doktorska disertacija
Urban Bogataj (Author), Nada Žnidaršič (Mentor)

Abstract

Diferenciacija epitelnih celic ima ključno vlogo pri morfogenezi cevastih organov kot je črevo in vključuje usklajene procese, ki potekajo v skladu s fiziološkimi spremembami med razvojem. V okviru doktorske disertacije smo s kombinacijo tehnik svetlobne in elektronske mikroskopije preučili diferenciacijo epitela zadnjega črevesa med razvojem raka Porcellio scaber. Epitel zadnjega črevesa raka enakonožca P. scaber ima tipične ultrastrukturne značilnosti transportnih epitelov, ter tvori dve funkcijsko in anatomsko različni regiji. Diferenciacija črevesnih celic časovno sovpada s ključnimi razvojnimi spremembami med poznim embrionalnim in zgodnjim postembrionalnim razvojem. Gubanje apikalne plazmaleme v apikalni labirint in diferenciacija septiranih stikov sovpadata s pričetkom prehranjevanja ob izvalitvi embrijev iz notranje jajčne ovojnice. Celice zadnjega črevesa marzupijskih mank imajo tako že intenzivno povečano apikalno površino za absorpcijo prebavnih produktov in vzpostavljeno obsežno difuzijsko pregrado za uravnavan paracelularni transport. Po sprostitvi mank iz valilnika v zunanje okolje se nadaljuje diferenciacija apikalnega labirinta in septiranih stikov, oblikuje pa se tudi bazalni labirint, kar je zlasti v papilatni regiji zadnjega črevesa najverjetneje povezano s povečanimi osmoregulacijskimi zahtevami. Mikrotubuli v črevesnih celicah so urejeni v apikalno-bazalno orientirane snope, ki jih je največ v mehansko bolj obremenjenih celicah in se postopno oblikujejo med razvojem mank. Apikalna plazmalema in septirani stiki se povsem preoblikujejo med tvorbo nove kutikule ob levitvi poznih marzupijskih mank. Apikalna plazmalema se preoblikuje v nizke izrastke z elektronsko gostimi konicami, obseg septiranih stikov na lateralnih plazmalemah pa se bistveno zmanjša. Raziskave intaktnih embrijev omogočajo vpogled v diferenciacijo epitelnih celic v fiziološko relevantnem okolju celotnega organizma in s tem interpretacijo ultrastrukturnih sprememb tudi s funkcijskega vidika.

Keywords

črevesni epitel;diferenciacija epitela;apikalni labirint;bazalni labirint;kutikula;celični stiki;citoskelet;embrionalni razvoj;ličinke manke;Isopoda;disertacije;

Data

Language: Slovenian
Year of publishing:
Typology: 2.08 - Doctoral Dissertation
Organization: UL BF - Biotechnical Faculty
Publisher: [U. Bogataj]
UDC: 595.3:576.311(043.3)
COBISS: 936567 Link will open in a new window
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Downloads: 225
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Other data

Secondary language: English
Secondary title: Ultrastructural differentiation of hindgut epithelium during development of crustacean Porcellio scaber (Crustacea: Isopoda)
Secondary abstract: Differentiation of epithelial cells has a key role in morphogenesis of tubular organs such as the gut and involves coordinated processes that procced according to physiological changes during development. With combination of light and electron microscopic techniques we have investigated hindgut epithelium differentiation during development of crustacean Porcellio scaber. The hindgut epithelium of isopod P. scaber exhibits typical ultrastructure of transport epithelia and comprises two anatomically and functionally distinct regions. Hindgut cell differentiation temporally coincides with key developmental transitions during the late embryonic and early postembryonic development. The folding of apical plasma membrane and the differentiation of septate junctions coincide with the hatching from inner egg envelope, associated by the onset of active feeding. These changes provide increased apical surface available for the absorption of digestion products and proficient diffusion barrier for the controlled paracellular transport. After mancae are released into the external environment, the apical plasma membrane and the septate junctions are further differentiated and the basal labyrinth is established, probably in association with increased osmoregulatory demands. The microtubules in hindgut cells are arranged in apico-basally oriented bundles, which are the most abundant in mechanically burdened cells and are gradually formed during the development of mancae. During the formation of new cuticle in molting late marsupial mancae the apical plasma membrane and septate junctions are completely remodelled. The apical plasma membrane forms shallow protrusions and the septate junctions at lateral plasma membranes are considerably reduced. Studies of intact embryos provide insight into epithelial cell differentiation in physiological relevant environment of the whole organism and thus the interpretation of ultrastructural changes from the functional aspect.
Secondary keywords: hindgut epithelium;epithelial differentiation;apical labyrinth;basal labyrinth;cuticle;cell junctions;cytoskeleton;embryonic development;larvae mancae;Isopoda;microscopy;dissertations;
Type (COBISS): Doctoral dissertation
Study programme: 0
Embargo end date (OpenAIRE): 1970-01-01
Thesis comment: Univ. v Ljubljani, Biotehniška fak.
Pages: X f., 164 str.,
ID: 11313354