Epithelial integrity, junctional complexes, and biomarkers associated with intestinal functions

Bacteria exhibit the ability to adhere to the apical surfaces of intestinal mucosal cells. These attachments either precede invasion of the intestinal wall by the bacteria with accompanying inflammation and degeneration of the mucosa or represent permanent anchoring sites where the bacteria never totally penetrate the mucosal cells.Endemic gram negative bacteria were found attached to the surface of mucosal cells lining the walls of crypts in the rat colon. The bacteria did not intrude deeper than 0.5 urn into the mucosal cells and no degenerative alterations were detectable in the mucosal lining.

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Pituitary Follicular Cells: Their Origin, Possible Function and Fate

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100050184 ◽

1974 ◽

Vol 32 ◽

pp. 34-35

Author(s):

E. Horvath ◽

K. Kovacs ◽

G. Penz ◽

C. Ezrin

Keyword(s):

Fine Structure ◽

Secretory Granules ◽

Follicular Cells ◽

Human Pituitary ◽

Rat Pituitary ◽

Pituitary Glands ◽

Junctional Complexes

Follicular structures, in the rat pituitary, composed of cells joined by junctional complexes and possessing few organelles and few, if any, secretory granules, were first described by Farquhar in 1957. Cells of the same description have since been observed in several species including man. The importance of these cells, however, remains obscure. While studying human pituitary glands, we have observed wide variations in the fine structure of follicular cells which may lead to a better understanding of their morphogenesis and significance.

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Freeze-etch observations on the tight junctions of sertoli cells grown in organ culture with FSH

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s042482010008256x ◽

1978 ◽

Vol 36 (2) ◽

pp. 340-341

Author(s):

Rita Meyer ◽

Zoltan Posalaky ◽

Dennis Mcginley

Keyword(s):

Organ Culture ◽

Tight Junctions ◽

Sertoli Cell ◽

Germ Cells ◽

Sertoli Cells ◽

Barrier Function ◽

Cell Junction ◽

Intramembranous Particles ◽

Junctional Complexes ◽

Oriented Parallel

The Sertoli cell tight junctional complexes have been shown to be the most important structural counterpart of the physiological blood-testis barrier. In freeze etch replicas they consist of extensive rows of intramembranous particles which are not only oriented parallel to one another, but to the myoid layer as well. Thus the occluding complex has both an internal and an overall orientation. However, this overall orientation to the myoid layer does not seem to be necessary to its barrier function. The 20 day old rat has extensive parallel tight junctions which are not oriented with respect to the myoid layer, and yet they are inpenetrable by lanthanum. The mechanism(s) for the control of Sertoli cell junction development and orientation has not been established, although such factors as the presence or absence of germ cells, and/or hormones, especially FSH have been implicated.

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Freeze-Fracture Examination of Tight Junctions of Human Eccrine Sweat Glands

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s1431927600002786 ◽

1980 ◽

Vol 38 ◽

pp. 634-635

Author(s):

J. V. Briggman ◽

J. Bigelow ◽

H. Bank ◽

S. S. Spicer

Keyword(s):

Cystic Fibrosis ◽

Freeze Fracture ◽

Sweat Glands ◽

Hypertonic Solution ◽

Dark Cells ◽

Clear Cells ◽

Junctional Complexes ◽

Secretory Coil ◽

Eccrine Sweat Glands ◽

Eccrine Sweat

The prevalence of strands shown by freeze-fracture in the zonula occludens of junctional complexes is thought to correspond closely with the transepi-thelial electrical resistance and with the tightness of the junction and its obstruction to paracellular flow.1 The complexity of the network of junc¬tional complex strands does not appear invariably related to the degree of tightness of the junction, however, as rabbit ileal junctions have a complex network of strands and are permeable to lanthanum. In human eccrine sweat glands the extent of paracellular relative to transcellular flow remains unknown, both for secretion of the isotonic precursor fluid by the coil and for resorption of a hypertonic solution by the duct. The studies reported here undertook, therefore, to determine with the freeze-fracture technique the complexity of the network of ridges in the junctional complexes between cells in the secretory coil and the sweat ducts. Glands from a patient with cystic fibrosis were also examined because an alteration in junctional strands could underlie the decreased Na+ resorption by sweat ducts in this disease. Freeze-fracture replicas were prepared by standard procedures on isolated coil and duct segments of human sweat glands. Junctional complexes between clear cells, between dark cells and between clear and dark cells on the main lumen, and between clear cells on intercellular canaliculi of the coil con¬tained abundant anastomosing closely spaced strands averaging 6.4 + 0.7 (mean + SE) and 9.0 +0.5 (Fig. 1) per complex, respectively. Thus, the junctions in the intercellular canaliculi of the coil appeared comparable in complexity to those of tight epithlia. Occasional junctions exhibited, in addition, 2 to 5 widely spaced anastomosing strands in a very close network basal to the compact network. The fewer junctional complexes observed thus far between the superficial duct cells consisted on the average of 6 strands arranged in a close network and 1 to 4 underlying strands that lay widely separated from one another (Fig. 2). The duct epitelium would, thus, be judged slightly more "leaky" than the coil. Infrequent junctional complexes observed to date in the secretory coil segment of a cystic fibrosis specimen disclosed rela¬tively few closely crowded strands.

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