The Fine Structure of the Compound Eye of Formica polyctena — Functional Morphology of a Hymenopterean Eye

The fine structure of the ommatidia in light- and dark-adapted eyes of male and female Simulium vittatum Zetterstedt was investigated using scanning and transmission electron microscopy. The male eye is divided into distinct dorsal and ventral regions. The facets in the dorsal region are approximately two times larger than those in the ventral one, which are similar in size to the ones in the female eye. All ommatidia of S. vittatum examined consist of two general regions: a distal dioptric apparatus with bordering primary and accessory pigment and Semper cells, and a sensory receptor layer. Each ommatidium in the female eye and ventral eye of the male has eight retinular cells (R cells): six peripheral (R1–6) and two central (R7, R8). R7 occurs distally and R8 basally. Strikingly, the ommatidia in the dorsal eye of the male lack the R7 cell. In all ommatidia, rhabdomeres on the inner surface of the peripheral R cells are separate throughout their length, creating an open rhabdom. A greater diameter of corneal facets, elongated peripheral R cells, and perhaps the lack of the R7 cell are specializations of the dorsal region of the eye that help the male to detect small, rapidly moving females against the skylight as they fly above the swarm of males. Differences observed between light- and dark-adapted eyes of male and female S. vittatum were the same and were associated with the internal components of the peripheral R cells.

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The Biology of Bothrimonus (=Diplocotyle) (Pseudophyllidea: Cestoda): Detailed Morphology and Fine Structure

Journal of the Fisheries Research Board of Canada ◽

10.1139/f74-025 ◽

1974 ◽

Vol 31 (2) ◽

pp. 147-153 ◽

Cited By ~ 4

Author(s):

M. D. B. Burt ◽

I. M. Sandeman

Keyword(s):

Electron Microscopy ◽

Nervous System ◽

Fine Structure ◽

Functional Morphology ◽

Light And Electron Microscopy ◽

Nerve Fibers ◽

Fish Host ◽

Extensive System ◽

And Function

Light and electron microscopy were used to describe the functional morphology of Bothrimonus sturionis in detail. In particular, the musculature, nervous system, osmoregulatory system, and tegument are dealt with, and the findings compared with those of other workers. The musculature of the scolex consists of several interrelated systems, the structure of each being discussed in relation to its function. Associated with the regular nervous system, considered typical of cestodes, is an extensive system of giant nerve fibers. The osmoregulatory system is unusual in that there are lateral "excretory" pores in many proglottides which open directly to the exterior of the worm. The microtriches of the tegument are long, like those of other primitive cestodes, and are covered by a noncellular sheath while the worm is in its gammarid host. The sheath is lost when the worm becomes established in its fish host; the nature and function of the sheath are discussed.

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Aspects of Insect Vision

The Canadian Entomologist ◽

10.4039/ent96320-1 ◽

1964 ◽

Vol 96 (1-2) ◽

pp. 320-334 ◽

Cited By ~ 8

Author(s):

Brian Hocking

Keyword(s):

Special Reference ◽

Functional Morphology ◽

Compound Eye ◽

Ultra Violet ◽

Early History ◽

Insect Vision ◽

Evolutionary Development ◽

History Of

AbstractThe functional morphology of the insect compound eye is reviewed with special reference to its surface and volume relationships with the rest of the head and its evolutionary development. Measurements of the more important parameters of the eyes of 28 species representing 14 major orders are given and interpreted in relation to this review. Recent histological and biophysical work on insect vision is also reviewed and some conclusions, especially those concerning the limit of sensitivity in the ultra-violet, are shown to be consistent with current theories of the early history of the oceans, the atmosphere, and of life.

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Cellular morphology of leg musculature in the water bear Hypsibius exemplaris (Tardigrada) unravels serial homologies

Royal Society Open Science ◽

10.1098/rsos.191159 ◽

2019 ◽

Vol 6 (10) ◽

pp. 191159 ◽

Cited By ~ 2

Author(s):

Vladimir Gross ◽

Georg Mayer

Keyword(s):

Fine Structure ◽

Functional Morphology ◽

Cellular Structure ◽

Evolutionary History ◽

Ancestral State ◽

Leg Muscles ◽

Open Questions ◽

Attachment Sites ◽

Functional Implications ◽

Water Bears

Tardigrades (water bears) are microscopic, segmented ecdysozoans with four pairs of legs. Lobopodous limbs that are similar to those seen in tardigrades are hypothesized to represent the ancestral state of Panarthropoda (Tardigrada + Onychophora + Arthropoda), and their evolutionary history is important to our understanding of ecdysozoan evolution. Equally important is our understanding of the functional morphology of these legs, which requires knowledge of their musculature. Tardigrade musculature is well documented but open questions remain. For example, while the muscular organization of each trunk segment and its legs is unique, three of the four trunk segments are nevertheless relatively homonomous. To what extent, then, do leg muscles show segmental patterns? Specifically, which leg muscles are serially repeated and which are unique? The present study addresses these questions using a combination of techniques intended to visualize both the overall layout and fine structure of leg muscles in the eutardigrade Hypsibius exemplaris . In doing so, we propose serial homologies for all leg muscles in each of the four legs and reveal new details of their cellular structure and attachment sites. We compare our results to those of previous studies and address the functional implications of specialized muscle cell morphologies.

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