Biology 107

Lecture Notes: Animal Development.

Reading: Chapter 47, Pages 1001-1007 in the text.

• Fertilization in mammals

• Capacitation

• Acrosomal reaction

• zona pellucida

• ZP3

o Cortical granules

• fast block to polyspermy

• slow block to polyspermy

Cleavage partitions the zygote into many smaller cells

• The basic body plan of an animal is established in three successive stages following fertilization: cleavage, gastrulation, and organogenesis. The following information is based upon studies of frogs.

• Cleavage

• blastula

• A definite polarity is shown by the eggs of most animals and the planes of division during cleavage follow a specific pattern relative to the poles of the zygote

• vegetal pole

• animal pole

• gray crescent

• morula

• blastocoel

• blastula

Gastrulation rearranges the blastula to form a three-layered embryo with a primitive gut

• Gastrulation involves an extensive rearrangement of cells which transforms the blastula, a hollow ball of cells, into a three-layered embryo called the gastrula (!)

• archenteron

• the primary germ layers

• ectoderm

• endoderm

• mesoderm

• blastopore

• Invagination

• dorsal lip

• Involution

• yolk plug

In organogenesis, the organs of the animal body form from the three embryonic layers

• organogenesis

• notochord

• somites

• As organogenesis continues, other organs and tissues develop from the embryonic germ layers

• Ectoderm gives rise to:

• Mesoderm gives rise to:

• Endoderm gives rise to:

• neural crest

• The developmental fate of cells depends on cytoplasmic determinants and cell-cell induction

• Induction