ACCELERATED MATURATION OF CHICK EMBRYO SKIN TREATED WITH A PROSTAGLANDIN (PGB1) - AN ELECTRON MICROSCOPIC STUDY

One of the fatty acid derivatives called prostaglandins, PGB1, when applied to organ cultures of developing chick skin with feather organ loci, completely blocks feather organ development, but stimulates proliferation and keratinization of the epidermis. Control and PGB1 treated explants were harvested after one, two, and three days in culture and processed for study by electron microscopy. Fine structural observation of control and treated skins indicate the following. (1) Tonofilaments appear much sooner in treated explants than in controls, and are distributed at all levels of the epidermis. (2) The cristae of mitochondria in epidermal cells of treated skins are long, closely apposed, and oriented parallel to the longest axis of the organelle as contrasted with a transverse orientation for them in control epidermis. (3) There is increased deposition of collagen in the mesenchyme of treated skins as contrasted to that observed in controls. (4) Unusual structures (inclusion bodies) occur throughout the stratified and superficial epidermis of treated skins and are composed of fine filaments and granules measuring about 30 Å in diameter. They are often associated with tonofilaments. (5) Small but numerous vacuoles appear in the epidermal cells of treated skins and seem to develop from cisternae of the Golgi apparatus or endoplasmic reticulum. The change in orientation of cristae of the mitochondria, vacuolation of the epidermis, and appearance of the inclusion bodies first occurs after two days of treatment with PGB1 in culture. These observations coincide with previous data demonstrating that restitution of feather organ development can be accomplished after one day of treatment with PGB1, but not after two days of treatment. The observations are consistent with an accelerated maturation process, but may be correlated with a specific and irreversible change in a metabolic event necessary for feather development. Copyright © 1969 Wiley‐Liss, Inc.