Variations in Tight and Gap Junctions in Mammalian Tissues
نویسندگان
چکیده
The fine structure and distribution of tight (zonula occludens) and gap junctions in epithelia of the rat pancreas, liver, adrenal cortex, epididymis, and duodenum, and in smooth muscle were examined in paraformaldehyde-glutaraldehyde-fixed, tracer-permeated (K-pyroantimonate and lanthanum), and freeze-fractured tissue preparations. While many pentalaminar and septilaminar foci seen in thin-section and tracer preparations can be recognized as corresponding to well-characterized freeze-fracture images of tight and gap junction membrane modifications, many others cannot be unequivocally categorized-nor can all freeze-etched aggregates of membrane particles. Generally, epithelia of exocrine glands (pancreas and liver) have moderate-sized tight junctions and large gap junctions, with many of their gap junctions basal to the junctional complex. In contrast, the adrenal cortex, a ductless gland, may not have a tight junction but does possess large gap junctions. Mucosal epithelia (epididymis and intestine) have extensive tight junctions, but their gap junctions are not as well developed as those of glandular tissue. Smooth muscle contains numerous small gap junctions The incidence, size, and configuration of the junctions we observed correlate well with the known functions of the junctions and of the tissues where they are found.
منابع مشابه
Gap Junctions Occur in Vertebrate Renal Proximal Tubule Cells
Renal proximal tubular cells are known to be electrically coupled (1) . In other tissues, three types of specialized junctions have been implicated in intercellular ionic communication : septate desmosomes (2), gap junctions (3, 4), and tight junctions (5, 6) . Of these, only the tight junction has been previously identified in kidney tubular epithelium (7) and, therefore, has been thought to b...
متن کاملA journey in doxorubicin-induced cardiotoxicity with emphasizing on the role of Connexin 43 and Sirtuin-3
Cancer has become a major health problem worldwide. The reported incidence of new cancer cases is estimated at 19.3 million, with a mortality rate of 10 million in the world in 2020. There are some approaches for cancer treatment such as chemotherapy, neoadjuant surgery, hormone therapy, and radiotherapy. Chemotherapy is an aggressive form of chemical drug therapy meant to destroy rapidly growi...
متن کاملInsect intercellular junctions: rapid freezing by jet propane.
The ventral nerve cord of the cockroach, Periplaneta americana, and that of the locust, Schistocerca gregaria, have been studied after rapid freezing by cryo-jet, using liquid propane. Such tissues, unfixed and uncryoprotected, have been compared with unfixed cryoprotected tissues, as well as with material fixed with glutaraldehyde and cryoprotected with glycerol or polyvinylpyrrolydone. The pe...
متن کاملBelt-like gap junctions in the ductuli efferentes of some mammalian testes.
Cellular junctions of the lining epithelium of the efferent ductules of the mouse, guinea pig, and human testes were examined by freeze-fracture. A belt-like gap juncion consists of a large aggregation of particles with a few fragments of the tight junctional strands and circumferentially occupies the adluminal area between the nonciliated cells. This type of gap junction appears to be one of t...
متن کاملDefinitive Evidence for the existence of tight junctions in invertebrates
Extensive and unequivocal tight junctions are here reported between the lateral borders of the cellular layer that circumscribes the arachnid (spider) central nervous system. This account details the features of these structures, which form a beltlike reticulum that is more complex than the simple linear tight junctions hitherto found in invertebrate tissues and which bear many of the character...
متن کاملذخیره در منابع من
با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید
عنوان ژورنال:
- The Journal of Cell Biology
دوره 53 شماره
صفحات -
تاریخ انتشار 1972