A quantitative study on the myenteric plexus of the distal end of the duodenum and the proximal part of the jejunum

4 necropsy specimens taken from adult individuals were used in order to estimate the density of nerve cell bodies of the myenteric plexus in the last distal 5 cm of the duodenum and the proximal 5 cm of the jejunum (including the duodenojejunal flexure), that were subdivided into parts of approximately 1 cm and stained by Giemsa's method according to Barbosa (1970). Except for the first 2 parts, an increase of the neuron number was observed toward the duodenojejunal flexure, the greatest being at this point, and then decreasing progressively. The first duodenal parts, which corresponds approximately to the intersection of the mesenteric artery with the duodenum, showed the same neuron density as the duodenojejunal flexure. In this paper the 2 parts with higher neuron density were related to functional sphincteric zones, previously described.     

Electron microscope study of the human neuromuscular junction

A preliminary electron microscope study of human neuromuscular junction is presented. The biopsy material was taken from the palmarus longus, and fixed routinely in osmium tetroxide and embedded in methacrylate. The structure of the motor endings and the relationship of the synaptic vesicles to the axolemmal membrane are described. The synaptic clefts are filled with an homogeneous material in continuity with the basement membrane covering the muscle fiber. The subneural apparatus is described, and special attention is paid to a vesicular component present in the sarcoplasm of the junctional area, which differs from synaptic vesicles and is presumed to be a derivate of the sarcoplasmic reticulum.     

Regeneration of proximal tubules of the rat kidney following sublimate necrosis. A scanning electron microscopic study

Necrosis of the proximal tubules of the rat kidney was induced by low (1.5 mg/kg) doses of sublimate. Epithelial necrosis and regeneration were followed by scanning electron microscopy for 10 days. Regressive and regenerative processes were observed simultaneously. The naked basement membrane is first invaded by flat epithelial cells lacking microvilli. Within a few hours microvilli appear followed by the formation of regular brush-border and interdigitations cells. After 7--10 days the newly formed epithelium cannot be distinguished from the intact one.     

A scanning electron microscopic study of the dorsal surface of the human tongue

To study the dorsal surface of the human tongue using a scanning electron microscopy (SEM), tissue specimens were taken from the anterior part of the tongues of 15 individuals aged from 21- to 28-years-old. The formalin-fixed samples were processed routinely for SEM. With SEM the surface of the normal tongue mucosa was shown to be rather evenly covered by filiform papillae, with some fungiform papillae scattered among them. Filiform papillae consisted of two parts: the body and hairs. The mucosal surface of the body was smooth; the squamous epithelial cells were polygonal, and their boundaries were prominent. On the surface of the superficial epithelial cells were parallel or branching microplicae. Each filiform papilla had 6-10 hairs, which were scaled and covered by an extensive plaque of microorganism. The upper surface of the fungiform papillae was smooth; only a few desquamating cells were seen. The superficial cells had a pitted appearance and cell boundaries overlapped. Taste pores, up to 3 pores in a single papilla, were found on the upper surface. Desquamation was more pronounced on the base of the fungiform papillae than on the upper surface. In almost all fungiform papillae some hairs protruded from the base. Parallel microplicae were found on the surface of the superficial cells of the base. The structure and function of the human tongue, as well as the microplicae of its superficial cells, are compared to those of various species of animals.     

An electron microscopic study of the human infundibulum

Summary For a limited period during the oogenesis of Protopterus, blebs of the perinuclear cistern contain, in addition to other inclusions, a special kind of microtubular elements. Most of these blebs face parts of multiple nucleolar bodies that extend toward and make contact with the inner nuclear membrane. The microtubular lumen contains a finely dispersed material of moderate electron density which seems to be in contact with this nucleolar material.Aside from these intracisternal structures there are, within both the perinuclear cytoplasm and the nucleoplasm, similar microtubular arrays without apparent connection with the nuclear envelope. These are either enclosed by membranes derived from those of the envelope or unconfined, having escaped through breaks in their respective bounding membranes. Extracisternal tubules are presumed to have passed their period of putative functional activity and to be undergoing a process of regression and subsequent disintegration.Among possible roles attributable to the intracisternal microtubular apparatus are the following: (1) It may serve for the transport of special nucleolar components to the cytoplasm, possibly to be incorporated in the matrix of developing perinuclear mitochondria; (2) it may provide openings in the nuclear membranes for the direct passage of particulate elements between nucleus and cytoplasm; (3) it may be instrumental in the breakdown of parts of the nuclear envelope prior to its restitution during the subsequent phase of oogenesis.Supported by grants NB-00840 and NB-05219 from the U.S.P.H.S.     

Collagenous network in cartilage of human femoral condyles. A light microscopic and scanning electron microscopic study

To determine the spatial arrangement of collagen fibrils in articular cartilage of the human femoral head, three healthy femoral heads, obtained at necropsy, were examined by light microscopy and scanning electron microscopy. Light microscopic observations revealed no collagen fibril organization. Scanning electron microscopic observations showed a fine fibrillar texture throughout the articular cartilage. At the articular surface, smooth and fibrillated areas were detectable. Underneath the articular surface, the collagen network in the superficial zone showed a tighter appearance when compared with the homogeneous collagen network of the matrix in the deeper zones. The calcified cartilage zone was well demarcated from the uncalcified cartilage. The arcade model of Benninghoff [Z. Zellforsch. Mikrosk. Anat. 2: 783-862 (1925)] could not be confirmed. It was concluded that the organization of collagen fibrils in hyaline cartilage shows a three-dimensional network of randomly oriented fibrils.     

Calcium containing lysosomes in the normal chick duodenum: a histochemical and analytical electron microscopic study.

Absorptive cells of the normal chick duodenum contain numerous supranuclear vesicular/vacuolar structures. By routine transmission electron microscopy, such structures are membrane bound and demonstrate a granular content. These vesicles appear to move laterally and eventually coalesce with the lateral plasma membrane (exocytosis). The granular contents are resistant to high temperature microincineration, thus revealing their mineral-containing nature. The granular vesicular matrix also stains intensely with osmium pyroantimonate EGTA chelation of pyroantimonate-stained vesicles selectively extracts the granules indicating a high concentration of calcium. X-ray microanalysis also demonstrates a significant intravesicular calcium localization. When tissues were incubated for the presence of acid phosphatase, the supranuclear vesicles were markedly positive for this lysosomal enzyme. A possible role for these calcium-containing lysosomes in the transcellular flux of calcium ions across the intestinal absorptive cell is discussed.     

Electron microscopic study of the cytoskeleton of human podocytes

The ultrastructural study of man's cytoskeleton of podocytes is carried out. Populations of podocytes with two different types of structure of the cytoskeleton in dependence on age (2, 4, 6, 37 and 65 years) is revealed in kidneys. The first type of cytoskeleton of the podocyte is peculiar for children's age and is characterized by branched, high density microfilament network, expressed by system of microtubules and single myofilaments. The intermediate filaments here are either utterly absent or present so feebly they find themselves "disguised" by other strongly developed components of cytoskeleton and revealing them with the help of technique of electron microscope is impossible. In kidneys of adults, and especially of old aged persons podocytes with other type of organization of the cytoskeleton are mainly identified. The distinctive signs of the last are bundle arrangement of microfilaments, plural bundles of intermediate filaments and individual microtubules. This study permits to make a conclusion that during individual development and growing old in kidneys of high animals and man, probably, physiological changes causing morphological reconstruction of cytoskeleton which is accompanied by intensive development of intermediate filaments' system with simultaneous "involution" of microtubules and microfilaments' systems take place.     

An electron microscopic study of the human epidermal keratinocyte

Summary 1. The epidermis of the flexor surface of the upper arm of human subjects was studied with the electron microscope. 2. The cytoplasm of the keratinocytes in the basal layer contained many tonofilaments, ribosomes and other cell organelles. The tonofilaments were arranged singly or in loose bundles and many were attached to the inner membrane of the desmosomes. Along the basal border of the cells pinocytotic vesicles could be seen at different stages of development. 3. The keratinocytes in the stratum spinosum differed from those in the basal layer in two main ways: (a) The tonofilaments were grouped together into large compact bundles known as tonofibrils and it was possible to determine a definite beading or cross banding along the length of some of the filaments. (b) The cells were assuming a flattened shape. 4. The keratinocytes in the stratum granulosum possessed large numbers of irregularly shaped keratohyaline granules. The granules were strongly osmiophilic and were always situated on a meshwork of tonofibrils. The keratohyaline granules had no internal structure. The nuclei and mitochondria showed evidence of degeneration. 5. The keratinocytes in the stratum corneum were long and flattened. The cell walls showed increased electron density and were considerably thickened. The cytoplasm was filled with closely packed fibres separated by a small amount of lucent matrix. The fibres were grouped together in bundles running in different directions within the flattened squames. The fibres had along their entire length alternating areas of high and low electron density. The keratohyalin granules had disappeared and nothing remained of the nuclei or the organelles. In the deepest cells of this region the fibres were sometimes loosely packed leaving large irregular open spaces. This area corresponded to the stratum lucidum. In the most superficial layers of the stratum corneum the fibres appeared to be breaking down so that little remained within the keratinocyte except large lucent spaces. The desmosomes showed distinct structural changes. 6. An attempt was made to correlate the structural changes in the different epidermal layers with the process of keratinization. The possible part that keratohyalin may play in the process of thickening of the cell walls was discussed. The relationship between the desmosome and its dynamic environment was considered.I wish to express my sincere thanks to Dr. David Hilding of the Department of Otolaryngology for the use of an R.C.A. electron microscope and other facilities in his laboratory. This research was supported by the United States Public Health Service and American Cancer Society grants. USPHS CA 04679-07, NB 03995.     

Microcirculatory bed of the human duodenum

In preparations impregnated with silver nitrate (25 corpses of mature persons), the hemomicrocirculatory bed of the intestine wall tunics has been stated to possess a layer-by-layer organization. The most powerful submucosal vascular plexus, formed by branches of the arteries perforating the external tunics of the intestine, supplies with blood all the layers of the intestinal wall and their main working and integrating elements: intestinal and duodenal glands, villi, neural ganglia and trunks of the submucosal and intermuscular plexuses. Summarizing morphometrical criteria for estimating the capillary bed of the tunics of all the anatomical parts and the large duodenal papilla, it is clear that there are specific conditions in microvascularization of the upper part of the organ.     

Embryonic development of the human duodenum

Epithelial duodenal anlage takes place at the end of the first month of the human embryogenesis in connection with appearance of the pancreatic epithelial germs. It has a form of a short arch with a spindle-like enlargement of the middle ductal part. Formation of the hepato-duodenal ligament and of the duodenal mesentery results in appearance of the given organ anlage with a three-layered wall in 5.5-6-week-old embryos. The anlage makes an arch, protruding to the right and forward with a spindle-like enlargement of the middle ductal part. It is tightly connected with the forming anlage of the pancreatic head, when the pancreatic epithelial anlages are fusing. An intensive growth of the pancreatic head is accompanied with emergence and enlargement of the superior, descending and inferior parts of the duodenum, that acquires a semicircular form in 8-8.5-week-old embryos. Its transitional stage is a curved semicircle having a form of a distended spiral coil; that reflects an uneven growth of the organ in the human embryogenesis.     

The role of the duodenojejunal junction in regulating the evacuatory function of the duodenum

Chronic experiment on dogs was performed to study the effect of duodenojejunal junction exclusion from the evacuatory process on dynamics of gastric and duodenal emptying of the carbohydrate and fatty food. It is established that in the case of exclusion of the duodenojejunal junction, the degree of coordination of gastric and duodenal emptying decreases, dynamics of chyme evacuation from the duodenum considerably changes. It is concluded that the duodenum is not a mere transporter of food coming from the stomach, but has its own regulation mechanisms represented by the duodenojejunal junction and the Treitz ligament.