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Biomedical subjects

A Kikuta

Publications and source records attributed to A Kikuta.

At least 73 records · Page 4Linked to original sources
PubMed1991

Microvascular architecture of rat nasal associated lymphoid tissue.

The blood vascular architecture of the rat nasal associated lymphoid tissue (NALT) was studied by scanning electron microscopy of corrosion casts. To examine the correlation of the vasculature with the distribution of lymphocyte subsets, the NALT was also studied by light microscopy of immuno-stained samples. The NALT was supplied by a branch of the inferior nasal artery which arose from the sphenopalatine artery. This branch reached the bottom of the NALT and ramified arterioles to the follicles and the parafollicular regions. These arterioles ascended toward the subepithelial region, giving off capillaries en route to form a coarse plexus within the follicles and the parafollicular regions. The arterioles reached the subepithelial region and formed a subepithelial capillary network consisting of a single layer of flat meshwork. The follicular, parafollicular and subepithelial capillaries anastomosed one another. The capillaries in each region were gathered into collecting venules, which in turn drained into high endothelial venules (HEVs) in the parafollicular region. The HEVs ran through the parafollicular regions around the follicular perimeters, and flowed into ordinary veins to leave the NALT. Lymphocytes labeled with an anti-T cell antibody were mainly distributed in the parafollicular regions, where HEVs were situated. B cells were mostly observed in the follicular and dome areas. The microvascular structure and its correlation with lymphocyte subset domains in the NALT were essentially similar to those in other mucosa associated lymphoid tissues (MALTs) such as tonsils and Peyer's patches.

Animals↗
PubMed1991

Ovarian microvasculature in normal and hCG stimulated rabbits. A study of vascular corrosion casts with particular regard to the interstitium.

The microvasculature of rabbit ovaries, with special regard to the interstitial-stromal tissue, was studied by scanning electron microscopy (SEM) of vascular corrosion casts. The casting medium (Mercox) was injected in normal animals and in animals in which ovulation was induced by 100 I.U. of human chorionic gonadotropin (hCG) i.v. Vascular baskets of different size and architecture related to follicles in various developmental stages were observed in the ovarian cortex. Small (primary) follicles showed thin and thready capillaries. Larger (secondary and antral) follicles showed a progressive increase in number, size and tortuosity of round-meshed capillaries, related to adaptation of the growing follicle to the approaching ovulation. Capillary sprouts, due to the enhanced angiogenesis of growing follicles, were seen. These aspects were more evident in ovulatory follicles. In addition, numerous resin leakages, due to the increased permeability of the sinusoidal net, were seen in the cavities of ovulatory follicles. Interstitial-stromal tissue capillaries were diffusely distributed in the cortex among the follicular baskets. Their morphology remained unchanged after hCG stimulus. In the periphery of the cortex, the microvascular net showed large (70-90 microns) irregularly rounded meshes, with thin, thready capillaries often anastomosed with those of primary follicles. Inner cortex capillaries were thin, thready and arranged in polygonal meshes of 40-70 microns. The arrangement and the distribution of the interstitial-stromal capillaries may have some special role during the cyclic activity of the ovary.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1989

Microvascular organization of human palatine tonsils.

We describe the three-dimensional organization of the microvasculature of human palatine tonsils as revealed by the vascular corrosion casting/scanning electron microscope method and light microscopy of sections. The tonsillar arteries travel in the connective tissue septa and give off many branches. They further branch into arterioles which in turn enter the follicle and the interfollicular region. These arterioles, giving off capillaries en route, reach the subepithelial region where they break up into sinusoidal capillaries. The subepithelial capillary network overlying the follicle protrudes hemispherically towards the crypt, while that overlying the interfollicular region has many switch-back loops of capillaries projected towards the crypt. The subepithelial sinusoids gather into the high endothelial venules (HEVs) which, collecting capillaries in the follicle and the interfollicular region en route, course down into the interfollicular region alongside the follicle. The HEVs surround the lateral and basal surfaces of the follicle and ultimately lead into the ordinary veins in the septa. The subepithelial sinusoids seem to be involved in taking up immunoglobulins secreted by plasma cells and any other substances released by lymphocytes and/or macrophages as well as supplying the tissues with necessary oxygen and nutrients. That the HEVs are downstream to the subepithelial sinusoids suggests that some substances which are taken up into the sinusoids and transported to the postcapillary venules induce differentiation of HEVs and maintain them.

Humans↗
PubMed1988

The blood vascular architecture of the extra-adrenal chromaffin body in the adult rat: a scanning electron microscopic study of corrosion casts.

A well developed extra-adrenal chromaffin body with an axis of 200-400 micron was found in seven out of thirty adult male Wistar rats under a stereomicroscope. All seven bodies were located between the left and right kidneys. Blood vascular beds of the five bodies were reproduced with a methacrylate casting medium and observed with a scanning electron microscope. It was revealed that the extra-adrenal chromaffin body contained remarkedly numerous capillaries, which anastomosed with each other to form a conglomerated network. The blood capillaries were of small and uniform caliber and did not represent swollen sinusoids as in the adrenal medulla. The capillary network was denser than that in the adrenal medulla and had no direct vascular linkage with the adrenal cortex or an extra-adrenal cortical body. Histological examination of the two bodies treated with dichromate containing fixatives confirmed that they mainly consisted of chromaffin cells. These findings suggest that in the rat, extra-adrenal chromaffin bodies survive throughout life, actively producing catecholamines.

Adrenal Cortex↗
PubMed1988

Collagen fibrillar networks as skeletal frameworks: a demonstration by cell-maceration/scanning electron microscope method.

A cell-maceration/scanning electron microscope (SEM) method was employed to demonstrate the arrangement of the collagen fibrillar network of various tissues. Immersion of fixed tissues in NaOH (25 degrees C) for 3-7 days, followed by rinsing in distilled water successfully removed the cellular elements, exposing collagen fibrils which were identified as such by transmission electron microscopy in their natural locations. SEM observations of the preparations are able to demonstrate the three-dimensional architecture of collagen fibrils much more precisely than other methods, including the silver impregnation method. Collagen fibrils, forming sheaths for housing individual cardiac myocytes, fused together, thus ensuring an equal stretch of contiguous myocytes and preventing the slippage of adjacent cells. Individual skeletal muscle fibers and nerve fibers were ensheathed by the meshwork of collagen fibrils running in two opposite helices. Such structures seem to play an important role in resisting the stretching impetus. At the epithelial-connective tissue junction of the tongue and fingertip skin, interwoven collagen fibrils formed numerous microridges which probably provide a broad anchorage for the epithelium. In the intestinal mucosa, the collagen fibrillar network immediately below the basal laminae of the villous epithelium possessed heterogeneous pores. As the collagen fibrillar network shows morphological features specific to individual organs and tissues, it is suggested that such formations not only constitute the skeletal framework but also provide those cells which are housed there with a microenvironment suitable for their activities.

Animals↗
PubMed1988

Blood vascular architecture of the rat extra-adrenal cortical body: a scanning electron microscopic study of corrosion casts.

A well developed extra-adrenal cortical body with an axis of 200-700 micron was found in eighteen of thirty adult male Wistar rats under a stereomicroscope. All eighteen bodies were located between the kidneys. Blood vascular beds of sixteen of the eighteen bodies were reproduced with a methacrylate casting medium and observed with a scanning electron microscope. The extra-adrenal cortical body was found to contain remarkably numerous capillaries which anastomosed with each other to form a conglomerated network; it received one afferent vessel and issued one to three (usually, one) efferent vessels. The blood capillaries were of sinusoidal and uniform calibers, and resembled those of the adrenal cortex. The network with an axis of 300-700 micron possessed a typical, deep efferent rootlet which corresponds to the central vein of the adrenal gland. Histological examination of the two bodies treated with Orth's or Helley's fixative confirmed that they consisted of non-chromaffin cells similar to those of the adrenal cortex. These findings suggest that in the rat, the extra-adrenal cortical bodies persist throughout life, actively producing cortical hormones.

Adrenal Cortex↗
PubMed1988

The blood vascular wreath of rat ovarian follicle, with special reference to its changes in ovulation and luteinization: a scanning electron microscopic study of corrosion casts.

Blood vascular casts of rat ovaries were prepared by injection of a low viscosity methacrylate medium, and observed by scanning electron microscopy. The proper vascular pattern of the rat ovarian follicle starts as a basket-like wreath of fine capillaries around the primary follicle. As the follicle grows larger, the wreath becomes more developed. The fully developed wreath around the Graafian follicle consists of sinusoidal capillaries. In ovulation, the apical area of the wreath is opened and the basal area of the wreath is elevated. After ovulation, the wreath shrinks and its opened area is closed, with markedly dilated vessels directly continuous with the arterial capillaries. The wreath then transforms, by intense new formation of capillaries, into a conglomerated sinusoidal capillary plexus with an avascular area within it. The avascular area soon disappears by continued intense formation of capillaries, in the plexus, and a complete and dense vascular network of the corpus luteum is formed. The capillaries of the fully developed corpus luteum are small in caliber and not sinusoidal in nature. Discontinuities of the capillaries and a flattening of the efferent branches are the initial signs of the degeneration of the corpus luteum. The small markedly degenerated corpus luteum contains only scattered thready capillaries. The corpus albicans contains few blood vessels.

Animals↗
PubMed1988

The blood vascular architecture of the rat pineal gland: a scanning electron microscopic study of corrosion casts.

The blood vascular bed of the rat pineal gland was reproduced through a low viscosity methacrylate casting medium and observed with a scanning electron microscope. The pineal gland was located in front of the confluens sinuum which was formed by the confluence of the left and right transverse sinuses and the superior sagittal and great cerebral veins. The pineal gland was found to contain a rich vascular network of freely anastomosing capillaries. This network received a few afferent arteries from the posterior cerebral arteries while emitting ten to fifteen efferent veins. Most of these efferent veins drained into the upper segment of the great cerebral vein; the remaining one or two efferent veins continued directly into the confluens sinuum. A marked constriction, probably representing a venous valve or valve-like projection, was observed in the opening area of the great cerebral vein. Circular constrictions, probably representing sphincters, were imprinted in the efferent vessels. No direct vascular connection was noted between the pineal gland and the nervous tissues or between the pineal gland and the choroid plexuses of the third and lateral ventricles.

Animals↗
PubMed1988

Deep plantar arteries of some mammals, with special reference to the plantar metatarsal arteries.

The plantar metatarsal arteries of some mammals were studied. In the dog, raccoon dog and cat, the second proximal perforating branch was fully developed and produced the plantar metatarsal arteries. These plantar metatarsal arteries ran on the plantar surfaces of the interosseous muscles along the metatarsal bones or intermetatarsal spaces, and gave rise to the digital arteries of the second to fifth toes. In the rabbit, a branch of the medial plantar artery ran transversely on the plantar surfaces of the metatarsal bones at a level distal to the bases of these bones, and produced the plantar metatarsal arteries. These plantar metatarsal arteries ran deep in the interosseous muscles along the metatarsal bones or intermetatarsal spaces, and joined with the digital arteries which were derived from the medial plantar artery. The plantar metatarsal arteries could be classified into four kinds of arteries (sM, sI, dM and dI) in relation to the interosseous muscles and metatarsal bones. This classification largely coincides with that of the human hand and foot (Murakami, 1969, 1971), the monkey hand and foot (Nakai et al., 1987; Hinenoya et al., 1987), and the forepaws of some animals, including the dog and cat (Murakami et al., 1987).

Animals↗
PubMed1988

Visualization of human vestibular aqueduct with computer-aided serial section reconstruction system.

The computer-aided serial section reconstruction system (SERSERS) was employed to elucidate the entire configuration of the vestibular aqueduct in the human temporal bone. The advantages and the disadvantages of this system are discussed in comparison with several conventional methods such as X-ray visualization, plastic casting and graphic reconstruction. In spite of some limitations encountered, such as difficulty in placing a marker on each section or time consumption in data input, SERSERS can be useful in the study of the vestibular aqueduct, since a three-dimensional structure which can be observed from multidirectional aspects is reconstructed.

Computer Graphics↗
PubMed1987

Blood vascular architecture of the rat cerebral hypophysis and hypothalamus. A dissection/scanning electron microscopy of vascular casts.

Complete casts of the hypophyseal and hypothalamic blood vascular beds of newborn, pubescent, adult and aged rats were produced by infusion of low viscosity methacrylate media, dissected under a binocular light microscope, and observed with a scanning electron microscope. The primary capillary plexus projected capillary loops into the median eminence and infundibular stalk. These loops were composed of anastomosing capillaries, being numerous in the central area of the anterior lip of the median eminence. The well developed long loops received their proper afferent arterioles from the arterial terminals in the primary plexus, and emitted their proper efferent venules continuous with the long portal vessels. The loops in newborn rats were poorly developed, appearing as simple ball-like protrusions of the capillaries of the primary plexus. Many branches of the anterior, middle and accessory middle hypophyseal arteries penetrated the primary plexus, and ascended as infundibular ascending arterioles in the median eminence and infundibular stalk. These infundibular ascending arterioles continued into the capillary bed of the hypothalamus, especially in its basilar and peri-ventricular areas. The subependymal capillary network was fairly independent, and located dorsal to the loops. This network received some of the infundibular ascending arterioles, and emitted infundibular descending venules continuous with the long portal vessels. The subependymal network also received the infundibular descending arterioles from the hypothalamic arteries, and emitted the infundibular ascending venules continuous with the hypothalamic veins. Thus, neither a feedback nor a retrograde portal route from the hypophyseal capillaries to the hypothalamic capillaries was noted. The capillary bed of the pars tuberalis was observed only in the adult and aged rats; it was a very coarse network which was derived from the primary capillary plexus and connected to the secondary capillary plexus.

Aging↗
PubMed1987

Pedal arteries of monkeys, with special reference to the plantar metatarsal arteries.

In the Japanese, Formosan and crab-eating monkeys, the dorsal metatarsal arteries and their lateral distal perforating branches were well developed and supplied, directly or via the catella plantaris distalis, the plantar digital arteries. In the black ape, the plantar digital arteries arose from the medial plantar artery. The plantar metatarsal arteries of these monkeys, including the black ape, arose from the catella plantaris proximalis or deep plantar arch and were classified into the superficial plantar metatarsal (sM), superficial plantar intermetatarsal (sI), deep plantar metatarsal (dM) and deep plantar intermetatarsal (dI) arteries in relation to the interosseous muscles and metatarsal bones. This classification largely coincides with that of the human hand and foot (Murakami, 1969, 1971) and the monkey hand (Nakai et al., 1987).

Animals↗
PubMed1987

Deep palmar arteries of monkeys, with special reference to the palmar metacarpal arteries.

The palmar metacarpal arteries in monkey hands were studied. The palmar metacarpal arteries arose from the deep palmar arch or catella palmaris proximalis and descended in the deep palm, forming the catella palmaris distalis at the distal end of the metacarpus. The palmar metacarpal arteries could be classified into four kinds in relation to the interosseous muscles and metacarpal bones: (i) the superficial palmar metacarpal (sM) arteries descending on the palmar surfaces of the interosseous muscles along the metacarpal bones, (ii) the superficial palmar intermetacarpal (sI) arteries descending on the palmar surfaces of the interosseous muscles along the intermetacarpal spaces, (iii) the deep palmar metacarpal (dM) arteries descending deep in the interosseous muscles along the metacarpal bones, and (iv) the deep palmar intermetacarpal (dI) arteries descending deep in the interosseous muscles along the intermetacarpal spaces. These findings largely coincide with those obtained from studies of the human hand by Murakami (1969).

Animals↗