Auditory epithelial migration. III. development of the stratified squamous epithelium of the tympanic membrane and external canal in the mouse

The development of the stratified squamous epithelium of the tympanic membrane and external auditory canal was studied in serial sections of 124 mouse ears aged from 11 gestational days to 100 days. A fold developed from the edge of the fundus of the primary canal. It possessed two regions: firstly the meatal plate, which produced the pars tensa-covering epithelium (zone 2) and most of the deep ear canal epithelium (zone 3), and secondly the fundal extension plate, which grew from that part of the fundus not forming the meatal plate. The fundal extension plate gave rise to the pars flaccida-covering epithelium (zone 1) and also to the adjacent deep canal epithelium (zone 3). A difference from human development was that zone 3 in the mouse, in both the meatal plate-and the fundal extension plate-derived areas, formed adnexal structures. In the early development of the meatal plate, zone 3, at its tip, was swollen and actively mitotic and extended always for a short distance on to the zone 2 side. Zone 2, first perceived two days after zone 3, became progressively attenuated, and by the fourth day after its formation was a single thin layer. It is suggested that the proximal part of zone 3, situated in the mature ear around the periphery of the tympanic membrane, is a generation center for unidirectional outward flux of epithelium which terminates in the mouse at the first adnexal structure. It may cause the whole of zone 2 to move in the same direction by negative contact inhibition.     

Co-localization of multiple ErbB receptors in stratified epithelium of oral squamous cell carcinoma.

The expression of all four ErbB receptors was compared by immunohistochemistry, using receptor-specific polyclonal antisera, in 32 invasive, 11 in situ carcinomas, six benign lesions, and 22 samples of histologically normal mucosa adjacent to specimens of carcinoma originating from oral cavity epithelium. Among invasive and in situ carcinoma, EGFR expression was the most prevalent (in 29/32 and 8/11 cases, respectively) followed by ErbB2 (17/32 and 2/11) and ErbB4 (9/32 and 1/10), while ErbB3 was only detected in invasive tumours (12/32). Specific patterns included invasive tumours with expression of EGFR (8/32) or ErbB4 (1/32) alone, as well as different receptor combinations (EGFR+ErbB2, EGFR+ErbB4, EGFR+ErbB2+ErbB3, EGFR+ErbB2+ErbB4, and all four receptors). Simultaneous expression of three or four ErbB receptors correlated with tumour invasion (p=2.2x10(-4)) and localized in the intermediate epithelial cell layer of well and moderately differentiated tumours. No other significant correlation with clinico-pathological features was noticed. Some benign lesions and histologically normal mucosa adjacent to carcinomas showed weak immunostaining of EGFR (10/28), ErbB2 (4/28) or ErbB4 (3/28). By comparison, overexpression, as indicated by increased staining intensity, was observed in invasive tumours for EGFR (18/32), ErbB2 (8/32), ErbB4 (3/32), and ErbB3 (3/32). Statistical evaluation demonstrated a significant association of EGFR or ErbB2 overexpression with invasive carcinoma when compared with benign lesions and apparently normal epithelium (p=5.2x10(-7) and p=5x10(-3), respectively). Tumour-specific overexpression of ErbB receptors and their co-expression, most frequently involving EGFR and ErbB2, in the same cell layer of neoplastic epithelium, implicate receptor heterodimers in the pathogenesis of oral squamous carcinoma.     

The effect of some local anesthetics on protein metabolism in stratified squamous epithelium

Summary A study was carried out to discover the effect of local anesthesia on the intensity of incorporation of S⁵⁵-labelled methionine into the cells of stratified epithelium of the tongue mucosa in white rats. It was established that the velocity of incorporation of S⁵⁵ into the cells of stratified epithelium is retarded under the effect of local a nesthesia (10–20% xycaine or cocaine). Consequently, the velocity of protein resynthesis in this tissue is also retarded. However, the character of distribution of S⁵⁵ in various layers of the epithelium is not changed. No pronounced difference was noted in the intensity of incorporation of S⁵⁵ in administration of cocaine or xycaine. It was demonstrated that both anesthetics affect the intensity of metabolism in the same way, and retard the resynthesis of protein to about the same degree.Presented by Active Member Acad. Med. Sci. USSR, S.V. Anichkov     

Secretion of lung fluid by the developing fetal rat alveolar epithelium in organ culture.

We studied lung explants in submersion organ culture to examine the role of the developing fetal alveolar epithelium in the production of lung fluid. Fourteen-day-gestation fetal rat lungs were grown in a collagen gel matrix supplemented with F-12 media and 10% fetal calf serum. In this model, the lung continues to grow, secrete fluid, and become progressively cystic in morphology. There is gradual thinning of the distal epithelial layer, which is lined by alveolar type II cells and their precursors. After 6 to 8 days in culture, we impaled the cyst walls with a microelectrode and continuously recorded the transepithelial potential (psi t). Stable, baseline transepithelial potentials of -1.1 to -6.2 mV (mean +/- SEM = -3.3 +/- 0.11 mV, lumen negative, n = 34) were measured in bicarbonate-buffered Ringer's solution, suggesting active electrolyte transport. When bumetanide, an inhibitor of chloride secretion in other systems, was added to the bathing solution, psi t decreased from a baseline of -3.5 +/- 0.07 mV (mean +/- SEM) to a value of -2.2 +/- 0.07 mV, suggesting chloride transport contributes to the voltage (n = 18, P less than 0.0005). Isoproterenol hyperpolarized psi t from a baseline of -4.3 +/- 1.0 mV to -6.5 +/- 1.0 mV (n = 7, P less than 0.005). 8-(4-Chlorophenylthio) adenosine 3':5'cyclic monophosphate (CPT-cAMP) plus isobutylmethylxanthine (IBMX) similarly hyperpolarized psi t from a baseline of -4.6 +/- 0.4 mV to -7.3 +/- 0.7 mV (n = 11, P less than 0.005). Addition of bumetanide after stimulation with isoproterenol or CPT-cAMP/IBMX depolarized psi t.(ABSTRACT TRUNCATED AT 250 WORDS)     

Squamous metaplasia of the tracheal epithelium in organ culture. I. Effects of hydrocortisone and beta-retinyl acetate.

Organ cultures of hamster trachea were incubated for periods of as long as 16 weeks in chemically defined medium containing hydrocortisone sodium succinate or the vitamin A analog, β-retinyl acetate. Medium from replicate cultures was assayed weekly for acid phosphatase activity, and representative tissues were harvested after pulse labeling with [³H]thymidine. Explants maintained in medium containing hydrocortisone showed basal cell proliferation, squamous metaplasia, and extensive keratinization, whereas those in medium containing β-retinyl acetate exhibited a proliferative ciliated epithelium that gradually became hypoplastic after 8 weeks in vitro. Simultaneous addition of these agents in equal concentrations resulted in an epithelium which appeared dedifferentiated. Acid phosphatase activity in cultures containing hydrocortisone was elevated. In contrast, release of the enzyme was inhibited when β-retinyl acetate was added to culture medium. Results indicate that hydrocortisone and β-retinyl acetate act in a competitive fashion on differentiation of the basal cell.     

A morphometric analysis of rat ventral prostate in organ culture

A stereologic, morphometric method was used for determining the quantitative and qualitative changes in the rat ventral prostate during organ culture. The volume density of epithelium (VVEP), lumina (VVLU), and interstitium (VVIT) as well as the proportion of epithelium of the tissue, VVEP/(VVEP + VVIT), the length density of tubular structures (LV), mean diameter of the lumina (DLU), height of the epithelium (h), and mean width of the interacinar tissue (lambda AP) were evaluated. In the perfusion-fixed prostate these parameters gave the closest approximation for the in vivo situation: VVEP was 0.19 mm3/mm3; h 19.5 micron; VVEP/(VVEP + VVIT) 0.63 mm3/mm3; VVLU 0.70 mm3/mm3; DLU 230 micron; VVIT 0.11 mm3/mm3; lambda AP 84.1 micron; and LV 17.5 mm/mm3. Dissection of the prostate for culture caused leakage of prostatic secretions and a consequent diminution of VVLU (0.41 mm3/mm3) and DLU (151 micron), as well as folding of the epithelium and distortion of the interacinar tissue (VVIT 0.25 mm3/mm3). During 10 days culture in a defined medium, the prostate underwent involutive changes including loss of total weight, a decrease of VVEP, and an increase of VVIT. During the first day a stimulatory effect on the epithelium occurred, which might have been caused by a loss of androgenic control or by substances in leaking secretions. Testosterone postponed many of these changes and maintained the secretory function better. Thus, on day 4 the morphology of the prostate resembled better the situation in vivo than at the beginning of involutionary culture. However, later during culture changes, similar to those found without testosterone but weaker, were noted. Statistical analysis of data showed that it is more advisable to use many pieces from one prostate lobe rather than to use many animals. Analysis of one slice is also sufficient to give relevant data on that piece.     

Circadian influence on the frequency of labeled mitoses method in the stratified squamous epithelium of the mouse esophagus and tongue.

The frequency of labeled mitoses method (FLM) was used to study the cell kinetics in the stratified squamous epithelium of the mouse esophagus and tongue. FLMs were generated by injecting tritiated thymidine (TdR) at two different phases of the mouse circadian system: TdR was injected into one group of mice at 0900 and into a different, second group of mice at 2100. Three variables were monitored for each group; (1) the FLM, (2) the mitotic index and (3) the grain count over the labeled mitotic figures. In both the esophagus and the tongue there was a circadian rhythm in the mitotic index with the peak occurring during the first half of the diurnal phase and the trough occurring during the first half of the nocturnal phase. The FLM curves from each group revealed the following data.     

Incorporation of H3-thymidine in cells of the stratified squamous epithelium of rats after x-ray irradiation

Summary In the epithelium of the tongue in albino rats, mitoses disappear after irradiation and the percentage of cells synthesizing DNA markedly declines. In 96 h, the number of labelled nuclei sharply increases as compared to the control ones. Consequently, irradiation interferes with the transition of the cells from the G₁ period to the S period and the G₂ period. With the advent of a compensatory process, all periods of the mitotic cycle apparently become shorter.(Presented by Academician N. A. Kraevskii) Translated from Byulleten' Éksperimental'noi Bioligii i Meditsiny, Vol. 59, No. 5, pp. 99–103, May, 1965.     

Cytopathic effects of Treponema denticola chymotrypsin-like proteinase on migrating and stratified epithelial cells.

The effects of Treponema denticola and its outer membrane-bound chymotrypsin-like proteinase on periodontal ligament epithelial cell cultures at different stages of maturity were studied. In sparse cultures with migrating epithelial cells, large intracellular vacuoles were formed rapidly following exposure to live T. denticola. Treponemes showing structural damage were seen occasionally inside membrane-bound vesicles. Intensive membrane blebbing occurred in infected cells and continued for up to 48 h before the cell died. Blebbing could also be induced by a purified chymotrypsin-like proteinase of T. denticola. Cortical actin and alpha-actinin of the bacterium-treated cells showed disorganization, and pericellular fibronectin was degraded by both whole T. denticola and the isolated proteinase. Epithelial cells with well-formed lateral cell contacts appeared to be more resistant to the effects of T. denticola than migrating isolated cells. In multilayer epithelial cultures, adhesion of T. denticola and membrane blebbing were observed infrequently. There was no evidence of invasion of T. denticola into epithelial multilayers. However, immunogold electron microscopy showed rapid transport of T. denticola chymotrypsin-like proteinase into newly formed large intracellular vacuoles within the epithelial layers. These vacuoles were lined by membranes studded with ribosomes. T. denticola-treated epithelial multilayers had loose cell contacts, collapsed intercellular spaces, and increased permeability. Through its capacity to cause these unique cytopathic effects, the chymotrypsin-like proteinase of T. denticola has the potential to contribute to the initiation of periodontal disease.