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Biomedical subjects

H Okamura

Publications and source records attributed to H Okamura.

At least 757 records · Page 42Linked to original sources
PubMed1981

[Scanning electron microscopic observations of microcorrosion casts for rabbit ovarian vasculature before ovulatory stimulus (author's transl)].

Ovarian vasculature of juvenile and adult rabbits was studied using a method of resin injection-corrosion casts. Arteries and arterioles in the ovarian stroma and capillary networks surrounding the follicles were observed on a three dimensional scale by scanning electron microscopy with the following findings: 1) The strongly coiled arteries are observed in adult rabbit ovaries. The first order arterioles arise from the spiral artery, and the second order arterioles stemming from these first order arterioles enter into each follicle. 2) Vasculature of follicles starts as glove-finger-like ramified capillary networks. As follicles grow, follicular vessels increase remarkably and form multilayered complex vascular networks surrounding the follicles. 3) The observations of circular impressions around the arterioles near the follicle and in the follicular wall suggest the existence of sphincteric control mechanism of blood flow into the follicle. 4) There are several pathways of venous drainage from a wall of large follicle and arterio-venous shunts are observed in the wall of such follicles. These structures may exert an important effect upon the follicular hemodynamics in the process of follicle rupture.

Animals↗
PubMed1981

[Histological studies of multiple subperitoneal nodules produced by prolonged administration of estrogen (author's transl)].

It has been reported that multiple peritoneal fibroids were produced in guinea pigs treated with large doses of estrogens, and the nodules regressed when the steroid stimulant was discontinued. Recently, these experimental nodules were considered to be simulating the disseminated pattern of Leiomyomatosis Peritonealis Disseminata (LPD). Although these experimental nodules were considered to be composed of fibroblasts by light-microscopic studies, LPD was verified to be composed of smooth muscle by electronmicroscopic studies. Therefore, it is indispensable to study these experimental nodules by electronmicroscopy, when we discuss about the similarities between experimental nodules and LPD. Guinea pigs were treated with various doses of estradiol benzoate (E) [40, 80, 100, 200 microgram/day, thrice a week, intramuscular injection]. After treatment for three months, every dose of E produced the lesions simulating the disseminated pattern of LPD: multiple nodules in various sizes, scattered on the surface of the uterine horn, peritoneum, spleen and pancreas, and in the omentum and mesocolon. Ultrastructurally, the nodules were composed of the cells resembling fibroblast. We conjectured that estrogen differentiates and proliferates the cells of the features of fibroblast-like cells from subcoelomic mesenchyme, resulting in the production of multiple superitoneal nodules simulating the disseminated pattern of LPD.

Animals↗
PubMed1981

[Ultrastructural observation of the ovulatory changes in the capillary of the human follicular apex (author's transl)].

To clarify its possible participation and mode of action in follicle rupture at human ovulation, the capillary in the apex of the ovarian follicle was investigated electronmicroscopically with 16 human ovaries. In the follicle at the mid-proliferative phase with 6 mm diameter, capillary lumen was narrow and empty. Capillary vessels observed in the theca interna of the preovulatory follicle were dilated and filled with blood cells. Their endothelial cells had indented nuclei and elongated thin cytoplasm with unusually irregular membranous protrusions. In cytoplasm there were numerous vesicles, some of which had fine granule-like contents of low electron density to be released into extracapillary space. These results indicate increased capillary permeability due to active transport around the time of ovulation. Polymorphonuclear leucocytes, rich in specific granules containing collagenase activity, were often observed in the capillary lumen as well as extracapillary space only close to the time of ovulation. This observation implies possible roles of leucocytes in collagen degradation. The present ultrastructural results suggest that the vast capillary network in the follicle wall plays an important role in the mechanism of follicle rupture through its increased permeability and collagenolytic activities of leucocytes.

Adult↗
PubMed1980

Human fibroblastoid interferon: immunosorbent column chromatography and N-terminal amino acid sequence.

Three mice and one rabbit were inoculated with purified human fibroblastoid interferon. Neutralizing activity to human fibroblastoid interferon was observed in the serum of these animals with the rabbit showing the highest anti-interferon titers (10(6) neutralizing units/mL). Rabbit antiserum was coupled to cyanogen bromide activated Sepharose, and the resulting material was tested for use in the purification of human fibroblastoid interferon. Pure interferon obtained by this procedure was analyzed, and we report the sequence of the first 13 N-terminal amino acid residues of this protein.

Amino Acid Sequence↗
PubMed1980

Leiomyomatosis peritonealis disseminata.

The ninth documented case of leiomyomatosis peritonealis disseminata (LPD) combined with pregnancy is presented. Light and electron microscopic studies revealed that the smaller tumors were composed partly of decidual cells and partly of fibroblasts, and the larger tumors contained cells resembling smooth muscle cells. Plasma steroid levels were determined during pregnancy. Estrogen levels were within normal range, but progesterone levels were lower than normal, resulting in relative hyperestrogenism. In the case presented, pregnancy, especially with relative hyperestrogenism, may have been a major cause of LPD.

Adult↗
PubMed1980

Ovulatory changes in the wall at the apex of the human Graafian follicle.

The apical wall was studied ultrastructurally in 16 human follicles at various stages of development. In the theca externa and tunica albuginea at the apex of growing follicles, fibroblasts with little cytoplasm and abundant collagen fibres were observed. In the mature follicles, the fibroblastic cytoplasm was well developed, rich in lysosome-like granules and contained peripheral multivesicular structures. Intercellular collagen fibres were sparse. It is suggested that the collagen fibres are digested by the content of lysosomal granules and multivesicular structures, thus aiding follicular rupture.

Adult↗
PubMed1980

[Activities of collagenolytic enzymes in the human ovary (author's transl)].

To elucidate the mechanisms of follicular rupture at ovulation in human, activities of collagenolytic enzymes were measured in the human follicles at various stages of development by using two kinds of synthetic substrates, alpha-N-benzoyl-DL-arginine-2-naphthylamide HCl and N-carbobenzoxy-glycyl-prolyl-glycyl-glycyl-prolyl-alanine. The result clarified that human ovaries did have two kinds of collagenolytic activities, one cathepsin B1 with its optimal pH 6.0, the other neutral collagenase with its optimal pH 7.5. To examine the subtle changes of these enzymatic activities in the follicles during ovulatory processes, the follicle wall was dissected into three parts, namely, the granulosal layer, the apical wall and the basal wall without the granulosal layer. Activity of neutral collagenase presented a continuous increase in the follicular wall, while in the granulosal layer its gradual depletion was observed. Cathepsin B1 revealed a significant drop of its activity in the apical wall around a preovulatory period. These results indicate an involvement of collagenolytic enzymes in the human ovulatory process.

Cathepsin B↗
PubMed1980

[Activity of vertebrate collagenase in the human ovary (author's transl)].

Participation of collagenolytic activities in the ovulatory process had been recently studied in the experimental animals, though their existence in the human ovary remains obscure. In the previous report, we demonstrated the collagenolytic activity by using synthetic substrates N-carbobenzoxy-Gly-Pro-Gly-Gly-Pro-Ala and the cathepsin B1 activity in human ovarian follicles. To investigate the activity for degradation of native collagen in the human ovary, we used 14C-labeled collagen prepared from young rat skin in the present study. Collagenolytic activity for synthetic substrate DNP-Pro-Gln-Gly-Ile-Ala-Gly-Gln-D-Arg OH supposed to be specific for vertebrate collagenase was also measured. Our results clearly demonstrated that there existed vertebrate collagenase activity and the collagenolytic activity measured by using DNP-peptide in the human ovarian follicles. The correlation coefficient between both enzymatic activities was 0.56. The DNP-peptide-degrading activity seemed to partly represent the collagenolytic activity from vertebrate collagenase. It was concluded that vertebrate collagenase besides collagenolytic activities did exist in the human ovary and they seemed to be involved in the degradation of collagen fibers in the follicular apex at the time of ovulation.

Animals↗
PubMed1980

[Cytochemical demonstration of 3 beta-hydroxysteroid dehydrogenase activity in human corpora lutea (author's transl)].

3 beta-hydroxysteroid dehydrogenase (3 beta-HDS) activity was demonstrated ultrastructurally in human corpora lutea obtained from the women aged 32-46 who were treated by the hysterectomy for various gynecological indications. The corpora lutea were removed from ovaries and cut into small pieces of 1 mm3. Specimens were incubated at 25 degrees C for 20 min. in the media containing dehydroepiandrosterone 0.6 mg, 0.1 M sodium citrate 0.3 ml, 5 mM potassium ferricyanide 1 ml, 30 mM copper sulfate 1 ml, N.A.D. 3.6 mg, sucrose 1.0 g and 0.1 M phosphate buffer (pH 7.2) 6 ml. For a control study, 1.5 mg cyanoketone (by the courtesy of Dr G.O. Pott), the specific inhibitor for 3 beta-HSD, was added to the media. The materials were fixed in 4% glutaraldhyde and 1% OsO4 and embedded in Epon 812. Electron dense reaction products of copper ferrocyanide were observed in smooth endoplasmic reticulum (sER) and in intercristal and outer space of mitochondria. In control studies, 3 beta-HSD activity were completely abolished. It is concluded that not only sER but also mitochondria has 3 beta-HSD activity in human corpora lutea. Furthermore, mitochondria seems to have capability to synthetize progesterone from cholesterol by itself.

3-Hydroxysteroid Dehydrogenases↗
PubMed1980

[An ultrastructural study of primary carcinoma of the fallopian tube (author's transl)].

Primary carcinoma of the fallopian tube is one of the least common neoplasms arising from the female genital tract with rare preoperative correct diagnosis. Recently, we had chances to experience two cases of this tumor, one of which was examined electron microscopically. Both of them revealed the well-differentiated pattern of papillary adenocarcinoma. Electron microscopically, most of the cancer cells had pleomorphic nuclei, giant or multiple nucleoli, numerous mitochondria, poorly developed rER and abundant polysomes. Small number of cells rich in lysosome-like granules were also observed near the basement membrane. Among the cancer cells, "ultrastructural alveolar spaces", composed of several cancer cells, were prominent. In the cancer cells, there were observed the following interesting observations; annulate lamellae-like structure, unusual bundles of the filamentous elements and lamellar body-like structures. Normal tubal epithelium consisted of ciliated cells, secretory cells, peg cells and so-called "indifferent cells". The fact that the present tumor had no ciliated cells and few secretory cells indicated that this tumor was originated from "indifferent cells" or peg cells.

Adenocarcinoma, Papillary↗
PubMed1980

[An ultrastructural study of ovulatory changes in stromal tissue of the follicular apex in the human (author's transl)].

To elucidate the mechanism of follicular rupture at ovulation in human, ultrastructural changes of stromal tissue of the follicular apex during follicular growth and ovulation were studied by focusing on the collagen and fibroblasts in the stroma. Sixteen ovaries were obtained from women at their thirties who underwent the abdominal hysterectomy for gynecologic diseases. From follicles at various stages of development, apical portions were excised and processed for electronmicroscopy. At the apex of growing follicles, fibroblasts with poor cytoplasm and abundant collagen fibers among them were observed in the layers of tunica albuginea and theca externa. At the preovulatory follicles, fibroblasts had rich cytoplasm containing lysosomal granules and multivesicular structures and intercellular collagen fibers were rather sparse. These lysosomal granules and multivesicular structures in the fibroblasts were much conspicuous in the theca external layer of preovulatory and post-ruptured follicles and collagen fibers among these fibroblasts were almost disappeared. It seems that these intercellular collagen fibers and ground substance were digested by the content of lysosomal granules and multivesicular structures.

Adult↗
PubMed1980

[A cytochemical study of acid-phosphatase activity in follicular granulosa cells of human ovaries (author's transl)].

In order to clarify the nature and possible roles of lysosome-like granules observed electronmicroscopically in the granulosa cells of human preovulatory follicles, lysosomal activities in human preovulatory granulosa cells were investigated ultrastructurally by staining a marker enzyme acid phosphatase with modified Gomori technique. In the granulosa cells of follicles 10 approximately 15 mm in diameter, acid phosphatase reaction products were seen only in the Golgi apparatus. In follicles around 20 mm in diameter with extremely thin apical walls, granulosa cells with abundant nexuses and steroidogenic organelles (sER, large spherical mitochondria with tubular cristae and lipid-droplets), had many lysosome-like granules in the perinuclear regions and/or close to lipid droplets. Acid phosphatase reaction products were observed mainly in these granules, and infrequently in Golgi apparatus. These morphological results not only identify such granules as lysosomes, but also indicate that the granulosa cells are rich in the lysosomal activity. Possible roles of lysosomes in preovulatory granulosa cells deduced from the present results are as follows, 1) a role in steroidogenesis or in steroid-secretion, 2) an involvement in the ovulatory process with their proteolytic enzymes.

Acid Phosphatase↗
PubMed1980

[An ultrastructural study of capillaries of rabbit ovarian follicles during ovulatory process (author's transl)].

The observations that perifollicular capillaries of the ovary become engorged with prominent edema in the theca interna and externa around the time of ovulation, suggest a preovulatory increase in permeability of perifollicular capillaries. In order to obtain an ultrastructural evidence for this increased capillary permeability, we examined the perifollicular capillaries in the theca interna by using mature rabbit ovaries at various time intervals after the hCG injection for induction of ovulation. We observed a capillary engorgement at 9, 10, 12 hours after the hCG injection, most prominent at 9 hours, and edema in the pericapillary space at 10, 12 hours. Pinocytotic vesicles were seen through the all stages of follicular development and they did not show any significant changes in their size, number and distribution. Fenestrations were observed at 0, 3, 4, 6 hours after the hCG injection, most frequent at 4 hours. Intercellular gaps (500 approximately 1,200 A) between two endothelial cells were demonstrated at 10, 12 hours, and thrombocytes in these gaps were also noticed. The present observations suggest that increased permeability of perifollicular capillaries just prior to ovulation were mainly due to the formation of gaps between the endothelial cells.

Animals↗