Embryogenesis-1  
311 Syllabus

The Zygote undergoes an unequal Cell Division

The Apical Cell produces the Embryo while the Basal Cell produces the Suspensor.

Once the Apical-Basal Polarity is established, embryos pass through a programmed sequence of events which involve Cell Division, Enlargement and Differentiation.

The first discernable Stage of Embryo Development is called GLOBULAR. One of the Three Primary Meristems (Protoderm) is visible at this Stage.

Localized growth at the apical end produces Cotyledon Primordia. This is called the HEART Stage.

The Cotyledons and the Axis undergo extensive Elongation to produce the TORPEDO Stage.

The Shoot Apical Meristem (SAM) develops between the Cotyledons.

The Root Apical Meristem (RAM) develops at the opposite pole. The Hypophysis contributes to the RAM.

The Hypocotyl (H) develops from the middle region of the Axis.

Regions of the adult plant can be traced back to regions of the Embryo.

Heart Stage

Torpedo Stage

There are three Primary Meristems in Plants.

The Protoderm produces the Epidermis.

The Ground Meristem produces Ground Tissues.

The Procambium produces Vascular Tissues.

The Primary Meristems can be seen in cross-sections of the Root and Hypocotyl during Embryo Development.

This shows a cross section of an Embryonic Root. It  has an Epidermis which encloses the Ground Tissues. The Endodermis is the innermost layer of Ground Tissue. The Vascular Tissues are Phloem and Xylem.