EFFECT OF ISOLATED REMOVAL OF MEDIAN-EMINENCE (ME) AND PITUITARY STALK (PS) ON IMMUNOHISTOLOGY AND HORMONE-RELEASE OF ANTERIOR-PITUITARY GLAND GRAFTED INTO HYPOPHYSIOTROPHIC AREA (HTA) AND/OR OF INSITU PITUITARY-GLAND

  • 1 January 1977
    • journal article
    • research article
    • Vol. 28  (3) , 333-349
Abstract
Removal of the median eminence (ME) and pituitary stalk (PS) of female rats was performed under visual control, using a new instrument to open up the 3rd ventricle. Atrophy of the uterus, follicles and the ovarian interstitial tissue was accompanied by persistent corpora lutea and persistent diestrous vaginal smears in rats which had undergone successful removal of ME and PS. No change was detected in the weight of the thyroid and adrenal glands at the end of the 6 wk experimental period. An adenohypophysis implanted in place of the ME at the time of the surgery, did not prevent these changes. In animals in which the removal of the ME was not complete, gonadal system changes were less pronounced. Immunocytology of the pituitary [luteinizing hormone] LH-, [follicle stimulating hormone] FSH-, [thyroid stimulating hormone] TSH- and prolactin-cells in animals with completely removed ME and PS showed inactive LH- and FSH-cells both in the grafted and in situ pituitaries, while the TSH- and prolactin-cells appeared to be in a stimulated state. In animals with ME remnant, LH-RH [LH-releasing hormone] axon terminals were localized only on the blood vessels of the remnant. The part of the pituitary graft in contact with these blood vessels, as well as some areas of the in situ pituitary gland, contained active LH cells as judged by their size and immunohistological appearance. Since in the absence of the ME, the hypophysiotrophic area is not able to exert its regulatory effect on the gonadotrophs of the pituitary in plant in this area, the authors suggest that this effect is mediated by the ME blood circulation which is rich in releasing hormones and is drained toward both the anterior pituitary and the medial basal hypothalamus.