Membrane coating granules in nonkeratinizing oral epithelium

Squier, C. A.

doi:10.1016/s0022-5320(77)80066-x

Cited by 89 publications

(27 citation statements)

References 38 publications

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“…9a-c). They resemble the type of MCG as described for the oral mucosa [Squier, 1977;Hayward, 1979;Squier and Hall, 1984], for the human cervix [Grubb et al, 1968], the nonhuman primate vagina [King, 1983[King, , 1985a and the shrew vagina [Kress and Milian, 1987]. King [1985a] and Grubb et al [1968] describe the presence of both types of MCG in some cervix and vagina cells.…”

Section: Discussionmentioning

confidence: 65%

Changes in the Epithelium of the Vaginal Complex during the Estrous Cycle of the Marsupial <i>Monodelphis domestica</i>

Regli

Kress²

2002

Cells Tissues Organs

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The vaginal complex of marsupials differs from that of eutherians. Cervices open separately in a sinus vaginalis or cul-de-sac. Two lateral vaginae adjoin the sinus vaginalis and fuse at the level of the urethra opening and form the sinus urogenitalis. During the estrous cycle the vaginal epithelium undergoes a number of specified morphological changes. This paper is the first to describe these changes on an ultrastructural level in a marsupial. Investigations in Monodelphis vagina reveal that a cyclic switch exists between a keratinized and a stratified nonkeratinized epithelium. Keratinization starts during proestrus and reaches its maximum during estrus. In the postestrus, desquamation of the stratum corneum takes place, mostly in two steps. In metestrus one to two additional layers of the now nonkeratinized surface cells are shed into the vaginal lumen. Typical cell structures, such as keratin filaments, keratohyalin and membrane-coating granules, are involved in the keratinization process. Keratohyalin is found in the cytoplasm as well as in the nucleus of stratum granulosum cells, a phenomenon which is known from other parakeratinized epithelia of rapid turnover. Membrane-coating granules, responsible for the permeability barrier between the epithelial cells, are of the nonlamellated type in the nonkeratinized epithelium and produce an amorphous material in the intercellular spaces after extrusion. At periods, however, when the epithelium is keratinized, membrane-coating granules are of the lamellated type and form a lamellated barrier structure after extrusion in the intercellular space. The loss of the protective keratinized layers asks for an additional defense mechanism for the epithelium. The migration of leukocytes through the epithelium predominantly during post- and metestrus and their presence in the vaginal lumen may play a protective role together with the bacterial content.

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Section: Discussionmentioning

confidence: 65%

Changes in the Epithelium of the Vaginal Complex during the Estrous Cycle of the Marsupial <i>Monodelphis domestica</i>

Regli

Kress²

2002

Cells Tissues Organs

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“…Their content, rich in lipids and glycolipids, is discharged in the extracellular spaces covering and linking the cells of the stratum spinosum, which contains not flattened cells closely held together by desmosomes at various stages of differentiation [35] (Fig. 1b) Here, the content of MCGs also acts as a barrier to permeation of various molecules [36].…”

Section: Oral Mucosa: Histology Physiology and Permeability Featuresmentioning

confidence: 99%

“…In general, the permeability of oral mucosa decreases gradually from the sublingual through to the buccal and palatal mucosa [12]. This rank order is related to the relative thickness and degree of keratinization between these regions: sublingual mucosa is relatively thin and non-keratinized, the buccal thicker is non-keratinized, and the palatal is intermediate as regards thickness but keratinized [36]. Compounds with different chemical properties penetrate the "barrier region" by different routes.…”

Section: Absorption Pathwaysmentioning

confidence: 99%

“…For these reasons, new "attached" (better defined as adhesive) drug delivery systems for the local drug delivery have been developed [59]. Recent research on polymers with mucoadhesive properties has led to the development of several buccal delivery systems able to maintain a steady release of drug in the systemic circulation thanks to a closed contact with the mucosal membrane, resulting in high concentration in a local area and high drug flux through the mucosa [11][12][13][14][15][33][34][35][36][37][38][39][40][41]. Because the transient spikes in drug concentration, typical in a daily multiple-dose regimen, are not present with these delivery systems, the risk of toxic side-effects is decreased [57].…”

Section: Drug Delivery Via the Oral Mucosamentioning

confidence: 99%

See 1 more Smart Citation

Mucoadhesive Polymers for Oral Transmucosal Drug Delivery: A Review

Bagán¹,

Paderni²,

Termine³

et al. 2012

CPD

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Abstract:The oral mucosa offers an interesting site for the application of dosage forms that release drugs within/throughout the oral mucosa, by assuring a high drug bioavailability for topic and systemic effects. However, the relative permeability of the oral mucosa and the washing effect related to the oral fluids and mechanical stresses must be considered in the formulation of oral dosage forms. Since a sustained drug release can be guaranteed only if dosage forms remain in contact with the oral site of absorption/application for a prolonged time, the development of mucoadhesive dosage forms is mandatory. The mucoadhesion is a complex phenomenon and the mucoadhesive bond consists of two different parts, the mucoadhesive polymers and the mucous substrate. In addition to factors related to the oral mucosa and oral environment features, the physical-chemical characteristics of mucoadhesive polymers must be also considered as factors influencing the mucoadhesive bonds. While it is not possible to modify the mucosal features or it is possible to modify or inhibit only in part certain mucosal processes, the knowledge of polymer properties influencing mucoadhesive bonds allows to modify or to control these properties in developing increasingly effective mucoadhesive systems. The aims of this review are to discuss the several mechanisms and factors behind the phenomenon of mucoadhesion with particular reference to the features of the oral environment, oral mucosa, and polymeric compounds influencing mucoadhesion process. Finally, a brief mention to the main mucoadhesive dosage forms designed for oral transmucosal drug delivery is made.

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“…In this paper, these vesicles will be called membrane-coating granules (MCG). Nonlaminated MCG have been described in non keratinizing oral epithelium [9,10) and in hyperkeratotic skin lesions of Kyrle-Fiegel disease [11], Near the junction of the middle and distal third of the stratum spinosum, the MCG fused with the plasmalemma ( A third type of junction, which resembled a continuoustype septate junction 112J. and which will be called a septate-like junction in the present paper (reasons for using this name are given in the Discussion), was seen for the first time often in close association with a gap junction ( fig.9, 10).…”

Section: Stratum Spinosummentioning

confidence: 99%

Structural Changes in Intercellular Junctions during Keratinization of the Stratum Medium of the Equine Hoof Wall

Leach¹

1993

Cells Tissues Organs

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Cells of the intertubular horn of the stratum medium of the equine hoof wall are joined by three types of junctions. Desmosomes and gap junctions were present in all strata. Septate-like junctions and an intercellular line were seen in the distal stratum spinosum subsequent to extrusion of the contents of membrane-coating granules. At a later stage of keratinization, non-membrane-bound acid phosphatase reaction product appeared to leak into the intercellular space except into areas occupied by septate-like junctions and the intercellular line. It is proposed that the formation of septate-like junctions and the intercellular line prior to leakage of acid phosphatase into the intercellular space created stable areas of intercellular adhesion between fully keratinized cells.

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Membrane coating granules in nonkeratinizing oral epithelium

Cited by 89 publications

References 38 publications

Changes in the Epithelium of the Vaginal Complex during the Estrous Cycle of the Marsupial <i>Monodelphis domestica</i>

Changes in the Epithelium of the Vaginal Complex during the Estrous Cycle of the Marsupial <i>Monodelphis domestica</i>

Mucoadhesive Polymers for Oral Transmucosal Drug Delivery: A Review

Structural Changes in Intercellular Junctions during Keratinization of the Stratum Medium of the Equine Hoof Wall

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