灵长类月经周期的调控

灵长类月经周期的调控与啮齿类不同,在下丘脑没有促性腺激素释放激素(GnRH)的周期性分泌中枢。排卵前促性腺激素(GTH)峰的出现无需下丘脑活动的增强和GnRH分泌的增加。GnRH对垂体GTH的周期性分泌不起控制作用,只起“允许作用”,起控制作用的是卵巢雌激素。雌二醇作用于垂体促性腺细胞的两个功能池,控制GnRH对它们的作用,完成调节GTH分泌的作用。     

垂体浸出液诱发蟾蜍卵球成熟的实验分析

冬眠蟾蜍的长足卵母细胞,只需要与垂体促性腺激素作短暂的接触,在其细胞核尚未破裂以前,转入生理水培养,即可恢复成熟分裂,由第一次成熟分裂前期,发育到第二次成熟分裂中期。在垂体浸出液作用下,有核或去核的卵母细胞的细胞质中,都会出现促成熟的活性物质(MPF)。含有这种促成熟因子的微量卵质,一旦注入未经激素处理的卵球,即能诱发后者正常成熟。可是,在同一激素的作用下,卵母细胞细胞核(胚泡)的内含物,却不能诱发未经激素处理的卵球胚泡破裂,继续进行成熟分裂。卵母细胞的细胞质,既然可以不依赖于其细胞核的存在而形成促成熟的活性物质,而蛋白质合成的抑制剂又能妨障此活性物质的产生,这说明,激素导致卵母细胞胚泡破裂和继续减数分裂,所涉及的主要是翻译水平上的蛋白质合成问题。激素对卵母细胞细胞核的作用是间接的,是通过细胞质的活动予以调控的。     

大鼠动情周期垂体促性腺细胞周期性变化的定量免疫细胞化学研究

本报告用免疫细胞化学方法确定大鼠动情周期垂体促性腺细胞的周期性形态学变化。实验将大鼠垂体石蜡切片用兔抗HCG血清和辣根过氧化物酶标记抗体方法染色后,在光学显微镜下观察,并用分格计数法和修正的落点法分别测定促性腺细胞的数量和大小。测定和观察结果为:(1)每平方nam细胞的平均数目为间情期662±36、动情前期633±102、动情期449±105和动情后期472±76。用方差分析表明,间情期和动情前期受染色的细胞平均数目明显多于动情期和动情后期(n=12,P<0.05)。(2)受染色促性腺细胞的平均面积(μm~2)为间情期106.00±11.70、动情前期107.00±13.10、动情期95.70±10.30和动情后期101.00±5.95,在动情周期的不同时期细胞大小无显著差异。(3)在动情周期的不同时期促性腺细胞各种类型的分布特征呈周期性变化。此结果提示:受染色促性腺细胞数量和结构类型的周期性变化可能与大鼠动情周期中血清促性腺激素浓度的周期性变化有密切关系。     

细胞凋亡中p53转录依赖与非依赖性调控

p53介导由胞内压力诱导的细胞凋亡等多种细胞应答.传统上认为, p53主要在细胞核内作为转录因子调控多种促凋亡靶基因的表达, 从而发挥其促凋亡功能.而最新的研究表明, p53也能直接在细胞质中发挥其促凋亡作用, 并且该过程不依赖于其核内的转录活性.此外, 在特定的刺激下, p53的转录依赖性(细胞核内)与转录非依赖性(细胞质内)促凋亡作用存在着偶联和协同机制, 从而有效的决定细胞在生存与死亡间进行选择.现对近年来关于细胞凋亡中p53转录依赖性和转录非依赖性调控及它们之间的偶联机制的研究进行综述.     

中华蜜蜂工蜂蜡腺细胞的超微结构

本文描述了中华蜜蜂(Apis cerana)成体工蜂蜡腺细胞的超微结构.通过电镜观察发现蜡腺细胞具有许多质膜内陷形成的管腔,作为蜂蜡或其前体物的输送通道.细胞质中富含线粒体及粗面内质网,细胞核为不规则的形状,细胞质中还含有少量溶酶体,微管和微丝等结构.     

高效能的促黄体素释放激素类似物对金鱼促性腺激素分泌的作用

金鱼对LRH-A反应有明显的季节性变化,在早春(2月)生殖季节开始前诱导的血清GtH含量最高;在生殖季节过后(5—6月)GtH的释放反应减弱,而在夏季(8月)性腺处于退化状况时,反应很弱或者没有反应。LRH-A注射剂量的高低对血清GtH含量增高的影响并不都很明显,但高剂量(1.0微克/克体重)能诱导较高的血清GtH含量并能维持24小时。经过多次注射高剂量以后,脑垂体GtH含量下降。温度、注射剂量、注射间隔时间都和诱导的血清GtH含量有密切关系。连续9—10天每日注射LRH-A,能刺激性腺退化的金鱼恢复性腺发育,但对性腺已开始发育的金鱼,却抑制或减慢其性腺进一步发育。       

20-羟蜕皮素对家蚕后部丝腺细胞超微结构的影响

应用超薄切片和电镜技术,详细观察了蜕皮激素(MH)对家蚕Bombyx mori后部丝腺细胞超微结构的影响.电镜观察表明,家蚕后部丝腺细胞对MH处理极为敏感.一经MH处理,其细胞核的形态结构和细胞质中各种细胞器的发生、发展都呈现出明显的变化,并且与MH处理时期及剂量有关:五龄前期适量MH(4μg/头)处理,能促进与丝蛋白合成有关细胞器的形成与发展,加速腺细胞的成熟生长;较高剂量(8—16μg/头)处理,则导致自噬体的过早发生.五龄中、后期MH处理,一方面促进了粗面内质网等细胞器的进一步发达,另一方面也提高了自噬体的发生数量;处理剂量越高,后一种倾向越突出.这些结果证明,后部丝腺细胞超微结构的变化受MH调节.     

对垂体促性腺细胞可引起电压起伏

哺乳动物的腺垂体是一种至少有五种不同分泌细胞类型的非均一性细胞复合体。由于技术上的困难,下丘脑促性腺激素释放激素(GnRH)对垂体促性腺细胞的电生理活动的影响,一直未能阐明。作者用羊腺垂体结节部(PT)离体制备,作为促性腺细胞的自然富集源,并证明GnRH 诱导细胞Ca~(2 )通道的活化,Ca~(2 )内流为启动这种细胞分泌激素所必需。实验用胰蛋白酶分散了的羊PT 细胞作原代体外单层培养,4～7天后,用免疫细胞化学定位技术观察     

龟足白垩腺的组织学和超微结构

应用光学显微镜和透射电子显微镜对龟足(Capitulum mitella)白垩腺的组织学和超微结构进行观察。龟足的白垩腺由腺细胞和管道系统组成,外周覆有一层结缔组织膜。腺细胞为单细胞,其发育与个体发育不同步。年幼腺细胞较小,形态为圆形或椭圆形,细胞核也为圆形或椭圆形。随着腺细胞的发育,细胞及细胞核逐渐变大,形状不规则具多态性。成熟腺细胞的细胞质电子密度高,充满大量粗面内质网和游离核糖体;线粒体很丰富,但未见高尔基体。细胞质中含有丰富的颗粒状物质以及大小不一的囊泡,小囊泡的聚集和融合形成了大囊泡即胞内管。管道系统根据位置和功能分为4个层次:胞内管、收集管、次级管和初级管。收集管、次级管和初级管的管壁均由单层上皮细胞组成,初级管较收集管和次级管大且内腔衬有几丁质层。收集管的管壁上皮细胞与腺细胞之间形成隔状连接,各级管壁上皮细胞之间也形成隔状连接,这种结构保证了管道的紧密性。总之,龟足白垩腺的形态结构类似于茗荷(Lepas anatifera)和Dosima fascicularis。     

月经周期的生理调控

下丘脑-垂体-卵巢轴直接调控月经周期,三者之间通过促性腺激素与卵巢甾体激素对下丘脑、垂体产生的反馈机制产生生理性周期变化,卵巢局部产生众多的肽类因子形成卵巢内自分泌／旁分泌调节系统,参与垂体促性腺激素性腺内作用机制的调控。     

Co-localization of secretogranins/chromogranins with thyrotropin and luteinizing hormone in secretory granules of cow anterior pituitary

We investigated the co-localization in secretory granules of secretogranins/chromogranins, thyrotropin, and luteinizing hormone in ultra-thin frozen sections of cow anterior pituitary by double immunoelectron microscopy, using specific antibodies and protein A-gold particles of different sizes. The distribution of secretogranin II, chromogranin A, and chromogranin B (secretogranin I) was largely similar. In cells containing secretory granules of relatively small size (100-300 nm) and low electron density (identified as thyrotrophs and gonadotrophs by immunolabeling for the respective hormone) and in cells containing both small (170-250 nm) and large (300-500 nm) secretory granules of low electron density (also identified as gonadotrophs), all three secretogranins/chromogranins were detected in most if not all granules, being co-localized with the hormone. In cells containing both relatively large (400-550 nm), electron-dense granules and small, less electron-dense secretory granules (150-300 nm), identified as somatomammotrophs by double immunolabeling for growth hormone and prolactin, all three secretogranins/chromogranins were predominantly detected in the subpopulation of small, less electron-dense granules containing neither growth hormone nor prolactin. Interestingly, this granule subpopulation of somatomammotrophs was also immunoreactive for thyrotropin and luteinizing hormone. These data show that somatomammotrophs of cow anterior pituitary are highly multihormonal, in that the same cell can produce and store in secretory granules up to four different hormones and, in addition, the three secretogranins/chromogranins. Moreover, selective localization of the secretogranins/chromogranins together with thyrotropin and luteinizing hormone in a subpopulation of secretory granules of somatomammotrophs indicates the preferential co-packaging of the secretogranins/chromogranins and these hormones during secretory granule formation.     

Immunocytochemical localization of cathepsin B in rat anterior pituitary endocrine cells, with special reference to its co-localization with renin and prorenin in gonadotrophs

We examined by immunocytochemistry the localization of cathepsin B in endocrine cells of rat anterior pituitary lobe, using a monospecific antibody to cathepsin B. By light microscopy, granular immunodeposits for cathepsin B were detected in most endocrine cells of anterior pituitary lobe. Cells immunoreactive for luteinizing hormone (LH) were diffusely immunostained by anti-cathepsin B. By electron microscopy, immunogold particles for cathepsin B were localized in lysosomes of thyrotrophs, somatotrophs, and mammotrophs. In mammotrophs, immunogold particles for cathepsin B were also detected in crinophagic bodies. Double immunostaining co-localized immunogold particles for LH and cathepsin B in secretory granules of gonadotrophs. Immunocytochemistry was also applied to demonstrate localization of renin and prorenin in LH-producing gonadotrophs; immunogold particles for renin were co-localized with those for LH, cathepsin B, or prorenin in their secretory granules. Immunogold particles for prorenin were also co-localized with those for LH or cathepsin B in secretory granules, but prorenin-positive granules appeared less frequently than renin-positive granules. These results suggest that cathepsin B not only plays a role in the protein degradation in lysosomes of anterior pituitary endocrine cells but also participates in the activation of renin in gonadotrophs, as has been demonstrated in secretory granules of juxtaglomerular cells.     

Topology of chromogranin A and secretogranin II in the rat anterior pituitary: potential marker proteins for distinct secretory pathways in gonadotrophs

Summary Chromogranins (Cg)/secretogranins (Sg) are representative acidic glycoproteins in secretory granules of many endocrine cells where they are co-stored and co-released with resident amines or peptides. The exact distribution of these proteins in the rat anterior pituitary is unknown. Therefore, pituitaries from untreated male rats were investigated by light- and electron-microscopical immunocytochemistry for the cellular and subcellular localization of CgA, CgB, and SgII. Endocrine cells, identified light-microscopically as gonadotrophs in adjacent semithin sections immunostained for follicle-stimulating hormone (FSH) and luteinizing hormone (LH), concomitantly were immunoreactive for CgA, CgB, and SgII. Ultrastructurally, gonadotrophs exhibited two types of secretory granules which varied in their immunoreactivities for gonadotropins and Cg/Sg. Large-sized (500 nm), moderately electron-dense granules showed antigenicities for FSH, LH, and CgA. Smaller-sized (200 nm), electron-dense granules were immunoreactive exclusively for LH and SgII. The distinct localization of CgA and SgII to morphologically and hormonally different secretory granules indicates the existence of two regulated secretory pathways in rat pituitary gonadotrophs. Hence, these proteins are considered as valuable tools to analyze the intracellular trafficking during granule biogenesis and the possible different regulation of FSH and LH secretion.     

Topology of chromogranin A and secretogranin II in the rat anterior pituitary: potential marker proteins for distinct secretory pathways in gonadotrophs.

Chromogranins (Cg)/secretogranins (Sg) are representative acidic glycoproteins in secretory granules of many endocrine cells where they are co-stored and co-released with resident amines or peptides. The exact distribution of these proteins in the rat anterior pituitary is unknown. Therefore, pituitaries from untreated male rats were investigated by light- and electron-microscopical immunocytochemistry for the cellular and subcellular localization of CgA, CgB, and SgII. Endocrine cells, identified light-microscopically as gonadotrophs in adjacent semithin sections immunostained for follicle-stimulating hormone (FSH) and luteinizing hormone (LH), concomitantly were immunoreactive for CgA, CgB, and SgII. Ultrastructurally, gonadotrophs exhibited two types of secretory granules which varied in their immunoreactivities for gonadotropins and Cg/Sg. Large-sized (500 nm), moderately electron-dense granules showed antigenicities for FSH, LH, and CgA. Smaller-sized (200 nm), electron-dense granules were immunoreactive exclusively for LH and SgII. The distinct localization of CgA and SgII to morphologically and hormonally different secretory granules indicates the existence of two regulated secretory pathways in rat pituitary gonadotrophs. Hence, these proteins are considered as valuable tools to analyze the intracellular trafficking during granule biogenesis and the possible different regulation of FSH and LH secretion.     

Ultrastructural immunocytochemical localization of LH and FSH in the pituitary of the untreated male rat

Summary Rapid freeze-substitution fixation was employed in immunocytochemical studies on the localization of LH and FSH in the typical gonadotrophs of the anterior pituitary in the untreated male rat; a modification of a recently described ferritin antibody method (Inoue et al. 1982) was used in these studies. It was shown that rapid freeze-substitution fixation provides good preservation not only of the ultrastructure but also of the antigenicity. Both LH and FSH were clearly demonstrated in the same gonadotrophic cells, but the subcellular localization of these gonadotrophins differed: (i) LH was mainly located in small secretory granules, 250–300 nm in diameter; (ii) FSH was mainly present in large secretory granules, up to 500 nm in diameter. In the pituitary gland of the adult male rat, all gonadotrophs that react to antibodies against gonadotrophins are characterized by small and large secretory granules. Other types of cells of the anterior pituitary containing either small secretory granules or resembling corticotrophs with secretory granules assembled at cell periphery did not react to either anti-LH beta or anti-FSH beta serum.For light microscopy, the peroxidase antibody method was used. All of the gonadotrophin-positive cells contain both LH and FSH. None of the pituitary cells reacted to antibody against only one gonadotrophin. However, some cells are LH-rich while other cells are FSH-rich.     

Subcellular localization of gonadotrophic hormones LH and FSH in frog adenohypophysis using double-staining immunocytochemistry

We applied double post-embedding immunocytochemical methods using specific antibodies against bullfrog (Rana catesbeiana) luteinizing hormone (LH) and follicle-stimulating hormone (FSH) with immunogold staining (5- and 20-nm particles) to determine the subcellular localization of both gonadotropins and to observe their immunostaining patterns in anterior pituitary of the frog Rana pipiens. Results showed that individual gonadotrophs may store either one or both gonadotropins in a given secretory granule and in large globules (lysosomes?). Most gonadotrophs (50-88%) contain both hormones; 12-50% contain only FSH, and only a few (0-7%) contain LH alone. Individual secretory granules, even in cells that contain both hormones, may contain only one or both gonadotropin molecules. Evaluation of the percentage of monohormonal and multihormonal secretory granules revealed that multihormonal secretory granules were the most numerous and that LH monohormonal secretory granules were the least numerous. These results indicate that cellular storage of gonadotropin in amphibian pituitary is similar to that described for mammals, where a single cell type containing both gonadotropins predominates. Variability in hormone content both of cells and of granules in all individuals is consistent with the hypothesis that frog pituitary possesses a single multipotential gonadotroph.     

Presence of angiotensin II in the adult male rat anterior pituitary gland: immunocytochemical study after cryoultramicrotomy

Angiotensin II (AII)-like immunoreactivity and binding sites have recently been demonstrated at the pituitary level. This peptide also exerts a stimulatory effect on anterior pituitary hormone release. Immunocytochemistry on ultrathin sections obtained by cryoultramicrotomy was used with the aim of localizing endogenous AII-like material at the cellular and subcellular levels of the anterior pituitary gland. AII-like immunostaining was observed only in gonadotrophs, lactotrophs, and corticotrophs. In gonadotrophs, AII-like immunoreactivity was restricted only to secretion granules. In the two other immunoreactive cells, lactotrophs and corticotrophs, immunostaining was observed in the cytoplasm and in the nucleus. In the cytoplasm, AII-like material was visualized in the cytoplasmic matrix and in the secretory granules. In the nucleus, immunostaining was distributed in the euchromatin in the vicinity of the heterochromatin. AII-like immunoreactivity was also seen at the plasma membrane, but only scarcely. No reaction product was found when anti-AII serum preincubated with AII was used. These immunocytochemical results (1) provide evidence that gonadotrophs are only a site of synthesis and/or storage of AII-like material, (2) indicate that lactotrophs and corticotrophs are cells for AII and (3) provide cytological evidence for a direct participation of AII in the regulation of the lactotropic and corticotropic function.     

Electron-microscopic study on the anterior pituitary gland of spontaneous dwarf rats

Summary The spontaneous dwarf rat is a novel experimental model animal on the study of pituitary dwarfism. The fine structure of the anterior pituitary cells was studied in the immature and mature dwarf rats. Pituitary glands were removed from 5-, 10-, 20-day-old immature dwarfs, adult (45 days-16 weeks) dwarfs and normal 3-month-old rats and processed for electron-microscopic observation. In the control animals, growth hormone cells were readily identified by their ultrastructural characteristics, such as the presence of numerous electron-dense secretory granules, 300–350 nm in diameter, well developed rough endoplasmic reticulum and a prominent Golgi complex. In contrast, growth hormone cells were not found in the anterior pituitary gland of the spontaneous dwarf rat at any age examined. Other pituitary cell types, i.e., luteinizing hormone/ follicle stimulating hormone, thyroid stimulating hormone, adrenocorticotropic hormone and prolactin cells, appeared similar in their fine structure to those found in the control rats. In the pituitary gland of dwarf rats, a number of polygonal cells were observed either with no or relatively few secretory granules. The rough endoplasmic reticulum was arranged in parallel cisternae and the Golgi complex was generally prominent in these cells. In addition, many were found to have abundant lysosomes. A few minute secretory granules were occasionally observed; however, the immunogold technique failed to localize growth hormone or prolactin in the granules. The nature of these cells remained obscure in this study. Since their incidence and fine structural features, other than the secretory granules, were quite similar to those of the growth hormone cells in normal rats, we postulate that these cells are dysfunctional growth hormone cells. These results suggest that the cause of the growth impairment in the spontaneous dwarf rat is due to a defect in the functional growth hormone cells in the pituitary gland, and since other pituitary cell types appeared normal, the disorder seems to be analogous to the isolated growth hormone deficiency in the human.     

乌龟脑垂体显微及其腺垂体超微结构的研究

乌龟脑垂体由柄形神经垂体和椭圆形腺垂体两部分组成,神经垂体位于腺垂体后部上方呈背腹型排列。神经垂体中神经叶不发达,腺垂体分为远侧部和中间部,特殊空泡结构成为垂体门脉系统的特征。远侧部细胞分为嗜酸性细胞、嗜碱性细胞和嫌色细胞3种。通过透射电镜观察,腺垂体远侧部主要有5种分泌激素细胞:即生长激素(GH)分泌细胞、催乳激素(PRL)分泌细胞、促甲状腺激素(TSH)分泌细胞、促肾上腺皮质激素(ACTH)分泌细胞、促性腺激素(GTH)分泌细胞和非分泌类型滤泡-星形细胞(FS)。生长激素分泌细胞核大、分泌颗粒少的特征成为乌龟与其他动物最大的区别,可能与乌龟具有生长慢、寿命长的生物学特性有关。       

Immunocytochemistry of the pituitary glycoprotein hormones.

The storage sites of the pituitary glycoprotein hormones were identified with the use of electron microscopic immunocytochemical techniques and antisera to the beta (beta) chains of follicle-stimulating hormone (FSH), luteinizing hormone (LH) and thyroid-stimulating hormone (TSH). The TSH cells in normal rats is ovoid or angular and contains small granules 60-160 nm in diameter. In TSH cells hypertrophied 45 days after thyroidectomy, staining is in globular patches in granules or diffusely distributed in the expanded profiles of dilated rough endoplasmic reticulum. The gonadotrophs (FSH and LH cells) exhibited three different morphologies. Type I cells are ovoid with a population of large granules and a population of small granules. Staining for FSHbeta or LHbeta was intense and specific only in the large granules (diameter of 400 nm or greater). Type II cells are angular or stellate and contain numerous secretory granules averaging 200-220 nm in diameter. They predominate during stages in the estrous cycle when FSH or LH secretion is high. Type III cells look like adrenocorticotropin (ACTH) cells in that they are stellate with peripherally arranged granules. They generally stain only with anti-FSHbeta and their staining can not be abolished by the addition of 100 ng ACTH. In preliminary quantitative studies of cycling females, we found that on serial sections FSH cells and LH cells show similar shifts to a more angular population of cells during stages of active secretion. However, the shifts are not in phase with one another. Furthermore, there are at least 1.5 times more FSH cells than LH cells at all stages of the cycle. Our collection of serial cells shows that some cells (usually type I or II) stain for both gonadotropic hormones, whereas others (usually type II or III) contain only one.