What is optic placode?

Induction of the Lens The lens placode gives rise to only two cell types, lens fiber cells and lens epithelial cell, and it integrated into the forming eye. The placode is first visible around the 10-12 somite stage in the ectoderm next to the optic vesicle, which emerges from the ventral diencephalon.

What are placode cells?

Placodes are embryonic structures that give rise to structures such as hair follicles, feathers and teeth. The term “neurogenic placode” generally refers to cranial placodes that have neurogenic potential – i.e. those that give rise to neurons associated with the special senses and cranial ganglia.

What is an ectodermal placode?

Introduction. Ectodermal placodes are focal thickenings of the cranial ectoderm that generate many different components of the sensory systems of the head. The emergence and utilisation of these embryonic structures have long been viewed as being important for the evolution of the vertebrates.

What becomes otic Placode?

The inner ear is derived from the otic placode, which invaginates to form the otocyst, a closed vesicle located within the temporal bone. The otocyst, surrounded by mesenchyme, condenses during development and differentiates into the otic capsule.

What is the optic Placode and where does it originate?

An evagination (the optic vesicle) expands from the wall of the forebrain towards the overlying ectoderm, which has formed a placode (optic, lens placode). The optic vesicle remains attached to the forebrain by an optic stalk.

What is Epibranchial Placode?

Abstract. The epibranchial placodes are cranial, ectodermal thickenings that give rise to sensory neurons of the peripheral nervous system. Despite their importance in the developing animal, the signals responsible for their induction remain unknown.

What are Rhombomeres?

In the vertebrate embryo, a rhombomere is a transiently divided segment of the developing neural tube, within the hindbrain region (a neuromere) in the area that will eventually become the rhombencephalon. In human embryonic development, the rhombomeres are present by day 29.

What is Epibranchial placode?

Is the Adenohypophyseal placode a neurogenic placode?

And third, all placodes with the exception of adenohypophyseal and lens placode are neurogenic (e.g. D’Amico-Martel and Noden, 1983, Ma et al., 1998, Fode et al., 1998, Schlosser and Northcutt, 2000, Andermann et al., 2002, Begbie et al., 2002).

What is otic capsule?

The otic capsule or osseous (bony) labyrinth refers to the dense bone of the petrous temporal bone that surrounds the membranous labyrinth of the inner ear. It is surrounded by the less dense and variably pneumatized petrous apex and mastoid part of the temporal bone.