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  • 1
    Electronic Resource
    Electronic Resource
    Mesenchymal influences on the development of the adenohypophysis in the rat (1985)
    Springer
    Cell & tissue research 241 (1985), S. 67-76 
    Details
    ISSN: 1432-0878
    Keywords: Pituitary gland ; Pars anterior ; Cell differentiation ; Grafts ; Mesenchymal cells ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Comparative studies have been made of development of the adenohypophysis using the Rathke's pouch (RP)-derived model system. Rathke's pouch with associated mesenchyme and ventral hypothalamus, was microsurgically isolated from 15-day fetal rats and placed in mild trypsin solution. Three variations of donor tissue were isolated and transplanted beneath the kidney capsule of adult hosts: A) pure pouch epithelium; B) pouch epithelium plus mesenchyme; and C) pouch epithelium with mesenchyme and ventral hypothalamus. After 30 days the grafts were isolated and processed for light and electron microscopy. Cell types were characterized by immunostaining as well as by morphological criteria. In group A well differentiated mammotrophs dominated the grafts, many of which were hypertrophied with widely dilated endoplasmic reticulum and Golgi saccules. Mammotrophs, frequently with mitotic figures, were distributed evenly throughout the grafts. Somatotrophs and gonadotrophs were neither abundant nor well differentiated in group A, but were both abundant and more extensively differentiated in groups B and C. Both somatotrophs and gonadotrophs were typically localized at margins of the graft adjacent to connective tissue spaces. Well differentiated mammotrophs were present in groups B and C although there were fewer hypertrophied mammotrophs than in group A; and immunoreaction to prolactin was weaker than in group A. Tumor-like features found in all three groups included some loss of tissue integrity and large, vascular lakes unlined by endothelium. These findings suggest that differentiation of mammotrophs may be inhibited in part by mesenchyme associated with Rathke's pouch, since in the absence thereof these cells become hyperplastic. Conversely, differentiation of somatotrophs and gonadotrophs appears more dependent on these mesenchymal elements for normal development.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00214627
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  • 2
    Electronic Resource
    Electronic Resource
    Estradiol stimulation of pituitary primordia transplanted to the kidney capsule (1982)
    Springer
    Cell & tissue research 227 (1982), S. 41-53 
    Details
    ISSN: 1432-0878
    Keywords: Anterior pituitary ; Cytodifferentiation ; Kidney capsule grafts ; Estradiol stimulation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The purpose of this study was to define better the influence of hormones on the normal and pathological development of the anterior pituitary using Rathke's pouch (RP)-derived model system. RP from either 12- or 15-day fetuses were microsurgically isolated and transplanted beneath the kidney capsule (KC) of intact adult hosts. Eighteen days later the hosts were hypophysectomized. Ten-12 days after hypophysectomy hosts were injected daily with either 1.0 μg estradiol benzoate (EB) or 0.1 cc corn oil until necropsy at 80 days. Both 12- and 15-day RP differentiated into large, pars distalis tissues consisting of a variety of granulated and agranulated cell types, as well as large, secretory cysts. Cytodifferentiation was consistently most advanced in 15-day RP-derived grafts. Evidence of secretory granule synthesis, but not exocytosis, was apparent in granulated cells in oil-treated controls and EB-treated 12-day RP-derived grafts. Immunostaining and electron microscopy demonstrated hypertrophied somatotrophs and mammotrophs with numerous profiles of exocytosis in EB-treated 15-day RP-derived grafts. Mammotrophs and somatotrophs were infrequent and not well differentiated in 12-day RP-derived grafts whether EB- or oil-treated, nor in oil-treated 15-day RP-derived grafts. Radioimmunoassay demonstrated highest levels of plasma PRL in EB-treated 15-day RP-derived grafts. Implant invasiveness was noted only in EB-treated 12-day RP-derived grafts when basal laminae were disrupted or absent, and graft cells mixed with connective tissue elements. Results indicate that the Cytodifferentiation of pars distalis cell types derived from KC transplanted RP can be maintained to 80 days. Mammotrophs are especially well differentiated and responsive to EB treatment during this development. However, continued maintenance of a differentiated state by mammotrophs and somatotrophs appears to require the presence of host pituitary and/or end organ hormones as evidenced by the lack of maintenance in oil-treated controls. Furthermore, the loss of well defined tissue boundaries between host and graft tissues of EB-treated 12 day RP animals suggests tumorigenic transformation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00206330
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