Lab3_embryology

Lab3_embryology - Embryology All sexually reproducing...

Info iconThis preview shows pages 1–4. Sign up to view the full content.

View Full Document Right Arrow Icon
1 Embryology • All sexually reproducing multicellular organisms begin life as single-celled zygotes and process through –Growth : irreversible increase in size of an organism; – Differentiation : the structural and functional specialization of groups of cells; – Morphogenesis : the development of pattern, shape, and form. • Embryology is the study of these processes in the early development of an organism. • Early stages of embryology are similar in advanced invertebrates and vertebrates. • During development, embryos must overcome – Energy requirement – Protection – Waste disposal system • Different organisms have different adaptations to cope with these problems. • Compare features and developmental stages of three earliest stages of development of (1) sea star; (2) frog; and (3) chick. • Three early developmental stages studied in this lab: Fertilization : male and female gametes fuse to form a zygote. Cleavage : zygote divides into a larger and larger number of smaller and smaller cells that eventually form a hollow sphere of many cells. Gastrulation : cells of the sphere formed during cleavage continue to divide and move inward to form three cellular layers.
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
2 Model organisms •Deu te ro s tome – initially recognized because they undergo early embryonic development in a similar way. – Different from Protostomes (Table40.1 page 441 – coming soon!) – Include phyla Echinodermata, Hemichordata, Chordata • Sea Star – Echinodermata “spiny skin” (page 764) •F rog – Chordata amphibians (page 768) •Ch ick – Chordata aves (page772) (I) Sea Star Development - Fertilization Examine slides of eggs and zygotes. • Eggs and sperms are extruded from the body into seawater, and fertilization occur __ ? __ (externally or internally)
Background image of page 2
3 Egg and zygote • 1a – unfertilized egg, has a large and conspicuous nucleus. • 1b – zygote, has a nucleus less conspicuous (fertilization membrane is not present in this preserved material). Sea Star Development - Cleavage Examine slides of two- or four-celled cleavage stage and of blastula of a sea star. • One hour after fertilization, the zygote cleaves to form two cells
Background image of page 3

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Image of page 4
This is the end of the preview. Sign up to access the rest of the document.

Page1 / 13

Lab3_embryology - Embryology All sexually reproducing...

This preview shows document pages 1 - 4. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online