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The terminal portion of the optic nerve and its entrance into the eyeball, in horizontal section. The optic disc or optic nerve head is the point of exit for ganglion cell axons leaving the eye. Because there are no rods or cones overlying the optic disc, it corresponds to a small blind spot in each eye. The ganglion cell axons form the optic ...
Sieve tube element. Sieve elements are specialized cells that are important for the function of phloem, which is a highly organized tissue that transports organic compounds made during photosynthesis. Sieve elements are the major conducting cells in phloem. Conducting cells aid in transport of molecules especially for long-distance signaling.
Orbit (anatomy) Diagram of eye with surrounding superior, oblique, medial and inferior rectus muscles; supraorbital foramen shown above the eye, and inferior orbital fissure inferolaterally. In anatomy, the orbit is the cavity or socket/hole of the skull in which the eye and its appendages are situated. "Orbit" can refer to the bony socket, [1 ...
Lobules of liver. The structure of the liver’s functional units or lobules. Blood enters the lobules through branches of the portal vein and hepatic artery proper, then flows through sinusoids. In histology (microscopic anatomy), the lobules of liver, or hepatic lobules, are small divisions of the liver defined at the microscopic scale.
Hyaline cartilage is the glass-like (hyaline) and translucent cartilage found on many joint surfaces. It is also most commonly found in the ribs, nose, larynx, and trachea. [1] Hyaline cartilage is pearl-gray in color, with a firm consistency and has a considerable amount of collagen. It contains no nerves or blood vessels, and its structure is ...
Over the following 18 hours, both the inner and outer layers begin to flex inward at sharp angles, beginning the formation of a C-shaped edge (Phase 3). The final 18 hours involve continuing this apically convex invagination to form the optic cup [3] [4]. At this point, morphologies such as columnar epithelial cells, pseudo-stratified cells ...
Scleral Ring. The scleral ring is a hardened ring of plates, often derived from bone, that is found in the eyes of many animals in several groups of vertebrates. Some species of mammals, amphibians, and crocodilians lack scleral rings. [1] The ring is in the fibrous outer layer of the eye, called the sclera. The structure is commonly referred ...
Lens. A lens is a transmissive optical device that focuses or disperses a light beam by means of refraction. A simple lens consists of a single piece of transparent material, while a compound lens consists of several simple lenses (elements), usually arranged along a common axis.