BIOSC 1200 Study Guide - Midterm Guide: Germinal Disc, Primitive Streak, Lissamphibia

• School: Pitt
• Department: Biological Sciences
• Course: BIOSC 1200
• Professor: Anthony Bledsoe

Document Summary

Embryology study guide: define the technical terms used in lecture, compare and contrast microlecithal, mesolecithal, and macrolecithal eggs. For each kind of egg, name a craniate group that possesses it. Microlecithal: little yolk, evenly distributed in ovum theria. Mesolecithal: moderate yolk, unevenly distributed to one side in ovum lissamphibia, many. Macrolecithal: much yolk, extracellular (only blastodisc is cytoplasm) all non-therian amniota, all chondrichthyes (cartilaginous fish), some actinopterygii (ray-finned fish: define and distinguish between holoblastic and meroblastic cleavage. Holoblastic cleavage: entire zygote divides; yolk intracellular & occurs in micro- & mesolecithal eggs (little & moderate yolk) Involution (cells move toward blastopore & roll over its lip) occurs: epiboly (surface cells expand to cover embryo w/ ectoderm) occurs, blastocoel obliterates a(cid:374)d does(cid:374)"t persist i(cid:374)to adult, endodermal cells protrude into blastopore, forming yolk plug. Involution yields chordamesoderm, which becomes notochord: mesodermal cells multiply (proliferate) & expand between ectoderm & endoderm, describe gastrulation in amniotes (chicken = model).