摘要:

AbstractA systematic electron microscopic study was made of the structure of foveal cones of Macaca spp. Transverse sections of inner (IS) and outer segments (OS) were made in sequence, from the pigment epithelial zone (PEZ) to the outer limiting membrane (OLM). The smallest diameters of hundreds of cone sections were measured from electron micrographs with a Zeiss particlesize analyzer, and analyzed statistically. Some details are also included about Cebus photoreceptors.It is claimed in the literature that foveal cones are rod‐like (cylindrical) and untapered. Our study shows the foveolar cone to be a tapered structure.There has been some confusion between the foveola, which is rod‐free, and the fovea, which has a high concentration of cones, but is not rod‐free. Within the fovea, as the ratio of cones to rods falls from ∞ to 1, with distance from the central bouquet of cones, the cone center‐to‐center distances increase, the inner segment diameters increase, and the number of cones/sq mm decreases.The tapered calycal processes are more massive in M. irus than M. mulatta, and the lateral fins are better developed. Lateral fins are not present in the foveola.The cones are arranged in str

ISSN:0002-9106    

DOI:10.1002/aja.1001590202

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

年代:1980

数据来源: WILEY

摘要:

AbstractPrevious investigations in this laboratory have shown the flexor carpi radialis muscle (FCR) of the cat to be compartmentalized with regard to the distribution of muscle fiber types. This study was undertaken to determine whether each compartment of the FCR had a distinct motor innervation band, or whether there was only one innervation band, as has been reported previously for other muscles. In order to assess variation in motor innervation banding patterns, the innervation bands were correlated with the muscle‐tendon architecture. Each compartment of the FCR possessed a distinct innervation band. In addition, it was observed that the nerve to the FCR divided into a number of separate intramuscular branches which were distributed to the different histochemical compartments. It is possible that muscle fibers innervated by a single intramuscular nerve branch, and possessing a discrete innervation band, are locally organized within subdivisions of the FCR. It is hypothesized that the compartmental organization of the FCR would allow discrete regions of the muscle to function independently when performing different motor task

ISSN:0002-9106    

DOI:10.1002/aja.1001590203

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

年代:1980

数据来源: WILEY

摘要:

AbstractFollicle‐associated epithelium (FAE) from the mouse Peyer's patch consists of a dome part containing goblet as well as columnar epithelial cells and a crypt part, containing Paneth as well as goblet and undifferentiated epithelial cells. The proportions of columnar epithelial, goblet and Paneth cells in the FAE are similar to those found in normal crypt/villus complexes. Mitosis is confined to the crypts of the FAE. The cell‐renewal time for FAE columnar epithelial cells, estimated from experiments using tritiated thymidine, is approximately 60 hours. Large numbers of lymphoid cells are also present in the FAE, particularly in regions distal to the crypts. The similarity between follicle‐associated and villus epithelial structure is discussed, together with its possible relevance to “M” cell formation withi

ISSN:0002-9106    

DOI:10.1002/aja.1001590204

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

年代:1980

数据来源: WILEY

摘要:

AbstractThe distribution of “M” cells within the follicle‐associated epithelium (FAE) of mouse Peyer's patches has been estimated from a series of SEM micrographs. “M” cells are found generally to be distributed evenly throughout the higher regions of the FAE. The frequency with which “M” cells occur decreases in the lower regions of the FAE. No “M” cells are found in the follicle‐associated crypts. “M” cell microvilli are longer than those of enterocytes found at the base of the follicle‐associated crypts and shorter than those found on enterocytes in other parts of the FAE.No lymphoid cells occur within the epithelium of the follicle‐associated crypt. Lymphoid cells in the higher regions of the FAE are associated closely with “M” cells. There is, in the lower regions of the FAE, a transitional zone where lymphoid cells occur both free within the epithelium and closely associated with “M” cells. It is suggested that an initial close association of lymphoid cells with young, fully differentiated enterocytes is responsible for the latter's sub

ISSN:0002-9106    

DOI:10.1002/aja.1001590205

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

年代:1980

数据来源: WILEY

摘要:

AbstractThe effects of the administration of thyroxine (T4) and/or testosterone (TP) on the early postnatal differentiation of granular convoluted tubule (GCT) cells of the submandibular glands were studied in Swiss‐Webster mice. From birth, mice were injected daily with T4up to the time of killing at 15 or 20 days of age. In addition, groups of mice were given one injection of TP eight days before killing. Control animals received vehicles (saline and/or sesame oil). Sections of the glands were stained with toluidine blue, or immunocytochemically by the unlabelled antibody enzyme method, for the localization of protease A, epidermal growth factor, or renin. Supernatants of the gland were analyzed for protease activity (pH 8.5, substrate: tosyl‐glyclyl‐L‐prolyl‐L‐arginine nitroanilide acetate), or by radioimmunoassay for EGF content. At 15 days of age no GCT cells were present in the glands of control or TP‐treated mice. In T4‐injected mice many small GCT cells occurred, while larger and more numerous GCT cells were seen in the glands of mice that received both hormones. TP alone had no effect on levels of EGF or protease activity. In T4‐treated mice, protease levels increased 10‐fold and EGF content rose 28‐fold. TP administration to T4‐treated mice caused a further threefold, increase in both protease activity and EGF content. At 20 days of age the glands of control mice had a few small GCT cells, and both protease activity and EGF content were substantially increased. TP treatment was again without effect. However, daily injections of T4caused both protease activity and EGF levels to increase 20‐ and 11‐fold, respectively. Just as in 15‐day‐old mice, TP administration to T4‐primed mice resulted in further increases in the two polypeptides. Immunocytochemical staining for protease A and EGF confirmed the chemical data. Renin was detectable immunocytochemically at both ages in the glands of mice that had received T4, but it was seen in the glands of mice that had received TP alone only at 20 days of age. It is concluded that T4caused a precocious induction of GCT cells and their specific products. Although TP alone had no effect on their early differentiation, it acted synergistically with T4in inducing GCT cells. There were no obvious sex differences in any of these featu

ISSN:0002-9106    

DOI:10.1002/aja.1001590206

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

年代:1980

数据来源: WILEY

摘要:

AbstractThe ultrastructure of the epidermal cells which migrate over the wound surface of the amputated limb of the adult newt,Notophthalmus viridescens, was observed with transmission (TEM) and scanning (SEM) electron microscopy. In order to aid in the visualization of polyanionic surface materials on the wound epithelium and wound surface with TEM, the basic dye, ruthenium red, was introduced into the fixatives and buffer. Control limbs were processed without ruthenium red. Shortly after amputation, basal cells at the wound margin possessed elongated, flattened profiles with long pseudopodial projections (lamellipodia and filopodia) that appeared to make contact with the fibrin exudate covering the stump tissues. Epidermal cells proximal to the site of amputation were also in a state of mobilization. Large intercellular spaces and a reduction in the number of desmosomes were observed in the migrating cells. Epidermal cell nuclei became characteristically euchromatic with well‐developed nucleoli. Microfilaments were seen within the cytoplasm, extending toward the plasma membrane of cellular processes. Phagocytosed material was also present in the migrating cells. By approximately 9 hours post‐amputation, wound closure was complete, and the wound epithelium consisted of three to four cell layers of a non‐cornified epidermis. Generally, the amount of extracellular material present on the surface and in the enlarged intercellular spaces of migrating epidermal cells remained the same throughout the period of wound closure. A layer of polyanionic material was observed consistently over the fibrin meshwork covering the wound surface wit

ISSN:0002-9106    

DOI:10.1002/aja.1001590207

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

年代:1980

数据来源: WILEY

摘要:

AbstractThe structure and development of the female reproductive tract, fetal membranes and placenta have not previously been recorded for any member of the family Thyropteridae. Recently implanted embryos were obtained in late January, limb‐bud stages in March, and full‐term fetuses in late May, suggesting a possible gestation length of approximately five months. It is likely, however, thatThyropteraexperiences at least two breeding cycles per year. The uterus was narrowly bicornuate; the corpus uteri was unusually large and lacked the glandular density observed in the cornua. The cervix was long, pleated, and relatively aglandular. The oviducts opened at the apices of the cornua; oviductal papillae were absent. A bursa ovarii surrounded the ovary, but there was a small pore opening to the peritoneal cavity adjacent to the fimbriated end of the oviduct. Never more than a single embyro or fetus was present, and only a single corpus luteum was observed; thusThyroptera, like most bats, is monovular. Ovoimplantation was interstitial; a decidua capsularis was present early but disappeared by the late limb‐bud stage. The decidual reaction involved both glandular epithelium and stromal cells, but most of the decidua was destroyed by term. Amniogenesis was initiated after implantation, by cavitation. Primitive entoderm was formed precociously above, as well as below, the presumptive embryonic disc, and a thin extension of Reichert's membrane passed over the cell mass, separating it from the cytotrophoblast of the chorionic placenta. During the amniogenic period, the yolk‐sac entoderm fused to the parietal trophoblast via an intervening Reichert's membrane, forming an extensive bilaminar omphalopleure; this was rapidly converted to a trilaminar structure in early post‐implantation stages. An avascular chorio‐vitelline relationship involved most of the chorionic wall in early post‐implantation stages and persisted to term in the abembryonic hemisphere after the partial inversion of the yolk‐sac roof in late presomite embryos. The invaginated yolk‐sac roof (splanchnopleure) also persisted to term as a viable paraplacental component. A small sac‐like allantois was formed between late pre‐somite and early limb‐bud stages but disappeared by the late limb‐bud stage. Development of the definitive chorioallantoic placenta resembled that in other bats, but the maternal endothelium disappeared relatively early, and trophoblastic differentiation was precocious. The ultrastructural organization of the interhemal membrane was hemodichorial, and otherwise generally resembled the organization previously described in vespertilionid bats. Similarities and differences in the structure of the uterus, placenta, and paraplacental organs of Thyropteridae, in comparison with other families of bats, are discussed. On the basis of fetal membrane characteristics, the Thyropteridae show closer affinities with the Phyllostomatoidea than with the Vespertilionoidea, to which th

ISSN:0002-9106    

DOI:10.1002/aja.1001590208

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

年代:1980

数据来源: WILEY

ISSN:0002-9106    

DOI:10.1002/aja.1001590209

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

年代:1980

数据来源: WILEY