Okada T, Shimomuro T, Oikawa M, Nambo Y, Kiso Y, Morikawa Y, Liptrap R M, Yamashiro S, Little P B, Sasaki F
Department of Veterinary Anatomy, College of Agriculture, Osaka Prefecture University, Japan.
Am J Vet Res. 1997 Aug;58(8):920-4.
To analyze and characterize adenoma and hyperplasia of the pars intermedia (PI) of Thoroughbred mares.
165 Thoroughbred mares, without clinical signs of hyperadrenocorticism that had been euthanatized or had died, of causes such as sudden death, colic, pneumonia, or trauma, and were necropsied. Five of those horses, 17 to 25 years old, had a large pituitary gland at necropsy. Eight mares, 5 to 15 years old with normal-size pituitary gland, were selected at random for comparison.
A morphologic comparison of the pituitary gland between horses with and without tumors of the PI was conducted by use of immunocytochemistry and morphometry.
In horses with normal pituitary gland, the PI was supplied by a vast capillary or sinusoidal plexus, which connected that in the pars distalis (PD) with that in the pars nervosa (PN). Cells of the PI stained slightly with ACTH antiserum, but some cells in the border region, which is contiguous to the PD, were strongly ACTH immunoreactive. At necrospy, horses with an enlarged pituitary gland also had adenoma of the pituitary gland involving the PI. Cells of the border region were hypertrophied and stained strongly with ACTH antiserum. The area and number of individual tumor cells of the border region of the PI of horses with adenoma were significantly increased, compared with those in horses with normal pituitary gland.
Cells of the PI-PD border region may secrete substantial quantities of ACTH, owing to stimulation by corticotropin-releasing factor. Adenoma and hyperplasia of the PI in Thoroughbred mares may be associated with hyperadrenocorticism.
分析和描述纯种母马垂体中间部（PI）的腺瘤和增生情况。
165匹纯种母马，无肾上腺皮质功能亢进的临床症状，因猝死、绞痛、肺炎或外伤等原因实施安乐死或死亡后进行尸检。其中5匹马，年龄在17至25岁之间，尸检时发现垂体较大。随机选择8匹年龄在5至15岁、垂体大小正常的母马作为对照。
通过免疫细胞化学和形态计量学对有或无PI肿瘤的马匹垂体进行形态学比较。
在垂体正常的马匹中，PI由广泛的毛细血管或窦状丛供血，该丛将远侧部（PD）和神经部（PN）的血管相连。PI细胞用促肾上腺皮质激素抗血清染色较浅，但与PD相邻的边界区域的一些细胞促肾上腺皮质激素免疫反应强烈。尸检时，垂体增大的马匹也有累及PI的垂体腺瘤。边界区域的细胞肥大，用促肾上腺皮质激素抗血清染色强烈。与垂体正常的马匹相比，患有腺瘤的马匹PI边界区域单个肿瘤细胞的面积和数量显著增加。
由于促肾上腺皮质激素释放因子的刺激，PI-PD边界区域的细胞可能分泌大量促肾上腺皮质激素。纯种母马PI的腺瘤和增生可能与肾上腺皮质功能亢进有关。
