Atlas of plant and animal histology

Ear: it is a structure composed of two systems: the auditory and the vestibular systems. The auditory system allow us to hear, that is, to perceive sounds. The vestibular system is participates in maintaining the body balance. Ear is divided in three compartments: outer, middle and inner ear.

♣ Animal organs: Senses .

Eccrine gland: it is a type of gland that releases its content directly into the skin surface.

Ectoderm: it is one of three primary germ layers of animal embryos. Ectoderm is the germ layer that initially covers the embryo and gives rise to structures such as epidermis and the nervous system.

Efferent nerve: it is a nerve that arises in a region and takes information from this region to other region. For instance, efferent nerves that carry information from the encephalon and spinal cord to other regions of the body.

♣ Animal organs: Peripheral nervous system .

Elastic artery: aorta and pulmonary arteries, and their primary branches are called elastic arteries. They contain many elastic fibers in their thick walls, that allow to counteract the heart pumping pressure and recover their nomal diameter after an expansion. The tunica media is very thick and contains elastin, collagen and smooth muscle cells.

Elastic cartilage: it is type of cartilage characterized by the abundant elastic fibers in the extracellular matrix. They provide elasticity and flexibility. Elastic cartilage is found in organs like ears.

♣ Animal tissues: Cartilage, Elastic cartilage

Elastic fiber: is is a type of fiber composed of proelastin, fibrillin and desmosin. Elastic fibers are abundant in the animal tissues under mechanical stress such as dermis and wall of large blood vessels. The role of elastic fibers is to recover the rest state of a tissue after stretching.

♣ The cell Extracellular matrix: proteins .

♣ Animal tissues: Connective proper .

Elastic lamina: it is a layer of connective tissue with many elastic fibers that separated the tunica intima from the tunica media in arteries and arterioles. Sometimes, it can also be observed in veins.

♣ Animal organs: Cardiovascular, Elastic artery .

Elastin: it is a protein found in the extracellular matrix of many animal tissues. Elastin associates with other proteins like fibrillin and desmosin to form the elastic fibers, which provide elasticity to structures like the skin and blood vessel walls. Elastine molecule contains long sequences of hydrophobic amino acids that makes the protein globular under aqueous environment. This feature lets elastin to recover the globular conformation after a mechanical stretch.

♣ The cell: Extracellular matrix proteins .

♣ Animal tissues: Connective proper tissue .

Embryo sac: (in plants) it is the female gametophyte. Embryo sac becomes the embryo and the endosperm of the seed. It is found in the ovary of the pistil of flowers.

Encapsulated receptor: it is a type of sensory receptor with the nerve ending surrounded by layers of mostly connective tissue, organized as onion leaves. Encapsulated receptors are found in the dermis, and they function as mechanoreceptors, although some may be thermoreceptors.

Encephalon: it is the rostral part of the central nervous system. The encephalon consists in telencephalon, hypothalamus, diencephalon, mesencephalon and rhomencephalon. The encephalon is covered and protected by the cranium. It develops high cognitive functions like thinking, emotions and memory, but also others more basic roles like controlling breathing and cardiac rhythm. It is also a key center of the endocrine system. The encephalon is known as brain.

♣ Animal organs: Nervous system, Central nervous system , Senses.

Endocarp: (in plants) it is the inner layer of the pericarp. The pericarp is the fruit part that covers the seed, and the endocarp is the layer contacting the seed. The endocarp is the hardest part of fleshy fruits and it is made up of support cells like sclereids. However, the endocarp is the softest and juicy part in tomatoes and other fruits.

♣ Plant organs: Fruit , Orange .

Endodermis: (in plants) it is a layer of cells found in primary roots and other aerial parts of plants. Endodermis is made up of cells with primary cell walls containing suberin, which form belt-like thickenings called Casparyan band. In de deeper parto of the roots, endodermis functions as a filter for the incoming substances from the environment, such as water and minerals. These substances must cross the plasma membrane and cytoplasm of the endoermal cells to reach the vascular tissue.

♣ Plant organs: Primary root , Monocot primary root , Dicot primary root .

Endoderm: it is one of the three primary germ layers during the embryo development. Endoderm is found in the inner parts of the embryo. For instance, the gut epithelium and gastric glands are derived from the endoderm.

Endolymph: it is the liquid that fills the cavities of the inner ear. It is the movement of the endolymph what is detected by receptors found in the semicircular canal ampullae and in the scala media of the cochlea.

Endomysium: it is the layer of connective tissue that overlays each skeletal muscle cell.

♣ Animal tissues: Muscle tissue , Skeletal muscle.

Endoneurium: it is the layer of connective tissue that wraps the myelinated and amyelinated axons in peripheral nerves.

Endosperm: (in plants) it is a storage tissue found in seeds that nurtures the embryo. The endosperm originates from cells of the embryonary sac (female gametophyte), although the mechanism is different in angiosperm and gymnosperms.

♣ Plant organs: Seed , Apple seed .

Endosteum: it is a thin layer of connective tissue covering the cavities of the bone marrow, bone trabeculae surfaces and the inner surface of the Harvesian canals of osteonic bone. In the endosteum, there are also messenchymal cells that function as bone cell progenitors and differentiate into osteoblasts.

♣ Animal tissues: Bone .

Endothelium: it is the layer of simple squamous epithelium that lines the inner surface of blood and lymphatic vessels.

♣ Cell types: Endothelial cell. .

♣ Animal tissues: Epithelium, Covering epithelium, Simple squamous epithelium .

Eosinophil: it is a type of granular leukocyte found in the blood and in other tissues, mostly in the connective tissue proper. Eosinophils show a nucleus with two prominent lobes. In the cytoplasm, many eosinophil granules can be visualized, so they contain basified material. These cells work against pathogens and infections, and they can abandon the blood stream and move through connective tissues.

♣ Animal tissues: Blood, Blood cells .

♣ Cell types: Eosinophil .

Ependyma: it is the layer of cells that line the surface of the brain ventricles and the central canal of the spinal cord. The cells that form the ependyma are known as ependymocytes, and sometime there are other cells like tanicytes. Cerebrospinal fluid fills the ventricles and the central canal.

♣ Animal tissues: Nervous tissue, Ependyma .

♣ Animal organs: Spinal cord .

Epidermal ridge: it is a projection from the epidermis of the animal skin toward the underlying dermis. Epidermal ridges are abundant in those regions of the body undergoing heavy mechanical stress, such as palms and soles.

Epicarp: see exocarp