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C Chi

Publications and source records attributed to C Chi.

44 records · Page 3Linked to original sources
PubMed1976

The large pigment cell of the compound eye of the house fly Musca domestica. Fine structure and cytoarchitectural associations.

The fine structure and cellular associations of the large pigment cells (LPC's) of the compound eye of the house fly were studied with high voltage and conventional electron microscopy. Depending on the sector of the compound eye, the facets are either rectangular or hexagonal. The underside of each facet has indentations exactly aligned with those on top into which inserts an angulated sleeve of LPC's. Under the rectangular lens facet 6 or 8 small compact (in cross section) LPC's join four elongate LPC's. Clusters of compact cells alternate in this ring with elongate ones. Compact cells compress together and become quadrangular (in cross section) several microns below their insertion into the lens and form "building block" corners while elongate cells form "side rails" for the rectangular type of distal pseudocone enclosure. Beneath hexagonal facets all LPC's are rather elongate with out corner cells. In both facet types LPC's enclose the pseudocone for a longitudinal distance of 4 mum and then are displaced as bordering cells by a sleeve of two corneal pigment cells (CPC's), each of which encloses half of the proximal pseudocone. For the following 6 mum of longitudinal distance these concentric sleeves of CPC's and LPC's form a double layer around the pseudocone. At about 10 mum below lens base the two sleeves separate; LPC's become attenuated and extend cable-like to the basement membrane and CPC's enclose the proximal pseudocone, Semper cells and distal retinula. The junction between lens and LPC's has critical structural value in that (1) this is the sole anchorage to the lens by the lengthy remainder of the ommatidium, and (2) LPC's enclose the semiliquid pseudocone in the most distal portion of the pseudocone. In addition to vertical support, the LPC's send out numerous lateral processes that make structural contact among themselves, with the corneal pigment cells and the photoreceptor cells. The structural features of this array are discussed relative to possible physiological roles.

Animals↗
PubMed1976

High voltage electron microscopy of the optic neuropile of the housefly, Musca domestica.

Synaptic cartridges of the first optic neuropile (lamina ganglionaris) of the housefly were examined by high voltage electron microscopy (HVEM). Stereo pairs (from thick, i.e., 0.25 mum, sections viewed at 1,000 kV) provided a three dimensional representation of cartridge neurons and clearly revealed the lateral spread, bifurcation and some functional associations of Type I (L1, L2) monopolar interneurons. Slightly proximal to cartridge neck level, pairs of retinular (R) axons made contact with each other and it appeared that R processes projected through the cleft between the Type I interneurons. No junctional modifications were seen between contiguous R axon terminals. The speculation was made that functional contact might exist between neighboring R axons prior to their extensive synapses with principal first order interneurons. Such alleged coupling between R axons would account for several electrophysiological findings from other laboratories. Modifications in EM technique applicable for HVEM were detailed. The value of obtaining thick serial sections and the use of the HVEM in expediting three dimensional reconstructions of neuropile were demonstrated.

Animals↗
PubMed1976

The housefly interfacetal hair: ultrastructure of a presumed mechanoreceptor.

The external and internal fine structure of the housefly interfacetal hair and its sensory dendrite was studied with the scanning and transmission (high and low voltage) electron microscopes. The hair shaft contains no dendrites, and is usually situated within a socket on the lens surface. Immediately beneath and directly connected to the base of each hair is a bipolar neuron whose dendrite tip is enveloped in a shealth cell which, in turn, is surrounded by a second sheath cell. Septate junctions are seen between all these cells and contiguous portions of a large pigment cell. At the hair base, the dendrite of the neuron terminates in a tubular body only 1.5 mum in diameter which is filled with about 400 microtubules in highly ordered (in parallel pentagonal and hexagonal) arrays and whose sides are fused to neurofilaments in parallel. Another filament (ca. 70 A diameter) is in the center of each microtubule-neurofilament polygon. Structures proximal to the tubular body are typical for a scolopoid sensillum, i.e., connecting cilium (9 times 2 + 0 microtubules) with rootlet and basal bodies, unmodified dendrite, perikaryon and axon. The axon has not been traced to its synapse. The high degree of internal organization and shortness of the tubular body, as well as its eccentric insertion into the hair shaft lead to the hypothesis that this hair may be a highly sensitive mechanoreceptor. On the basis of their single innervation, these hairs could monitor flight speed from the degree of hair deflection caused by wind in general or particular laminar air currents flowing past the eyes during flight.

Air Movements↗
PubMed1976

The normal squamous epithelium of the human uterine cervix: a histological study.

The normal squamous epithelium of the uterine cervix was investigated in 50 foetuses and newborns, as well as in 207 adult women operated upon because of various benign conditions of the uterus. The epithelium was divided according to the presence or the absence of prominent epithelial papillae. Epithelial papillae occurred in 32% of the cervices in the paediatric age and in 17% in adult women. They were present in the whole squamous epithelium covering the portio vaginalis in all pediatric patients. In 49% of the adult patients epithelial papillae covered the whole portio and/or the transitional zone; in the remaining 51% only a reduced area presented epithelial papillae. Micrometric determinations demonstrated that normal epithelium with papillar formation was thicker than epithelium with smooth epithelial border. This was most prominent in the paediatric patients. The possibility that oestrogenic stimulation (in paediatric patients) and oestrogenic stimulation as well as chronic stromal inflammation (in adult patients) could account for the formation of prominent epithelial papillae was discussed.

Adult↗
PubMed1975

The distal ommatidium of the compound eye of the housefly (Musca domestica): a scanning electron microscope study.

The distal aspect of the housefly ommatidium was surveyed by the scanning electron microscope. Attention was directed to the somal eminence of the superior central cell and the lens to large pigment cell junction. The underside of each lens facet exhibits six hexagonally arranged incisures. Into each of these indentations are fitted several large pigment cells. This hexagonal indentation appears to be a tenacious anchorage. Two corneal pigment cells laterally encircle the pseudocone and at their proximal extension they enclose the Semper cells and neck of the retinula. The somal eminence of the superior central cell is about 10 mum from the base of the corneal pigment cell enclosure. Micrographs were used to construct a diagram of the ommatidium above the basement membrane. Suggestions are made as to the functional correlates of the observed ommatidial structures.

Animals↗