STAGE 5. Age 2 ¾ hours; length 1.4 - 1.5 mm.

Ext. Crit.: *Advanced sixteen cell stage*. Dorsal micromeres distinctly smaller and less pigmented than ventral ones. *Macromeres entirely separated by cleavage grooves*.

Int. Crit.: Individual blastomeres varying in size and form. Cleavage cavity about as large as a micromere, located slightly excentrically towards dorsal side.