifer or Onagrad type (e.g., Ranunculaceae, Brassicaceae).

CC. Basal cell and apical cell both contribute to the development of the embryo - Asterad type (e.g., Asteraceae, Violaceae).

BB. Apical cell of 2- celled proembryo divides transversely so that the 4-celled proembryo is usually linear.

D. Basal cell does not participate or only contributes a little to development of embryo proper.

E. Basal cell usually forms a suspensor - Solanad type (e.g., Solanaceae, Linaceae).

EE. Basal does not divide further and the suspensor, if present, is derived from the apical cell - Caryophyllata type (e.g., Caryophyllaceae, Crassulaceae).

DD. Basal cell and apical cell both divide and contribute to formation of the embryo - Chenopodium type (Chenopodiaceae, Boraginaceae).


Related Discussions:- Types of embryogeny

Polarity - root and shoot morphogenesis, Polarity - Root and Shoot Morphoge...

Polarity - Root and Shoot Morphogenesis Polarity is defined as having a difference (morphological, physiological or both) between the two ends of an axis or cells. This is lar

What is cerebrum, What is Cerebrum Cerebrum is divided into right and l...

What is Cerebrum Cerebrum is divided into right and left parts known as cerebral hemisphere. It is the largest part of the brain. The functions of the cerebrum:  It recei

Action of natural selection in changing environments, Directional or progre...

Directional or progressive selection is the mode of selection associated with environmental change. We said earlier that in an unchanging environment stabilising selection removes

Energy flow - ecosystem, Energy Flow - Ecosystem Our world is a solar-...

Energy Flow - Ecosystem Our world is a solar-powered system, and green plants are the entry gates of energy into ecosystem. The total incoming solar energy, only a very small

Zoology , phylum platyhelminthes

phylum platyhelminthes

Significant for chromosomes, Q. Why is it significant for chromosomes to be...

Q. Why is it significant for chromosomes to be condensed during mitosis and decondensed during interphase? During mitosis the major problem to be solved is the correct separati

Community, COMMUNITY If you look around yourself you will notice that pop...

COMMUNITY If you look around yourself you will notice that populations of plants and animals seldom occur by themselves. The reason for this is quite obvious. In order to survive

What is sodium-potassium pump atpase, What is sodium-potassium pump ATPase?...

What is sodium-potassium pump ATPase?   A.  There is a net flux of sodium from intracellular spaces into luminal spaces through sodium-potassium pump ATPase spanning proteins l

Explain precautions for gram staining of bacterial cultures, Explain Precau...

Explain Precautions for Gram Staining of Bacterial Cultures? 1. Heat fix the smear, otherwise cells would be washed off. 2. Fresh 24 hrs old culture should be used. Gram var

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