摘要:

AbstractStretch‐overload has been shown to elevate muscle mass in the avian anterior latissimus dorsi (ALD) by increasing both fiber size and fiber number; however, it is not known if these adaptations result in uniform regulation of myosin isoform expression along the length of the fibers in this slow tonic muscle. When a weight was added to the left wing of 20 adult quail for 30 days, ALD mass was increased by 161%. ALDs were divided into proximal, middle, and distal portions. Tissue cross‐sections from each muscle portion were reacted against monoclonal antibodies for either fast (FM) or slow myosin (SM), or processed for identification of native myosin isoforms. The number of fibers expressing FM increased by 190% in the distal region after stretch; however, most of these were small fibers. Electrophoretic analyses of stretched muscles demonstrated an upregulation of SM2 in all regions of the ALD. SM1 was only down‐regulated in the proximal region of the ALD. FM isoforms had greater increases in the proximal region than other regions of the overloaded ALD. These data indicate that stretch‐induced hypertrophy induces a non‐uniform increase in fast myosin isoforms and SM1 along the length of the fibers of the ALD. © 1993 Wiley

ISSN:0003-276X    

DOI:10.1002/ar.1092370102

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

年代:1993

数据来源: WILEY

摘要:

AbstractThis study investigated the immunohistochemical distribution of collagen type I and laminin during remodeling of the uterine extracellular matrix in response to embryo implantation in the rat. Collagen type I was found to be virtually absent around the embryo on the evening of day 5 of pregnancy. On days 6 to 8 of pregnancy the areas of primary and secondary decidualized tissue contained very little collagen in contrast to the outer nondecidualized stroma and myometrial tissues in which the staining patterns did not appear to alter. Day 8 of pregnancy was also notable for the appearance of collagen type I at the site of the developing placenta. Localization of laminin corresponded to areas of basement membrane and was associated with the redistribution of blood vasculature during implantation. By day 7 laminin staining was diminished in the basal areas of the lumenal epithelium around the implanting embryo. Laminin was also located in a punctate fashion at the margins of the primary decidual cells on day 6 of pregnancy, but by days 7 and 8 this staining pattern was no longer evident. This study has provided further evidence for a decline in a major fibrillar collagen during natural decidualization and also revealed a localized and transient expression of laminin in association with the differentiation of cells during primary decidual formation. © 1993 Wiley‐Liss, I

ISSN:0003-276X    

DOI:10.1002/ar.1092370103

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

年代:1993

数据来源: WILEY

摘要:

AbstractTo establish the mode of fertilization in a marsupial, a morphological investigation was made of the gametes of the South American grey short‐tailed opossum,Monodelphis domestica, at the time of fertilization in vivo and in vitro. Oestrus was induced in females by the introduction of an unfamiliar male. To obtain oocytes recently fertilized in vivo, females were killed 18–24 hours after the first mating and the region of the oviduct containing eggs excised and fixed. Unfertilized mature oocytes were recovered from ovarian follicles 15–18 hours after first mating and fertilized in vitro with cauda epididymal spermatozoa in a modified MEM medium supplemented with bovine serum albumin at 37°C in 5% CO2in air. Following sperm‐egg binding and fertilization, oocytes were fixed and prepared for light and electron microscopy.Spermatozoa unpaired prior to fertilization in vivo and in vitro and single spermatozoa bound to the zona surface by their plasmalemma overlying the acrosome on the dorsal face of the sperm head. The acrosome reaction was only observed at the zona surface (suggesting that it may be induced by zona components) and involved a vesiculation of sperm plasma and acrosomal membranes over the main body of the acrosome but not over the narrow, marginal region which persisted after the acrosome reaction was complete. Sperm penetration of the zona pellucida caused a large breach in the zona and the dispersal of perivitelline material. The fusion of the spermatozoon with the oolemma occurred first over the marginal acrosomal region and was accompanied by a fertilization cone which protruded through the zona penetration hole. Activation of the egg was characterized by the release of material from vesicles in the peripheral cytoplasm and extrusion of the second polar body.The mode of fertilization inMonodelphiswas compared with what is known in other marsupials (New World and Australian) and eutherian (placental) mammals. It was concluded that the general features of the acrosome reaction and sperm‐egg fusion may be essentially similar in both groups and that an evolutionary schism did not occur following the development of the eutherian mode of fertilization. © 1993 Wile

ISSN:0003-276X    

DOI:10.1002/ar.1092370104

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

年代:1993

数据来源: WILEY

摘要:

AbstractApplying the zone concept described previously, we quantitatively analyzed fetal rat lung development. The zone concept allowed us to coherently define reference spaces in the developing lung, a prerequisite for morphometric analysis.The peripheral zone I corresponds to a zone of growth of yet undifferentiated tissues; zone II arises from zone I and represents a region of structural and cellular differentiation; zones III and IV comprise the conducting airways and vessels.Lungs of fetal rats aged 17–23 days and 20 hours postnatal were fixed with OsO4and glutaraldehyde and processed for light and electron microscopic morphometry implemented by point and intersection counting.Fetal lung volume grew in proportion to body weight. Zone II being the largest compartment, its volume changes largely determined lung growth rates. Zone II increased in mass owing to differentiation processes at the interface to zone I where the proximal portions of zone I were continuously shifted into zone II by differentiation. New tissue was generated within zone I. Due to these combined processes zone I changed little in volume until it disappeared at the end of the canalicular stage. The presence in the pseudoglandular stage of half of the parenchymal epithelial mass available around birth indicated that parenchymal development started earlier than assumed so far.While the endothelial surface increased most at birth, the epithelial surface grew by more than 600% at day 21, reflecting the onset of canalisation.The study confirmed the usefulness of the zone concept for morphometry and provided some new insights into lung development. © 1993 Wiley‐Liss,

ISSN:0003-276X    

DOI:10.1002/ar.1092370105

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

年代:1993

数据来源: WILEY

摘要:

AbstractIn cultures of dissociated quail epiblast the basic constituents of the vascular system, blood cells and endothelial cells can be induced by basic fibroblast growth factor (Flamme and Risau, Development,116:435–439, 1992). As we show here, in those cultures three types of vascular plexus differentiate spontaneously under different culture conditions: At the 3rd day a vascular plexus appears in situ closely resembling the vascular plexus of the quail area opaca vasculosa (vasculogenesis). Vascular sprouts are formed, extending long filopodia at their tips. Such filopodia are shown to build the first intervascular bridges in the growing vascular plexus of the area vasculosa at embryonic day 3. Connections of filopodia turn out to be precursors of new capillaries interconnecting pre‐existing blood vessels (angiogenesis). Two further types of in vitro capillary plexus differentiate in long term endothelial cell cultures derived from induced angioblasts. Whereas one closely resembles so‐called angiogenesis in vitro, the third type comprises mainly multinucleated giant endothelial cells lining loop like capillaries and represents a differentiation of aging endothelial cell culture. Thus, the present in vitro model is an approach to the sequence of angioblast induction, vasculogenesis, and angiogenesis. © 1993 Wiley‐L

ISSN:0003-276X    

DOI:10.1002/ar.1092370106

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

年代:1993

数据来源: WILEY

摘要:

AbstractFormation and extension of the notochord is one of the earliest and most obvious events of axis development in vertebrate embryos. In birds, prospective notochord cells arise from Hensen's node and come to lie beneath the midline of the neural plate, where they assist in the process of neurulation and initiate the dorsoventral patterning of the neural tube through sequential inductive interactions. In the present study, we examined notochord development in avian embryos with quantitative and immunological procedures. Extension of the notochord occurs principally through accretion, that is, the addition of cells to its caudal end, a process that involves considerable cell rearrangement at the notochord‐Hensen's node interface. In addition, cell division and cell rearrangement within the notochord proper contribute to notochord extension. Thus, extension of the notochord occurs in a manner that is significantly different from that of the adjacent, overlying, midline region of the neural plate (i.e., the median hinge‐point region or future floor plate of the neural tube), which as shown in one of the previous studies from our laboratory (Schoenwolf and Alvarez:Development106:427–439, 1989), extends caudally as its cells undergo two rounds of mediolateral cell‐cell intercalation and two‐three rounds of cell division. © 1993 Wiley

ISSN:0003-276X    

DOI:10.1002/ar.1092370107

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

年代:1993

数据来源: WILEY

摘要:

AbstractThe suprachiasmatic nucleus (SCN) is a principal controller of mammalian circadian rhythms. However, in spite of documented disturbance of biological rhythms in old animals, few significant age‐related changes have been observed in this nucleus. This study examined age‐related differences in SCN volume, neuronal number, density, and ultra‐structural features in the entire rat SCN and in its two divisions, the denser ventromedial (compacta) and less dense dorsolateral (dissipata). Light and electron microscopic morphometric techniques were utilized in weanlings (21–28 days), young adults (3–6 mo), and aged (30–36 mo) animals.The total SCN volume, as well as volumes of‐the compacta regions, were significantly greater in young adult and aged rats than in weanlings. Thus, as the rat ages the SCN increases in total size. However, the dissipata region appears to decrease in volume while the compacta increases. Even though the total number of SCN neurons was quite constant in the three age groups, the number of neurons in the dissipata region was decreased significantly in the young adult and aged groups as compared to the weanling.Neurons in the compacta region were usually spindled‐shaped with two dendritic processes, while oval to spheroidal cells with 3–4 processes predominated in the dissipata. Nuclei of SCN cells were often invaginated. In weanlings, more SCN neuronal nuclei had invaginated nuclei in the dissipata region (66%) compared to the compacta (37%). In the two older age groups of rats, a higher percentage of invaginated neuronal nuclei were found in both regions. However, more were still found in the dissipata (90%) compared to the compacta (72%), even though the number of these cells in the compacta doubled. Thus, there was a large increase in the number of invaginated nuclei, as well as the number of invaginations, in the young adult rats compared to the weanling group, and this increase persisted in aged rats.SCN neurons usually had nuclei surrounded by a thin perimeter of cytoplasm containing sparse mitochondria and granular endoplasmic reticulum, multiple Golgi regions, and a moderate number of free ribosomes. In weanlings, mitochondria contained dense cristae and the granular endoplasmic reticulum was relatively prominent. Degenerative ultrastructural changes which included mitochondrial enlargement/vacuolation, Golgi vacuolation, lysosome, and lipofuscin development occurred in less than 10% of young adult SCN cells, and were more frequently found in the dissipata. In aged, rats 30% of the neurons showed degenerative changes in the dissipata compared with 18% in the compacta. Degenerative changes appeared highly correlated with the degree of membrane folding. Ultrastructural degenerative cell changes and light microscopic morphometric observations are discussed in relation to loss of circadian rhythms with advancing age. © 19

ISSN:0003-276X    

DOI:10.1002/ar.1092370108

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

年代:1993

数据来源: WILEY

摘要:

AbstractThe retrograde tracer wheat germ agglutinin‐conjugated horseradish peroxidase was used to establish the organization of the extraocular muscle motoneuron pools in a prosimian,Galago senegalensis, for comparison with the organization in monkeys and non‐primates. Medial rectus motoneurons were distributed in three subgroups in the ipsilateral oculomotor nucleus, a pattern similar to that of the monkey. Furthermore, the other component of the near response system, the preganglionic parasympathetic motoneurons, were confined within the Edinger‐Westphal nucleus, as in the monkey. In contrast, the distribution of the levator palpebrae and superior rectus motoneurons was similar to that of the cat. Specifically, the majority of levator palpebrae motoneurons were located contralaterally, in the caudal central subdivision of the oculomotor nucleus, and the superior rectus motoneurons had a dorsocaudal location in the contralateral oculomotor nucleus. The distributions of motoneurons supplying the superior oblique and lateral rectus muscles were similar to those of other mammals. Unlike previously studied species, the galago was found to have two accessory muscles, that lie beneath the medial and lateral rectus muscles. Motoneurons supplying the accessory rectus muscles were found ventrolateral to the main abducens nucleus, in a position similar to that occupied by the cat accessory abducens nucleus; although others may be present in the main nuclei. Taken together, these results suggest that the organization of extraocular and preganglionic motoneurons in the galago exhibits both monkey and non‐primate features. These observations are consistent with the notion that the galago is a primate species whose oculomotor organization is more similar to the general mammalian scheme. © 1993 Wiley

ISSN:0003-276X    

DOI:10.1002/ar.1092370109

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

年代:1993

数据来源: WILEY

摘要:

AbstractThe quantitative morphological changes in neurons and glia during the aging process were analyzed in the different cortical layers, grouped as I, II–IV, V, and VI, of the frontal cortex of the rat. The parameters analyzed were cortical volume, neuronal density, glial density, and neuronal soma and nucleus areas. No changes with age were found in the volume of the layers, in neuronal density (with the exception of layer I), or in the area of the neuronal soma. However, older animals showed a 10 to 20% increase in glial density, depending on the layer studied. In addition, there was an age‐related decrease in the area of the neuronal nucleus in layers II–IV, V, and VI. These results support the idea that the aging frontal cortex undergoes structural changes that may be involved in the morphological basis of memory and cognitive impairments characteristic of aging. © 1993 Wiley‐L

ISSN:0003-276X    

DOI:10.1002/ar.1092370110

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

年代:1993

数据来源: WILEY

摘要:

AbstractThe cytoarchitectural subdivisions of the nucleus ambiguus of the rabbit and its myotopical and neurotopical representations were investigated with HRP labeling. The nucleus was subdivided into the compact cell group (CoG), the medial and lateral scattered cell groups (SGm and SGl), and the diffuse cell group (DiG). The CoG was formed by esophageal, pharyngeal constrictor, and palatal motoneurons in the rostral half of the nucleus. The SGm and SGl were located medial and lateral to the CoG, respectively, in the rostral one‐third of the nucleus. Stylopharyngeal and cricothyroid motoneurons were located in the most rostral one‐fifth of the SGm and the remaining four‐fifths, respectively, whereas the SGl was not labeled with HRP injections into the palatal, pharyngeal, esophageal, and laryngeal muscles. The DiG was formed by recurrent laryngeal motoneurons in the caudal two‐thirds of the nucleus. Neurons of origin for the glossopharngeal nerve occupied the stylopharyngeal region, with a few of them scattered in the CoG and SGl. Neurons giving rise to axons in the superior laryngeal nerve occupied the cricothyroid region, with a few of them scattered in the pharyngeal constrictor region; whereas the pharyngeal vagal branch originated from the pharyngeal constrictor and palatal regions. Neurons of the DiG, SGl, and esophageal region contributed to the infranodosal vagus nerve; esophageal fibers of the recurrent laryngeal nerve originated from the dorsal esophageal region. Laryngeal fibers of the recurrent laryngeal nerve originated from the DiG, the caudal neurons of which had axons traversing the cranial accessory root. © 1993 Wiley

ISSN:0003-276X    

DOI:10.1002/ar.1092370111

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

年代:1993

数据来源: WILEY