Deafferentation of the medial basal hypothalamus showed that if deafferentation was complete, the animals became acyclic, LH RH disappeared from the isolated HTA, and their uteri and ovaries became atrophic. If deafferentation was not quite complete, the animals remained cyclic, considerable amounts of LH RH were present in the HTA, and the uteri and ovaries showed only a minor reduction in weight. These observations suggest that the medial basal hypothalamus either does not participate in the synthesis of LH RH at all, or that the amount of LH RH synthesized in this region is insufficient to maintain tonic gonadotrophic hormone secretion. At serial sections of hypothalami bearing pituitary grafts stained alternately for gonadotroph cells and LH RH fibers, no relationship was found between the presence of LH RH containing fibers and active gonadotroph cells of the graft. This indicates that the presence of, and direct contact with, the LH RH containing neuronal elements of the HTA is not the decisive factor in the maintenance of the secretory activity in the graft. Considering that the cerebrospinal fluid and ependymal elements do not provide the pituitary grafts with hypophysiotrophic hormones, the original concept of Halasz et al.,/1962/must be modified by assuming that the vascular link between capillaries of the median eminence and the HTA is the decisive factor in the effect.
|Title of host publication||AKAD.KIADO, BUDAPEST|
|Number of pages||12|
|State||Published - Dec 1 1976|
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