摘要:

AbstractOvariectomized mice were given estrogen and progesterone either independently, or simultaneously, or in sequence. Thymidine‐H3was also injected, and the tissues were radioautographed. Analysis of modulation and differentiation was based on the morphological changes seen in cell populations identified by the presence or absence of radioactive nuclei. Estrogen induced cells newly formed in the basal layer to differentiate into a stratified squamous, keratinizing epithelium but did not convert the slowly proliferating surface cells. Progesterone accelerated basal cell proliferation, although this effect was expressed about a day later than when estrogen was used. When both hormones were used in succession, neither could do more than modify the appearance of the cells produced under the influence of the other hormone. However, either hormone could cause proliferation, migration and differentiation of cells from the same basal cells that had previously been the source of cells induced to differentiate by the other hormone. Therefore, the same basal cells can give rise to either stratified squamous or mucous epithelium. Shortly after cells leave the basal layer under the influence of one hormone they cannot be induced to follow the opposite path of differentiation by reversal of hormone treatment. That is, estrogen or progesterone can induce true differentiation as cells leave the basal layer, but only modulation above this level. Consequently, the initiation of relatively irreversible differentiation in this system is closely associated with the stage at which a cell is produced by mitosis from a less differentiated cell and does not appear related to obvious cytoplasmic differentiatio

ISSN:0003-276X    

DOI:10.1002/ar.1091540112

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

年代:1966

数据来源: WILEY

摘要:

AbstractThe epidermal melanocytes which, except in the ears, face and friction surfaces, are normally nonmelanotic become gradually DOPA positive and melanogenic after exposures to ultraviolet light. Peak melanogenic activity is attained after 23 exposures (over a one‐month period). With continued treatment, however, both DOPA positivity and melanogenic activity decline. After 46 exposures (over a two‐month period) the population of DOPA positive melanocytes is about one‐half of that found after 23 exposures. The population of Langerhans cells, normally high in untreated skin, drops steadily as the melanocytes become melanogenic. When, after 46 exposures, the active melanocyte population drops, that of the Langerhans cells rises. There is, thus, an inverse relation between melanocyte activity and the number of Langerhans

ISSN:0003-276X    

DOI:10.1002/ar.1091540113

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

年代:1966

数据来源: WILEY

摘要:

AbstractAccurate determination of the neuron populations of the medial and lateral mammillary nuclei in normal cat brains, and of the same structures (after quasi‐equilibrium of the cellular populations is achieved) in brains of these experimental animals modified by unambiguous lesion arrays, provides the foundation for deciphering features of the neuronal circuitry that cannot be elucidated on the basis of qualitative neuroanatomic knowledge. This paper is concerned first with the closeness of agreement of cell population values between bilaterally corresponding mammillary nuclei in the same brain and with the degree of reproducibility of the ratio of the populations of the lateral and medial nuclei of this complex from one brain to another. Second, it is concerned with illustrating in specific cases the usefulness of population ratios determined from normal and from modified brains in revealing important neuroanatomic relations: (1) clarifying the structure of the dorsal bifurcation of the principal mammillary tract into the mammillothalamic and mammillotegmental tracts for fibers projecting from the medial mammillary nucleus, and (2) deciphering the neuronal circuitry of the bilateral projection of each lateral mammillary nucleus to the anterior dorsal nuclei of the thalamu

ISSN:0003-276X    

DOI:10.1002/ar.1091540114

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

年代:1966

数据来源: WILEY

摘要:

AbstractA ridge of fatty tissue partly encircles the midsection of the human ascending aorta. This structure was constant in occurrence, position, and form in all examined adult and late fetal specimens. The ridge terminates as an expanded cushion that is situated on the right wall of the aortic bulb in apposition to the edge of the right auricle. A fascial cleft beneath the cushion permits a mobility which would enable the structure to relieve pressure and friction caused by the expansion of the auricle against the aorta. A vascular plexus within the cushion is formed by the anastomoses of the coronary and extracardiac branches of the aortic vasa vasorum.

ISSN:0003-276X    

DOI:10.1002/ar.1091540115

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

年代:1966

数据来源: WILEY

ISSN:0003-276X    

DOI:10.1002/ar.1091540101

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

年代:1966

数据来源: WILEY