Membrane specializations in the peripheral retina of the housefly Musca domestica L

Membrane specializations of the peripheral retina of the housefly (Musca domestica) are revealed in thin sections and freeze fracture/etch replicas. Septate junctions are abundant in corner areas of the pseudocone enclosure bonding: between homologous corneal pigment cells (CPC); between homologous...

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Bibliographic Details
Published in:Cell and tissue research 1979-05, Vol.198 (3), p.501-520
Main Authors: Chi, C, Carlson, S.D, St Marie, R.L
Format: Article
Language:English
Subjects:
Animals
arthropods
Basement Membrane - ultrastructure
Cell Membrane - ultrastructure
Desmosomes - ultrastructure
entomology
Epithelium - ultrastructure
Houseflies - ultrastructure
insects
Intercellular Junctions - ultrastructure
Mitochondria - ultrastructure
Retina - ultrastructure
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Summary:Membrane specializations of the peripheral retina of the housefly (Musca domestica) are revealed in thin sections and freeze fracture/etch replicas. Septate junctions are abundant in corner areas of the pseudocone enclosure bonding: between homologous corneal pigment cells (CPC); between homologous large pigment cells (LPC); between CPC-LPC; between Semper cells (SC); between SC-CPC. Spot desmosomes are present between Semper cells. It is likely that septate junctions function as strengthening adhesions in this area. A new membrane specialization similar to a continuous junction was observed between retinular cells of the same or adjacent ommatidium. This junction has indistinct septa in the 115 A intermembrane cleft and is intermittent in character. When this junction is absent, the apposed cells gape apart. In freeze fracture studies, this junction is characterized by bridges composed of fused membrane particles and randomly arranged particles on the P face, and noncorresponding grooves on the E face. The ridges are elongate and roughly parallel and sometimes they form enclosures. Mitochondria line up along these junctions, often within 90 A of the unit membrane. This membrane specialization has characteristics of tight and continuous junctions. In line with previous findings, we suggest that this junction assists in retinular cell orientation, possibly in enforcing the ommatidial twist and in maintaining localized ionic concentration gradients between retinular cells.
ISSN:0302-766X
1432-0878
DOI:10.1007/BF00234194