The pancreatic islets of several species of amphibians undergo differentiation from a larval to an adult type at the time of metamorphosis (Frye, ’59). Some of the changes include an increase in the amount of cytoplasm, an increase in cytoplasmic basophilia and afFinity for standard pancreatic stains, lengthening of the cells and pronounced polarization toward the capillaries, and an accumulati...

The mode in which the force exerted by the contraction of myofibrils is transmitted to tendon has been debated for many years (as reviews HAGGQVIST 1931 and 1956). It is generally accepted that the major union of muscle with tendon is established at the end of muscle fibers. Light-microscopically, two main opposing theories appear in the literature regarding the muscle-tendon attachment. One is...

Organization and Development of the Embryo is based on a series of Silliman Lectures at Yale University given by Ross G. Harrison in 1949 under the same title. Professor Harrison was unable to prepare these lectures for publication because of illness, but his assistant, Miss Sally Wilens, has assembled in this volume the notes and papers of Professor Harrison on which the content of the lecture...

Anyone who has even the dimmest conception of evolution has seen the iconic image of a trail of creatures crawling out of the ocean, growing hair, gradually standing erect, and eventually becoming Man. It seems easy enough, but each stage of that 3-billion-year journey was a labored and complicated process. This is no truer than with that crucial step from the ocean to the land. Since the earli...

An emerging problem in marine environment is represented by the plastic presence in the water column (THOMPSON et al., 2004) and the risk of their input and accumulation in the trophic web (TEUTEN et al., 2009; GALGANI et al., 2013a). Plastics are worldwide distributed, from surface to deep waters, include particles less than 20 mm of several polymers such as polyester, nylon, polyethylene, pol...

s Prochloron, a prokaryotic alga, is an obligate symbiont of some tropical ascidian colonies belonging to the family Didemnidae. In this symbiosis, the host (ascidian) is thought to acquire photosynthetic metabolites provided from the symbionts (Prochloron), while the host provides a habitat for the symbionts. Radio-labeling studies suggested that Prochloron cells transfer photosynthetically fi...