INSECT DEVELOPMENT

Spermatogenesis

2N

2N

N N

N N N N

Germarium

Zone of Growth

Zone of Maturation

Zone of Transformation

Oogenesis

Oogonium

Mitosis to produce more germ cells

2N

2N Primary oocyte(meiosis I prophase - arrested - present at birth)

N

Complete meiosis I

Secondary oocyte(arrested at metaphase of meiosis II)

N Ovum

Onset of meiosis I

Ovulation

First polar body

Second polar body

Structure of Egg

micropyle

aeropyle

yolk spheres

nucleus

nuclear cytoplasm

vitelline membrane

periplasm (cytoplasm)

chorion

polar granules

aeropylesmicropyle

Sperm Transfer

1. Spermatophore

spermatophore

sperm

nutrients for female

Does female actually get the nutrients?

Inject male with radioactive protein

Spermatophore takes up

radioactive protein

Spermatophore passed to female

Eggs contain radioactive protein

Sperm Transfer

2. Direct intromission

Sperm Transfer

2. Direct intromission

Penes of maleArgia (Odonata)

Sperm Transfer

3. Traumatic (Haemocoelic) insemination

Development - Fertilization

germ cells

Syncytial blastoderm

Development - Germ Band Formation

Blastoderm cells migrate ventrally

Germ band

Insect Development - Gastrulation

1

2

3

ectodermmesoderm

germ band

1

2

3

4

Amnionic sac

Midgut rudiments

neuroblasts

dorsal closure

Gastrulation in Tribolium

Stage 2 -3 from previous slide

Heart

Ectoderm

fat body

tracheal invagination

somatic muscles

Ventral nerve cord

mesoderm

endoderm

Gut

Hemocoel

cleavage energids

blastodermpole cells

ectoderm mesoderm endoderm

midgut

mesodermal bands

epidermistrachea salivary glands

stomodeumproctodeum

neuroblasts CNS

gametes visceral muscles heart

somatic muscles

fat bodygonad

Fate of the Germ Layers