Biology 624 - Developmental Genetics

Lecture #3 - Gametogenesis and Fertilization

Gametogenesis-

-the formation of GERM CELLS that will go on to form progeny-

1. Begins during embryogenesis2. Involves several steps that are independent of sex3. Continues with sex-specific processes (ie differ between egg and sperm)

Germ cell competence

Germ cell specification

Germ cell migrationto gonads

Sperm-egg contact

Spermatogenesis-results in motile gamete withhaploid DNA content

Oogenesis-results in relativelylarge gamete withnutritional and informational molecules

Sperm-egg fusion

Development initiates

Specification of Mammalian PGCs

Segregation of P-granules into the Germ LineLineage of the C. elegans Embryo

Segregation of P-granules into the Germ LineLineage of the C. elegans Embryo

The Pole Plasm of Drosophila

Maternal Effect Genes

Localization of Germ Cell-Less Gene Products in the Posterior of the Egg and Embryo

Inhibition of Transcription in Germ Cell Precursors of C. elegans

Inhibition of Transcription at Ectopic Sites in Drosophila by germ cells-less

HoechstGCL H5 staining

WT + GCL

WT

Leatherman et al (2002) Curr Biol 12, 1681-1685

Pathway for the Migration of Mammalian Primordial Germ Cells

Pathway for the Migration of Mammalian Primordial Germ Cells

The Modification of a Germ Cell to Form a Mammalian Sperm

The Ovarian Follicle of Mammals

The Formation of 16 Interconnected Cystocytes in Drosophila

In Amphibian Oocytes, Lampbrush Chromosomes are Active During First Meiotic Prophase

The Formation of 16 Interconnected Cystocytes in Drosophila

Specifying the Anterior-Posterior Axis of the Drosophila Embryo During Oogenesis

Specifying the Anterior-Posterior Axis of the Drosophila Embryo During Oogenesis

Formation of the Anterior-Posterior Axis of the Drosophila Embryo

Events Leading to the Fusion of Egg and Sperm Plasma Membranes

Wave of Calcium Release across Sea Urchin Eggs During Fertilization

Possible Mechanisms of Egg Activation