摘要:

AbstractTo study the fetal morphogenesis of the lateral nasal wall and nasal conchae as well as the initial development of the paranasal sinuses, 15 specimens were investigated. Their crown‐rump lengths ranged from 25 to 263 mm. The specimens were fixed in Bouin's solution. Serial sections were stained with hematoxylin and eosin, and Mallory's trichrome stain. The objectives were to ascertain the time and course of development of: (1) ossification in the maxilla and palate, (2) formation of the nasal capsule and the conchae, (3) chondrification and ossification in the nasal capsule and conchae, (4) the maxillary sinus and ethmoidal cells, and (5) glands in the respiratory mucosa. The earliest appearance of the conchae was observed in a 25 mm CR fetus. In a 32 mm CR fetus, ossification in the maxilla and palate was begun and the first maxillary sinus primordium was observed. The glands associated with the maxillary sinus and the inferior concha developed in a 49 mm and in a 90 mm CR fetus, respectively. The ethmoid and three conchae started to ossify in a 160 mm CR fetus. It was concluded that the transformation of mesenchyme into the bony skeleton was accomplished in a 263 mm CR fetus. Both groups of paranasal sinuses and the respiratory glands in the 263 mm CR fetus were morphologically well differentiated. In addition to an extensive survey of the literature, the possible role of the mucosal glands in development of the paranasal system was discusse

ISSN:0002-9106    

DOI:10.1002/aja.1001300202

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

年代:1971

数据来源: WILEY

摘要:

AbstractThe ultrastructure and cytochemistry of the Golgi apparatus was studied in acinar cells of the parotid and von Ebner's glands of the rat. The Golgi apparatus was composed of four to six stacked cisternae, numerous small vesicles, and condensing vacuoles. The latter appeared to form as dilatations of the innermost Golgi cisterna, and their irregular membrane suggested fusion with or fission of small vesicles. Nucleoside diphosphatase and thiamine pyrophosphatase activities were localized to the inner Golgi cisternae. Acid phosphatase activity was localized to condensing vacuoles, coated vesicles, and an irregular, narrow cisterna found in the internal region of the Golgi apparatus and termed the internal Golgi lamella. The morphology and relationships of the Golgi apparatus indicate that it plays an important role in secretory granule formation. The presence of nucleoside diphosphatase activity may reflect the role of the Golgi apparatus in the addition of carbohydrates to the secretory proteins. It is suggested that the internal Golgi lamella develops from the inner Golgi cisterna after secretory granule formation is completed. Acid phosphatase activity in condensing vacuoles may be a mechanism for lysosomal regulation of the secretory process.

ISSN:0002-9106    

DOI:10.1002/aja.1001300203

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

年代:1971

数据来源: WILEY

摘要:

AbstractThe affinities of the isolated rodent family Anomaluridae are unknown. Both sciuromorphous and specialized features characterize its placental morphology. A shallow preplacenta consists of inner cytotrophoblastic and outer syncytiotrophoblastic layers. The early chorio‐allantoic placenta consists of the following zones: a hemochorial zone of interconnected trabeculae, lined with outer syncytiotrophoblastic and inner cytotrophoblastic layers; anchoring trabeculae attached to a zone of decidual giant cells, with the giant cells gradually disappearing in later stages; a zone of acidophilic, PAS‐positive necrotic material underlying the giant cells; and a zone of decidua basalis underlying the necrotic zone and probably contributing to it. An allantoic vesicle lies on the surface of the early placenta; it is reduced in later stages. The bilaminar omphalopleure persists, and it is attached to the margins of the placental disc. The fetal membranes ofAnomalurusare most similar to those of sciuromorphs,PedetesandCtenodactylus; this may be the result of primitive retenti

ISSN:0002-9106    

DOI:10.1002/aja.1001300204

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

年代:1971

数据来源: WILEY

摘要:

AbstractDuring development and maturation of skin and its derivatives, bundles of extracellular filamentous elements appear, which traverse a cross section of dorsal skin from deep mesenchyme to the basal lamina of the dermo‐epidermal junction. Observations on freshly fixed tissue and on pieces of skin grown in culture for three to five days, especially in areas where the presence of anchor filaments could be predicted, indicate that the filaments most likely originate from fibroblasts which are usually located in a stratified layer of the deeper mesenchyme. The distal end, or termination, appears to be the basal lamina into which the anchor filament blends and is dispersed.The anchor bundles are composed of long thin filaments in close aggregation and they demonstrate cross‐striations separated by approximately 400 Å in the midportions, and up to 600 Å near their origin and termination. The diameters of the bundles average approximately 0.33 μ at their thickest part. However, at or near their origin, they measure 0.2 μ or less in diameter.The analogy of the filaments to a growing tree is suggested in that, the roots, or origins of the filaments are thin, tortuous and in many cases widely separated. In certain areas they converge into one main trunk which tapers toward their termination in the basal lamina. The observations also suggest that some bundles may have several roots or rootlets, while others have only one or two.Although collagen is often seen close to the bundles, the data indicate that the latter are distinct from, and not derived from c

ISSN:0002-9106    

DOI:10.1002/aja.1001300205

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

年代:1971

数据来源: WILEY

摘要:

AbstractA wedge of parenchymal tissue was excised from the left submandibular gland of six week old male Sprague‐Dawley rats. The animals were randomly grouped by body weight and killed at intervals of one day to five weeks following the operation. Tissue from and adjacent to the site of injury was removed and prepared for routine light and electron microscopy. Light microscopic findings consisted of degeneration and necrosis of the parenchymal tissue during the first 24 hours, followed by hyperemia and endothelial as well as epithelial proliferation from one to three days. Extensive epithelial proliferation occurred during the next two weeks, followed by regeneration of new lobules, beginning at the periphery of the injured lobes.Ultrastructurally, the new parenchymal tissue appeared to have regenerated from residual duct cells. Dedifferentiated epithelial cells gave rise to two different cell lines: one line which transformed into terminal tubules and acinar cells, and another which became striated ducts. These differentiating cells were organizing into lobules as early as three weeks after the operation. Because of their proximity to cells of regenerating striated ducts as well as intercalated ducts and acini, the myoepithelial cells appeared to be of epithelial origi

ISSN:0002-9106    

DOI:10.1002/aja.1001300206

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

年代:1971

数据来源: WILEY

摘要:

AbstractMorphological changes in mouse eggs due to aging become evident after the eggs have spent approximately 12 hours in the oviduct. The spindle rotates at first and is radially disposed. Later the entire spindle migrates to the center of the egg. In most eggs the spindle is maintained throughout the first 24 hours after ovulation. In some eggs a nucleus is reconstituted without formation of polar body II. Other eggs break into several cytoplasmic fragments but a nucleus is seen only in the largest fragment. The cortical granules lose their proximity to the cell membrane, migrate centrad and frequently swell. The cumulus cells and the cells of the corona radiata degenerate and/or disperse.

ISSN:0002-9106    

DOI:10.1002/aja.1001300207

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

年代:1971

数据来源: WILEY

摘要:

AbstractAlbino rats kept at normal body and room temperature develop a progressive retinal degeneration when exposed to ordinary animal room intensities of fluorescent light. Early changes at the light microscope level include stratification of the inner and outer segments of the receptor cells, followed by rapid fragmentation of these elements. Concurrently, cells not usually seen in control retinas invade the outer plexiform and receptor cell layers. These cells, which are first seen after 60 hours of light exposure, resemble microglia and are apparently phagocytic in function, since cytoplasmic inclusions can be detected. Attempts to mark these cells with intraocular India ink or with intraperitoneal trypan blue were unsuccessful. Removal of cellular debris after degeneration of the receptor cells was followed by gliosis in the area of the retina between the bipolar nuclei and the remnants of the pigment cell layer. The extensive retinal damage occurring after fragmentation and removal of the outer segments was irreversible when animals were removed from continuous light and placed into cyclic lighting.

ISSN:0002-9106    

DOI:10.1002/aja.1001300208

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

年代:1971

数据来源: WILEY

摘要:

AbstractA study of the development of the subarcuate fossa and its relationships to the semicircular canals and to the paraflocculus was made in the rat. Specimens ranging from 12‐day embryos through 31 days after birth and adults were used for dissection and microscopic studies.Two distinct steps are identified in the development of the fossa. First preceded by the differentiation of the semicircular canals, a primitive subarcuate fossa, which is completely filled with loose vascularized connective tissue, develops in the periotic capsule. Second, the primitive dura mater of the posterior cranial fossa evaginates into the area of the primitive fossa displacing the loose connective tissue contained therein, to form a laterally projecting cavity from the posterior cranial fossa, the definitive subarcuate fossa. Thus, the primitive subarcuate fossa appears passively as a product of the pattern of development of the periotic capsule.The paraflocculus of the cerebellum does not appear to influence the development of the definitive subarcuate fossa since it secondarily occupies the area of the fossa. The pedunculated nature of the paraflocculus is associated with, and probably results from, the diameter of the ostium of the fossa being smaller than its greatest width.A comparison is made of the development of the subarcuate fossa within the periotic capsule in the rat and man. In the adult rat a definitive subarcuate fossa is present, while in adult man only a rudimentary counterpart exist

ISSN:0002-9106    

DOI:10.1002/aja.1001300209

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

年代:1971

数据来源: WILEY

ISSN:0002-9106    

DOI:10.1002/aja.1001300201

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

年代:1971

数据来源: WILEY