Titlbach M, Fält K, Falkmer S
Diabetes Res. 1985 Jan;2(1):5-15.
The endocrine pancreas of lambs was found to offer an interesting animal model for some aspects of normal and pathological postnatal maturation of the islet parenchyma also in man. Normal features in lambs, previously observed in man, were the high volume density (5-8%) of the islet parenchyma, the high incidence of D (somatostatin) cells (about 30% even in young adult sheep), and the concentration of PP cells to the posterior part of the head of the pancreas. Particularly interesting was the presence in newborn lambs of large islet bodies (0.2-2 mm in diameter), consisting (to more than 90%) of large, argyrophil (Grimelius), granulated, parenchymal cells which were found to be insulin immunoreactive. Their secretion granules were smaller and more electron dense than those of the mature non-argyrophil B (insulin) cells. The argyrophil insulin immunoreactive cells often formed intercellular cavities and they could be equipped with microvilli and even cilia. At birth, these large islet bodies constituted more than half of the total islet parenchyma, but already during the first 10 days they underwent marked regressive changes (i.e. with large haemorrhages; "Blutinseln"); in 2-month-old lambs and in young adult sheep they had practically disappeared. These argyrophil insulin immunoreactive islet cells were considered to represent immature B cells with some persisting foetal characters. In 1- and 4-day-old lambs some non-argyrophil B cells in small islets of Langerhans harboured secretion granules of both types of B cells, indicating that a transformation could occur from 1 type to the other in this dual population of islet B cells. It was speculated that the argyrophil insulin immunoreactive cells could be homologues to the argyrophil islet cells often occurring in insulin-producing islet-cell neoplasms and in nesidiodysplasia in man.
人们发现，羔羊的内分泌胰腺为研究人类胰岛实质在出生后正常和病理成熟的某些方面提供了一个有趣的动物模型。羔羊身上先前在人类身上观察到的正常特征包括：胰岛实质的高体积密度（5 - 8%）、D（生长抑素）细胞的高发生率（即使在成年幼羊中也约为30%）以及PP细胞在胰头后部的集中分布。特别有趣的是，新生羔羊体内存在大胰岛体（直径0.2 - 2毫米），其组成（超过90%）是大型、嗜银（格里米柳斯法染色阳性）、有颗粒的实质细胞，这些细胞被发现具有胰岛素免疫反应性。它们的分泌颗粒比成熟的非嗜银B（胰岛素）细胞的分泌颗粒更小且电子密度更高。嗜银胰岛素免疫反应性细胞常常形成细胞间腔，并且可能配备有微绒毛甚至纤毛。出生时，这些大胰岛体占胰岛实质总量的一半以上，但在出生后的头10天内它们就经历了显著的退行性变化（即伴有大量出血；“血岛”）；在2月龄羔羊和成年幼羊中它们几乎消失了。这些嗜银胰岛素免疫反应性胰岛细胞被认为代表具有一些胎儿特征残留的未成熟B细胞。在1日龄和4日龄的羔羊中，一些位于胰岛小体中的非嗜银B细胞含有两种类型B细胞的分泌颗粒，这表明在这种双重的胰岛B细胞群体中可能发生从一种类型到另一种类型的转变。据推测，嗜银胰岛素免疫反应性细胞可能与人类胰岛素产生性胰岛细胞瘤和胰岛发育异常中经常出现的嗜银胰岛细胞同源。
