摘要:

AbstractThis is a special communication in an area of special interest to all researchers using avian material. Avian embryos in the Northeast, representing four species (chicken, quail, duck, guinea hen), have been found to be drastically deficient in presomitic tissue (segmental plate tissue) between 45 and 60 h of incubation. These deficiencies first appear in the embryo as blisters, then, through tissue repair, they disappear and the embryos continue seemingly normal development. Similar blisters and excrescences appear in the area pellucida and area opaca between 20 and 30 h of incubation. Associated with these blisters and excrescences in very young embryos and blisters in segmental plates, but not necessarily the result of them, is a high incidence of congenital malformation during later development. These anomalies may be affecting the results obtained in avian research.

ISSN:0003-276X    

DOI:10.1002/ar.1092280402

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1990

数据来源: WILEY

摘要:

AbstractThe distribution of hyaluronic acid in the oocyte‐cumulus complexes collected from the oviduct ampulla of superovulated hamsters was revealed by use of hyaluronidase coupled to colloidal gold. On thin sections of Lowicryl‐embedded oocyte‐cumulus complexes, gold particles were associated specifically with interconnecting fibrillar materials that make up the cumulus matrix. Inside the cumulus cells, gold particles were found over the cisternal membrane of the rough endoplasmic reticulum, in the contents of lysosomes and multivesicular bodies, and over Golgi vesicles of some cumulus cells. A high concentration of gold labeling was observed over the peripheral condensed chromatin and perinucleolar components in the nucleus. The cell surface of the cumulus cells also appeared to be labeled. Gold particles, however, were absent over the mitochondria and lipid vacuoles. In the oocytes, labeling was found to be associated mainly with rough endoplasmic reticulum and arrays of lamellar structures; cortical granules, mitochondria, and coated vesicles were essentially devoid of gold particles. Gold particles were also seen along the plasma membrane of the oocytes and within the perivitelline space. The zona pellucida was not labeled by hyaluronidase‐gold. Different control experiments confirmed the specificity of the labeling. Digestion of thin sections with hyaluronidase prior to incubation with hyaluronidase‐gold abolished the initial reaction, whereas treatment of thin sections with chondroitinase did not prevent labeling of oocyte‐cumulus complexes by hyaluronidase‐gold. Although the function of hyaluronic acid in the oocyte‐cumulus complex at the time of ovulation and fertilization is not known, the high concentration of this particular compound in the cumulus matrix and the cumulus cells and its specific locations in the perivitelline space and in the superovulated oocytes implicate the significance of its presence and warrant future

ISSN:0003-276X    

DOI:10.1002/ar.1092280403

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1990

数据来源: WILEY

摘要:

AbstractCharacterization of mineral deposition has been studied by electron optical methods during early ontogenesis of lepidotrichia, the bony fin rays, of the troutOncorhynchus mykiss(the former Salmo gairdneri). The fin rays consist of an extracellular granular ground substance containing in part a network of collagen fibrils within the basal lamella of the fin dermoepidermal interface. Growth of individual rays proceeds in a proximodistal direction. The mineral phase appears as electron‐dense needle or plate‐like particles and is associated with the collagenous matrix. On analysis of progressively maturing tissue, the mineral was characterized as a poorly crystalline hydroxyapatite with Ca/P molar ratios in the range of 1.0–1.4, corresponding to distal and proximal areas, respectively. With selected‐area electron diffraction and dark field imaging of lepidotrichia, the mineral particles were found to be about 3–10 nm thick and 12–20 nm in length (along their crystallographic c‐axes), possibly aggregated into larger crystals 35–40 nm long observed with bright field microscopy. No definitive relation was found between either the c‐ or a,b‐axes images of the crystals and the periodic structure of collagen, which forms the framework for mineral deposition in this and in other vertebrate

ISSN:0003-276X    

DOI:10.1002/ar.1092280404

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1990

数据来源: WILEY

摘要:

AbstractLight microscope histochemistry and immunohistochemistry, and routine electron microscopy techniques were performed to analyse elastin distribution and structure in the human liver compared with that in baboon and mouse. In man and baboon, elastic fibers stained by iron hematoxylin or orcinolnew fuchsin seemed to be solitary and were few in number; in the mouse they were thinner but abundant, both in the portal tract and in hepatic veins. Orcein or resorcin‐fuchsin stains, employed after oxidation of tissue sections, revealed a network comprising elastic, elaunin, and oxytalan fibers, which was also demonstrated by immunofluorescence with anti‐elastin antibody in man and baboon. At the ultrastructural level, the elastic fibers of the human portal tract corresponded to discontinuous patches of amorphous material intermingled with few microfibrils. These contrasted with the thinner elastic fibers of baboon and mouse liver which had a core of amorphous material. In man and baboon, these fibers meshed into slender bundles of microfibrils often exhibiting small spots of amorphous material (elaunin fibers) and terminated as isolated microfibrils (oxytalan fibers). Immunoelectron microscopy of elastin carried out on baboon liver tissue labelled the amorphous material and also its microfibrillar component. Immunoperoxidase deposits were also associated with isolated bundles of microfibrils in the baboon portal stroma. Immunolabelling and elastic stains disclosed an important elastin portal network located around vascular, biliary structures and interspaced with collagen bundles. The structural polymorphism of elastin, assembling different relative amounts of amorphous material and microfibrils, might have a relationship with the required elasticity in a given spec

ISSN:0003-276X    

DOI:10.1002/ar.1092280405

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1990

数据来源: WILEY

摘要:

AbstractThe neonatal period in male development is characterized by an acute rise in serum testosterone, which peaks at 2 to 3 months of age. The purpose of this study is to examine the neonatal human testicular interstitium at 4 months for evidence of Leydig cell maturation, as well as any morphological criteria relating to the fate of Leydig cells during this period, specifically, for signs of cell regression.Leydig cells are described with impressive development of the steroid secreting apparatus, which are consistent with the mature Leydig cells found during early fetal development and in the adult. The outstanding feature of these cells is the “organelle association” of extensive, anastamosing tubules of smooth endoplasmic reticulum (SER), pleomorphic mitochondria with a component of tubular cristae, and abundant microperoxisomes associated with the SER. Well‐developed Golgi elements, regionalized RER, and diverse cell inclusions are also characteristics of these cells. Reinke crystals and paracrystalline inclusions are absent. Gap junctions are common in this system and are notable in the asymmetric nature of the adjacent cytoplasmic components.These findings provide a morphologic correlate to the reported neonatal phase of testosterone production in man.Intermediate forms of Leydig cells are described with “organelle associations” including decreased SER with increased lipid droplets, and decreased SER with prominent cytoplasmic filaments and/or dramatic mitochondrial changes supportive of mitochondrial involution. Cells consistent with immature Leydig cells are also present. The rather impressive diversity in cell morphology present during this time frame of 4 months, slightly past the peak in testosterone production, provides evidence of Leydig cell regression and a continuity of the mature neonatal Leydig cells with the immature Leydig cells of childhood (Prince, 1984). There is also some evidence of cell degeneration.Although the developmental history of Leydig cells has been described for years as biphasic, it is time to view Leydig cell development in man as a triphasic event, fetal, neonatal, and

ISSN:0003-276X    

DOI:10.1002/ar.1092280406

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1990

数据来源: WILEY

摘要:

AbstractAn interrelationship between atrial natriuretic peptide (ANP) and the renin‐angiotensin system has been established. Both of these hormonal systems are modulated by sodium balance. The role of the beta‐adrenoceptor in the regulation of release of ANP is not clear. We therefore undertook a study to examine changes in atrial‐specific granule number and plasma ANP level following beta‐adrenoceptor blockade in rats on low and high sodium intakes. A low‐sodium diet, as compared with a high‐sodium diet, elevated right and left atrial‐specific granule number (right atria 54.6 ± 8.7 vs. 42.3 ± 5.7; left atria 47.7 ± 7.7 vs. 30.6 ± 3.4 granules/unit area) and plasma renin activity (28 ± 3.7 vs. 5.4 ± 0.8 ng Al/ml/hr). Plasma ANP levels were lower in the low‐sodium animals (98 ± 34 vs. 345 ± 38 pg/ml). When treated with the nonspecific beta‐adrenoceptor blocker propranolol, the elevated plasma renin activity and atrial‐specific granule number in rats on a low sodium intake were significantly less. Neither of these parameters changed in rats on a high sodium intake. Conversely, propranolol treatment resulted in lower plasma ANP levels in rats with high sodium intake. The already‐suppressed plasma ANP level in rats on a low‐sodium diet was unaltered with beta‐adrenoceptor blockade. The results suggest that dietary sodium intake is an important determinant of the response of atrial‐specific granule number and plasma ANP levels following beta‐a

ISSN:0003-276X    

DOI:10.1002/ar.1092280407

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1990

数据来源: WILEY

摘要:

AbstractAn indirect immunoperoxidase procedure was used to detect the presence of calbindin‐D28K and calbindin‐D9K in the cerebellum, kidney, and duodenum of the baboonPapio ursinus.Antibodies to chick calbinding‐D28K and to both rat and mouse calbindin‐D9K were used. The cerebellum and kidney were shown to contain calbindin‐D28K; the doudenum contained calbindin‐D9K. In the cerebellum, positive staining was found in the Purkinje cells only; in the kidney, positive staining was found in the distal convoluted tubules, connecting tubules, and collecting tubules, extending deep into the medullary regions of the kidney. Staining in the duodenum was confined to the enterocytes of the villi, with no stain present in the crypt regions or goblet cells. Thus the baboon, a primate, contains the larger of the calbindins in both the cerebellum and kidney as does the human and monkey, but its distribution in the kidney is more generalized than that found in humans. The molecular weight of calbindin‐D9K was found to be similar to that found in other animals. However, the calbindin‐D28K from the baboon tissues appears to be slightly smaller than the protein found in other animals and may therefore be of similar size to the human calbindin

ISSN:0003-276X    

DOI:10.1002/ar.1092280408

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1990

数据来源: WILEY

摘要:

AbstractFunctional differentiation of the notochord in rhesus monkey embryos at stages 11–12 (25–28 days of gestation) was analyzed by means of ultrastructural cytochemistry. The notochordal cells exhibited well developed Golgi complexes, rough endoplasmic reticulum, mitochondria, and numerous coated vesicles. Large irregular intercellular spaces were common, and some contained fibrils and particulate matter similar to that observed in the perinotochordal space immediately surrounding the notochord. With the glycogen‐specific thiocarbohydrazide‐silver proteinate technique, solitary particles as well as large aggregates of glycogen were present within the notochordal cells. The center of some aggregates was electron lucent and contained collapsed membranous structures. The results indicate that as early as stage 11 the nonhuman primate notochord exhibits ultrastructural features suggestive of secretory activity and cytological com

ISSN:0003-276X    

DOI:10.1002/ar.1092280409

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1990

数据来源: WILEY

摘要:

AbstractHensen's node, regarded as the avian and mammalian homologue of Spemann's neural inducer (i.e., the amphibian dorsal blastoporal lip), has been transplanted in many previous studies to the germinal crescent of avian blastoderms to examine ectopic neural induction. All these studies have suffered from one or more major shortcomings, the most significant of which has been the lack of a reliable cell marker to determine the contributions of graft cells to ectopic embryos. In the absence of such marker, induced (i.e., derived from the host) and self‐differentiated (i.e., derived from the graft) neurepithelium cannot be distinguished from one another with certainty. We have transplanted quail Hensen's nodes to chick host blastoderms and have subsequently used the quail nucleolar heterochromatin marker to identify graft cells unequivocally. We systematically varied both donor and host ages (i.e., stages 3–8 and 3–5, respectively) to examine the effects of age on ectopic neural induction and self‐differentiation. Our results demonstrate that the age of the donor is more critical than that of the host over the stages examined. With advancing donor age, the frequency of host induction decreases, while the frequency of graft self‐differentiation increases. Previous studies not using cell markers have concluded that the craniocaudal level of the induced neuraxis is determined by the age of the donor, that is, young donors induce cranial neuraxial levels, whereas old donors induce caudal levels. By contrast, we found that with grafts from older donors, neurepithelium was more commonly self‐differentiated rather than induced and that progressively more caudal levels of the neuraxis self‐differentiated with advancing donor age. Induction of caudal neuraxial levels never occurred in the absence of induced cranial levels. The frequency of neural induction was inversely correlated with the age of the donor and directly correlated with the quantity of graft endodermal cells contributed to the ectopic embryo, supporting a previous assertion that in avian embryos, the earliest and principal source of neural inducer lies within the endoderm rather than mesoderm. From our results, we propose that the role of neural induction is to produce neurepithelium of unspecified regional character, and that the formation of regional character depends on subsequent morphog

ISSN:0003-276X    

DOI:10.1002/ar.1092280410

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1990

数据来源: WILEY

摘要:

AbstractThe calcium ion has been implicated in the mediation of the morphogenetic movements that occur during neural tube formation. The present study identifies high levels of calcium in the neuroepithelium of the neural plate, folds, and tube. These levels are substantially higher than those discerned elsewhere in the embryo. The calcium is localized in morphogenetically active regions by using the antibiotic chlortetracycline (CTC) which chelates calcium and is demonstrated in this investigation by both autoradiography and calcium‐linked fluorescence. The specificity of CTC reaction for calcium in the developing neural axis is confirmed by EGTA competition.A comparison of the actual calcium levels in the developing neural axis (dorsal) with equivalently weighted ventral tissues was obtained by atomic absorption spectrometry (AAS). This method provides a total count of the calcium without any loss during tissue processing. For AAS, living tissues were precisely excised and immediately dessicated. Each tissue sample (dry weight 1.5 mg) was then solubilized for analysis. The spectrometric data reveal that the embryonic dorsal aspect forming the neural tube contains 57% more calcium than an equivalent weight of the ventral aspec

ISSN:0003-276X    

DOI:10.1002/ar.1092280411

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1990

数据来源: WILEY