INTRODUCTION Growth hormone and prolactin secretion is affected by thyroid hormones. To see if this influence is subsidiary to the hyptothalamus, we investigated the effects of thyroxin (T4) on hormone secretion and histology of sellar pituitaries and pituitary grafts detached from the hypothalamus (autografted or allografted under the kidney capsule). MATERIALS AND METHODS Male Wistar rats were divided into eight groups: control, thyroidectomised, pituitary autografted, pituitary allografted, and four additional groups that were injected with T4 for two weeks, starting four weeks after surgery. At sacrifice, adenohypophysial hormone blood levels were assessed, and tissue from sellar and grafted pituitaries were investigated by histology and electron microscopy. RESULTS Growth hormone and prolactin blood levels, as well as the number of growth hormone immunopositive cells increased in T4-treated groups. Both pituitary auto- and allo-grafts showed lactotroph hyperplasia and displayed spongiform areas containing cells with vesicles in their cytoplasm resembling thyroidectomy cells. This phenomenon was minimized in their respective T4-treated group. Thyroidectomy cells were identified in pituitary grafts, indicating that hypothalamic control was not essential to induce them. DISCUSSION AND CONCLUSION It is intriguing that the pituitary allografted group, even maintaining normal T4 blood levels, developed thyroidectomy cells in their grafts, suggesting that a long- term deficit of vascularization (>4 weeks) prevented T4 from reaching the graft. After 6 weeks, post T4 treatment of two weeks seemed to be the determining factor to minimize thyroidectomy cells in both pituitary autografted + T4 and pituitary allografted + T4 grafts compared to the untreated groups, although more time and/or higher T4 doses may be required to fully restore the euthyroid morphology.

中文翻译：

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甲状腺素对大鼠垂体移植物细胞形态和激素分泌的影响。

简介生长激素和催乳激素的分泌受甲状腺激素的影响。为了了解这种影响是否是下丘脑的附属因素，我们研究了甲状腺素（T4）对下丘脑（自体移植或同种异体移植）的下丘脑垂体和垂体的激素分泌和组织学的影响。材料与方法将雄性Wistar大鼠分为八组：对照组，甲状腺切除，垂体自体移植，垂体同种异体移植，以及另外四组，分别在术后四周开始注射T4，持续两周。处死时，评估腺垂体激素血水平，并通过组织学和电子显微镜检查来自鞍和垂体的组织。结果生长激素和催乳素的血液水平，T4处理组的生长激素免疫阳性细胞数量增加。垂体自体移植和同种异体移植均显示出乳营养型增生，并显示出海绵状区域，其细胞质中含有类似于甲状腺切除细胞的囊泡。在他们各自的T4处理组中，这种现象最小化。在垂体移植物中鉴定出甲状腺切除细胞，这表明下丘脑控制不是诱导它们的必要条件。讨论与结论令人惊讶的是，即使维持正常的T4血水平，垂体同种异体移植组的移植物中也会发育甲状腺切除细胞，这表明长期的血管生成不足（> 4周）阻止了T4到达移植物。6周后