摘要:

AbstractA study was undertaken to analyze the ultrastructural aspects and the enzyme acid phosphatase cytochemistry and biochemistry of the pathogenesis of cyclophosphamide (CP)‐induced cleft palate in hamster fetuses. The initial CP‐induced alterations were the appearance of lysosomes in the mesenchymal cells of the vertically developing palatal primordia within 8 hr of drug administration. The mesenchymal lysosomal activity, which increased during the next 16 hr, was abnormal and interpreted as a sub‐lethal response to CP treatment. Subsequently, the lysosomal activity in the mesenchyme diminished gradually and, 48 hr after CP treatment, was absent. At this time, lysosomes were seen in the epithelial cells of the vertical palate. Fifty‐six hours after CP treatment, unlike controls where palatal shelves were already fused, lysosomal activity subsided in the epithelial cells. Changes, however, continued to be seen at the epithelial‐mesenchymal interface. These changes were characterized by discontinuity in the basal lamina, and by epithelial‐mesenchymal contacts. They persisted for 8 hr but were absent thereafter. Sixty‐four hours after CP administration, the vertical shelves became horizontal and remained so until term. Following analysis of data, both from the literature and from the present study, it was suggested that CP first affected mesenchymal cell proliferation, and then its cytodifferentiation, during the critical phase of early vertical development; consequently the reorientation of the shelves to a horizontal plane was delayed, inducing

ISSN:0002-9106    

DOI:10.1002/aja.1001870102

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

年代:1990

数据来源: WILEY

摘要:

AbstractThree different types of lingual papilla were observed by scanning electron microscopy on the dorsal lingual epithelium of the lizardGekko japonicus. Dome‐shaped lingual papillae were located at the apex. Flat, fan‐shaped lingual papillae were seen in the widest area of the lingual body. Long, scale‐like lingual papillae were arranged on the latero‐posterior dorsal surface. At higher magnification, microvilli and microridges were seen to be widely distributed over the surface of the papillae. By light microscopy, the epithelium of the dome‐shaped papillae was composed of single, columnar epithelial cells filled with secretory granules. The tip of the epithelium of the fan‐shaped and scale‐like papillae was composed of stratified squamous epithelial cells without granules. The major part of the epithelium of these two types of papilla, except the tip area, was also composed of single, columnar epithelial cells with secretory granules. By transmission electron microscopy, a nucleus without a defined shape was seen to be located in the basal part of each of the single, columnar epithelial cells. Rough‐surfaced endoplasmic reticulum and Golgi apparatus were well developed around the nucleus. The other, major part of the cytoplasm was filled with the spherical secretory granules, a large number of which had very electron‐dense cores and moderately electron‐dense peripheral regions. In the stratified squamous epithelium, a nucleus, which tended to be condensed on the free‐surface side, was located in the center of each cell. Mitochondria, endoplasmic reticulum, and vesicles were obse

ISSN:0002-9106    

DOI:10.1002/aja.1001870103

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

年代:1990

数据来源: WILEY

摘要:

AbstractIn order to elucidate the functional significance of accessory cells in freshwater fishes, such as the rainbow trout, which displays a poor adaptability to seawater life, a search for such cells was performed in two stenohaline freshwater fishes: the loach and the gudgeon. Accessory cells were never encountered in these species; but, in contrast, two types of chloride cells were observed consistently that strikingly resembled the α‐ and β‐cells previously described in the guppy, a freshwater‐adapted euryhaline fish. The α‐cell, a pale and elongated chloride cell, was located at the base of the secondary lamellae in close contact with the arterioarterial pillar capillary. Darker, ovoid chloride cells resembling the β‐cell were found exclusively in the interlamellar region of the primary epithelium facing the central venous sinous. The latter cells frequently formed multicellular complexes linked together by deep, narrow, apical junctions.In another experiment, a stenohaline seawater fish, the turbot, was adapted to diluted 5% saltwater and to fresh water. In seawater, the gill epithelium contained only one type of chloride cell, always associated with accessory cells. Due to numerous cytoplasmic interdigitations between the accessory cells and the apical portion of the chloride cell, there was a noticeable increase in the length of the shallow apical junction, sealing off the intercellular space between the two cell types. In 5% saltwater, there was a decrease in the number of these interdigitations and a concomitant decrease in the length of the shallow apical junction. In fresh water, chloride cells were partially or completely separated from the outside medium by modified accessory cells.It is thus concluded that accessory cells are found exclusively in fish living in seawater or preadapted to seawater and that they probably are involved in the formation and modulation of paracellular pathways for ionic excretion. In contrast, the respective roles of the two types of chloride cells observed in freshwater fishes are still to

ISSN:0002-9106    

DOI:10.1002/aja.1001870104

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

年代:1990

数据来源: WILEY

摘要:

AbstractMale adult (200‐day‐old) Chinese hamsters (Cricetulus griseus) raised from weaning under either LD 16:8 or LD 8:16 were used. The pineal gland of the Chinese hamster consists of superficial (major) and deep (minor) components and a continuous, or interrupted, narrow parenchymal stalk interposed between them. The volume of the superficial pineal including the parenchymal stalk is greater under LD 16:8 than under LD 8:16. Under both photoperiods, pinealocytes in the superficial pineal have larger nuclei and more abundant cytoplasm than those in the deep pineal. Nuclei in the superficial pineal appear pale and usually have irregular profiles, whereas those in the deep pineal appear dark and have round profiles. In the superficial pineal, pinealocyte nuclei are larger, paler, and more irregular; and, in addition, nuclear density is lower under LD 16:8 than under LD 8:16. Similar, but less prominent, photoperiod‐induced changes occur in the volume of the deep pineal, the size of pinealocytes, and pinealocyte nuclear morphology in the deep pineal. The results indicate that the development and differentiation of pinealocytes in both pineal portions may be advanced under long photoperiods and delayed under short photoperiods, although pinealocytes in the deep pineal may remain not fully differentiated even in adults. Since testicular weights and body weights are similar under both photoperiods, the photoperiod may exert marked influences on the development of the pineal gland without affecting reproductive activity and growth rates of an

ISSN:0002-9106    

DOI:10.1002/aja.1001870105

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

年代:1990

数据来源: WILEY

摘要:

AbstractPineal “synaptic” ribbons are a heterogeneous population of organelles. “Synaptic” ribbons (SR) sensu stricto, “synaptic” spherules (SS), and intermediate forms (IMF) are present. Their function and origin are unknown, and a knowledge of their prenatal development is lacking. Thus the pineal glands of prenatal, neonatal, and adult guinea pigs were prepared for electron microscopy. “Synaptic” ribbons were studied morphologically and quantitatively. The three categories of “synaptic” ribbons reported in adult pineal glands were also present in prenatal pineal glands. Their structural features, distribution, grouping, and composition patterns are similar to those in adults. “Synaptic” ribbons were first detected in pinealocytes of the distal region of a 42‐day postcoitus (PC) pineal gland and were comparable with those in adults. They increased in number with age and reached a peak at 63 days PC, followed by a steep decline at 66 and 67 days PC. By day 69 PC, the numbers increased again and showed a dramatic increase after birth. Several true ribbon synapses were seen at day 63 PC between pinealocyte cell processes or between pinealocyte cell process and pinealocyte cell body. Since true ribbon synapses have not been found in adult guinea pig pinealocytes, their synaptic nature could have been lost during development. No precursors for the “synaptic” ribbons were found. The endoplasmic reticulum cisternae may be the origin for the ribbon vesicles because of their close associatio

ISSN:0002-9106    

DOI:10.1002/aja.1001870106

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

年代:1990

数据来源: WILEY

摘要:

AbstractCarbonic anhydrase (CA) III was demonstrated immunocytochemically in epithelium in some regions of salivary gland ducts, colon, bronchi, and male genital tract and in adipocytes, in addition to skeletal muscle and liver where the isozyme was previously localized. Basal cells beneath the submandibular gland's excretory ducts in guinea pig stained for CA III. Carbonic anhydrase III occurred alone in some and with CA II in other sites but was often absent from CA‐II‐containing types of cells. This was exemplified by CA III's abundance in CA‐II‐positive proximal colon and its sparsity in the CA‐II‐rich distal colon of the mouse. Striated ducts in guinea pig, but not mouse salivary glands, stained darker for CA and appeared accordingly to function more actively in ion transport compared with excretory ducts. Carbonic anhydrase content varied among genera in liver and pancreas and between mouse species and strains in salivary glands and kidney. Newly observed murine sites of CA II activity included Auerbach's plexus and a population of leukocytes infiltrating the lamina propria in small intestine, and several types of cells in the male genital tract. In immunoblot tests, antisera to CA III showed no cross reactivity with antisera to CA II, but those to CA II disclosed weak cross reactivity

ISSN:0002-9106    

DOI:10.1002/aja.1001870107

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

年代:1990

数据来源: WILEY

摘要:

AbstractDevelopment of the trigeminal nerve branches was studied in stage ‐17 to ‐27 chick embryos stained with an antibody to neurofilament protein. The following findings were obtained. (1) Ectopic ganglia transiently appeared in the ectoderm of the supraorbital region and were considered as remnant ophthalmic‐placode‐derived ganglia. (2) Most of the cutaneous sensory branches of the maxillomandibular nerve arose from a loosely arborized mass of neurites, provisionally termed themaxillomandibular reticulum, in which the fibers intermingled in a seemingly random fashion. (3) The growth of the trigeminal branches was mainly correlated with the development of the facial processes; however, irregular communications between different groups of branches were observed, suggesting that topographical organization of the peripheral branches is not rigid in early stages. (4) From the ophthalmic nerve around stage 23, transient dorsal rami developed and were distributed in the mesenchymal space, the cavum epiptericum, and passed near the ectoderm. Their homology with the rr. tentorii in human anatomy is su

ISSN:0002-9106    

DOI:10.1002/aja.1001870108

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

年代:1990

数据来源: WILEY

摘要:

AbstractOviducts were obtained from a series of cycling and ovariectomized steroidtreated baboons. The lining epithelium of the ampulla and isthmus was analyzed by light and electron microscopy. Both morphological and cytomorphometric analyses revealed that the morphological and functional state of the oviductal epithelium in the baboon is controlled by the ovarian steroids. Additionally, a clear cephalocaudal steroid‐responsive gradient was observed when the data from the ampulla and isthmus of the same animal were compared. Within the ampulla, estradiol induced hypertrophy, hyperplasia, ciliogenesis, and secretory activity, whereas adding progesterone to the treatment regimen (± estradiol) resulted in atrophy, deciliation, apoptosis, and loss of the secretory activity. These cyclic processes were less evident in the isthmus. We also used an indirect electron microscopic immunogold technique and a previously characterized polyclonal antibody to determine the localization of oviduct‐specific glycoproteins. These glycoproteins were present in every secretory granule observed, regardless of oviduct region, electron density, or size of the secretory granule. In summary, our data show that (1) estradiol induces and maintains the mature epithelium of the baboon oviduct, (2) steroid withdrawal or the administration of progesterone causes regression of the epithelium, and (3) the previously identified estradiol‐dependent oviduct‐specific glycoproteins are synthesized within and released from the secretory epitheli

ISSN:0002-9106    

DOI:10.1002/aja.1001870109

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

年代:1990

数据来源: WILEY

摘要:

AbstractAlteration of tooth function is assumed to change stress/strain on the adjacent alveolar bone and its mucoperiosteum, producing changes in morphology similar to those described for other load‐bearing bones. The present study suggested that crestal alveolar bone and its mucoperiosteum respond differently to stress/strain than load‐bearing bones in other locations, possibly due to differences in the mechanism of bone loading by muscles and teeth. Occlusal hypofunction was initiated by extraction of agonist teeth; the contralateral teeth were placed in hyperfunction by the surgery. Untreated animals were also studied.3H‐proline was injected, animals were killed 1–5 weeks later, and the thicknesses of new bone and transseptal ligament were measured. After 5 weeks of altered function, total thickness (new bone + transseptal ligament) was similar in untreated and in hypofunctional and hyperfunctional situations; however, a new ratio between transseptal ligament and new bone thicknesses was established. Occlusal force was negatively correlated with new bone and positively correlated with transseptal ligament thickness; both thicknesses were statistically correlated in each functional situation (P<0.001). Hyperfunction resulted in increased transseptal ligament thickness, but decreased new bone thickness as compared to untreated controls (P<0.001). In contrast, hypofunction resulted in an increased new bone thickness, but a decreased transseptal ligament thickness (P<0.001). Tissue responses assure appropriate support for the teeth in each functional si

ISSN:0002-9106    

DOI:10.1002/aja.1001870110

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

年代:1990

数据来源: WILEY

摘要:

AbstractThe brain cooling capacity of the altricial pigeon increases during posthatching growth at a higher rate than that of the precocial duck and chicken. To determine if this difference between the altricial and the precocial modes of development can be related to growth rates of the vascular heat exchanger involved in brain cooling (the ophthalmic rete), we performed a morphometric analysis of this structure during the posthatching maturation of the three species. The number of vascular units in the rete did not change during development but differed significantly among species. The retia continued to grow in length and diameter in an exponential relation with body mass at similar rates in all species. The surface area of the retial arteries, which reflects the area available for countercurrent heat exchange, also increased exponentially with body mass, but without significant differences among the three species. However, the effectiveness of the rete in brain cooling, as indicated by the degree of brain cooling per unit of heat‐exchange area in the rete, was higher in the altricial pigeon than in the precocial chicken and duck. It is concluded that the posthatching morphometric changes in the ophthalmic rete (rete ophthalmicum) are important for the development of brain cooling capacity, but cannot solely explain differences in brain cooling between growing altricial and precocial birds. These differences are most likely related to differences in the maturation of the central thermoregulatory control system and the peripheral effector mechanisms among the two groups of bird

ISSN:0002-9106    

DOI:10.1002/aja.1001870111

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

年代:1990

数据来源: WILEY