Otic placode
Encyclopedia
In embryology
, the otic placode is a thickening of the ectoderm
on the outer surface of a developing embryo
from which the ear
develops. The ear, including both the vestibular system
and the auditory system
, develops from the otic placode beginning the third week of development. During the fourth week, the otic placode invaginates into the mesenchyme
adjacent to the rhombencephalon
to form the otic pit, which then pinches off from the surface ectoderm to form the otic vesicle.
Embryology
Embryology is a science which is about the development of an embryo from the fertilization of the ovum to the fetus stage...
, the otic placode is a thickening of the ectoderm
Ectoderm
The "ectoderm" is one of the three primary germ cell layers in the very early embryo. The other two layers are the mesoderm and endoderm , with the ectoderm as the most exterior layer...
on the outer surface of a developing embryo
Embryo
An embryo is a multicellular diploid eukaryote in its earliest stage of development, from the time of first cell division until birth, hatching, or germination...
from which the ear
Ear
The ear is the organ that detects sound. It not only receives sound, but also aids in balance and body position. The ear is part of the auditory system....
develops. The ear, including both the vestibular system
Vestibular system
The vestibular system, which contributes to balance in most mammals and to the sense of spatial orientation, is the sensory system that provides the leading contribution about movement and sense of balance. Together with the cochlea, a part of the auditory system, it constitutes the labyrinth of...
and the auditory system
Cochlea
The cochlea is the auditory portion of the inner ear. It is a spiral-shaped cavity in the bony labyrinth, making 2.5 turns around its axis, the modiolus....
, develops from the otic placode beginning the third week of development. During the fourth week, the otic placode invaginates into the mesenchyme
Mesenchyme
Mesenchyme, or mesenchymal connective tissue, is a type of undifferentiated loose connective tissue that is derived mostly from mesoderm, although some are derived from other germ layers; e.g. some mesenchyme is derived from neural crest cells and thus originates from the ectoderm...
adjacent to the rhombencephalon
Rhombencephalon
The rhombencephalon is a developmental categorization of portions of the central nervous system in vertebrates.The rhombencephalon can be subdivided in a variable number of transversal swellings called rhombomeres...
to form the otic pit, which then pinches off from the surface ectoderm to form the otic vesicle.