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PubMed1988

Histological variation of the lining epithelium of the calcifying odontogenic cyst. A light microscopic study.

The lining epithelium of thirty cases of calcifying odontogenic cysts (COC) was studied light microscopically. Results show two distinct types: 1. the classical highly-differentiated lining epithelium characterised by a basal layer of columnar cells with nuclear polarisation supporting suprabasally several layers of stellate reticulum-like cells and containing variable amount of ghost cells present in all the cases and a necessary criteria for the diagnosis of COC; 2. the undifferentiated lining epithelium which is of 2-3 cells to 5-8 cells thick, non-, para- or orthokeratinised and resembled reduced enamel epithelium. This is seen in some cases in some parts of the cystic lining. Variations within the highly-differentiated epithelium include spindle-cell change, epithelial pearl formation and ghost cell dominant type. In the present series, ten cases were associated with odontome formation, three with melanin pigment and one with clear cells. The study supports the concept that COC are lesions of odontogenic origin that may arise as primary lesions from the remains of the dental epithelium or secondarily from the lining epithelium of pre-existing lesions.

Adolescent↗

PubMed1987

Comparison of central and peripheral human corneal epithelium in tissue culture.

Past attempts to grow human corneal epithelium in culture had limited success, with confluence rarely attained. This work is to determine whether different areas of human corneal epithelium grow better in tissue culture. We compared the extent, the mitotic rates, and morphology of outgrowths and histology of explants from central and peripheral human corneas in culture. Explants, 2 mm in diameter, removed from eye bank eyes, were placed epithelial side up on a culture dish with modified SHEM tissue culture medium (Jumblatt et al, 1983). After 7 days, the tissues were fixed, stained and the area of outgrowths from explants measured using an image processor. For eight eyes from donors averaging 66 yr old, the average area of central outgrowths was 7.8 +/- 1.1 mm2, while that of peripheral outgrowths was 52.8 +/- 5.2 mm2 (P less than 0.001). The mitotic rate of outgrowths of central epithelium was significantly less than that of peripheral epithelium (1.1 +/- 0.5% vs 18.8 +/- 0.8%) (P less than 0.001). After 14 days, central outgrowths had not attained confluence and consisted of large cells. Peripheral outgrowths had attained confluence and consisted of small polygonal cells. Histology of explants showed that only one layer of epithelium remained on the stroma in central explants, but several layers were present on the peripheral explants. Thus, peripheral human corneal epithelium grows better in culture than does central human corneal epithelium.

Cornea↗

PubMed1982

The surface structure of the human nasal mucosa. I. Ciliated and metaplastic epithelium in normal individuals. A correlated study by scanning/transmission electron and light microscopy.

This study is part of a larger investigation, which includes morphometric and histopathologic studies, with the common objective of obtaining a comprehensive description of normal and altered nasal mucosa. Specimens from normal young subjects of both sexes (4 girls and 10 boys, 4-14 years of age) and middle-aged male persons (40-60 years of age) were investigated. Squamous metaplasia starts at an early age and becomes more prominent with increasing years. Pseudostratified epithelium is replaced by fully developed stratified squamous epithelium through a sequence of epithelial alterations starting with stratified cuboidal epithelium followed by mixed stratified cuboidal/stratified squamous epithelium. Each stage during this transformation can be readily recognized by its fine structural surface pattern. The changes in surface features during metaplastic transformation include (i) an increase in number and shortening of the microvilli, (ii) the appearance of microridges in squamous epithelium and (iii) alterations in mucus secretion, changing from macroapocrine in pseudostratified epithelium to microapocrine secretion in metaplasia. Metaplasia usually appeared in sharply demarcated areas, and each type is always surrounded by the directly preceding or succeeding variety of epithelium.

Adolescent↗

PubMed1984

Methods for the determination of epithelial cell kinetic parameters of human colonic epithelium isolated from surgical and biopsy specimens.

The purpose of this study is to introduce the application of new approaches to the determination of human colonic epithelial cell kinetic parameters. The isolation of pure and intact colonic epithelium from both surgical and biopsy specimens forms the basis of these approaches. The isolated epithelium is used in the determination of cell kinetic parameters by (a) flow cytometry, (b) Coulter counting, (c) dried cell preparations, and (d) crypt squashes. Using these methods, the following results were derived. The proportion of cells in the various phases of the cell cycle in the sigmoid epithelium was determined to be 81.6% +/- 2.15% (means +/- SE) in G1/G0 phase, 15.2% +/- 1.86% in S phase, and 3.2% +/- 0.62% in G2 + M phases. In the rectal epithelium, there were 79.6% +/- 3.35% in G1/G0 phase, 16.4% +/- 4.86% in S phase, and 4.08% +/- 1.90% in G2 + M phases. The total cell population in sigmoid epithelium was approximately 4.2 X 10(6) +/- 5.46 X 10(5) cells per cm2, and there were approximately 2.5 X 10(3) +/- 1.57 X 10(2) cells in each colonic crypt. Therefore, the number of crypts per square centimeter of human sigmoid mucosa could be estimated to be approximately 1.68 X 10(3). Lastly, in sigmoid epithelium, columnar cells of human sigmoid mucosa could be estimated to be approximately 1.68 X 10(3). Lastly, in sigmoid epithelium, columnar cells accounted for 76.3% +/- 6.18% of the epithelial cells, whereas the remaining epithelial cells, 23.7% +/- 4.08%, consisted of mucous cells.

Cell Count↗

PubMed1977

[Pathological ultrastructural findings in the epithelium of the respiratory passages in children and adults with repeated and chronic respiratory diseases (author's transl)].

The ultrastructure of the respiratory passages epithelium of children, adolescents and older adults suffering from repeated or chronic respiratory disease was studied in the material obtained as a small excision during bronchoscopy. The findings were classified into 4 groups according to the character of the ultrastructural changes found in the epithelium. In large bronchi was found: I--a completely unaltered pseudostratified columnar ciliated epithelium, II--a pseudostratified columnar epithelium with various signs of pathological alteration, III--an altered pseudostratified columnar epithelium with first ultrastructural signs of the development of squamous metaplasia, IV--a developed stratified squamous epithelium. In our opinion, in the respiratory passages of children and adolescents, even if they suffer from repeated respiratory diseases, the pseudostratiified ciliated epithelium persists however damaged to various degree. These patients were classified into the second or at most into the third group. The observation of fully developed squamous metaplasia is reserved to older patients with longer history of chronic respiratory disease.

Adolescent↗

PubMed2003

UV irradiation causes multiple cellular changes in cultured human retinal pigment epithelium cells.

BACKGROUND: The retinal pigment epithelium maybe causally involved in the development and progression of age-related macula degeneration; however, the mechanisms leading to the development of age-related macula degeneration remain largely unknown. The purpose of this study was to examine cellular changes in the retinal pigment epithelium induced by direct irradiation with UV light in culture. METHODS: Retinal pigment epithelium cells from post-mortem human retinas were used to obtain dissociated cultures with cells retaining the ability to differentiate in vitro. These cells were cultured over several days to weeks. The UV radiation (UV-A and UV-B) occurred under sterile conditions with a 100 HBO/mercury bulb attached to a dissecting microscope, delivering co-axial illumination. The time dependence of irradiation effects was analysed using morphometric, immunohistochemical, functional and apoptosis-detecting techniques. RESULTS: Vital and proliferating retinal pigment epithelium cell cultures could be prepared consistently. The cells showed tissue-specific morphologies in vitro for several days to weeks. Pigment epithelium-derived factor was detected in these cells using immunocytochemistry and Western blots. The UV irradiation but not white light resulted in measurable alterations of cell shape and size. The irradiated cells showed partial swelling and shrinkage reminiscent of progressing apoptotic degeneration. TUNEL staining revealed that apoptosis was induced by UV light, but not detectably by white light. The phagocytosis of fluorescent micro-particles diminished after irradiation. These effects were dependent on the duration of irradiation. CONCLUSIONS: Cultures of retinal pigment epithelium are suitable and sensitive models to study cell damage and may contribute to unravelling the pathogenetic mechanisms of retinal degeneration.

Apoptosis↗

PubMed1992

Effects of melatonin and light on porphyrin synthesis in the bovine retina, pigment epithelium and choroid.

The quantity of porphyrin synthesized in the presence of 10(-3) M delta-aminolevulinic acid (ALA) is several times higher in the bovine pigment epithelium than in the retina. Synthesis in the retina was found to be increased by illumination, whereas synthesis in the pigment epithelium was decreased if the whole anatomical unit (retina-pigment epithelium-choroid) was cultivated together. The quantity of porphyrin synthesized in the presence of 10(-3) M ALA or 10(-6) M melatonin was different when the pigment epithelium and retina were separated. The combination 10(-3) M ALA with 10(-6) M melatonin inhibited retinal porphyrin synthesis after green light adaptation, while in the pigment epithelium green light adaptation induced porphyrin synthesis. It is postulated that the light-sensitive porphyrin-haeme synthesis of the retina-pigment epithelium-choroid functional unit may serve and modulate the synthesis of guanylate cyclase for cGMP.

Adaptation, Physiological↗

PubMed2006

Unique distribution of thrombospondin-1 in human ocular surface epithelium.

PURPOSE: The study was conducted to elucidate the detailed expression pattern of angiogenesis-related factors in human ocular surface epithelium. The focus was factors with significantly higher gene expression in corneal epithelium (CE) than in conjunctival epithelium (CJE). METHODS: The relative gene expression of 36 angiogenesis-related factors was compared in human CE and CJE, by using the introduced amplified fragment-length polymorphism (iAFLP) METHOD: Also examined were the expression patterns in the CE, limbal epithelium (LE), and CJE of factors with significantly higher expression in the CE, by using real-time PCR, in situ hybridization, immunohistochemistry, and immunoelectron microscopy. RESULTS: Only thrombospondin (TSP)-1 exhibited significantly higher expression in the CE. In situ hybridization and real-time PCR showed TSP-1 transcripts in the basal cells of the CE and LE. Compared with the CJE, they were significantly upregulated at those sites. Immunohistochemistry revealed that TSP-1 was strongly expressed in the basal region of the CE. Its expression was faint in LE and absent in CJE. Immunoelectron microscopy revealed that the CE and LE demonstrated TSP-1 labeling just below the epithelium, in the basal region of basal cells, and occasionally in the basal cell membrane. There was little or no labeling in the CJE. CONCLUSIONS: In the human ocular surface epithelium, basal cells of the CE and LE, but not of the CJE, synthesize TSP-1. High levels of TSP-1 are present only just below the CE. Its unique distribution may be related to corneal avascularity and integrity.

Angiogenic Proteins↗

PubMed1980

[Comparative study of lipid peroxidation in the eye pigment epithelium of pigmented and albino animals].

The induction of lipid peroxidation in the eye pigment epithelium of pigmented rabbits by the Fe2+ + ascorbate and xanthine--xanthine oxidase systems did not result in accumulation of malonic dialdehyde. In albino rabbits the lipid peroxidation of the non-pigmented pigment epithelium and retina occurred at a high rate under the same conditions. The rate of lipid peroxidation also showed an increase after removal of melanoprotein granules from the pigmented pigment epithelium. The latter inhibited the rate of lipid peroxidation in the eye retina. In albino animals the rate of lipid peroxidation in a mixture of the tow tissues (i.e. pigment epithelium and retina) is almost 4 times that in the pigmented animals. Consequently, the pigmented pigment epithelium of the eye is much more resistant to the effect of prooxidant systems as compared to the non-pigmented one. It is assumed that one of the main functions of the melanoprotein granules in the eye pigment epithelium cells is their protective effect.

Albinism↗

PubMed1991

Antioxidant enzymes in the aging human retinal pigment epithelium.

The antioxidant enzymes catalase and superoxide dismutase have integral roles in controlling reactive oxygen radicals that can harm cells. In the present study, we quantitated catalase activity in retinal pigment epithelium, retina, iris, and vitreous from human donors. To our knowledge, our results represent the first quantitation of catalase activity in human retinal pigment epithelium and show six-fold greater catalase activity in retinal pigment epithelium than in other ocular tissues analyzed (P less than .0001). To investigate whether aging or macular degeneration affects retinal pigment epithelium catalase or superoxide dismutase activities, we measured enzyme levels in retinal pigment epithelium from donors 50 to 90 years of age with and without evidence of macular degeneration. Superoxide dismutase activity showed no significant correlations with aging or macular degeneration, while catalase activity decreased with age (P less than .02) and macular degeneration (P less than .05) in both macular and peripheral retinal pigment epithelium.

Aged↗

PubMed1997

Pseudomonas aeruginosa adherence to external auditory canal epithelium.

BACKGROUND: Pseudomonas aeruginosa is an important causative agent for external otitis. The specific bacterium-host reaction has not been investigated. It is therefore unknown whether adhesion of the external otitis strain to the external auditory canal epithelium is increased compared with strains isolated from other infections. DESIGN: A cohort study was designed to outline adhesion of P aeruginosa to the external auditory canal epithelium, cultured in vitro, of the guinea pig. Factors important for pathogenesis were also studied. PATIENTS: Pseudomonas aeruginosa strains from nonhospitalized patients were collected consecutively at the bacteriological laboratories at Karolinska Hospital, Stockholm, and Huddinge Hospital, Huddinge, Sweden. External otitis strains were compared with strains from leg ulcers, urinary tract infections, and cystic fibrosis. METHODS: Adhesion to the external auditory canal epithelium cultured in vitro was measured and compared groupwise with the mean profile of pathogenic factors. RESULTS: Adhesion to the epithelium was significantly increased for external otitis strains. These strains also had a significantly increased deoxyribonuclease production and a significantly decreased production of pyocyanin and alginate. CONCLUSIONS: The significantly increased ability of P aeruginosa, isolated from external otitis, to adhere to external auditory canal epithelium was combined with a significant production of pathogenic factors. The P aeruginosa that causes external otitis could therefore be considered a particular phenotype. The enzyme profile for external otitis strains was similar to that of the control groups except for the strains from cystic fibrosis. Adhesion to guinea pig vs human epithelium must be compared, and the effects of extracellular proteins on adhesion should be studied to further understand how P aeruginosa adheres to the external auditory canal.

Animals↗

PubMed1998

Fatty acid composition of phospholipids in epithelium and stroma of human benign prostatic hyperplasia.

BACKGROUND: Although it is well known that prostatic 5alpha-reductase is active only in its membrane-bound form, rather limited information is available concerning the composition of cellular lipids in human BPH. Therefore, in the present study, the phospholipid fatty acid composition and content in epithelium and stroma of human BPH have been investigated for the first time. METHODS: Phospholipids separated on TLC plates were methylated and fatty acid methyl esters were analyzed by capillary gas chromatography. RESULTS: The fatty acid composition of total phospholipids was significantly different between epithelium and stroma. In particular, the percentage of oleic acid was significantly higher in epithelium as compared with stroma, whereas that of arachidonic acid was significantly lower in epithelium than in stroma. In addition, significant differences between epithelium and stroma were found in regard to the fatty acid composition of the main phospholipid subclasses. Another remarkable finding were the age-dependent changes of the fatty acid composition in human BPH. CONCLUSIONS: This study shows that the fatty acid composition of phospholipids is significantly different between epithelium and stroma of human BPH. Furthermore, age-dependent alterations of the fatty acid composition were found. Further studies are needed to determine whether the endogenous hormonal milieu in the prostate modulates the fatty acid composition of the prostatic cells, as well as what impact such modulation could have on the properties of membrane proteins, i.e., enzymes like the 5alpha-reductase and receptors, which are thought to be affected by alterations in membrane fluidity or composition, or both.

3-Oxo-5-alpha-Steroid 4-Dehydrogenase↗

PubMed1997

Epithelium is required for maintaining FGFR-2 expression levels in facial mesenchyme of the developing chick embryo.

In the developing chick embryo, fibroblast growth factor-2 (FGFR-2) expression patterns correlate with outgrowth of facial prominences. Frontonasal mass prominences that form the pre-nasal cartilage and upper beak express high levels of FGFR-2 receptor, whereas maxillary prominences that form the flattened corners of the beak and palatal shelves express low FGFR-2 transcript levels. Facial epithelium is an abundant source of FGFs and is required to support outgrowth of mesenchymal tissue, including cartilage rod formation. Because FGFR-2 is highly expressed in regions of facial outgrowth and because epithelium is required for outgrowth of facial prominences, epithelium could be required to maintain FGFR-2 transcripts in facial mesenchyme. To test this hypothesis, we removed epithelium to inhibit outgrowth of regions of the embryonic face, grafted frontonasal mass and maxillary prominences into a host limb bud, and then examined changes in FGFR-2 expression using in situ hybridization. We also hybridized adjacent sections with collagen II probe to identify regions undergoing chondrogenesis. Our results indicate that removal of epithelium from frontonasal mass led to a decrease in FGFR-2 and collagen II expression 24 hr after grafting to host and that neither FGFR-2 nor collagen II expression increased to expected levels at 48 hr. These results suggest that there are signals in the epithelium required for increasing FGFR-2 and collagen II gene transcription, and the expression of these genes are linked to outgrowth of facial prominences.

Animals↗

PubMed1997

Ultrastructural study of the keratinization of the dorsal epithelium of the tongue of Middendorff's bean goose, Anser fabalis middendorffii (Anseres, Antidae).

BACKGROUND: Comparative studies of ultrastructural features of tongues allow deductions to be made about relationships between structure and function, as reflected by an animal's feeding habits. The present study was performed to serve as a basis for further studies of avian feeding mechanisms and of relationships between the fine structure of the lingual epithelium and the development of the expression of keratins. METHODS: The light microscope, scanning electron microscope, and transmission electron microscope were used. RESULTS: The dorsal surface of the tongue of Middendorff's bean goose, Anser fabalis middendorffii, has a distinctive anterior region that extends for five-sixths of its length and has a clear posterior region. The anterior region, when observed macroscopically and by scanning electron microscopy, is distinguished along its forward half by a clear median line. The back half of the anterior region has an indistinct median sulcus in some parts. There are no lingual papillae on the entire dorsal surface of the anterior and posterior regions. Giant conical papillae are located in a transverse row between the anterior and posterior regions. On both lateral sides of the anterior region for five-sixths of the length of the tongue, lingual hairs are compactly distributed, and small numbers of large cylindrical papillae are arranged at almost regular intervals between these lingual hairs. Examination of the dorsal lingual epithelium by light and transmission electron microscopy provided histological and cytological criteria for distinguishing the anterior and posterior regions, both of which were composed of stratified squamous epithelium. Basal cells were similar throughout the dorsal epithelium. The intermediate layer of cells in the anterior region contained numerous tonofibrils in electron-dense bundles composed of tonofilaments of 10 nm in diameter. The outer layer was composed of electron-dense, well-keratinized cells, with layers of electron-lucent cells on the outermost surface. The cells in the intermediate layer in the posterior region of the tongue were almost completely filled with unbundled tonofilaments. The surface layer exhibited features of parakeratinization. In all of the giant conical papillae, the large cylindrical papillae, and the lingual hairs, the epithelium was strongly keratinized. CONCLUSIONS: The three-dimensional microanatomy and cytological features of the dorsal lingual epithelium of avians seem to be related to the functional role and shape of the tongue of each species in feeding.

Age Factors↗

PubMed1997

Distribution of leukocytes in the epithelium and interstitium of four regions of the Lewis rat epididymis.

BACKGROUND: Leukocytes expressing different surface markers were studied in four regions of the epididymis of Lewis rats. Cells resembling lymphocytes or monocytes had been described in the epididymis, but previous studies differed as to their nature and immunologic significance. METHODS: Frozen sections were immunocytochemically stained with monoclonal antibodies W3/25, OX-8, OX-42, and RLN-9D3, which are directed toward markers on CD4+ cells, CD8+ cells, macrophages, and B lymphocytes, respectively. The concentration of stained cells in the epithelium and interstitial tissue of the initial segment, caput, proximal cauda, and distal cauda regions was determined by a procedure based on the optical disector method. RESULTS: CD4+ leukocytes were present in greater concentration than CD8+ cells or macrophages in both the epithelium and interstitial tissue of all four regions. In the epithelium, the concentration of CD8+ leukocytes was greater than that of macrophages in the initial segment, caput, and distal cauda. In the interstitium, however, the concentration of macrophages exceeded that of CD8+ cells in both parts of the cauda. Macrophages and T lymphocytes were generally present in greater concentrations in the interstitium than in the epithelium, especially in the more proximal parts of the epididymis. In contrast to T cells, B lymphocytes were not detected in the interstitium or epithelium of any of part of the epididymis, despite prominent staining of B cells in other locations. CONCLUSIONS: The epididymal epithelium of the Lewis rat contains many T lymphocytes, which may correspond to 'halo' cells. CD4+ leukocytes predominate in all regions of the epididymis. The interstitium may function as a reservoir of leukocytes for the epithelial compartment. The epididymis is not normally a site for local immunoglobulin synthesis.

Animals↗

PubMed1996

Factors affecting neuronal birth and death in the mammalian olfactory epithelium.

To identify factors regulating neurogenesis and neuronal death in mammals and to determine the mechanisms by which these factors act, we have studied mouse olfactory epithelium using two different experimental paradigms: tissue culture of olfactory epithelium purified from mouse embryos; and ablation of the olfactory bulb in adult mice, a procedure that induces olfactory receptor neuron (ORN) death and neurogenesis in vivo. Studies of olfactory epithelium cultures have allowed us to characterize the cellular stages in olfactory neurogenesis and to identify factors regulating proliferation and differentiation of precursor cells in the ORN lineage. Studies of adult olfactory epithelium have enabled us to determine that all cell types in this lineage-proliferating neuronal precursors, immature ORNs and mature ORNs-undergo cell death following olfactory bulb ablation and that this death has characteristics of programmed cell death or apoptosis. In vitro studies have confirmed that neuronal cells of the olfactory epithelium undergo apoptotic death and have permitted identification of several polypeptide growth factors that promote survival of a fraction of ORNs. Using this information, we have begun to explore whether these factors, as well as genes known to play crucial roles in cell death in other systems, function to regulate apoptosis and neuronal regeneration in the adult olfactory epithelium following lesion-induced ORN death.

Animals↗

PubMed1976

Light and electron microscopic study of the degeneration and early regeneration of olfactory epithelium in the mouse.

Degeneration and early regeneration of olfactory epithelium from two strains of mice was studied at the light and electron microscopic levels from 12 hours to 3 days following nasal irrigation with 1% aqueous solution of zinc sulfate (ZnSO4) (a compound known to selectively damage olfactory epithelium). Distinct patterns of degeneration and stages of regeneration were evident following treatment. During the first 24 hours after treatment three progressive manifestations of the degenerative process were seen: (1) a relatively mild condition which was characterized by surface irregularities produced by cell protrusions, highly vacuolated cytoplasm, presence of large lysosome-like bodies and prominent intercellular spaces, (2) a more severe condition in which large areas of the epithelium were detached from the basement membrane cellular debris was present in the nasal chamber, and (3) a condition of total or near-total denudation of the epithelium of olfactory mucosa. The basal lamina was continuous and intact in most regions and the integrity of the subadjacent connective tissue was mostly well-preserved. Nerve bundles of the fila olfactoria were noted in varying degrees of degeneration during the course of the experiment. The most advanced neural degeneration was seen 24 to 72 hours after treatment. Onset of regeneration was suggested by the appearance of a simple squamous layer of cells above the basement membrane 48 to 72 hours after treatment. In addition to the simple epithelium a stratified epithelium consisting of two to four cell layers was also observed at this time. Glandular cells, containing secretory granules identical to those in Bowman's glandular cells, were noted in an apparent process of migration from the lamina propria into the the stratified epithelial layer. The last mentioned observation supports the proposition that new supportive epithelial cells originate from cells of Bowman's gland.

Animals↗

PubMed1989

Development of the stratified squamous epithelium of the human tympanic membrane and external canal: the origin of auditory epithelial migration.

The development of the stratified squamous epithelium of the tympanic membrane and external canal was studied in 167 embryonic, fetal, and postnatal human ears. It originates as a tube derived from the epithelium of the fundus of the primary external canal (zone 1). The tube is composed of a thin, flat epithelium on the medial side (zone 2), continuous with a thicker one (zone 3) on the lateral side; zone 3 thereafter merges with the external epithelium of the primary external canal (zone 4). Proliferative activity, as indicated by a thickened epithelium, with rete ridges in later fetal life, is present mainly in zones 1 and 3. Cornification at 18 weeks gestation is followed by clearing of keratinous debris to the exterior. Subsequently the canal widens, zone 1 now covering the pars flaccida region, a tongue-shaped area passing inferiorly from it and a part of the postero-superior deep canal adjacent to it; zone 2 covers the pars tensa and zone 3 most of the deep external canal. On the basis of the original embryonic growth, migratory epithelial movement throughout life is postulated to be generated in zone 1 by mitotic interposition and then to pass to zone 2. It then moves en masse through to zone 3, where unilateral progression by mitotic means takes the epithelium up to the cartilaginous canal. Such a pathway is approximately that seen in the marked, living eardrum and canal.

Cell Movement↗