TLS Online TPP Program

#Id: 4736

#Unit 5. Developmental Biology

The zygote of C. elegans exhibits rotational holoblastic cleavage.

TLS Online TPP Program

#Id: 4737

#Unit 5. Developmental Biology

During early cleavage, each asymmetrical division produces:

• One founder cell (denoted AB, E, MS, C, and D) that produces differentiated descendants
• One stem cell (the P1–P4 lineage) 

TLS Online TPP Program

#Id: 4738

#Unit 5. Developmental Biology

The anterior-posterior axis is determined before the first cell division, and the cleavage furrow is located asymmetrically along this axis of the egg, closer to what will be the posterior pole.

TLS Online TPP Program

#Id: 4739

#Unit 5. Developmental Biology

The stem cell lineage always undergoes meridional ,division to produce

(1) An anterior founder cell (AB)

(2) A posterior cell (P1) that will continue the stem cell lineage.

TLS Online TPP Program

#Id: 4740

#Unit 5. Developmental Biology

The founder cell (AB) divides equatorially, while the P1 cell divides meridionally (transversely) to produce another founder cell (EMS) and a posterior stem cell (P2).

TLS Online TPP Program

#Id: 4741

#Unit 5. Developmental Biology

The decision of the anterior and posterior axis depends on the position of the sperm pronucleus in egg.