Betchaku T, Douglas W W
Anat Rec. 1981 Mar;199(3):403-21. doi: 10.1002/ar.1091990309.
The rostral pars distalis of the anterior pituitary gland of the marine alewife, Alosa pseudoharengus, during its annual spawning run to fresh water was examined histologically. The rostral pars distalis is composed of many interconnecting follicles of various sizes. Contrary to earlier reports, the follicular epithelium contains not only prolactin (PRL) cells but corticotropic (ACTH) cell and thyrotropic (TSH) cells (in addition to two nonendocrine cell types). Basally all three endocrine cell types make direct contact with the basement membrane which separates the follicles from the neurohypophysial processes. Apically, however, only the prolactin cells, the largest of the three, protrude into the follicular lumen by means of the small ciliated apical protruberance. All other cellular elements are sealed from the follicular lumen by a layer of covering cells which have properties of transitional epithelial cells. In the follicular epithelium, the slender TSH cells are intercalated between the large conspicuous prolactin cells. The ACTH cells, the smallest of the three endocrine cells, lie in deep invaginations in the basal regions of the individual PRL cells in such a way that on cursory examination they can be mistaken for the nuclei of the latter. Only a small portion of the cellular surface of the ACTH cell escapes the enveloping prolactin cell to make contact with the basement membrane of the follicle. In teleosts, prolactin, ACTH, and TSH have all been implicated in the regulation of hydromineral metabolism and reproductive development. The intimate spatial relation between the three endocrine cells in the alewife rostral pars distalis thus raises the possibility of some functional interactions at the adenohypophysial level, perhaps as an adaptation of this anadromous teleost whose reproductive development and behavior is associated with large changes in ambient salinity. The functional significance of the follicular lumen is discussed together with possible sensory functions of the PRL cells.
在洄游至淡水进行一年一度产卵的过程中，对海产美洲河鲱（Alosa pseudoharengus）脑垂体前叶的嘴侧远侧部进行了组织学检查。嘴侧远侧部由许多大小各异、相互连接的滤泡组成。与早期报告相反，滤泡上皮不仅含有催乳素（PRL）细胞，还含有促肾上腺皮质激素（ACTH）细胞和促甲状腺激素（TSH）细胞（此外还有两种非内分泌细胞类型）。在基部，所有这三种内分泌细胞类型都直接与将滤泡与神经垂体突起分隔开的基底膜接触。然而，在顶端，只有三种细胞中最大的催乳素细胞通过小的纤毛顶端突起突入滤泡腔。所有其他细胞成分都被一层具有移行上皮细胞特性的覆盖细胞与滤泡腔隔开。在滤泡上皮中，细长的TSH细胞夹在大而明显的催乳素细胞之间。ACTH细胞是三种内分泌细胞中最小的，以这样一种方式位于单个PRL细胞基部区域的深陷窝中，即乍一看它们可能被误认为是后者的细胞核。ACTH细胞只有一小部分细胞表面未被包绕它的催乳素细胞覆盖，从而与滤泡的基底膜接触。在硬骨鱼中，催乳素、ACTH和TSH都与水盐代谢和生殖发育的调节有关。因此，美洲河鲱嘴侧远侧部中这三种内分泌细胞之间紧密的空间关系增加了腺垂体水平存在某些功能相互作用的可能性，这可能是这种溯河产卵硬骨鱼的一种适应，其生殖发育和行为与环境盐度的巨大变化相关。文中还讨论了滤泡腔的功能意义以及PRL细胞可能的感觉功能。
