This website uses cookies to ensure you have the best experience. Learn more

Regulator Of Inner Ear Progenitor Fate And Outer Hair Cell Function

3101 words - 13 pages

Question 1
Hollyfield: Regulator of inner ear progenitor fate and outer hair cell function.
Located within the mammalian cochlea and critical to hearing function, the organ of Corti is a sensory epithelium, comprised of auditory receptors, called hair cells, and their supporting cells. In avians, hair cells and supporting cells share common progenitors in the auditory epithelia (Fekete et al., 1998; Kirjavainen et al., 2008). During embryonic development it is crucial to have the right number of hair cells and supporting cells from progenitor cells for proper organ function. Loss or even gain of supernumerary hair cells and/or supporting cells can lead to deafness (Chen et al., ...view middle of the document...

The arrangement of IHCs and OHCs is important for micromechanics involved in sensory transduction (Lim, 1986). IHCs are located close to the osseous spiral lamina, of which the motion of the basiliar membrane is minimal, whereas, OHCs are located on the basiliar membrane where there is greater motion (Lim, 1986). Not only can the loss of inner hair cells lead to deafness, but so can the loss of outer hair cells. In rats, loss of 1/3 of OHCs will cause hearing impairment, and 2/3 loss will lead to deafness (Chen et al., 2008) .
Supporting cells: Within the organ of Corti, there are also five different types of supporting cells with distinct morphologies: Hensen’s cells are cuboidal or slightly oblong, inner phalangeal cells and border cells are columnar, and Deiters’ and pillar cells are elongated and have strong cytoskeletons for large structural demands (Wan et al., 2013). Like hair cells, supporting cells are also precisely arranged in the organ of Corti, by rows from the outer edge to the inner edge of the organ in the order of: Hensen’s cells, Deiters’ cells, pillar cells, inner phalangeal cells, and border cells (Wan et al., 2013). One should note that supporting cells do not just take up space in the auditory epithelium. Loss of Deiters’ and pillar cells enviably leads to a loss of OHCs, causing deafness due lack of amplification (Mellado Lagarde et al., 2013). In addition, supporting cells also provide trophic factors, which are vital to the maintenance of spiral ganglion neurons (Monzack and Cunningham, 2013)
Cell cycle exit and p27kip1
To get the right number of hair cells and supporting cells during development, cell cycle exit in the organ of Corti needs to be properly timed (Chen and Segil, 1999; Lee et al., 2006). Regulation of cell division during embryonic cochlear development of the prosensory domain is correlated with p27kip1 expression (Lee et al., 2006). In wildtype (WT) mice, cell cycle exit in the developing organ of Corti starts at approximately E12.5 and proceeds in a wave marked by p27kip1 expression from apex to base of the cochlea, until around E14.5 (Lee et al., 2006). The wave of cell cycle exit marked by p27kip1, creates a zone of non-proliferating cells, so that hair cell differentiation can take place (Lee et al., 2006). In p27kip1-/- mice, cell cycle exit is delayed to approximately E14.5 and follows instead the wave of hair cell differentiation from base to apex (Lee et al., 2006). The delay in cell cycle exit causes the formation of supernumerary hair cells and supporting cells (Chen and Segil, 1999). Cell cycle exit needs to be precisely timed to govern the correct number of progenitor cells, which will give rise to hair cells and supporting cells in the developing organ of Corti (Lee et al., 2006) .
Differentiation of hair cells and supporting cells
Hair cells: Once cell cycle exits are completed, progenitor cells can undergo differentiation to become the diverse cell types that make up the organ of Corti....

Find Another Essay On Regulator of inner ear progenitor fate and outer hair cell function

What Cruel Acts of Fate Teach Us about Brain Function

1448 words - 6 pages What Cruel Acts of Fate Teach Us about Brain Function Much of the research and discoveries regarding how our brain functions can be attributed to cruel acts of fate- the brain injuries and disorders which damage key areas of the brain. It is through studying how these injuries and disorders affect human behavior, that we gain insight into how different brain structures contribute to human functional capability. The literature of

Physical and Natural Geography of the North Carolina Outer Banks

1059 words - 5 pages Introduction Outside of the North Carolina and the southern Virginia shoreline lays the Outer Banks. They are considered barrier islands. “Barrier islands are depositional offshore linear features separated from the mainland by a lagoon and orientated parallel to the coast. They are usually comprised of sand that is built above the high-tide level and stabilized by vegetation” (Haslett 2000). The Outer Banks are defined as “extending about 320

Hair and make up of the Rennaisance

1504 words - 7 pages Hair styles and make-up have been a significant part of the culture for centuries. It has been changing with every era, decade or style of art. The difference can be as small as a change of a shape of the eyeliner or it can be a complete change of people’s looks. What was considered beautiful in Renaissance was absolutely outdated 100 years after this era. In this essay I will be talking about the hair and make-up in Renaissance. It all started

Symbols of Fate and Coincidence

1040 words - 5 pages , three beautifully constructed symbols that relate to a common theme of fate and coincidence are the wine, echoing footsteps, and the shadow. The first major symbol developed throughout the novel is the wine. The wine symbol is introduced during the wine cask scene that takes place in Saint Antoine when a large cask of wine is dropped into the street and the townspeople rush to drink it. The wine is being compared to red blood from the revolution

Role and Function of Law

797 words - 3 pages Role and Function of LawRole and Function of LawThis paper will be discussing how the roles and functions of law pertaining to businesses and our society as it today. Laws actually play a huge role in our business and in our society lives. They help to regulate our social behaviors and in turn we get an efficient running society. Also, laws help with ethical expectations and standards by providing much needed rules. Such as rules of conduct, the

The Physics of the Sound Wave and its Effects on the Human Ear

1327 words - 5 pages (whose units for expressing the intensity of a sound wave are Watts/Meter^2) for determining the amount of amplitude is written as follows3:The human ear is able to perceive the many aspects of sound. As seen by the figure to the right3, there are three regions of the human ear. The first region is the outer ear, which consists of two main parts: (1) the auricle and (2) the external auditory canal. The auricle is the most external part of the ear

Disarment, Weapons of Mass Destruction and Outer Space: Mongolia´s Stand

1504 words - 7 pages The topics before the First Committee are: Relationship between Disarmament and Development, Measures to prevent Terrorists from acquiring Weapons of Mass Destruction, Prevention of arms Race in Outer Space. Mongolia is dedicated to collaborative

Time and fate of Romeo and Juliet

837 words - 3 pages Time and Fate in Romeo and JulietRomeo and Juliet, said to be one of the most famous love storiesof all times, is a play anchored on time and fate. Some actions arebelieved to occur by chance or by destiny. The timing of each actioninfluences the outcome of the play. While some events are of lesssignificance, some are crucial to the development of this tragedy. Thesubstantial events that inspire the conclusion of Romeo and Juliet are;the Capulet

Structure And Function Of The Spleen

1110 words - 4 pages marginal zone which contains B lymphocytes concentrated in lymphoid follicles, either primary 'unstimulated' follicles or secondary 'stimulated' follicles. The centre of the secondary follicles has a lower B cell density than the outer region of the secondary follicles as it contains larger and fewer B lymphocytes differentiating into either plasma cells or memory cells, but mainly the memory type.The central artery is normally distorted outwards from

Rome and Juliet: Victims of Fate

615 words - 2 pages The phenomenon of fate is exemplified on a daily bases in society. Fate can be best described as many acts ironically going in the opposite direction that one expects. From the beginning of the Shakespearean play Romeo and Juliet the two characters are called, “star cross’d lovers,” fate produces the destiny of their death. Events like Friar Laurence’s well deceived planes gone wrong, the timing of Romeo and Juliet’s suicide and finally the

Structure and Function of Rainbow Trout Fins

1001 words - 4 pages The structure and function of the different fins of the Rainbow Trout, Oncorhynchus mykiss The Rainbow trout, belonging to the family Salmonidae, Class Actinopterygii (ray finned fish), inhabitscold streams, rivers and lakes in North America. Ones living in lakes have silver scales apart from those on their back which are dark green. They are covered in dark spots that usually go no further than the lateral line. The lateral line is a line of

Similar Essays

Inner And Outer Beauty In Dorian Gray

1488 words - 6 pages to look to the inside – into the soul. This is the place where the real beauty and ugliness are hidden. The notion of inner and outer beauty is perfectly presented in the novel ‘The Picture of Dorian Gray’ by Oscar Wilde. The story described in this book shows how the external attractiveness influences people’s behavior and corrupts the inner beauty. The plot situated in the XIX England perfectly describes the higher class of this period

Biocompatibility Testing Of Putrescine Derived Polyurethanes By Cardiac Progenitor Cell Culture

1432 words - 6 pages samples were prepared, on SiO2 wafer fragments of 3.8 cm2 by solvent casting 90 µl of a 1% w/w solution of the PUUs in 2-propanol. After solvent evaporation a Lentech SE400 ellipsometer was used to measure film thickness. Cell culture assays Murine cardiac progenitor cells were kindly provided by Dr. JQ Ye who sorted SCA-1+/CD45- cells from cardiospheres (CS) from 1-week post-MI hearts of adult mice, and clonally expanded these in culture from

Larvicidal Activity Of Insect Growth Regulator Igr And Insecticides

1872 words - 7 pages 2. Larvicidal activity of insect growth regulator IGR and insecticides: 2.1. Insect growth regulator IGR: Bakr, et al. (1984) evaluated some IGR's Dimilin (25% WP), Bay Sir 8514 (6.5% EC), Altosid (10% EC) and RO-08-9801 (50% EC) against Culex pipiens. Results revealed that, all the tested compounds inhibit the moulting process of the third and fourth larval instars with different degrees of morphogenetic changes. The developmental events of

Describe The Role And Function Of Different Cell Types Of Innate Immunity

1206 words - 5 pages . These cells are all present in the myeloid lineage of the haematopoietic stem cells of the bone marrow. The stem cell is made up to two cells namely the myeloid progenitor and the lymphoid progenitor. The myeloid progenitor produces more dendritic, monocytes, neutrophils and basophils cells whereas the T and B cells are produced more in the lymphoid progenitor. Macrophages and dendritic cells play a vital role in the both types of immunity. These