Endocrine changes during the annual reproductive cycle of the red porgy, Pagrus pagrus (Teleostei, Sparidae)

Changes in 17-estradiol (E2), estrone (E1), testosterone (T), 11-ketotestosterone (11KT), and 17,20-dihydroxy-4-pregnen-3-one (17,20-P) levels were correlated to changes in gonadosomatic index (GSI), vitellogenin concentration (Vg), ovarian and testicular histology during the annual reproductive cycle of the red porgy, Pagrus pagrus. The production of E2, E1, T and 17,20-P was confirmed by analysis of the steroidogenic activity of ovaries. In females, the average concentration of E2 was lower than 2 ng ml^–1. E2 values first increased significantly at the stage of endogenous vitellogenesis and remained high during exogenous vitellogenesis. E1 levels were lower values than E2 (less than 300 pg ml^–1), but they increased at the beginning of exogenous vitellogenesis. Estrogens concentrations followed similar pattern to Vg and were significantly correlated. Mean levels of T were mostly lower than 1 ng ml^–1. They followed a pattern similar to that of E2 except for a further increase observed at the stage of final maturation. T and E2 levels were significantly correlated. The concentration of 11KT did not change significantly. The levels of 17,20-P ranged between 0.22 and 1.22 ng ml^–1 but changes were not related to gametogenesis. In males, the concentrations of T and 11KT fluctuated significantly during the sexual maturity stages, showing a similar pattern and were significantly correlated to GSI changes. T levels increased during spermiogenesis and spermiation stages to reach about 3 ng ml^–1. 11KT levels stayed about half those of T. The levels of estrogens showed no significant changes. Level of 17,20-P showed no significant variation related to male maturity. Results are discussed in relation to changes in plasma steroid levels during gametogenesis of other multiple spawner species.     

长江刀鲚性腺发育的组织学研究

在长江的南通及安庆江段捕捞刀鲚样本,对样本进行各种常规生物学数据的测量,并对解剖标本的性腺用Bouin氏液进行固定保存后,将性腺制作成组织切片,通过切片观察,了解洄游至南通及安庆江段的刀鲚性腺发育的状况。切片观察表明,刀鲚自当年2-3月洄游入长江后,不断溯江而上,在南通江段性腺发育处在II-III期,历经3-4个月洄游到达安庆江段,其性腺由入江时的Ⅱ-Ⅲ期,逐渐发育到Ⅳ-Ⅴ期。切片观察还表明,在不同洄游群体中,不同个体的卵巢发育程度不一致,有些发育的较快,有些稍慢,但对于雄性个体来说,洄游到安庆江段后,90％以上已达到成熟阶段。此外,文中还对发育中的卵细胞形态结构进行了详细描叙。     

Seasonal changes in reproductive condition and plasma levels of sex steroids in the blue cod,Parapercis colias (Bloch and Schneider) (Mugiloididae)

Gonad and plasma samples were taken from blue cod captured throughout the reproductive cycle, gonad condition was assessed, and plasma levels of 17-hydroxyprogesterone (17OHP), 17,20-dihydroxy-4-pregnen-3-one (17,20P), testosterone (T), 17-estradiol (E₂) and estrone (E₁) were measured by radioimmunoassay. It was confirmed that spawning occurred over an extended period in late winter and spring, with individual fish being involved in multiple spawning events. Plasma levels of T were bimodal in both sexes with peaks (maximum of 6.0 ng.ml^–1) occurring 2 months prior to, and also during the early part of the spawning period. 17,20P was elevated in males (2.1 ng.ml^–1) in mid-spermatogenesis coinciding with the first T peak (4.9 ng.m.^–1). 17,20P was detectable but not significantly elevated (0.6–1.2 ng.ml^–1) at any sample time in females. E₂ was elevated in mature females (1.0 ng.ml^–1) early in the spawning period but remained at assay detection limits (0.3 ng.ml^–1) at all other sample times. Neither 17OHP nor E₁ were detectable in the plasma of either sex. It is suggested that bimodal increases in sex steroids prior to spawning may be a feature of species with rapid recrudescence.     

脊尾白虾的性腺发育及组织结构观察

为系统研究脊尾白虾的性腺发育及组织学特征,采用常规的石蜡切片及H.E染色方法对脊尾白虾的性腺发育及其组织结构进行观察。结果表明,脊尾白虾的雌性生殖系统由卵巢、输卵管及排卵孔组成。卵子发生经历了卵原细胞、卵黄合成前期卵母细胞、内源性卵黄合成期卵母细胞、外源性卵黄合成期卵母细胞,最后发育为成熟的卵母细胞。卵巢发育可分为增殖期、小生长期、大生长期、成熟期及产后恢复期。脊尾白虾雄性生殖系统由精巢、输精管及排精孔组成。精巢由生精小管构成,不同生精小管内精子发育可不同步。精子发生经历了精原细胞、初级精母细胞、次级精母细胞、精细胞,最后发育为精子。输精管可分为前、中、后输精管及末端壶腹,精荚在输精管中形成。     

Monoaminergic substances in the teleost brain: Catecholamine levels in male and female winter flounder,Pseudopleuronectes americanus Walbaum,associated with gonadal recrudescence

High performance liquid chromatography with electrochemical detection (HPLC-EC) was used to quantitate catecholamine (CA) levels in the winter flounder brain following perchloric acid extraction/alumina purification of CNS tissues. Greater concentrations of norepinephrine (NE) and dopamine (DA) were present in the hypothalamus compared with the CA levels in whole brain. A seasonal study of CA brain levels in reproductively active male and female flounder demonstrated that monoamine levels reach their maxima in October in association with the rapid increases in gonadosomatic index. When perchloric acid extracts of the teleost and rat hypothalamus were submitted to direct HPLC-EC analysis, without alumina purification of CA neurotransmitters, similar hypothalamic profiles were obtained indicating the presence of identifiable biogenic amine neurotransmitters substances including NE, DA and serotonin (5-HT).     

三倍体雌性虹鳟性腺发育阶段细胞色素相关基因的表达

Cyp19a1b、Cyp11a1、Cyp11b2、Cyp17a1、Hsd3b1等细胞色素相关基因能够调节硬骨鱼类性类固醇的合成,对性腺发育和性别决定产生影响。本研究以全雌三倍体虹鳟(Oncorhynchus mykiss)为研究对象,正常雌性二倍体虹鳟为对照,选取31~68 dpf(days post fertilization)时间段的虹鳟仔鱼脑组织,采用q RT-PCR和酶联免疫的方法研究以上几种基因的表达状况和脑芳香化酶的活性变化,以期探明导致三倍体雌性虹鳟性腺发育异常的关键原因。q RTPCR结果显示,二倍体中Cyp19a1b在30~50 dpf时表达量上调并且维持在较稳定水平,但50~56 dpf时表达量逐渐下调,之后56~68 dpf表达量持续上调;三倍体中Cyp19a1b表达量在30~35 dpf开始上调,35~47 dpf逐渐下调,47~55 dpf开始第二次上调,之后维持在较稳定水平直至68 dpf,但三倍体Cyp19a1b的表达量显著(P0.05)低于同期二倍体的。二倍体Cyp11a1表达量在34 dpf出现峰值,三倍体Cyp11a1在38 dpf时出现峰值。二倍体Hsd3b1表达量在33~42 dpf时维持在较高水平,在38 dpf时出现高峰;三倍体Hsd3b1表达量在47~59 dpf时较高,在49 dpf出现高峰。二倍体中Cyp11b2在37 dpf出现峰值,之后开始下调;三倍体在40 dpf出现峰值,之后逐渐下调,但三倍体Cyp11b2表达量显著低于同期二倍体。二倍体Cyp17a1的表达量在35~46 dpf时逐渐上升,在45 dpf时达到高峰之后直至69 dpf逐渐下降,并且维持在较为平稳的水平上;但是在相同的实验条件下未检测到同一时期三倍体Cyp17a1的表达量。酶联免疫结果显示,在40 dpf时二者的脑芳香化酶活性到达高峰,但在40~60 dpf时期,二倍体虹鳟脑芳香化酶活性显著(P0.05)高于三倍体虹鳟,尤其在45~50 dpf时,该酶活性分别较三倍体的高1.15倍和1.12倍。以上结果表明三倍体虹鳟早期性腺发育迟缓的原因之一是Cyp19a1b、Cyp11a1、Cyp11b2、Cyp17a1、Hsd3b1等基因的表达晚于二倍体,且表达量低于二倍体,造成雌二醇不能正常合成,最终导致性腺发育迟缓。     

Reproductive cycle of the south American scallop Amusium laurenti (Gmelin, 1791) (Bivalvia, Pectinidae)

Amusium laurenti is a functional hermaphroditewith well differentiated male and female gonadalareas. The gonadal index varies throughout the yearwith maximum values occurring in January, March andJuly, and minimum ones in August and September. Partial spawning (with respect to the individual andthe population) occurred from January to February andMarch to May. The major spawning event coincided withthe end of the period during which bottom watertemperature increased to temperatures above 26°C(July–August). Subsequently temperature decreased to22°C, with a period of gonadal restoration andincreasing gonadal index. Histological analysis ofthe gonads correlated with the gonadal index.     

褐藻羊栖菜繁殖生物学特征和生活史流程的补充研究

以温州市洞头区人工养殖羊栖菜和野生羊栖菜为研究样本,详细描述了羊栖菜成熟孢子体有性生殖,假根与侧生枝无性生殖的繁殖生物学特征和生活史流程。详细记录了羊栖菜卵、精子和受精卵的减数分裂和有丝分裂过程,假根、茎(主茎和侧生茎)、叶(气囊)和生殖托(雌托和雄托)等4类器官生长、发育和分化过程,胚、幼孢子体和成熟孢子体形态结构特征。在此基础上对现有羊栖菜繁殖生物学特征及生活史流程进行了补充和修正,增加了羊栖菜侧生枝无性生殖和羊栖菜幼孢子体期有性生殖的相关内容,并重新绘制了羊栖菜生活史流程图。该研究结果将为开展羊栖菜养殖生态学研究,深层次解析羊栖菜生殖节律、种群繁衍与环境关系奠定基础。     

金钱鱼性腺发育及其组织结构观察

采用常规石蜡切片,H.E染色研究了金钱鱼性腺发育及组织结构特征.结果显示,2+龄的金钱鱼性腺发育成熟.金钱鱼精巢为管型,可分为:精原细胞增殖期、精母细胞生长期、精母细胞成熟期、精子细胞变态期、精子成熟期等5个时期.从Ⅱ期精巢起,金钱鱼精巢的成熟系数(GSI)为0.2％～1.5％,精巢成熟系数在发育到精子细胞成熟期(Ⅴ期)达到峰值,肝重指数(HSI)在精子细胞变态期(Ⅳ期)达到峰值.金钱鱼卵巢的卵母细胞发育过程可分为5个时相,相对应的卵巢发育亦分为5个时期.从Ⅱ期卵巢起,金钱鱼卵巢的成熟系数为1.2％～14.9％,在发育到Ⅴ期时达到峰值,HSI在Ⅳ期达到峰值.Ⅱ时相卵母细胞出现卵黄核和滤泡膜.Ⅲ时相卵母细胞中开始出现油滴,卵黄颗粒.Ⅳ时相卵母细胞中卵黄颗粒与油滴的数量迅速增多.Ⅴ时相卵母细胞中卵黄颗粒融合成片,在卵母细胞中卵黄颗粒与油球之间在数量上没有明显的差异.根据切片观察,Ⅴ期卵巢中,除了Ⅴ时相卵母细胞外,还有一定数量的Ⅱ、Ⅲ和Ⅳ时相卵母细胞,卵母细胞发育呈现非同步型.并且发现在多数产完卵后的卵巢中,除空的滤泡外亦存在一定数量的Ⅱ、Ⅲ和Ⅳ期卵母细胞,因此推测,金钱鱼的产卵类型为分批非同步产卵类型.     

Photoperiodic manipulations of the reproductive cycle of sea bass (Dicentrarchus labrax) and their effects on gonadal development, and plasma 17ß-estradiol and vitellogenin levels

The annual profile of plasma vitellogenin (VTG) and 17ß-estradiol (E₂) levels, as well as gonadal development and spawning characteristics were investigated in captive female sea bass (Dicentrarchus labrax). Endocrine and gonadal changes were studied in fish reared under natural conditions or exposed to manipulated photothermal cycles. In natural conditions of photoperiod and temperature, sea bass spawned from February through March (East coast of Spain, 40°N 0°E). One or two months of constant long-days (15L/9D) in a constant short-day photoperiod regime (9L/15D) all-year-round, given early in the year (March and March–April), advanced spawning by 3 months. The same treatment applied later in the year (September–October) delayed spawning by 1 month, compared to controls.In all groups, changes in plasma VTG levels were correlated with E₂ levels, oocyte growth and spawning time. In control females, VTG was low (<100 ng ml^-1) during the summer, until its first surge in plasma 4 months before the beginning of spawning. The VTG (3.1 ± 0.3 mg ml^-1) and E₂ (4.1 ± 0.5 ng ml^-1) levels showed a single annual peak during late vitellogenesis, the time of the highest proportion of vitellogenic oocytes in the ovary. Constant high levels of VTG (1–1.4 mg ml^-1) and E₂ (1.6–1.9ng ml^-1) were maintained during the entire spawning time, together with the presence of vitellogenic oocytes, suggesting the existence of several waves of oocyte growth in the ovary and thus, several spawns per female. Endocrine profiles and oocyte development in fish exposed to constant photoperiods were similar to controls, but were shifted in time in relation to the displacement of the spawning time. In the fish showing advanced spawns, the duration of the gametogenic proces was compressed when compared to controls. The differences observed in the evolution of the reproductive-related factors in the advanced groups, which were exposed to a reduction in temperature to 15°C, suggest an influence of the temperature in the early stages of the reproductive cycle in sea bass.     

温度对许氏平鲉性腺分化的影响及其机制

本研究以许氏平鲉为实验对象,设置3组不同温度,即高温组(24℃)、对照组(20℃)和低温组(16℃),利用组织切片技术、酶联免疫法(ELISA)和实时荧光定量PCR(q RT-PCR)等技术探究温度对许氏平鲉性腺分化的影响及其潜在机制。结果显示,在40 dpb时,24℃下性腺发育最快,16℃下最慢,24℃、20℃和16℃下雌性率分别为70.0%、42.9%和33.3%。24℃和20℃下,E_2在较高水平持续时间较长,T水平在30～35 dpb时急剧降低,16℃下的E2水平迅速下降,35 dpb时T仍处于较高水平,说明在性腺分化期间,温度较高时,E_2水平较高,T水平较低,性腺偏雌性发育;反之,性腺偏雄性发育。在24℃下,35～40 dpb时的cyp19a1a mRNA的表达显著上调,可能与高温导致性腺分化偏雌性发育有关;在16℃下,30～50 dpb时ERβ2 mRNA的表达显著下调,说明ERβ2的表达被抑制可能与性腺偏雄性发育有关;24℃和20℃下,foxl2 mRNA的表达在25～35 dpb时处于较高水平,而低温组在30 dpb时表达水平开始上升,说明foxl2在性腺分化早期的高表达水平可能与卵巢分化的速率有关;在30～50 dpb,sox3、sox9和dmrt1的表达水平变化总趋势基本一致,说明三者之间的表达有一定的联系,可能与精巢的分化速率有关。     

Seasonal variations of trimethylamine oxide and urea in the blood of a cold-adapted marine teleost,the rainbow smelt

Trimethylamine oxide (TMAO), which has previously not been known to occur in significant amounts in the blood of marine teleosts, rose to concentrations of approximately 50 mM in the blood of winter-acclimatized rainbow smelt, Osmerus mordax. Urea also increased in the blood of cold-acclimatized smelt, and, with TMAO, contributed significantly to the winter freezing point depression. TMAO and urea also varied seasonally in muscle and liver tissues. TMAO and urea appeared to be reabsorbed from the urine. Losses of TMAO and urea from the head region of the fish, where most of the losses appeared to occur, were approximately 9 μmol and 8 μmol 100 g⁻¹ h⁻¹, respectively. Despite the effluxes, TMAO and urea levels in both the blood and muscle either increased or were maintained in starved, cold-acclimated fish, suggesting that they were synthesized in response to cold temperature. TMAO was also found in the blood of some other cold-hardy teleosts.     

怒江裂腹鱼鳃的显微和超微结构

通过光镜、扫描电镜及透射电镜技术,研究了怒江裂腹鱼(Schizothorax nukiangensis)鳃的组织结构和超微结构。结果表明,怒江裂腹鱼鳃基本结构与其他硬骨鱼相似,均由鳃耙、鳃弓、鳃丝以及鳃小片构成,且各部分具有不同的组织结构和细胞类型。扁平上皮细胞覆盖于整个鳃表面,其表面的纹路主要有3种类型,在鳃上不同的部位具有不同的结构和功能。线粒体密集细胞主要分布于鳃小片基部,仅有一种细胞类型,顶端膜内凹呈浅滩型,细胞内具有大量圆形的线粒体。怒江裂腹鱼鳃内扁平上皮细胞和线粒体密集细胞的形态结构与其在急流中游泳和摄食活动等生活习性相适应。本研究结果丰富了怒江裂腹鱼的基础生物学资料,并为阐明鱼类鳃的结构特征与其生活习性之间的关系提供参考。     

Fluctuations in gonadotropin and ovarian steroids during the annual cycle and spawning of the common carp

The main objective of the paper is to describe the annual changes in hormones associated with reproduction in the female carp under the conditions prevailing in the Israeli fish culture. Fish were sampled monthly throughout 1984; gonadosomatic index (GSI) was calculated and the diameter of ovarian follicles was measured. Gonadotropin (GTH) content in the pituitary and the circulating GTH, estradiol, testosterone and 17, 20-dihydroxy-4-pregnen-3-one (17, 20-P) were determined by specific radioimmunoassays. GTH, estradiol and testosterone showed a bimodal annual pattern. The late summer peak was associated with initial vitellogenesis while the peak in spring occurred just before spawning, which took place in April-May. A resting phase in ovarian activity was noted in June and July. The levels of 17, 20-P were very low compared with those occurring during spawning induction. The paper summarizes a previous study by our laboratory on the changes in circulating hormones, as related to oocyte stages, in female carp induced to spawn by a GTH-calibrated pituitary extract. This study associates the short but prominent peak in 17, 20-P with the presence of follicles with maturing oocytes in the ovary. A correlation was found between the percentage of oocytes with eccentric germinal vesicle initially present in ovarian biopsies of females carp and their spawning success after hypophysation. The paper describes simple means to ensure successful induction of spawning in carp by utilizing a calibrated pituitary extract and prior selection of females that would respond to the induction treatment.     

牙鲆三倍体批量化诱导及其生长和性腺发育观察

对牙鲆三倍体鱼苗的诱导、生长及性腺发育进行了一系列研究,发现在14.8～15.5 ℃的海水温度条件下授精,授精后3 min将受精卵放入3 ℃的海水中冷休克处理45 min,可以得到牙鲆三倍体;120日龄、348日龄、630日龄时对三倍体和二倍体的全长和体质量进行测量,发现在120日龄时二倍体与三倍体体质量差异不显著,348日龄时三倍体体质量明显大于二倍体体质量(P<0.05),630日龄时三倍体的全长和体质量均高于二倍体,且差异极显著(P<0.01)。通过比较630日龄时的性腺指数,发现二倍体牙鲆雌性和雄性的性腺指数分别是三倍体的3.3倍和3.1倍,三倍体牙鲆性腺明显小于二倍体,二倍体和三倍体卵巢指数之间及精巢指数之间差异均极显著(P<0.001);组织切片观察显示,在二倍体卵巢中可见正常卵母细胞,三倍体卵巢处于未分化的卵原细胞阶段,三倍体精巢中有精母细胞,但数量明显少于二倍体精巢。结果表明,研究采用的方法能够大量获得诱导率为100%的三倍体牙鲆鱼苗,三倍体成鱼性腺发育不良,并且其生长速度显著快于二倍体对照,适合在生产中推广。     

Effects of vasoactive intestinal polypeptide,substance P, 5-hydroxytryptamine,met-enkephalin and neurotensin on the swimbladder smooth muscle of two teleost species,Gadus morhua andAnguilla anguilla

The effects of vasoactive intestinal polypeptide (VIP), substance P (SP), 5-hydroxytryptamine (5-HT), neurotensin (NT) and met-enkephalin (mEnk) on the smooth muscles of the teleost swimbladder were studied in two teleost species, the Atlantic cod (Gadus morhua) and the eel (Anguilla anguilla). The study was made on isolated strip preparations of the muscularis mucosae, using putative transmitters corresponding to the immunoreactive materials that have previously been localized by immunohistochemical methods in nerves or endocrine/paracrine cells of the teleost swimbladder and/or the gastrointestinal canal. VIP was relaxatory on both cod and eel swimbladder smooth muscle, SP and 5-HT were constrictory in both species, and mEnk was excitatory on the eel swimbladder smooth muscle. Clear effects of these agents were usually seen at a concentration ofca. 10 nM in cumulative concentration/effect experiments. NT had no effect in either species. In the eel, the effects on the pneumatic duct were generally greater than on the swimbladder proper. The study indicates that the 5-HT and peptides previously observed by immunohistochemistry have physiological functions in the swimbladder.     

Differentiation and development of Leydig cells,and changes of testosterone levels during testicular differentiation in tilapiaOreochromis niloticus

Initial appearance and development of Leydig cells (LCs) during testicular differentiation in tilapia,Oreochromis niloticus, were investigated histologically. In addition, changes of testosterone levels in gonadal tissue and serum were examined by radioimmunoassay. In the gonads of fry at 23–26 days after hatching, initial testicular differentiation was confirmed by the observation of the differentiation of connective tissues into tissues which are characteristic of the adult testis. LCs, which were identified by the ultrastructural features (a moderate number of mitochondria with tubular cristae, well developed smooth endoplasmic reticulum and many free ribosomes) appeared initially at the time of testicular differentiation. LCs increased in number rapidly in the testes of fish at 70 days after hatching. Concomitant with this increase, spermatogonia increased in number. Testosterone was detectable in the fish at 40–50 days after hatching, but levels in tissue and serum were low. Testosterone levels increased gradually in the fish beginning at 70 days after hatching and increased still more at 100–150 days accompanying active spermatogenesis.     

三疣梭子蟹甲基转移酶2基因克隆及在胚胎、幼体和性腺发育过程中的表达分析

本研究采用SMART RACE方法克隆了三疣梭子蟹(Portunus trituberculatus)Dnmt2(Pt Dnmt2)基因。该基因c DNA全长为1291 bp,开放阅读框为1203 bp,编码400个氨基酸。结构域分析显示,PtDnmt2基因有典型的C5-DNA甲基化酶结构域。同源分析表明,PtDnmt2氨基酸序列与其他物种有较高的同源性。系统进化分析显示,三疣梭子蟹PtDnmt2氨基酸序列与罗氏沼虾(Macrobrachium rosenbergii)Dnmt2关系最近。qRT-PCR结果显示,PtDnmt2基因在三疣梭子蟹所有组织中均有表达,在卵巢中表达量显著高于其他组织(P0.05)。PtDnmt2基因在胚胎和幼体发育过程中的表达量随发育时期而变化,其在受精卵和多细胞时期无表达,从囊胚期开始出现,随着胚胎的发育表达量逐渐上升。在性腺发育不同时期PtDnmt2基因表达量存在显著差异,其在卵巢II期表达量最高,之后逐渐下降;在精巢中该基因的表达量随着精巢的发育逐渐上升,在IV期达到峰值。本研究结果表明,PtDnmt2基因参与了三疣梭子蟹胚胎、幼体和性腺发育调控。     

绿鳍马面鲀CYP17-I基因克隆及其在繁殖周期中的表达

为探究CYP17-I基因在绿鳍马面鲀繁殖周期中的作用及其与性激素水平变化的相关性,实验首先通过SmartTMRace技术克隆得到了绿鳍马面鲀CYP17-I c DNA全长序列1 580 bp,编码511个氨基酸。通过半定量RT-PCR技术检测了CYP17-I基因的时空表达,并采用放射免疫测定法检测雄鱼和雌鱼血清睾酮(T)和雌二醇(E2)的含量变化。结果发现,CYP17-I在卵巢、精巢和脑中表达量较高,其次为胃、心脏、脾脏、肾脏,在垂体和鳃中也检测到了微弱表达。在周期表达中发现,无论在卵巢还是精巢中,CYP17-I基因的表达水平与血清T含量密切相关,呈明显周期性变化,最高值均出现在5月份的卵细胞或精子成熟期,而与血清E2含量无显著的相关性。研究表明,CYP17-I在鱼类繁殖周期中对雄性激素睾酮的生成起关键的调控作用。     

Similarities and differences in oxynticopeptic cell ultrastructure of one marine teleost, Gadus morhua and one freshwater teleost, Oncorhynchus mykiss, during basal and histamine-stimulated phases of acid secretion

Oxynticopeptic cells (OC) from rainbow trout, Oncorhynchus mykiss, and Atlantic cod, Gadus morhua, were studied during basal acid secretion and during stimulation with histamine. An in vitro method for measuring acid secretion from isolated stomac a was used. The OC ultrastructure was studied using electron microscopy. During basal acid secretion, the OC had short apical microvilli, an extensive tubulovesicular network, large electron-dense vesicles and many mitochondria. Stimulation of acid s tion with histamine and ultrastructural changes in the OC occurred simultaneously. The acid stimulation promoted large increases in the length of microvilli, a decrease in the size of the tubulovesicular network and an increase in the diameter of the ndular lumen in cod. Large vacuoles were found to characterize the histamine-stimulated OC. These were located close to the apical membrane and sometimes opened into the lumen. During stimulation, electron-dense vesicles were often observed close to apical membrane and the large vacuoles. Sometimes these vesicles were observed inside the glandular lumen and/or the large vacuoles. It is concluded that the ultrastructure of the OC in the saltwater cod and the freshwater trout show similar characte ics as OC in other animal groups both during basal and high rates of acid secretion. In addition, vacuoles were found in both species OC during basal rates of acid secretion and they significantly increased in size during high rates of acid secretion propose that the OC vacuole have a part in the osmoregulation, since the increase was tenfold in cod but less then one-fold in trout, this difference was statistically significant.