The toxicity of mercury ion and pesticide cy-permethrin to tetrahymena pyriformis was observed in this study according to the method of aquatic toxicology.
There are 5 stages during the development of embryo, including the stage of 2-celled proembryo, multicellular proembryo, globular proembryo, pyriform proembryo, differential embryo and mature embryo.
The gallbladder, a pear-shaped sac behind the lower portion of the liver, stores bile, which is continuously secreted by the hepatic cells between meals.
In the uniquely mammalian process of lactation, a special class of milk-secreting cells known as mammocytes line up in a single layer around pear-shaped alveoli.