Week 3 Objective 2: major genes involved in early development in the undifferentiated state of cells

Question 1

Polarity

Answer 1

8-16 cell stage appears polarization of blastomeres, which creates recognizable apical basal surfaces

Question 2

Polarization of blastomeres determines

Answer 2

whether cells are destined to become part of ICM or TB

Two theories: inside out hypothesis and cell polarity model

Question 3

Two theories

Answer 3

Inside out theory says ICM or TB membership is purely based on location in the embryo

cell polarity theory says that cleave direction determines what/where

Question 4

Cell Polarity Model

Answer 4

depends on plane of cleavage

if perpendicular to the plane of cells, both become TB

if parallel, lateral most cell becomes TB (polar) and medial most cell becomes ICM (apolar). outer cells pick up outer cell membrane containing microvilli and ezrin