Reproduction & Development

Amixis Amixis by fragmentation Nemertean may aestivate within a mucous cyst.

Alternating Life Cycles Obelia colonial proliferation & gonochoristic amphimixis Marine – no diapause

Alternating Life Cycles Hydra – Clonal proliferation & gonochoristic amphimixis Note: diapause as egg (c)

Alternating Life Cycles Crustacean apomixis & amphimixis Diapause as diploid embryo in ephippium

Alternating Life Cycles Rotifer: apomixis & arrhenotoky Diapause as diploid egg

Alternating Life Cycles Bryozoan colonial proliferation, amphimixis or autogamy, & clonal proliferation Diapause as multicellular statoblast

Alternating Life Cycles Scyphozoan – Aurelia sp. Clonal proliferation & gonochoristic amphimixis Marine – no diapause

Alternating Life Cycles Aphid: apomixis & gonochoristic amphimixis Diapause as diploid egg

Parasite Life Cycles Trematode – human lung fluke Gonochoristic amphimixis & Polyembryony at several stages

Annelida - Epitoky Some Polychaetes produce bags of gametes for mixis either by conversion of body part or amictic budding Coordinated seasonal release

Annelid Mixis Simultaneous Hermaphrodites with cross-fertilization Cocoon formation

An Hermaphroditic Reproductive Tract : Pallifera sp. alb = albumin gland, at = atrium, bc = bursa copulatrix, bcp = bursa peduncle, chd = common hermaphroditic duct, fov = free oviduct, ovt = ovotestis, p = penis, spov = spermioviduct, vd = vas deferens copyright 2007 J.W. Atkinson

First TEM pictures of sperm entering egg – 1960s by Colwin & Colwin using the polychaete, Hydroides TEM Acrosome reaction – sea urchin, Arbacia

Developmental Patterns I

Developmental Patterns II

Developmental Patterns III Mesoderm formation Coelom formation - enterocoely

Unique Development: a triclad turbellarian (some critters don’t fit the patterns)

Developmental Control: mosaic vs regulative Determination of cell fate occurs before differentiation Early Experimental Embryology - Dichotomy Mosaic vs Regulative early (determinate egg?) late (Indeterminate egg?) Prospective Potency = prospective fate PP> pf pf laid down in egg pf results from cell interactions elimination of cell – loss of structure elimination of cell –adjustment Protostome vs Deuterostome Later Experimental Work – Breakdown of Dichotomy cell interactions also important localized cytoplasmic factors 4d cell gradients of determinants tissue & organism exceptions Current View: Differences in timing of events & stability of Bauplans, i.e. no longer fits the protostome/deuterostome split

Octopus: Direct Development pvm = pervitelline membrane, ar = arm, est = eye stalk, mn = mantel, oc = optic lobe, y = yolk f = funnel

Insect Larvae & Metamorphosis Hemimetabolous Incomplete metamorphosis

Insect Larvae & Metamorphosis Holometabolous: Complete Metamorphosis

Imaginal Discs Nemertea: Pallidium larva

Metamorphosis Sea Urchin: Pluteus Larva

Metamorphosis Urochordate:

Adult Cell Turnover Hydra from stem cells

Growth: control in arthropods

Drosophila hox gene expression