INSECT DEVELOPMENT

Spermatogenesis Germarium Zone of Growth Zone of Maturation Zone of Transformation N N N N

Oogenesis Ovum Oogonium Mitosis to produce more germ cells Onset of meiosis I Primary oocyte (meiosis I prophase - arrested - present at birth) 2N Complete meiosis I First polar body N Secondary oocyte (arrested at metaphase of meiosis II) Ovulation Ovum Second polar body N

Structure of Egg polar granules micropyle yolk spheres nuclear cytoplasm aeropyle chorion nucleus periplasm (cytoplasm) polar granules vitelline membrane

aeropyles micropyle

Sperm Transfer 1. Spermatophore

spermatophore sperm nutrients for female

Does female actually get the nutrients? Spermatophore takes up radioactive protein Inject male with radioactive protein Spermatophore passed to female Eggs contain radioactive protein

Sperm Transfer 2. Direct intromission

Sperm Transfer 2. Direct intromission Penes of male Argia (Odonata)

Sperm Transfer 3. Traumatic (Haemocoelic) insemination

Development - Fertilization Syncytial blastoderm germ cells

Development - Germ Band Formation Blastoderm cells migrate ventrally Germ band

Insect Development - Gastrulation 1 ectoderm mesoderm 2 3 germ band

Amnionic sac Midgut rudiments 2 1 dorsal closure neuroblasts 3 4

Gastrulation in Tribolium Stage 2 -3 from previous slide

Heart endoderm Ectoderm mesoderm Gut fat body Hemocoel tracheal invagination somatic muscles Ventral nerve cord

Fate of the Germ Layers cleavage energids blastoderm pole cells ectoderm mesoderm endoderm midgut stomodeum proctodeum epidermis trachea salivary glands mesodermal bands neuroblasts CNS gametes gonad visceral muscles somatic muscles fat body heart