Biomedical subjects

H Sumida

Publications and source records attributed to H Sumida.

At least 37 records · Page 2Linked to original sources

PubMed1993

Sex differences in the anteroventral periventricular nucleus of the preoptic area and in the related effects of androgen in prenatal rats.

The density of cells in the anteroventral periventricular nucleus (AVPv) of the preoptic area of female rats was greater than that of males on day 21 of gestation. It appears that this difference between the sexes is caused by the action of androgen since the density of cells in the AVPv of female fetuses fell to the density in males when the mother received injections of testosterone propionate (TP) on days 14-18 of gestation. Pycnotic cells were more frequently found in oil-treated control males and TP-treated female fetuses than in control female fetuses. This result suggests that the prenatal injections of TP enhanced the rate of degeneration of the cells in the AVPv.

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PubMed1993

Formation of neurons in the sexually dimorphic anteroventral periventricular nucleus of the preoptic area of the rat: effects of prenatal treatment with testosterone propionate.

An examination was made of neurogenesis in the anteroventral periventricular nucleus (AVPv) of the preoptic area of the rat using bromodeoxyuridine (BrdU), a thymidine analog, and a BrdU-specific antibody. Cells in the AVPv of adult rats were labeled with the antibody when BrdU was injected into pregnant rats once during day 13 to 18 of gestation, but not during day 10 to 12 nor 19 to 20 of gestation nor on postnatal day 1, indicating the neurogenesis of the AVPv occurs during a limited period from day 13 to 18 of gestation. Next, to examine the effects of androgen on neurogenesis, BrdU was injected once on day 15 into pregnant rats that also received injections of testosterone propionate (TP). The number of BrdU-labeled cells in the AVPv was similar in control female and male fetuses and female fetuses from pregnant rats that received daily injections of TP during days 14 to 16, when fetuses were examined on day 17 of gestation. These results suggest that the neurogenesis that was recognized by labeling with BrdU was not affected by the treatment with TP. On day 21 of gestation, BrdU-labeled cells in the AVPv of control male fetuses and female fetuses that received TP during days 14 to 18 were fewer in number than those in female fetuses of the control group, whereas treatments with TP during days 14 to 16 and during days 17 to 18 did not cause any significant decrease in number of BrdU-labeled cells. These findings can support the hypothesis that elimination of a population of cells, for example, by cell death as described previously, is enhanced in male fetuses and in female fetuses treated with TP repetitively.

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PubMed1992

Role of vitronectin in embryonic rat endocardial cell migration in vitro.

Vitronectin is one of the extracellular matrices that mediate cell spreading and attachment in vitro. In the present paper, we demonstrate the involvement of vitronectin in the migration of cushion mesenchymal cells of the embryonic rat heart. Immunohistochemistry established the localization of vitronectin in the myocardial cells and in some of the cushion mesenchymal cells of the truncus arteriosus and atrioventricular canal. In vitro, vitronectin, fibronectin, and collagen type-I revealed significant stimulating activity for cushion mesenchymal cell migration. The distance migrated by cushion mesenchymal cells cultured on vitronectin, collagen type-I, or both vitronectin and fibronectin was similar, but that on fibronectin was significantly shorter. Following the addition of anti-vitronectin IgG to the medium, the migration distance of cushion mesenchymal cells on fibronectin was remarkably increased. Most explants on vitronectin or on both vitronectin and fibronectin became detached from dishes after the addition of the antivitronectin antibody. Immunostaining revealed that cushion mesenchymal cells cultured on substrata other than vitronectin synthesized vitronectin. From these results, it is suggested that vitronectin is synthesized by myocardial cells and some cushion mesenchymal cells, and that vitronectin inhibits cell movement on fibronectin. This feature of vitronectin may be important in the regulation of the migration of cushion mesenchymal cell in vivo.

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PubMed1991

Actin bundles on the right side in the caudal part of the heart tube play a role in dextro-looping in the embryonic chick heart.

The role of actin bundles on the heart looping of chick embryos was examined by using cytochalasin B, which binds to the barbed end of actin filaments and inhibits association of the subunits. It was applied to embryos cultured according to New's method. Looping did not occur when cytochalasin B was applied diffusely in the medium. Further, we disorganized actin bundles in a limited part of the heart tube to examine the role of actin bundles in each part in asymmetry formation. A small crystal of cytochalasin B was applied to the caudal part of the heart tube on either the left or right side. The disorganization of actin bundles on the left side resulted in the right-bending of the heart, an initial sign of dextro-looping (normal pattern), and right side disorganization resulted in left-bending. We suggest that actin bundles on the right side of the caudal part of a heart tube generate tension and cause dextro-looping. Embryos whose hearts bent to the right rotated their heads to the right, and embryos with left-bent-hearts rotated their heads to the left. The rotation of the heart tube may therefore decide in which direction the body axis rotates.

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PubMed1991

Relation of the distribution of fibronectin to the obliteration of the arch artery in the chick.

Fibronectin has been believed to be involved in vasculogenesis. This study demonstrates by immunohistochemistry the distribution of fibronectin around the systemic arteries of chick embryos during the periods of aortic arch formation, and examines the possible relationship between the distribution of fibronectin and the obliteration of the arch artery. In embryos at stage 23, no obliteration of arch arteries was recognized on sections. At this stage, intense staining with an anti-fibronectin antibody was seen in the developing tunica media of the carotid artery and dorsal aorta. Staining around the arch arteries was much weaker. At stage 26, the intensity of anti-fibronectin antibody staining was weaker around the left arch artery, although the diameter of the 4th arch artery was not different between the left and right. At stage 27, which is the early period for the obliteration of the left 4th arch artery, the intensity of the anti-fibronectin antibody staining for the left arch artery was much less than that for the right arch artery. These results show that fibronectin does not accumulate around the left 4th arch artery during aortic arch formation and suggest the possibility that a smaller amount of fibronectin is responsible for the obliteration of the left 4th arch artery.

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PubMed1990

Distribution of vitronectin in the embryonic chick heart during endocardial cell migration.

In the early phase of heart development, the endocardial cells migrate into the truncal swellings and atrioventricular (AV) cushions, and become mesenchymal cells. Vitronectin is a glycoprotein which is thought to mediate cell migration. The present study demonstrates by immunohistochemistry the distribution of vitronectin in order to elucidate its contribution to endocardial cell migration in the developing chick heart. At Hamburger and Mamilton's stage 23, the network of fibrillar material filled the extracellular space of both truncal swellings and AV cushions. The fibrillar network has been thought to be a matrix for endocardial cell migration. The network was stained with the anti-vitronectin antibody. At stage 29, the swellings and cushions were packed with mesenchymal cells, though immunoreactivity to the antibody was still observed in the extracellular matrix. The myocardium facing the AV cushions reacted to the antibody, but the myocardium surrounding the truncus arteriosus did not. The intensity of the immunohistochemical staining of the myocardium facing the AV cushions increased and reached a peak at stages 24 to 26, and then became weak by stage 29. The endocardial sheet, aortico-pulmonary septum and developing tunica media of the great arteries were not stained by the antibody at any stage. These results strongly suggest that vitronectin is involved in the migration of endocardial cells, and that the myocardium facing the AV cushions produces vitronectin.

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PubMed1989

Lectin histochemistry of the embryonic heart: fucose-specific lectin binding sites in developing rats and chicks.

Glycoconjugates, particularly their sugar side chains, play important roles in embryonic development. Changes in cell-surface-associated glycoconjugates are known to affect cell differentiation, cellular interactions, and other developmental phenomena during embryogenesis. The embryonic heart goes through a series of complicated morphologic events during development. Of particular interest is morphogenesis of the outflow tract. This region of the embryonic heart originates from more than one cell population and undergoes a complex process of septation during formation of the great vessels. Histochemical analysis with a series of fucose-specific lectins conjugated to horseradish peroxidase has revealed the presence of a fucosylated glycoconjugate in the outflow tract of the developing heart. The results reveal further that the expression of the fucosylated glycoconjugate is stage-dependent and thus probably genetically regulated. The timing and distribution of staining with the lectin OFA suggest that this fucosylated glycoconjugate may play a role in directing the migration of neural crest cells into the heart and subsequent formation of the conus septum.

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PubMed1989

Lectin histochemistry of the embryonic heart: expression of terminal and penultimate galactose residues in developing rats and chicks.

Rat embryos at days 10-18 of gestation and chicken embryos at days 3-6 of incubation were fixed and processed for lectin histochemistry. The distribution of binding sites for a lectin from the peanut Arachis hypogaea (PNA) conjugated to horseradish peroxidase (HRP) was determined on tissue sections both before and after enzymatic cleavage of sialic acid with neuraminidase (sialidase). Endocardial cushion tissue in the rat, but not in the chick, reacted with PNA-HRP prior to digestion with sialidase. Endocardium of both species (12 and 13 days in rat, 5 and 6 days in chick), particularly at the level of endocardial cushions, reacted strongly with the sialidase-PNA sequence; this staining decreased markedly after day 14 of gestation in the rat. PNA binding sites capped by sialic acid were most abundant in the developing rat heart during the critical period of endocardial cushion formation and decreased as development proceeded. The marked changes in the appearance and distribution of cardiac cell and tissue glycoconjugates during cardiogenesis support the concept that rapid changes occur in the structure of complex carbohydrates during embryonic and fetal development. The findings also suggest that such glycosylation-related events may be species specific.

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PubMed1989

Cytoplasmic stress fibers in the developing heart.

Rhodamine-conjugated phalloidin staining was used to study the distribution of filamentous actin in the developing heart of embryonic chicks and rats during the morphogenetic period of cardiac septation. In the chick, intense fluorescence indicative of abundant filamentous actin was observed along the myocardium and in the mesenchymal condensations that formed within the aorticopulmonary septum at day 5. Such cellular condensations and concentration of filamentous actin were not seen in the atrioventricular cushions nor in the preseptation outflow tract. Similar results were found in the 14-day rat embryo. In electron micrographs, microfilament bundles with irregular dense bodies were seen in elongated mesenchymal cells between the valve sites of both species. Cell-cell contacts were observed between such elongated cells and myocyte processes protruding from the nearby myocardial sheath. These histochemical and ultrastructural observations suggest that such mesenchymal condensations serve a specialized mechanical tensile role during embryonic septation of cardiac outflow channels.

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PubMed1989

Distribution of the neural crest cells in the heart of birds: a three dimensional analysis.

The distribution of neural crest derived cells (NC) in the heart of quail-chick chimeric embryos was analyzed three-dimensionally after computer reconstruction. During the division of the truncus arteriosus into the aorta and the pulmonary trunk, ventral and dorsal columns of NC-derived cells were found in the truncal swellings. These columns were elongations from the aorticopulmonary (AP) septum. The dorsal column extended more proximally than did the ventral column. Around hatching, NC-derived cells located between the proximal aorta and the pulmonary trunk, differentiated into cartilage and connective tissue. They formed a part of the cardiac skeleton. A small number of NC-derived cells were scattered in the cusps of the arterial valves. Cells derived from the right NC were located around the aorta and the right arch arteries but not around the distal pulmonary trunk and the left arch arteries. At the proximal level, cells derived from the right NC were located in both the dorsal and ventral columns. These results suggest that the AP septum is mainly formed by NC-derived cells, right and left NC cells migrating into assigned areas in the heart. Location of two columns of NC-derived cells may support a translocation hypothesis for the AP septum during truncal division.

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PubMed1989

The localization of fibronectin and 140 Kd fibronectin receptor in the truncus arteriosus of the chick embryonic heart.

The distribution of fibronectin and 140 Kd fibronectin-receptor was examined in the truncus arteriosus of the chick embryonic heart during aortico-pulmonary (AP) septation by immunohistochemistry. In 4-day-old chick embryos, immunoreactivity of both anti-fibronectin and anti-140 Kd fibronectin-receptor was seen in the primordia of the AP septum. In 5-day-old embryos, cells stained with anti-140 Kd fibronectin-receptor antibody were rarely found in the AP septum, though strong immunoreactivity of the anti-fibronectin antibody was observed in the AP septum. In 6-day-old embryos, at a late stage of septation, cells stained with anti-140 Kd fibronectin-receptor antibody were not found in the AP septum, and immunoreactivity of the anti-fibronectin antibody had decreased. In the cushion tissue, immunoreactivity of the anti-fibronectin antibody was seen, but that of the anti-140 Kd fibronectin-receptor antibody was recognizable only on a few cushion cells in the 4-day-old embryos. These findings suggest that fibronectin is involved in the formation of the AP septum primordia, that fibronectin does not promote the development of the AP septum, and that the migration mechanism of cushion cells is different from that of neural crest cells.

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PubMed1988

Effects of fine-grained diet on annulospiral endings of muscle spindles in the masseter muscle in developing and adult mice.

In the masticatory muscles, neuromuscular spindles have a very important role in controlling the jaw movement since they act as stretch receptors in skeletal muscles. The continuous intake of fine-grained diet which is easily chewable leads to degeneration of the sensory endings of Ia fibers in many muscle spindles of the mouse masseter muscle in only 120 d after birth.

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PubMed1988