Macroscopic description of the external and middle ear of paca (Cuniculus paca Linnaeus, 1766)

Abstract: Paca (Cuniculus paca), one of the largest rodents of the Brazilian fauna, has inherent characteristics of its species which can conribute as a new option for animal experimantation. As there is a growing demand for suitable experimental models in audiologic and otologic surgical research, the gross anatomy and ultrastructural ear of this rodent have been analyzed and described in detail. Fifteen adult pacas from the Wild Animals Sector herd of Faculdade de Ciências Agrárias e Veterinárias, Unesp-Jaboticabal, were used in this study. After anesthesia and euthanasia, we evaluated the entire composition of the external ear, registering and ddescribing the details; the temporal region was often dissected for a better view and detailing of the tympanic bulla which was removed and opened to expose the ear structures analyzed mascroscopically and ultrastructurally. The ear pinna has a triangular and concave shape with irregular ridges and sharp apex. The external auditory canal is winding in its path to the tympanic mebrane. The tympanic bulla is is on the back-bottom of the skull. The middle ear is formed by a cavity region filled with bone and membranous structures bounded by the tympanic membrane and the oval and round windows. The tympanic membrane is flat and seals the ear canal. The anatomy of the paca ear is similar to the guinea pig and from the viewpoint of experimental model has major advantages compared with the mouse ear.

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External ear canal cholesteatoma after ventilation tube insertion and mastoidectomy

Vojnosanitetski pregled ◽

10.2298/vsp1204363d ◽

2012 ◽

Vol 69 (4) ◽

pp. 363-366 ◽

Cited By ~ 1

Author(s):

Dragoslava Djeric ◽

Milan Jovanovic ◽

Ivan Baljosevic ◽

Srbislav Blazic ◽

Milanko Milojevic

Keyword(s):

Tympanic Membrane ◽

Middle Ear ◽

Membrane Surface ◽

Tube Placement ◽

External Ear ◽

Ventilation Tube ◽

Ear Canal ◽

Tube Insertion ◽

Tissue Mass ◽

External Ear Canal

Introduction. Etiopathogenetically, there are two types of chollesteatomas: congenital, and acquired. Numerous theories in the literature try to explain the nature of the disease, however, the question about cholesteatomas remain still unanswered. The aim of the study was to present a case of external ear canal cholesteatoma (EEC) developed following microsurgery (ventilation tube insertion and mastoidectomy), as well as to point ant possible mechanisms if its development. Case report. A 16-yearold boy presented a 4-month sense of fullness in the ear and otalgia on the left side. A year before, mastoidectomy and posterior atticotomy were performed with ventilation tube placement due to acute purulent mastoiditis. Diagnosis was based on otoscopy examination, audiology and computed tomography (CT) findings. CT showed an obliterative soft-tissue mass completely filled the external ear canal with associated erosion of subjacent the bone. There were squamous epithelial links between the canal cholesteatoma and lateral tympanic membrane surface. They originated from the margins of tympanic membrane incision made for a ventilation tube (VT) insertion. The position of VT was good as well as the aeration of the middle ear cavity. The tympanic membrane was intact and of normal appearance without middle ear extension or mastoid involvement of cholesteatoma. Cholesteatoma and ventilation tube were both removed. The patient recovered without complications and shortly audiology revealed hearing improving. Follow-up 2 years later, however, showed no signs of the disease. Conclusion. There could be more than one potential delicate mechanism of developing EEC in the ear with VT insertion and mastoidectomy. It is necessary to perform routine otologic surveillance in all patients with tubes. Affected ear CT scan is very helpful in showing the extent of cholesteatoma and bony defects, which could not be assessed by otoscopic examination alone.

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Expression of Cytokeratins 13 and 16 in Middle Ear Cholesteatoma

Otolaryngology ◽

10.1177/019459989411000309 ◽

1994 ◽

Vol 110 (3) ◽

pp. 310-317 ◽

Cited By ~ 12

Author(s):

Hiroyuki Sasaki ◽

Cheng-Chun Huang

Keyword(s):

Tympanic Membrane ◽

Middle Ear ◽

Basal Layer ◽

External Ear ◽

Ear Canal ◽

Suprabasal Layer ◽

External Ear Canal ◽

Cytokeratin Expression ◽

Middle Ear Cholesteatoma ◽

Cytokeratin 13

The accumulation of keratinizing epithelium in the middle ear cavity is a crucial factor in the pathogenesis of cholesteatoma. We hypothesize that keratinocytes from the skin of the ear canal migrate and hyperprollferate in response to Inflammation in the middle ear cavity to cause accumulation of keratin debris. In the present study, we Investigated the expression of specific cytokeratins (CKs) in the cholesteatoma matrix to determine whether cholesteatoma is a hyperproliferative disease. Cytokeratin expression was examined in cholesteatoma, meatal skin, and tympanic membrane with two monoclonal antibodies, one for both cytokeratins 13 and 16 (antibody K8.12), and another for cytokeratin 13 only (antibody K5–1A3). CK 13 (MW 51 KD) Is a marker of differentiation and CK 16 (MW 48 KD) is a marker of hyperproliferatlon of keratinocytes. The use of immunoblot probes showed that CKs 13 and 16 were present in cholesteatoma. Immunofluorescenf staining showed the presence of CK 16 In the suprabasal layer of cholesteatoma, which was located near the external ear canal. CK 16 was also localized in the suprabasal layer of meatal skin and tympanic membrane. CK 13 was localized in the basal layer of the cholesteatoma, distal to the external ear canal, but not in the meatal skin and tympanic membrane. Taken together, the present data suggest that cholesteatoma is a hyperprollferative disease and that cholesteatoma expresses CK 16 near the external ear canal and transforms to express CK 13 during growth distally.

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Effects of External Ear Canal Pressure on the Middle-Ear Muscle Reflex Threshold

Journal of Speech and Hearing Research ◽

10.1044/jshr.1703.526 ◽

1974 ◽

Vol 17 (3) ◽

pp. 526-530 ◽

Cited By ~ 3

Author(s):

Frederick N. Martin ◽

Sherry Coombes

Keyword(s):

Tympanic Membrane ◽

Middle Ear ◽

External Auditory Canal ◽

Acoustic Impedance ◽

Normal Hearing ◽

Air Pressure ◽

External Ear ◽

Ear Canal ◽

Acoustic Reflex ◽

Reflex Threshold

Twenty normal-hearing individuals served as subjects in an experiment designed to determine the relationships between positive and negative air pressure in the external auditory canal and the intensity required to elicit the acoustic reflex. Pressure was varied from +240 to −240 mm H 2 O. Changes in the magnitude of acoustic impedance were measured on an acoustic impedance meter and displayed graphically on a Y-T recorder. As air pressure was varied in the canal and the tympanic membrane was displaced from its position of greatest compliance, systematic increases in the intensity required to elicit the reflexes were noted. The magnitude of the differences was smaller than might have been anticipated, not exceeding a mean of 5.1 dB at −240 mm H 2 O.

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Does occurrence of keratinizing stratified squamous epithelium in the middle-ear cavity always indicate a cholesteatoma?

The Journal of Laryngology & Otology ◽

10.1258/0022215042450805 ◽

2004 ◽

Vol 118 (10) ◽

pp. 757-763 ◽

Cited By ~ 2

Author(s):

Lars-Eric Stenfors

Keyword(s):

Tympanic Membrane ◽

Middle Ear ◽

Squamous Epithelium ◽

External Ear ◽

Defence Mechanism ◽

Ear Canal ◽

Non Invasive ◽

Tympanic Membrane Perforations ◽

Acquired Cholesteatoma ◽

Stratified Squamous Epithelium

The origin and behaviour of keratinizing stratified squamous epithelium, anessential component of cholesteatoma occurring in the middle-ear cavity, has puzzled otologistsfor decades. In this experimental study in 16 cats, central (n = 23) and peripheral (n = 9) tympanic membrane perforations were observed for up to 63 days before sacrifice. The tympanic membranes with bony rim were excised, decalcified and embedded in Epon 812. Sections werestained with toluidine blue and examined using a light microscope. The perforation had been sealed by meatal epithelium exhibiting pronounced hyperplasia and keratin formation, lying on abedof granulation tissue. Subtotal central perforations healed within 14 days, forming a bowl-shaped tympanic membrane and leaving parts of the handle of the malleus (with meatal epithelium) protruding freely into the middle-ear cavity. Stratified squamous epithelium, morphologicallyidentical with that of external ear canal epidermis, could be observed on the malleus even 63 days after operation. This meatal epithelium was non-keratinizing, non-invasive, and showed no destructive properties typical of acquired cholesteatoma. During certain circumstances, the cellcycle of hyperplastic epidermal epithelium within the middle-ear cavity can evidently be arrested and inactivated by a local defence mechanism.

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Chapter-12 Middle Ear Dissection and External Ear Canal Widening

Step by Step� Temporal Bone Dissection ◽

10.5005/jp/books/12134_12 ◽

2014 ◽

pp. 63-67

Author(s):

Gauri Belsare

Keyword(s):

Middle Ear ◽

External Ear ◽

Ear Canal ◽

External Ear Canal

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Squamous Epithelium in the Middle Ear and Sinus

Ear Nose & Throat Journal ◽

10.1177/014556139407300112 ◽

1994 ◽

Vol 73 (1) ◽

pp. 47-48

Author(s):

Alper Tutkun ◽

Caglar Batman ◽

Cüneyt Üneri ◽

Mehmet Ali Sehitoglu

Keyword(s):

Middle Ear ◽

Statistical Difference ◽

Squamous Epithelium ◽

Normal Skin ◽

University Hospital ◽

Control Group ◽

Study Group ◽

External Ear ◽

Ear Canal ◽

Superior Part

This study has been performed between December 1990—March 1991 in the Microsurgery laboratory of the Marmara University Hospital. Twelve healthy albino guinea pigs were used as a study group while the control group consists of three animals. The potentials for cholesteatoma formation of the squamous epithelium, namely the squamous epithelium of the posterior superior part of the external ear canal skin and normal skin, were investigated. Among 24 subjects who were implanted by canal skin, cholesteatoma was fanned in 21 of them. Likewise, 19 of 24 animals implanted by normal skin came out with cholesteatoma formation. Between these two types of epithelium, there is no statistical difference in cholesteatoma formation (p >0.5).

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Side-Hole Suction for Ear Surgery

Otolaryngology ◽

10.1177/019459987908700121 ◽

1979 ◽

Vol 87 (1) ◽

pp. 87-88 ◽

Cited By ~ 2

Author(s):

N. Wendell Todd

Keyword(s):

Soft Tissue ◽

Middle Ear ◽

Surgical Trauma ◽

External Ear ◽

Ear Canal ◽

Ear Surgery ◽

Graft Placement ◽

Side Hole ◽

External Ear Canal

Surgical trauma to the soft tissue of the external ear canal and middle ear increases inflammation and scarring. A side-hole suction tip has been found to minimize suction-tip trauma, preclude the need to aspirate through synthetic sponge or cotton, and facilitate graft placement.

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