Rettig T, Halata Z
Department of Anatomy, University of Hamburg, FRG.
Acta Anat (Basel). 1990;137(3):189-201. doi: 10.1159/000146820.
The sensory innervation of the anal canal of the pig was investigated by light and electron microscopy. The distribution of the different types of sensory nerve endings correlates with the histology of different zones: (1) After the rectal mucosa there was a zone lined with nonkeratinized stratified squamous epithelium. (2) A middle zone was lined with keratinized stratified squamous epithelium. Here the dermis already showed a papillary and reticular layer. (3) The last zone showed hairy skin with a high hair density. The following nerve endings were found: Free nerve endings reached the stratum superficiale in nonkeratinized squamous epithelium and the stratum granulosum in the keratinized squamous epithelium. Dermal free nerve endings were found in all zones near the epithelium and two different types were identified as those derived from C-fibers and those from A-delta-fibers. Merkel nerve endings showed different features depending on their location. Few Merkel-like cells were found in the epithelium of the anal crypts. Typical Merkel Tastscheiben were located at the base of epithelial ridges or pegs in zones 2 and 3. The number of Merkel cells varied up to 200. The myelinated afferent fiber supplied 10-15 Merkel cells. Merkel cells were also found regularly in the outermost layer of the external rooth sheath of hair follicles at about the same level as perifollicular nerve endings. Lamellated corpuscles were found in the dermis of all zones except the cranial part of zone 1, where the anal crypts are located. Generally they consisted of a central nerve terminal which may be branched. Each terminal was surrounded by an inner core of concentrically arranged lamellae of the terminal Schwann cell and one or several inner cores were included in a capsule of perineural cells. The size of the corpuscle, the regularity of the inner core and the number of capsular layers depended on the location of the corpuscle.(ABSTRACT TRUNCATED AT 250 WORDS)
通过光镜和电镜对猪肛管的感觉神经支配进行了研究。不同类型感觉神经末梢的分布与不同区域的组织学相关：（1）直肠黏膜后有一个内衬非角化复层鳞状上皮的区域。（2）中间区域内衬角化复层鳞状上皮。此处真皮已显示出乳头层和网状层。（3）最后一个区域为毛发密集的多毛皮肤。发现了以下神经末梢：游离神经末梢到达非角化鳞状上皮的浅表层和角化鳞状上皮的颗粒层。在靠近上皮的所有区域均发现了真皮游离神经末梢，并且鉴定出两种不同类型，即源自C纤维的和源自Aδ纤维的。默克尔神经末梢根据其位置表现出不同特征。在肛门隐窝的上皮中发现很少的默克尔样细胞。典型的默克尔触觉小体位于第2和第3区上皮嵴或乳头的基部。默克尔细胞的数量变化可达200个。有髓传入纤维支配10 - 15个默克尔细胞。在毛囊外根鞘的最外层也经常发现默克尔细胞，其位置与毛囊周围神经末梢大致相同。除了第1区靠近肛门隐窝的颅部外，在所有区域的真皮中均发现了环层小体。一般来说，它们由一个可能分支的中央神经终末组成。每个终末被施万细胞同心排列的薄片组成的内核包围，一个或几个内核被神经周细胞的被膜包裹。小体的大小、内核的规则性和被膜层数取决于小体的位置。（摘要截断于250字）
