39 人胚胎胰岛发生的研究

<正>本文系用新鲜人胚胎标本58例,通过HE染色,嗜银染色、改良Gomori法染色.组织化学方法以及透射电镜技术对胰岛的发生及分化进行研究,结果表明:胰腺原基在第8周时融合成多分支的管状结构,第13周在胰管中分化出胰岛细胞团,其中可见嗜银细胞;第14周发现含醛复红颗粒的B细胞,散在存在,且随胎龄增加而增多.胚胎期胰尾的胰岛数多于胰头,胰腺内、外分泌部及间质比例随胎龄变化,其中内分泌部比例一直增加,到新生儿最高.电镜观察第15周时胰岛细胞中可见特征性的分泌颗粒,A、B、D三种细胞可识别;在高尔基复合体附近可见有电子密度低的颗粒;整个胚胎期可见一种无颗粒、细胞器少的细胞存在于内、外分泌部;第16周时A、B二种细胞出现分泌活动,主要以胞吐的方式进行;但在毛细血管内皮中发现的分泌颗粒,表明其分泌方式尚可以另外的途径进行.胚胎期胰腺中还可见内分泌细胞夹杂于外分泌细胞之间,外分泌细胞中出现内分泌细胞的颗粒.     

胎儿胰腺的显微形态学观察

目的观察胎儿胰腺的结构特点,为胎胰临床应用提供资料.方法取30例21～41W胎儿胰腺,利用超薄切片及透射电镜观察和石蜡包埋切片HE染色、SP免疫组化方法进行染色.结果胎儿胰腺内分泌部随胎龄增加而相对减少;外分泌部逐渐增加.A、B细胞超微结构在21～41W无明显变化.结论 25～35w胎儿更适合临床应用.     

大鼠增龄中胰腺超微结构的变化及胰岛的分布规律

目的探讨胰腺超微结构的增龄变化及胰岛的分布规律,以提供胰腺移植的参考。方法取30只健康sD大鼠,分3组,幼年、青年、老年各10只,每只取胰头、体、尾做组织切片光镜观察。每组选3只取胰尾做透射电镜观察。结果透射电镜观察老年鼠胰腺外分泌部的腺细胞,胞核固缩,酶原颗粒减少,线粒体脱嵴肿胀,粗面内质网扩张,出现脂滴,溶酶体增多,而内分泌部的B细胞分泌颗粒空晕增宽,数量减少,粗面内质网脱粒,线粒体减少。A细胞无明显年龄变化。光镜观察老年鼠胰腺小叶间结缔组织增生,胰岛的分布以幼鼠胰尾数量为多。结论胰腺外分泌部的腺细胞和内分泌部的B细胞呈现与年龄相关的结构变化,胰岛的分布以幼鼠胰尾的胰岛数目为最多。提示胰腺移植的供体以幼年胰尾为佳,老年不宜。     

人胚胎发育中胰腺细胞的增殖变化

目的：探索人胚胎发育过程中胰腺细胞增殖水平。方法：应用免疫组织化学EnVision法，检测30例人胚胎胰腺组织PCNA的表达。结果：各胎龄段胰腺外分泌细胞PCNA的阳性表达均显著高于内分泌细胞，胚胎发育早期阶段(9-14w)外分泌细胞PCNA的阳性表达明显高于其它胎龄，胚胎发育晚期阶段(29-37w)内分泌部PCNA阳性率高于其它胎龄组。结论：在胚胎发育过程中胰腺外分泌部细胞增殖水平高于内分泌部，随着胎龄的变化，胰腺内、外分泌细胞的增殖水平也发生了变化。     

大鸨(Otis tarda limaells)胰腺超微结构研究

目的　观察大鸨胰腺超微结构 ,探讨大鸨胰腺功能。　方法　透射电镜观察 3例大鸨胰腺。　结果　大鸨的胰外分泌部为管泡状腺 ,腺小叶由于缺乏叶间结缔组织而界限不如哺乳动物的明显。叶间隙似导管 ,小叶间导管管壁简化以至由胰腺分泌细胞代替。仅在 3个小叶间能见到单个长梭状结缔组织细胞 ,其胞质变细伸展进入两叶间隙中间构成 1条中等密度线。外分泌细胞可分为明暗两种。胰的内分泌细胞呈岛状或单个散布于胰外分泌腺中。胰岛分A和B两种 ;A胰岛仅由A细胞构成。B胰岛主要由B和D两种细胞构成 ,其中B细胞数量多 ;D细胞含量少。　结论　大鸨胰腺具有一些不同于其他动物及适应于飞翔的结构特点     

胰抑素在人,猪和豚鼠胰腺分布的免疫组织化学研究

胰抑素(pancreastatin,PS)是一种具有抑制胰岛分泌作用的新肽。本研究用ABC免疫染色法,在Bouin液固定的常规石蜡切片上,研究了胰抑素在豚鼠,猪和人胰腺内的定位和分布,并用相邻切片双标记法,观察了它与胰岛素的共存关系。结果发现,在人胰腺胰抑素样免疫反应(PLI)细胞主要分布于胰岛的周边部。在猪和豚鼠,大部分胰岛细胞呈阳性胰抑素样免疫反应。用相邻薄切片免疫染色技术证明,猪和豚鼠的PLI细胞主要是B细胞。在3个种属胰腺外分泌部的导管和腺泡等处,也均见有PLI细胞分布,在豚鼠胰腺尤为多见。本文对胰抑素在3个种属胰腺不同分布方式的意义进行了讨论。     

胃肠激素与胰腺外分泌

胰腺是具有内外分泌双重功能的重要器官。内分泌的胰岛细胞可分为A、B、D、和PP细胞等,分散在外分泌的胰腺腺泡之间。胰腺的内外分泌功能是互相影响,互相调节的。本文主要介绍胃肠激素与胰腺外分泌的关系。 一、胃肠激素对胰腺外分泌功能的调节 胰腺外分泌受神经和激素两方面调节。近年研究发现有些神经调节是通过多肽类神经递质发挥作用。可影响胰腺外分泌的激素     

肝部分切除后再生期间胰岛细胞的免疫组织化学研究

成年雌性大鼠50只,分为肝部分切除组、假手术组和正常对照组。手术后d 1、2、3、6、14分批取胰尾。石蜡切片用免疫组织化学PAP法,分别显示含胰岛素的B细胞、含C肽的B细胞、含高糖素的A细胞和含生长抑素的D细胞,观察肝再生期间胰岛B、A和D细胞激素分泌活动的变化。根据胰岛细胞内免疫反应物含量不等,将胰岛细胞分泌活动分成3级:+、++和+++,分别计算各级胰岛细胞所占的百分比,作为判断胰岛细胞激素分泌活动的指标。结果发现,肝部分切除后1～3 d B细胞释放胰岛素活动增强,术后3～6 d转为胰岛素的合成和/或贮存加强。术后1～3d,A细胞逐次增强高糖素的释放。此时,D细胞的释放活动却减弱。至术后d 6,A细胞分泌活动已趋正常,但D细胞增强生长抑素的释放。至术后d 14,胰岛细胞的激素分泌活动均恢复到正常水平。胰岛B细胞和A细胞激素分泌活动的变化,与肝再生过程呈现密切而平行的关系。D细胞的变化则可能反映出对B细胞和A细胞内分泌活动的调控作用。     

胰岛细胞分化与胚体发育的相关性研究

目的探讨胚胎发育中胎龄及胚体大小与胰岛细胞分化的相关性。方法收集妊娠6～14周的胚胎20例,测其重量,顶臀径并通过免疫组织化学染色观察胰高血糖素（glucagon）在胰岛细胞分化过程中的表达。结果妊娠9周左右,胚体重约2．89±0．12g,顶臀径约80．0±2．8mm,此时胰腺导管上皮细胞开始分化出胰岛细胞,并且具有内分泌功能。结论妊娠发育的胚胎在胎龄9w、顶臀径30mm、重量约为2．89g左右时,胰岛细胞开始从胰腺导管上皮细胞分化。     

人胎胰腺GnRH免疫反应细胞

目的：探讨促性腺激素释的激素(GnRH)免疫反应细胞在人胎胰腺的存在部位和数量变化。方法：用免疫组织化学SABC法，对37例第10-32w人胎胰腺内的GnRH-IR细胞进行观察，并用体视方法分析其数量变化。结果：人胎胰腺GnRH-IR细胞出现于第13w，其数密度随胎龄增加而增大；分布于胰岛及外分泌部的腺泡上皮、导管上皮细胞间。位于胰岛的GnRH-IR细胞呈圆形、卵圆形或多边形。位于腺泡上皮细胞间的GnRH-IR细胞多为锥体形，外分泌部的GnRH-IR细胞均为开放型细胞。结论：胰腺GnRH-IR细胞于胚胎第13w出现，广泛存在于内、外分泌部，其数量随胎龄增加而增加。     

Insulin-like growth factor I in the pancreas of normal and diabetic adult rats

Insulin-like growth factor I (IGF-I, somatomedin C) was mapped by immunocytochemistry in the pancreas of normal and experimentally influenced rats. The polyclonal IGF-I antiserum K 37 was characterized and demonstrated to be specific. In the exocrine pancreas some duct cells showed IGF-I immunoreactivity, other components being negative. The three main endocrine cell types in the islets of Langerhans were IGF-I immunoreactive, most strikingly the D cells. Hypophysectomy resulted in loss of IGF-I immunoreactivity in all three endocrine cell types, i.e. D, A and B cells, while the levels of somatostatin, glucagon and insulin, respectively, remained unchanged. Starvation seemed to increase and feeding to decrease the IGF-I immunoreactivity in the B cells. Cysteamine pre-treatment reduced the normally intense IGF-I and somatostatin immunoreactivities in the D cells. In rats made diabetic with alloxan or streptozotocin, the B cells were irreversibly damaged and lost both their insulin and IGF-I immunoreactivities, while the IGF-I immunoreactivity was increased in A cells; the D cells remained unchanged. The concentrations of IGF-I mRNA in the pancreas were almost equal in normal and alloxan diabetic rats as were the concentrations of extractable IGF-I. We conclude that IGF-I immunoreactive material can be demonstrated in adult animals in all endocrine islet cells, most prominently in the D cells. The expression of IGF-I immunoreactivity is in part under pituitary control. In the adult rat only one islet cell type synthesizes IGF-I immunoreactive material, i.e. the D cells, while, in contrast, the B cells are likely to be a major IGF-I source in fetal and neonatal islets.     

Morphometric analysis of the endocrine cell composition of rat pancreas following treatment with streptozotocin and nicotinamide

Using immunohistochemistry and linear scanning, a morphometric analysis was made of the composition of the rat endocrine pancreas at sequential intervals after combined injections of streptozotocin (SZ) and nicotinamide (NA). One week after treatment, the volume of islet tissue was significantly higher than that of the corresponding, saline-injected controls, probably as the result of acute hyperplasia of insulin- and somatostatin-positive cells. However, at all time periods thereafter (6, 20, and 36 weeks), the drug-treated rats showed decreased islet volumes compared to controls. Analysis of aggregate (total) volumes of hormone producing cells at various time periods after drug treatment indicated that decreases in insulin (B-cell) volumes only partially accounted for the observed changes in total islet volume. There were, in addition, early decreases in glucagon (A-cell) and increases in somatostatin (D-cell) volumes. The results suggest that SZ/NA treatment caused limited islet B-cell destruction and transient changes in the proportions of islet A and D cells. Microscopic endocrine tumors were observed at 20 weeks, and both gross and microscopic tumors were observed 36 weeks after SZ/NA treatment. When islet and tumor tissues were included in computation, aggregate volumes of insulin and somatostatin-positive cells were markedly increased, with no significant changes in glucagon-positive cell volumes compared to controls, indicating that the tumors were rich in B and D cells, but poor in A cells. These results are discussed in relation to changes in glucose tolerance and serum insulin levels, and to islet cell volumes following treatment with a diabetogenic dose of streptozotocin alone.     

Major histocompatibility complex protein expression on pancreas and pancreatic islet endocrine cell subsets

To determine which cells in the human and rat pancreas and islets express class I and II histocompatibility complex proteins, double indirect immunofluorescence and the Staphylococcus aureus rosette method were used. Islet preparations used permitted positive endocrine and class I or II protein identification. Class I and II proteins were expressed in pancreatic vascular endothelium and passenger cells of the mononuclear cell type. Antibodies directed to class I or beta 2 microglobulin reacted with dispersed islet B, A, and D cells, whereas class II protein antibodies were associated with only islet B and A cells. Islet B-cell class II proteins decreased after 20 days of in vitro culture. These results suggest that 1) a variety of pancreas and islet nonendocrine cells can express class I and II proteins, 2) normal pancreatic islet endocrine cells not only express class I proteins but also class II proteins, and 3) in vitro islet culture results in reduced expression of class II proteins by islet B cells.     

Phases in the early development of the human islet organ

The study included morphometric examination and biochemical investigation of 41 human pancreata taken from 14th to 26th weeks of fetal development. 3 phases of development were observed. Phase I (weeks 14 to 16) is characterized by the presence of mainly islet buds. They were originated from the ducts and are vascularized during week 16. During phase II (17th to 20th weeks) the islet buds were detached from the ducts and they formed new mantled islets with the B cells in the centre. Non-B cells are situated on the periphery around the insulin producing cells. Phase III lasts from week 21 to week 26. During this phase B cells and non-B cells become more irregularly positioned within the islet, a cytology, which is similar approximating that of as also found in adult human islets. The changes of islet structure during pancreatic development are accompanied by other typical phenomena: Islet size increases during phases I and II, but decreases again during phase III. The proportion of isolated B cells outside of the islets varies during this stage of fetal development, but they generally account for about 15% of the total islet organ. This should be taken into account when assessing the islet function De Pablo et al. (1985) on a morphological basis.     

Neuron-specific enolase (NSE) as a neuroendocrine cell marker in the human fetal pancreas

Using the PAP technique, we investigated the presence of neuron-specific enolase in the human fetal pancreas of 10, 12, and 14 weeks of gestational age. Neuron-specific enolase is present in the islet cells in the 10th week. Positive cells are situated mainly in duct epithelium. The number of cells with a positive reaction increases from the 12th to the 14th week. In the 14th week, they are clustered either near the ducts or between the acini. The numbers and localizations of the cells correspond to those obtained in previous studies with 4 basic islet cell types in the same material. The present results are a further proof that islet cells are biologically active during early fetal development.     

Transplantation of the fetal rat pancreas: Quantitative morphological analysis of islet tissue growth

When pancreases from fetal rats were transplanted beneath the kidney capsule of isologous normal adult recipients, continued growth and differentiation of the endocrine portion of the pancreas occurred. While limited amounts of acinar tissue were identifiable in the early transplant period (7 days), such cells were absent in long term transplants (14 and 21 days). In contrast, while few definitive islet beta cells were present at the time of transplantation, following 21 days at the kidney site large circumscribed islets comprised of heavily granulated beta cells in association with duct epithelial cells predominated. Mitotic figures were seen in both these cell populations. Total islet mass had increased over 20-fold during the transplantation period. Similar results were observed if fetal pancreases were grown in organ culture for ten days prior to transplantation. Continued islet and duct cell growth, as evidenced by mitotic figures and an increase in absolute islet cell mass was obtained in such cultured explants when transplanted to either isogenic or allogenic recipients. These observations support the hypothesis that fetal pancreas may be the best source of donor material for transplantation to diabetic recipients, in part, due to the continued growth and differentiation of the islet tissue during the transplantation period.     

Islet amyloid polypeptide in proliferating pancreatic B cells during development, hyperplasia, and neoplasia in humans and mice.

The occurrence of islet amyloid polypeptide (IAPP) immunoreactivity was investigated in fetal pancreas, islet cell hyperplasia, and tumors in humans and mice. Transgenic mice heritably developing endocrine tumors of the pancreas (AVP/SV40, Rip 1 Tag2/Rip2PyST1 and Glu2-Tag strains) were used as murine models of islet cells proliferative disease. In the mouse, IAPP immunoreactivity was found in B cells at embryonic day 12 (E12), paralleling the onset of insulin immunoreactivity. In hyperplastic/dysplastic islets and in B-cell tumors of transgenic mice (n = 16), IAPP immunoreactivity was localized consistently to insulin-immunoreactive cells. Ultrastructural single- and double-immunogold labeling of transgenic mice B-cell tumors (n = 3) showed insulin and IAPP to be colocalized in beta granules. In human fetuses, IAPP immunoreactivity was found in insulin-immunoreactive B cells, but at a later gestational age than the onset of insulin immunoreactivity. In pancreatic specimens of infantile/neonatal persistent hyperinsulinemic hypoglycemia (11 cases) and in pancreatic endocrine tumors (21 cases, 10 of which were functioning insulinomas), IAPP immunoreactivity was found consistently in insulin-immunoreactive B cells. Congo-red-positive amyloid deposits present in tumors also were IAPP immunoreactive. Ultrastructural single and double immunogold labeling of infantile/neonatal persistent hyperinsulinemic hypoglycemia cases (n = 3) and functioning insulinomas (n = 2) showed IAPP and insulin to be colocalized in beta granules. In addition, IAPP immunoreactivity was observed in amyloidlike fibrils. These findings indicate that IAPP is a constitutive component of B cells. Possible relationships between IAPP and insulin expression and interspecies differences are suggested and discussed.     

Nesidioblastosis and endocrine hyperplasia of the pancreas: a secondary phenomenon

Diffuse endocrine cell proliferation (nesidioblastosis) and islet cell hyperplasia are considered causes of organic hyperinsulinism but have not been distinguished (by histometric or immunohistologic methods) from the normally variable pancreatic islet cell population during development and in adults. Therefore, in this study morphologic, immunohistologic (to detect insulin, glucagon, somatostatin, and pancreatic polypeptide), and morphometric features were evaluated in 1) normal pancreases (from fetal to adult; n = 49); 2) pancreases from patients with nesidioblastosis (n = 5); and 3) tumor-associated pancreases (TAP) from patients with insulin-producing islet cell tumors (n = 8). The study of normal postnatal development revealed that all features of fetal development remain present after birth and that the diagnosis of any diffuse endocrine disorder should therefore be based essentially on quantitative histometric parameters (total endocrine area, islet size distribution, distribution of each endocrine cell type). With these parameters endocrine cell hyperplasia was demonstrated in TAP from adults due to increased numbers of A and D cells. However, in the cases previously diagnosed as pathologic nesidioblastosis, all parameters were within the normal range. Thus, nesidioblastosis does not appear to be a pathologic entity. Careful re-examination of the pancreases, prompted by these data, revealed small islet cell tumors in three of these five cases. It is concluded that the endocrine pancreas can react rapidly, both morphologically and functionally, to changes in hormonal feedback, e.g., islet cell tumors. Therefore, the observation of a diffuse islet cell disorder in a patient with hyperinsulinism should not be considered an indication that an islet cell tumor is not present.