Mitrofanis J
Department of Human Anatomy, University of Oxford, UK.
Eur J Neurosci. 1994 Feb 1;6(2):253-63. doi: 10.1111/j.1460-9568.1994.tb00268.x.
This study describes the development of the ferret thalamic reticular nucleus from Nissl-stained and from parvalbumin-immunostained sections. From early stages [embryonic day (E) 23-E25], there is a large group of ventral thalamic cells which lies between the dorsal thalamus and the primordial internal capsule. This group of cells, the primordial reticular nucleus, gives rise to the main body of the reticular nucleus, the perigeniculate nucleus and the perireticular nucleus. In the reticular nucleus, there are two waves of parvalbumin expression during development. The first wave begins prenatally in small cells which are seen rarely after birth. Their fate is not clear: they may have lost immunoreactivity, migrated elsewhere, or died. At the end of the first wave, a second wave begins in a distinct group of larger ovoid reticular cells, which appear to remain into adulthood. At about birth, the dorsocaudal pole of the reticular nucleus first forms the perigeniculate nucleus. During this developmental stage, cells which make up the reticular and perigeniculate nuclei are the only parvalbumin-immunostained structures in the thalamus. Thus, rather than develop from the dorsal thalamus, the perigeniculate nucleus seems to have its origins in the ventral thalamus together with the reticular nucleus. During development, the reticular nucleus is associated closely with a large mass of cells located in the internal capsule, called the perireticular nucleus. Later, the perireticular nucleus is dramatically reduced in size: that is, there is a large reduction in the number of perireticular cells seen per section and in the extent of the nucleus across the internal capsule. There are two cytoarchitectonically distinct groups of perireticular cells. One group of cells, called the large-celled perireticular zone (LPR), enters the internal capsule from early prenatal development (E25). Many of these cells reach the globus pallidus and extend as far as the cortical subplate zone. The LPR together with the subplate form an extensive neuronal network in the white matter during early development, which disappears later in development (about postnatal day 20). The second group of perireticular cells is made up of smaller cells and is called the small-celled perireticular zone (SPR). These small cells enter the internal capsule from the reticular nucleus just prior to birth. Many of the cells in the SPR remain in the adult.
本研究描述了雪貂丘脑网状核在尼氏染色切片和小白蛋白免疫染色切片中的发育过程。在早期阶段[胚胎日（E）23 - E25]，有一大群腹侧丘脑细胞位于背侧丘脑和原始内囊之间。这群细胞，即原始网状核，发育为网状核的主体、膝周核和网状周核。在网状核的发育过程中，有两波小白蛋白表达。第一波在产前开始于小细胞，出生后很少见到这些细胞。它们的命运尚不清楚：它们可能失去了免疫反应性、迁移到其他地方或死亡。在第一波结束时，第二波开始于一群明显的较大的卵圆形网状细胞，这些细胞似乎会持续到成年期。大约在出生时，网状核的背尾极首先形成膝周核。在这个发育阶段，构成网状核和膝周核的细胞是丘脑中仅有的小白蛋白免疫染色结构。因此，膝周核似乎并非起源于背侧丘脑，而是与网状核一起起源于腹侧丘脑。在发育过程中，网状核与位于内囊的大量细胞紧密相连，这些细胞被称为网状周核。后来，网状周核的大小显著减小：也就是说，每切片中可见的网状周核细胞数量以及该核横跨内囊的范围都大幅减少。网状周核细胞在细胞构筑上有两个不同的群体。一组细胞，称为大细胞网状周带（LPR），从产前早期发育（E25）就进入内囊。这些细胞中的许多到达苍白球并延伸至皮质下板区。在早期发育过程中，LPR与下板一起在白质中形成广泛的神经元网络，该网络在发育后期（约出生后第20天）消失。第二组网状周核细胞由较小的细胞组成，称为小细胞网状周带（SPR）。这些小细胞在出生前刚从网状核进入内囊。SPR中的许多细胞会保留到成年期。
