摘要:

AbstractMetamorphic reorganization of the head in anuran amphibians entails abrupt restructuring of the jaw complex as larval feeding structural lM transformed into their adult configurations, In this morphometric study, light microscopy was used to analyze the larval maturation and metamorphic transfiguration of the adductor jaw muscles in the leopard frog (Rana pipiens). Larval jaw muscles, first established during embryogenesis, continue to grow by fiber addition until prometamorphosis, stage XIL Thereafter, fiber number remains stable but additional muscle growth continues by hypertrophy of the individual fibers until metamorphic climax. During metamorphic stages XIX‐XXIII, a complete involution of all larval myofibers occurs. Simultaneously, within the same muscle beds, a second wave of myogenesis produces myoblasts which are the precursors of adult jaw myofibers. New muscle fibers continue to be added to these muscles well after the completion of metamorphosis; however, the total duration of the postmetamorphic myogenic period has not been defined. These observations provide clear evidence that the entire population of primary myofibers used in larval oral activity disappears from the adductor muscle beds and is replaced by a second wave of myogenesis commencing during climax. These findings indicate that the adductor jaw muscles are prepared for adult feeding by a complicated cellular process that retrofits existing muscle beds with a completely new complement of myofiber

ISSN:0002-9106    

DOI:10.1002/aja.1001840102

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

年代:1989

数据来源: WILEY

摘要:

AbstractThe uterine endometrium of menstruating primates (rhesus monkey, human) consists of a germinal basalis that regenerates a transient func‐tionalis during each menstrual cycle. The endometrium is further subdivided into 4 zones that differ histologi‐cally and in epithelial mitotic rate along the longitudinal axes of the uterine glands and microvasculature (Bartelmez et al:Contrib. Embryol. Carnegie Inst., 34:99‐146, 1951; Bartelmez:Am. J. Obstet. GynecoL, 74:931–955,1957; Padykula et al.:Biol. Reprod., 32:1103–1118, 1984;Biol. Reprod., in press, 1988). The zones are defined as follows: functionalis I, luminal epithelium; functionalis II (upper straight gland segments); basalis III (middle gland segments), and basalis IV (bottoms of the glands). The surrounding stroma and microvasculature also differ zonally.Ultrastructural epithelial differences are evident among the 4 zones during 3 distinct functional states during natural menstrual cycles and after ovariectomy: (1) basal level after ovariectomy and (2) estrogen dominance and (3) progesterone dominance. Zonal structural differences persist at a minimal level of differentiation after ovariectomy and thus zonation is an inherent property. During estrogen dominance, distinctive ultra‐structural differences are evident among the 4 zones, such as epithelial cell heterogeneity in functionalis I and homogeneity in functionalis II. Also a distinctive glandular cell type occurs in basalis III and IV that is recognized by a highly irregular cisternal rough endo‐plasmic reticulum that permeates the cytoplasm. During progesterone dominance, ultrastructural differences exist among the 4 zones except for similarity between the epithelial cells of functionalis II and basalis III. Postovulatory epithelial cells of functionalis I and II and basalis III become postmitotic via progesterone inhibition but intracellular differentiation continues progressively. Postovulatory epithelial mitotic activity in basalis IV escapes progesterone inhibition as the [3H]thymidine labeling index continues to increase from 1 to 12% during the menstrual cycle (Padykula et al.:Reprod., 30(Suppl. l).‐92(Abstr. 123), 1984). This post‐ovulatory proliferation coupled with progressive differentiation in basalis IV may represent a stem‐progenitor set of cells for postmenstrual endometrial regeneration or alternatively for creation of th

ISSN:0002-9106    

DOI:10.1002/aja.1001840103

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

年代:1989

数据来源: WILEY

摘要:

AbstractPrevious studies of the intrapulmo‐nary conducting airways of sheep and rabbit have demonstrated marked diversity in the epithelial populations lining them. Because studies of trachea and centriaci‐nar regions of macaque monkeys suggested that primates may be even more diverse, the present study was designed to characterize the epithelial population throughout the airway tree of one primate species, the rhesus monkey. Trachea and intrapulmonary airways of the right cranial and middle lobes of glutaraldehyde/ paraformaldehyde‐infused lungs of five adult rhesus monkeys were microdissected following the axial pathway. Each branch was assigned a binary number indicating its specific location within the tree. The trachea and six generations of intrapulmonary airway from the right cranial lobe were evaluated for ultrastructure and quantitative histology as were those of the right middle lobe for quantitative carbohydrate histochemistry. Four cell types were identified throughout the tree: ciliated, mucous goblet, small mucous granule, and basal. The tallest epithelium lined the trachea; the shortest, the respiratory bronchiole. The most cells per unit length of basement membrane were in proximal intrapulmonary bronchi; the least, in the respiratory bronchiole. The nonciliated bronchiolar epithelial or Clara cell was restricted to respiratory bronchioles. Sulfomucins were present in the vast majority of surface goblet cells in the trachea and proximal bronchi. In proximal bronchi, neutral glycoconjugates predominated in glands and acidic glycoconjugates in surface epithelium. In terminal and respiratory bronchioles the ratio of acidic gly‐coconjugate to neutral glycoconjugate equaled that in proximal bronchi, although glands were not present. Sulfomucins were minimal in terminal airways. We conclude that the characteristics of the epithelial lining of the mammalian tracheobronchial airway tree are very species‐specific. The lining of the rhesus monkey does not have the diversity in cell types in different airway generations observed in sheep and rabbit. Also, the populations lining these airways in the rhesus are very different from either the sheep or rabbit in number, proportions of different cell types, glycoconjugate content, and distribution of specific c

ISSN:0002-9106    

DOI:10.1002/aja.1001840104

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

年代:1989

数据来源: WILEY

摘要:

AbstractLymphoepithelium and cells specialized for uptake and transport of foreign matter are characteristic of antigen sampling organs, Including lymphoglandular complexes (LGCs). Distribution, his‐tologic structure, and epithelial ultrastructure of co‐Ionic lymphoglandular complexes were determined in 5‐ to 13‐week‐old pigs. LGCs averaged 1,231 in number per colon, displayed a characteristic distribution pattern, and were most evenly distributed in colons of older pigs. LGCs consisted of well‐defined submucosal masses composed of lymphatic nodules and internodu‐lar lymphoid tissue penetrated by radially branching extensions of mucosal glands. Epithelial diverticula of each LGC entered the submucosa as a group through a circular collar derived from the muscularis mucosae. LGC epithelium contained goblet cells, cuboidal and columnar enterocytes, enteroendocrine cells, individual and clustered intraepithelial leukocytes, and cells morphologically compatible with follicle‐associated epithelial cells/M cells. We regard the colonic LGC as a distinct mucosal lymphoid organ and suggest a significant role for it in local and systemic immune responses. The porcine colonic LGC may serve as a model fo

ISSN:0002-9106    

DOI:10.1002/aja.1001840105

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

年代:1989

数据来源: WILEY

摘要:

AbstractThe three‐dimensional structure of the components of the Golgi apparatus was analyzed in plasma cells of rat duodenum. The spheroidal juxtanu‐clear Golgi apparatus was formed by a continuous rib‐bonlike structure composed of the following stacked elements. On the cis‐face of the Golgi stack, there was a tubular membranous network referred to as the cis‐element and/or a slightly dilated saccule perforated with small pores. The two or three subjacent saccules, which showed few pores, were slightly dilated and contained a fluffy granulofilamentous material. They were also perforated in register by cavities or wells containing 80‐nm vesicles. The next one or two underlying elements were fenestrated saccules showing flattened portions as well as distended portions containing a homogeneous material denser than that seen in the overlying saccules. The last two or three elements of the stack showed a partially separated or “peeling off” configuration. These last elements consisted of prosecretory granules attached to flattened, empty‐looking saccules showing buds at their surface; detached, more‐or‐less fenestrated, flattened saccules; and shrivelled residual trans‐tubular networks. In the trans‐region of the stack, in addition to numerous small vesicles, short membranous tubules, detached prosecretory granules, and denser fully formed secretion granules were also seen. These images were interpreted to indicate that secretory material present in the trans‐saccules flows toward the dilated portions which become prosecretory granules. The trans‐most elements seemingly peel off the stack to yield prosecretory granules and fragm

ISSN:0002-9106    

DOI:10.1002/aja.1001840106

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

年代:1989

数据来源: WILEY

摘要:

AbstractThe anatomical distribution of intra‐myocardial collateral arteries that develop from the septal to the other major coronary arteries was studied in dogs following gradual Ameroid occlusion of tftt circumflex artery. The septal artery was cannulated and injected with Batson's plastic compound resulting in a cast of the coronary circulation. Collateral vessels radiated from the septal vascular bed to both the circumflex and anterior descending arteries. The collaterals developed from the entire base‐to‐apex extent of the septal artery and were found on both the right and left sides of the septum. Collateral growth appeared to be more concentrated at the apex of the heart. The anatomical details of septal collateral circulation illustrate the importance of intramyocardial collateralization in the dog, which was thought to exhibit primarily epicar‐dial coll

ISSN:0002-9106    

DOI:10.1002/aja.1001840107

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

年代:1989

数据来源: WILEY

摘要:

AbstractThe α and β keratins are found as 10‐nm and 3‐nm cytoplasmic filaments, respectively. While the a keratins are produced in essentially all vertebrate epithelia (Franke et al.:Exp. Cell Res., 116:429‐445, 1978; Sun et ah:Proc. Natl. Acad. Set. USA, 76:2813–2817, 1979), the β keratins have been demonstrated only in specific epithelial tissues of birds and reptiles (Sawyer et ah: In:Biology of the Integument: Vertebrates.J. Bereiter‐Hahn, A.G. Matoltsy, and K, S. Richards, eds. Springer‐Verlag, Berlin, Vol. 2, pp. 194–238,1986; Land‐mann: In:Biology of the Integument: Vertebrates.J. Bereiter‐Hahn, A.G. Matoltsy, and K.S. Richards, eds. Springer‐Verlag, Berlin, Vol. 2, pp. 150–187, 1986). Recently, Homberger and Brush (Zoomorphology, 106:103‐114, 1986) have demonstrated that within the lingual epithelium of parrots, β keratins are expressed exclusively in the anterior ventral region. While it is well established that epidermal‐dermal interactions are important for the regional expression of the β keratin genes in the avian scutate scales and feathers, little is known about the expression of β keratins in other epithelial structures such as the tongue. We have used biochemical and immunocytochemical techniques to analyze the a and β keratins of the lingual epithelium of the chick as an initial step in the characterization of this model system for developmental studies. We have found that α keratins are present throughout the lingual epithelium. The anterior ventral epithelium contains α keratin polypeptides characteristic of skin‐type differentiation, while the epithelium of the dorsal and posterior ventral regions contains α keratin polypeptides characteristic of esophageal‐type differentiation (O'Guin et al.: In:Current Topics in Developmental Biology: The Molecular and Developmental Biology of Keratins.A.A. Moscona and A. Monroy, eds. R.H. Sawyer, vol. ed. Academic Press, New York, Vol. 22, pp. 282–306, 1987). Beta keratins are produced only in the differentiated epithelial cells of the anterior ventral region of the tongue. Immunoelectron microscopy demonstrates that the α and β keratins of the stratum intermedium and corneum of the anterior ventral region are found together in the large filament bundles characteristic of this region. The preexistence of the α keratins in the cells destined to produce β keratins as well as the colocalization of these keratins in the filament bundles of these cells suggests that a functional relatio

ISSN:0002-9106    

DOI:10.1002/aja.1001840108

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

年代:1989

数据来源: WILEY

摘要:

AbstractGlycoconjugates, particularly their sugar side chains, play important roles in embryonic development. Changes in cell‐surface‐associated glyco‐conjugates are known to affect cell differentiation, cellular interactions, and other developmental phenomena during embryogenesis. The embryonic heart goes through a series of complicated morphologic events during development. Of particular interest is morphogenesis of the outflow tract. This region of the embryonic heart originates from more than one cell population and undergoes a complex process of septation during formation of the great vessels. Histochemi‐cal analysis with a series of fucose‐specific lectins conjugated to horseradish peroxidase has revealed the presence of a fucosylated glycoconjugate in the outflow tract of the developing heart. The results reveal further that the expression of the fucosylated glycoconjugate is stage‐dependent and thus probably genetically regulated. The timing and distribution of staining with the lectin OFA suggest that this fucosylated glycocoiyu‐gate may play a role in directing the migration of neural crest cells into the heart and subsequent formation of the

ISSN:0002-9106    

DOI:10.1002/aja.1001840109

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

年代:1989

数据来源: WILEY

摘要:

AbstractRat embryos at days 10‐18 of gestation and chicken embryos at days 3‐6 of incubation were fixed and processed for lectin histochemistry. The distribution of binding sites for a lectin from the peanutArachis hypogaea(PNA) conjugated to horseradish per‐oxidase (HRP) was determined on tissue sections both before and after enzymatic cleavage of sialic acid with neuraminidase (sialidase). Endocardial cushion tissue in the rat, but not in the chick, reacted with PNA‐HRP prior to digestion with sialidase. Endocardium of both species (12 and 13 days in rat, 5 and 6 days in chick), particularly at the level of endocardial cushions, reacted strongly with the sialidase‐PNA sequence; this staining decreased markedly after day 14 of gestation in the rat. PNA binding sites capped by sialic acid were most abundant in the developing rat heart during the critical period of endocardial cushion formation and decreased as development proceeded. The marked changes in the appearance and distribution of cardiac cell and tissue glycoconjugates during cardiogenesis support the concept that rapid changes occur in the structure of complex carbohydrates during embryonic and fetal development. The findings also suggest that such glycosylation‐related events may be speci

ISSN:0002-9106    

DOI:10.1002/aja.1001840110

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

年代:1989

数据来源: WILEY

ISSN:0002-9106    

DOI:10.1002/aja.1001840101

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

年代:1989

数据来源: WILEY