Chapter 12 Isolation of Extracellular Matrix Structures from Xenopus laevis Oocytes, Eggs, and Embryos

Abstract

The extracellular matrix (ECM) surrounding amphibian eggs is composed of jelly coat layers, the egg envelope, and the fibrous elements of the perivitelline space. The oviposited egg envelope provides an initially penetrable structure to the sperm which is subsequently modified by products released in the cortical reaction to a sperm-impenetrable structure in the block to polyspermy reaction. At fertilization the egg envelope is chemically modified and its macromolecular permeability properties changed. This permeability change (hardening) results in an osmotically driven envelope elevation, owing to the influx of water into the perivitelline space. The jelly after fertilization functions as a “sticky substrate” for the adherence of the zygote to objects in its surroundings, protects the zygote against physical damage, and also provides a microbiological barrier (bacteria are rarely found within the jelly coat layers). Thus, after fertilization the ECM protects the developing embryo and functions as a barrier for the chemical and biological regulation of the embryo environment. This protective function of the ECM persists until the embryo develops into a free swimming tadpole and hatches from the ECM. Thus, the chapter briefly discusses isolation of ECM structures from Xenopus laevis oocytes, eggs, and embryos.