lamina

(noun)

the flat part of a leaf; the blade, which is the widest part of the leaf

Related Terms

Examples of lamina in the following topics:

  • Basement Membranes and Diseases

    • The basement membrane is the fusion of two lamina: the basal lamina and the reticular lamina (or lamina reticularis).
    • The lamina reticularis is attached to the basal lamina with anchoring fibrils (type VII collagen fibers ) and microfibrils (fibrillin).
    • The basal lamina layer can further be divided into two layers: the clear layer closer to the epithelium is called the lamina lucida, and the dense layer closer to the connective tissue is called the lamina densa.
    • The electron-dense lamina densa membrane is about 30–70 nanometers in thickness, and consists of an underlying network of reticular collagen (type IV) fibrils (fibroblast precursors) which average 30 nanometers in diameter and 0.1–2 micrometers in thickness.
    • The most notable examples of basement membranes are in the glomerular filtration of the kidney, by the fusion of the basal lamina from the endothelium of glomerular capillaries and the basal lamina of the epithelium of the Bowman's capsule; and between lung alveoli and pulmonary capillaries, by the fusion of the basal lamina of the lung alveoli and of the basal lamina of the lung capillaries, which is where oxygen and CO2 diffusion happens.

  • Types of Leaf Forms

    • Leaves may be categorized as simple or compound, depending on how their blade (or lamina) is divided.
    • There are two basic forms of leaves that can be described considering the way the blade (or lamina) is divided.
    • In simple leaves, the lamina is continuous.
    • In compound leaves, the lamina is separated into leaflets.

  • Epithelial Membranes

    • It consists of an epithelium layer and an underlying lamina propria of loose connective tissue.
    • The epithelial tissue sheet lies directly over the layer of loose connective tissue called lamina propria.
    • In some mucosa, the lamina propria rests on a deeper, third layer of smooth muscle.

  • Parts of a Vertebra

    • The vertebral arch is formed from two short thick processes called pediments which extend posteriorly from the lateral sides vertebral body, before joining together at the midline with the laminae.
    • Four articular processes originate from the join between the pedicles and laminae, two point superiorly and two point inferiorly and they interact with the zyhapophysis, a socket for the articular processes, of the adjacent vertebrae making the spine more stable and facilitating a small degree of articulation.
    • The two transverse process project laterally from the join between the pedicle and lamina and also serve as an attachment point for muscles and ligaments of the back.

  • Hemidesmosomes

    • Anchoring filaments traverse the lamina lucida space and appear to insert into the electron dense zone, the lamina densa.
    • Beneath the lamina densa, loop-structured, cross-banded anchoring fibrils extend more than 300 nm beneath the basement membrane within the papillary dermis.
    • In a normal mouse (a) there are well-defined, organized hemidesmosomes with darkened areas in the lamina densa abutting the hemidesmosome (arrows).

  • Mucosa

    • The mucosa is made up of three layers: epithelium, lamina propria, and muscularis mucosae.
    • The lamina propria is a layer of connective tissue that is unusually cellular compared to most connective tissue.

  • Histology of the Liver and Gallbladder

    • There are several different layers of the gallbladder: the mucosa (epithelium and lamina propria), the muscularis, the perimuscular, and the serosa .
    • The lamina propria is a thin layer of loose connective tissue, which together with the epithelium forms the mucosa.

  • Muscular Arteries

    • Muscular arteries can be identified by the well defined elastic lamina which lies between the tunicae intima and media.

  • Testes

    • Tunica vaginalis (parietal lamina), 11b.
    • Tunica vaginalis (visceral lamina), and 12.

  • Capillaries

    • Capillaries, which form part of the micro-circulation, are the smallest of the body's blood vessels at between 5-10 μm in diameter with the endothelial vessel wall being only one cell thick, and are surrounded by a thin basal lamina of connective tissue.
    • These types of blood vessels allow red and white blood cells (7.5μm - 25μm diameter) and various serum proteins to pass using a process that is aided by a discontinuous basal lamina.
    • Capillaries are surrounded by a thin basal lamina of connective tissue.