Developmental Biology

Fusion of haploid gametes to form diploid zygote. Sperm-egg recognition (ZP3), acrosome reaction, membrane fusion, cortical reaction…

Rapid early mitotic divisions without growth, partitioning zygote cytoplasm into blastomeres. Holoblastic (mouse, sea urchin) vs…

Large-scale morphogenetic movements converting blastula to gastrula with three germ layers. Wolpert: 'it is not birth, marriage, or death,…

Three primary embryonic tissue layers: ectoderm (skin, nervous system), mesoderm (muscle, bone, blood, kidney, heart), endoderm (gut,…

Secreted signalling molecule forming concentration gradients that specify positional information. Classical: Bicoid, BMP, Shh, Wnt,…

Homeobox-containing transcription factors specifying anterior-posterior body-plan identity. Collinear arrangement in chromosomal clusters;…

Formation of neural tube from ectoderm. Notochord-induced neural plate folds along midline → neural groove → neural tube closure. Defects:…

Dorsal lip of amphibian blastopore that induces secondary body axis when transplanted (Spemann-Mangold 1924). Secretes BMP antagonists…

Spemann: signals from one tissue redirecting fate of neighbouring tissue (organiser grafts induce secondary body axis). Mediated by Wnt,…

Nüsslein-Volhard & Wieschaus 1980 Drosophila screen: maternal → gap → pair-rule → segment-polarity gene cascade establishes segments. Nobel…