Scanning electron microscope studies of some lizard basilar papillae

The papillae basilares of eight species of lizards representing four different families were studied by scanning electron microscopy. The papilla of Eublepharis macularius (Gekkota; Eublepharidae) has a midaxial area devoid of hair cells separating anterior and posterior groups of hair cells, two types of tectorial membrane modifications, bidirectionality of each of the anterior and posterior groups of ventral hair cells, and unidirectionality of the dorsal hair cells. The papilla of Coleonyx variegatus (Gekkota; Eublepharidae) is essentially similar to that of Eublepharis, but shows anterior displacement of the axial hiatus and a considerable decrease in the number of hair cells in the dorsal part of the postaxial region. The papilla of Ameiva ameiva (Teiidae) has a dorsal enlargement almost constricted from the remaining portion of the papilla and the greater number (87%) of the hair cells oriented posteriorly. Tupinambis teguixin (Teiidae) exhibits multidirectional hair cell orientation in the expanded dorsal area, bidirectionality in the narrower central segment, and unidirectionality toward the ventral end of the papilla. Gerrhonotus multicarinatus (Anguidae) shows a ventral expansion covered by a thick tectorial plate overlying short-ciliated unidirectionally oriented hair cells and a longer dorsal segment with long-ciliated bidirectionally oriented hair cells. The papillae of Iguana iguana, Crotaphytus collaris, and Basiliscus basiliscus (Iguanidea) have middle segments of short-ciliated hair cells covered by a specialized tectorial plate and dorsal and ventral segments consisting of longciliated bidirectionally oriented hair cells. Basiliscus is divergent in lacking a part of the ventral long-ciliated hair cell segment.     

Scanning electron-microscopic evidence for attachment of a nonpersistently transmitted virus to its vector's stylets

A nonpersistently transmitted virus, pea seed-borne mosaic virus (PSbMV) was localized by an indirect immunospecific latex label on stylets of its vectors, the New London and Madison biotypes of potato aphids, Macrosiphum euphorbiae Thomas. On the efficient New London biotype, large quantities of label were observed mostly on the inner surfaces of the mandibles at about 50 μm from the tip. No specific label was found on the mandibular ridges, maxillary projections, food duct, common food chamber, or extraneous materials carried externally on the stylets. The transmissible nature of the virus labeled at 5-min acquisition was confirmed by the decreased labeling with two different inoculation feedings. The sparse label observed on the Madison biotype aphids indicated that this vector was inefficient because insufficient amounts of virus were acquired for effective transmissions.     

胎儿海绵窦微血管铸型的扫描电镜观察

目的：探讨海绵窦(CS)微血管的性质。方法：在扫描电镜下观察6例胎儿CS微血管铸型标本。结果：胎儿CS窦腔呈海绵样结构,主要由多个直径20～150μm的血窦组成。微静脉和动脉小分支穿行于其间。结论：胎儿CS形态学性质为静脉丛。     

Scanning electron microscopy of Malassezia furfur attachment to Broviac catheters

Malassezia furfur has been increasingly associated with Broviac-catheter-related sepsis in infants receiving fat emulsions for parenteral alimentation. We examined by scanning electron microscopy the appearance of M. furfur attached to Broviac catheter segments mock-infected in vitro and to Broviac catheters removed from two infants with catheter-related sepsis. In vitro attachment occurred equally on external and internal surfaces of the catheters. Although some organisms were attached next to surface defects in the catheters, we could not determine if such defects were preferential sites of attachment. In the patient catheters, a dense coating of yeast cells was found adhering to the luminal surface, most abundantly near the tip. No organisms were seen on the external surface of the catheters. These findings show the need to examine the mechanisms of intraluminal catheter colonization in order to understand better the pathogenesis of M. furfur infections.     

Scanning electron microscope study of the rabbit anterior chamber angle

The three-dimensional fine structure and the collagenous framework of the anterior chamber angle (chamber angle) of albino rabbits, which does not posses a Schlemms canal, were examined, with or without NaOH maceration, by scanning electron microscopy. The chamber angle is ill defined because the deep ciliary cleft appears parceled by iris pillars. The collagenous framework of the pectinate ligaments and iris pillars arising from the iris root join to the collagen bundles of the trabecular sheet, and the surface of the ciliary cleft is covered by an endothelial cell layer that screens the trabecular meshwork. Round openings are apparent in the recesses of the ciliary cleft, with junctions between more superficial or deeper trabecular sheets resulting in direct communication between adjacent trabecular spaces. Openings of the angular aqueous plexus/sinus in place of Schlemms canal were seen on the inner surface of the corneosclera after removing the trabecular meshwork. The framework of the trabecular sheet is basically formed of circumferentially arranged flat collagen bundles and reticularly diverged narrow collagen bundles extending from them. There is no shift between collagen bundles of the trabecular meshwork and the corneosclera, suggesting a frail connection between the two tissues.     

Scanning and transmission electron microscope observations on human gallbladder epithelium

Summary The early development of the human gallbladder epithelium was studied in 25 foetuses with crown-rump (CR) lengths from 6.0 to 22.5 cm by light and scanning and transmission electron microscopy. The PAS-reaction was used to locate cellular mucosubstances.The development could be devided into previllous and villous stages by light microscopy. The incipient formation of villi was observed in the present material at the 12.5 cm stage.Electron microscopically, three stages of development in the gallbladder epithelial cells were noticed. In the first stage, only one epithelial cell type was found. The microvilli were undeveloped, and there were no secretory granules in the epithelial cells.In the second stage, the epithelial cells contained secretory granules. The other characteristics of this stage were pseudopod-like projections on the apical cell surfaces and development of microvilli into a brush border-like structure.In the third stage, the epithelium showed the same zonal construction as that of the adult gallbladder. The apical surface of the epithelial cell was convex, and the microvilli were well developed. There were no pseudopod-like projections on the apical cell surface. The secretory granules were similar to those seen in the normal epithelial cells of the adult gallbladder. Degenerating cells were sometimes seen in this stage. The PAS-reaction was positive in the second and third stages.     

Scanning electron microscope study of the developing trout pelvic fin bud

The growth of the pelvic fin bud has been studied with the SEM along with the characteristics of the pseudoapical epidermal ridge which occupies the free margin of the bud. SEM revealed fluffy protuberances in many of the epidermal cells, distinguishing the fin bud territory from adjacent areas. When the pseudoapical ridge appears, all the cells show this feature but their relative number decreases and these cells, termed the "tassel cells," are finally restricted to the base of the fin bud. This particular surface structure of the superficial cells may be unique to the fish, since it has not been heretofore reported in SEM studies of tetrapod limb bud.     

兔不同血管段内皮细胞的扫描电镜观察

目的：观察兔不同血管段内皮细胞(EC)的形态特征,为兔血管的临床和实验研究提供资料。方法：动物灌注固定,取出相应血管,扫描电镜观察。结果：EC一般呈梭形,核区较隆起,长轴与血流的方向一致。在腹主动脉相邻细胞之间有纵行的沟,细胞连接处有较矮的嵴。在肺动脉有较丰富粗短的微绒毛和长短不一的桥样结构。在主动脉瓣和二尖瓣,细胞呈较大的圆形或椭圆形,微绒毛较矮,密度不均。在主动脉弓细胞形态多样。在下腔静脉,细胞呈窄长的梭形。结论：EC的形态、排列、微绒毛的长度和密度,桥样结构的多少等均随部位的不同而有差异,切应力可能是造成这些差异的重要因素。     

Scanning electron microscope studies of the auditory papillae of some iguanid lizards

The papillae basilares of 16 species (10 genera) of iguanid lizards were studied by scanning electron microscopy. Variations in the surface structures of the auditory papillae showed the following major differences: (1) papillae with localization of the unidirectional hair cells at the apical end of the papilla (Anolis carolinensis); (2) papillae with absence or loss of a portion of the apical bidirectional hair-cell segment (Basiliscus basiliscus); (3) papillae with a central, short-ciliated, unidirectional hair-cell segment, and 3–6 irregular rows of long-ciliated bidirectional hair cells located in the apical and basal regions (Iguana iguana, Crotaphytus collaris, C. wislizeni, Dipsosaurus dorsalis, Sauromalus obesus); (4) papillae in which the apical and basal bidirectional hair-cell segments are reduced to two rows of hair cells (Sceloporus occidentalis, S. clarki, S. orcutti, S. jarrovi, S. undulatus, S. magister, Callisaurus draconoides, Uta stansburiana). The above differences in auditory papilla structure agree closely with other anatomical differences that delineate iguanid assemblages. Thus the species in the four groups above fall respectively into the following iguanid groups: (1) anolines, (2) basiliscines, (3) iguanines, and (4) sceloporines.     

Comparison of a virtual microscope laboratory to a regular microscope laboratory for teaching histology

Emerging technology now exists to digitize a gigabyte of information from a glass slide, save it in a highly compressed file format, and deliver it over the web. By accessing these images with a standard web browser and viewer plug-in, a computer can emulate a real microscope and glass slide. Using this new technology, the immediate aims of our project were to digitize the glass slides from urinary tract, male genital, and endocrine units and implement them in the Spring 2000 Histology course at the University of Iowa, and to carry out a formative evaluation of the virtual slides of these three units in a side-by-side comparison with the regular microscope laboratory. The methods and results of this paper will describe the technology employed to create the virtual slides, and the formative evaluation carried out in the course. Anat Rec (New Anat) 265:10-14, 2001.     

Scanning electron microscope studies of the papilla basilaris of some turtles and snakes

The papillae basilares of three species of turtles and four species of snakes were studied by SEM. The papillae of turtles are relatively large among reptiles and are characterized by a long, horizontal middle section resting on a wide basilar membrane. Both terminal ends of the papilla extend onto the surrounding limbus in the form of a forked or “T”-shaped end or as a curved, “hook”-like process. Details vary with the species. In the three species of turtles studied, there were between 1,100 and 1,400 hair cells on a papilla. The tectorial membrane covering the horizontal portion of the papilla is heavy in appearance and tightly attached to the kinocilial bulbs. The terminal ends of the papilla are covered by a thin gelatinous material. In addition, a mat-like tectorial network covers the supporting cells and extends from the microvilli of the supporting cells to the overlying tectorial membrane. All hair cells are unidirectionally and abneurally oriented. The supporting cell surfaces form a large part of the papilla and, thus, hair cell density is low. The papillae of the two boid snake species studied are moderately long among snakes and contain a moderate number of hair cells (574 in Epicrates and 710–780 in Constrictor). Papillar form is elongate, ovoid, or canoe-shaped. The tectorial membrane may be either highly fenestrated or moderately dense and covers all but a few of the terminal hair cells. A tectorial-like mat covers all but a few of the terminal hair cells. Most hair cells are unidirectionally and abneurally oriented. A few terminal cells in boids may show reverse orientation. Hair cell density is similar to that of turtles.     

Scanning electron microscope study of the developing microvasculature in the postnatal rat lung

During postnatal growth the parenchymal septa of rat lung undergo an impressive restructuring. While immature septa are thick and contain two capillary layers, mature septa are slender and contain a single microvascular network. Using the Mercox casting technique and scanning electron microscopy, we investigated the mode and the timing of the transformation of the pulmonary capillary bed. During the third postnatal week the parenchymal septa rapidly mature to match adult morphology. Even in adult lungs, however, remnants of the immature status are present: A capillary bilayer is regularly found at the base and the tip of the septa. Our observations support the concept that reduction of intervening tissue, partial fusion of the two capillary networks, and preferential growth lead to the mature vascular arrangement. The fact that true mature interalveolar septa show a denser capillary network than alveolar walls abutting onto pleura, bronchi, or larger vessels is consonant with the fusion theory. Towards the nonparenchyma, the capillary network surrounding every airspace had no counterpart to fuse with. From quantitative data it can be calculated that owing to lung growth, mesh size should increase more than four times between birth and adult age. The adult lung network, however, is denser than the one in young animals. This means that new meshes must be added during growth. We propose that small holes observed in sheet-like regions of the microvasculature enlarge to form new capillary meshes. With this mechanism of in-itself or intussusceptional growth, sprouting of individual capillary segments to increase network size is no longer needed.     

Scanning electron microscope observations on third-instar Gasterophilus nasalis (Diptera: Oestridae)

Scanning electron microscope observations studied the morphology of 3rd-instar Gasterophilus nasalis (L.). Distinctive features are illustrated in a sequence of 16 micrographs, bearing indications of structures considered of special interest. The morphology of G. nasalis is compared with that of other larval bot flies.