The distribution of acetylcholinesterase(AChE)-positive nerves in chicken pancreas demonstrated by light and electron microscopy

The distribution of acetylcholinesterase (AChE)-positive nerve fibers in the chicken pancreas was investigated with histochemical methods at the light and electron microscopic level. AChE-positive nerve bundles were found to run along the pancreaticoduodenal artery and their branches proceed into interlobular connective tissue, form a plexus around the interlobular secretory ducts and small arteries, and penetrate the exocrine parenchyma. Intrapancreatic ganglia showing a strong AChE activity were detected within the interlobular connective tissue or between acini. The exocrine pancreas was richly innervated with AChE-positive terminals which contained a few large dense-cored vesicles (about 100 nm in diameter) and many small clear vesicles (about 50 nm in diameter). Such terminals made contact with intercalated ductular cells and the smooth muscles of larger blood vessels. The endocrine pancreas was supplied with fewer nerves than the exocrine pancreas. A different distribution of AChE-positive fibers was noticed between A- and B-islets which were distinguished immunohistochemically. B- and D-cells were richly innervated by AChE-positive nerves, whereas A-cells, only poorly. These observations make clear that the cholinergic system relates to the regulation of both exocrine and endocrine tissues, except A-cells, in the chicken pancreas.     

Muscular innervation of the proximal duodenum of the guinea pig

We investigated the muscular structure and innervation of the gastroduodenal junction in the guinea pig. In the gastroduodenal junction, the innermost layer of the circular muscle contained numerous nerve fibers and terminals. Since this nerve network continued onto the deep muscular plexus (DMP) of the duodenum, we surmised that the numerous nerve fibers in the gastroduodenal junction were specialized DMP in the most proximal part of the duodenum. The innermost layer containing many nerve fibers was about 1,000 microm in length and 100 microm in thickness in the proximal duodenum. This layer contained numerous connective tissue fibers composed of collagen and elastic fibers. Five to 30 smooth muscle cells lay in contact with each other and were surrounded by fine connective tissue. The nerve fibers in the proximal duodenum contained nerve terminals immunoreactive for choline acetyltransferase, dynorphin, enkephalin, galanin, gastrin-releasing peptide, nitric oxide synthase, substance P, and vasoactive intestinal polypeptide. Adrenergic fibers which contained tyrosine hydroxylase immunoreactivity were rare in the proximal duodenum. In the innermost layer of the proximal duodenum, there were numerous c-Kit immunopositive cells that were in contact with nerve terminals. This study allowed us to clarify the specific architecture of the most proximal portion of the duodenum. The functional significance of the proximal duodenum in relation to the electrical connection and neural cooperation of the musculature between the antrum and the duodenum is also discussed.     

Structure and distribution of the lymphatic vessels in the parietal pleura of the monkey as studied by enzyme-histochemistry and by light and electron microscopy.

The entire distribution of lymphatics in whole mount preparations of the Japanese monkey was studied using the enzyme-histochemical technique reported by KATO et al. (1990, 1991). In this staining, the lymphatic endothelium was colored dark brown by its positive 5'-nucleotidase activity, while most blood vessels (especially arterioles) were colored blue due to their positive alkaline phosphatase reaction. The whole mount preparations of the pleura treated enzyme-histochemically clearly indicated the distribution, branching patterns and running courses of lymphatic vessels. They revealed numerous short blind-ending knobs which represented the initial portions of lymphatics. These knobs were seen near the surface of the parietal pleura along its entire extent. In the costal and diaphragmatic pleura, the lymphatics ran parallel to the intercostal muscle fibers, but perpendicular to the tendinous and muscular fibers of the diaphragm; they formed ladders, independent of the courses of blood vessels. In the mediastinal pleura, lymphatic vessels showed a tree-like branching accompanying blood vessels. Under the light microscope, toluidine-blue stained semithin sections revealed the initial part of lymphatics as a small irregularly outlined cavity (7-10 microns in diameter) surrounded by a dense connective tissue. This lymphatic dilation was sometimes located close to a thin mesothelial layer. Such a structure suggesting a "stoma" was seen near the attachment of the muscular diaphragm to the sternum and along the borders of the ribs. Transmission electron microscopy revealed an occasional interruption in the mesothelium. This stoma continued to a submesothelial cavity whose base comprised an attenuated endothelium of an extended lymphatic vessel.     

The atrioventricular valves of the guinea-pig. II. An ultrastructural study

Each atrioventricular valve of the guinea-pig consists of a core of connective tissue and muscle covered by endothelial cells. The muscle forms an annulus at the attached margin of the valve adjacent to the fibrous annulus. Some fibers from the lower part of the muscular annulus turn sharply toward the free margin of the valve and form a complex meshwork. These fibers resemble atrial muscle, but are noteworthy in that each contains myofibrils that are oriented in different directions. Some muscle fibers have features similar to those of conducting fibers, i.e., glycogen rich cytoplasm containing few myofibrils. Unmyelinated nerve fibers are numerous in both the mitral and tricuspid valves, but myelinated fibers were found only in the mitral valve. Typical adrenergic terminals were found adjacent to some cholinergic endings. Mitochondria-filled terminals (sensory?) and a third type of motor terminal were present also. Bundles of collagenous fibers extend from the chordae tendineae into the valve cusps where they fan out into small bundles. The other formed elements of the stroma are microfibrils and a flocculent material. There are a few elastic fibers beneath the endothelium. Interstitial cells, many of which possess solitary flagella are scattered throughout the matrix.     

Acetylcholinesterase (AChE)-positive innervation of the guinea-pig spleen

The presence and intraorgan distribution of the acetylcholinesterase (AChE)-positive nerve structures in the guinea-pig spleen were studied by means of the direct thiocholine method. Visualized AChE-positive nerve fibres entered the guinea-pig spleen at its hilum in the vicinity of the splenic artery branches and intra parenchyma were gradually distributed to form thicker periarterial nerves and also fine adventitial nerve plexus. In described topography the AChE-positive nerve fibres were identified in association with the central artery running through the white pulp. Some of the perivascular nerve fibres associated with the central artery extended away and passed into the periarterial lymphatic sheath (PALS) to reach the marginal zone and in continuation entered into the mantle zone of lymphatic follicles. Several AChE-positive nerve fibres were seen in the red pulp but less in the splenic capsule. We did not find any AChE-positive nerve cells in the guinea-pig spleen.     

Postnatal development of lymphatic vessels and their smooth muscle cells in the rat diaphragm: a confocal microscopic study

This paper reports on how lymphatic vessels and their smooth muscle cells develop in the diaphragm of postnatal rats. Lymphatic endothelial cells in the diaphragm were labeled by an intraperitoneal injection of DiI-labeled acetylated low-density lipoprotein (DiIac-LDL). During postnatal week 1, DiI-ac-LDL was detected in many free cells in addition to distinct endothelial cells that formed lymphatic vessels. Occasionally, saccular lymphatics isolated from previously formed lymphatics were recognized; these were referred to as lymphatic islands. The DiI-ac-LDL-labeled free and lymphatic endothelial cells showed immunoreactivity for CD 34 and Flt-4, but most of them did not express either OX 62 or ED 1 immunoreactivity, with only some showing ED 1 immunoreactivity. This suggests that most of the DiI-ac-LDL-labeled elements were lymphatic endothelial cells, and that some were macrophages. After postnatal week 1, the DiI-ac-LDL positive cells were restricted to lymphatic vessels. Until postnatal week 6, lymphatic vessels increased as the diaphragm enlarged. Towards the end of postnatal week 2, free cells expressing alpha-smooth muscle actin (alpha-SMA) immunoreactivity increased in the diaphragm, and some of these were in contact with lymphatics. A coarse plexus of smooth muscle cells surrounding the lymphatic vessels first appeared at postnatal week 2, and this plexus became denser with age. Our findings indicate that lymphatic vessels are formed not only by sprouting from previously formed lymphatic vessels but also by migrating endothelial cells, and that smooth muscle cells may be differentiated from mesenchymal cells to form a plexus surrounding the lymphatic vessels.     

Ultrastructural localization of acetylcholinesterase activity in Hirschsprung's disease

Localization of acetylcholinesterase activity in congenital megacolon was studied by light and electron microscopy. Acetylcholinesterase activity was strongly positive at the light microscopic level in the Auerbach's plexus of the normal segment and in proliferated nerve fibers of the aganglionic segment. The reaction product observed by electron microscopy was deposited in and between the plasma membranes of the ganglion cells, nerve fibers, and their terminals. The product was also observed in the rough endoplasmic reticulum, nuclear envelope, and Golgi apparatus of the ganglion cells. Acetylcholinesterase activity in the aganglionic segment was observed in and between the plasma membranes of nerve fibers and nerve terminals, which terminated in proximity to smooth muscle cells. Reaction deposits were also observed in the interspace between nerve terminals and smooth muscle cells, suggesting direct innervation of smooth muscles by extrinsic nerve fibers.     

A co-localization study on the ovine pancreas innervation

The expression of DbetaH and several neuropeptides was investigated in neuronal elements of the ovine pancreas using double immunocytochemical stainings. Immunoreactivities to DbetaH, NPY, VIP and SP were seen to various extents in nerve terminals associated with the acini, islets, ducts, blood vessels, interlobular connective tissue as well as in the neurons of intrapancreatic ganglia. The expression of CGRP was limited to nerve fibers lying in the connective tissue septa, amongst the acini and in close vicinity to the pancreatic blood vessels. Single GRP-positive nerve endings were located around the acini, ducts and in the interlobular connective tissue. With the exception of the ductal system in a co-localization of NPY with DbetaH was frequently found in all regions of the pancreas. Moderately numerous blood vessel-associated VIP-positive nerve fibers as well as the vast majority of VIP-containing intrapancreatic neurons were found to co-express DbetaH. Single SP-immunoreactive (IR) nerve fibers of the exocrine pancreas and interlobular connective tissue as well as SP-positive intrapancreatic neurons additionally showed the presence of DbetaH. The co-localization of VIP and NPY was found in nerve terminals located around the blood vessels and acini, in the connective tissue septa as well as in numerous pancreatic neuronal perikarya. Rare nerve terminals located between the acini and around small blood vessels as well as several neurons of intrapancreatic ganglia were VIP-IR/ SP-IR. Simultaneous expression of SP and CGRP was found in nerve fibers supplying large pancreatic arteries and veins, interlobular connective tissue and, occasionally, around the acini. Throughout the pancreas the population of CGRP-positive nerve endings showed lack of VIP and NPY. In a moderate number of GRP-containing nerve fibers, a co-expression of NPY was noted. Nerve terminals containing both GRP and VIP were detected sporadically, whereas none of the GRP-positive nerve terminals showed expression of SP. We conclude that the presented noradrenergic as well as peptidergic innervation patterns of the ovine pancreas are species-dependent. On the basis of the occurrence of DbetaH, NPY, VIP and SP (alone or in combination) in pancreatic neuronal elements we can suggest that these substances presumably act as regulators of the endocrine and/or exocrine pancreas. Involvement of CGRP and GRP in the ovine pancreas physiology seems to be of minor importance. The co-localization study indicated that the pancreas of the sheep is innervated from several sources including intrinsic as well as extrinsic ganglia.     

Pulmonary lymphatics and their spatial relationship to venous sphincters

Background: Pulmonary lymphatics are critical to clearing lung fluid. Although their structure can be shown with light and transmission electron microscopy, scanning electron microscopy of their casts can better show their number, size, shape, distribution, and degree of filling. This technique has identified four forms of lung lymphatics, but these forms have not been fully evaluated by tissue microscopy. A most important site of pulmonary edema formation, the pulmonary capillary, is just upstream from small veins which have focal, smooth muscle tufts termed venous sphincters. Because of their constricting potential, these sphincters may control lung perfusion and cause edema. Methods: With light and transmission electron microscopy of tissue and scanning electron microscopy of casts, the lymphatic forms were explored in relation to the tissue anatomy in rats without pulmonary edema and with mild-to-moderate edema caused by extended vascular rinsing. Results: The edematous lungs had increased sacculo-tubular lymphatics adjacent to the venous sphincters. These lymphatics were in the adventitial connective tissue and were partially endothelialized. As lymphatics became more tubular their endothelium became more complete. Collagen fibers traversed the lumen of these lymphatics even where endothelial cells were present and caused the lines on the surface of the lymphatic casts. Overlapping endothelial cells caused clefts on the casts. Conclusions: Scanning electron microscopy of lymphatic casts better defines their ultrastructure and shows the spatial relationship of veins and their sphincters to venous lymphatics. Sphincter contraction may influence pulmonary lymph production which could affect other aspects of regional lung perfusion. © 1995 Wiley-Liss, Inc.     

A histochemical and ultrastructural study of serotonin-containing nerves in cerebral blood vessels of the lamprey

Lamprey, Entosphenus japonicus, cerebral blood vessel autonomic nerve supply was studied with fluorescence and cholinesterase histochemistry and electron microscopy. Nerve fibers emitting a yellow fluorescence characteristic of serotonin (Exc./Em. max.; 380/530 nm) were found on the major cerebral and pial arteries, but not acetylcholinesterase (AChE)-positive ones. Single ganglion cells also emitting a strong yellow fluorescence were seen in the artery adventitia. On rare occasions these cells were observed in pairs. Terminal varicosities of central catecholamine-containing nerves (Exc./Em. max.; 410/475 nm) were observed on parenchymal capillaries, but not central AChE-positive nerve terminals. In ganglion cells, dense cored vesicles (ca. 130 nm in average diameter; DCV) were abundant in the Golgi area, suggesting their formation at this site. Two types of DCV were observed; one with a homogeneous dense core and the other with a granular core. DCV were numerous in axons as well, axons in which many small clear vesicles (40–60 nm in diameter) as well as DCV were occasionally observed. The question of whether the small clear vesicles or the DCV contained serotonin could not be resolved.     

猪的皮下毛细淋巴管超微结构研究

对4只小白猪肢体皮下毛细淋巴管进行了电镜观察,见毛细淋巴管由内皮细胞构成。内皮细胞的形状很不规则,胞浆有许多突起,有一般哺乳动物细胞所具有的细胞器,胞质中育大量光滑的小囊泡,细胞间有紧密连接和开放连接。某些细胞的开放连接处有不规则的指状突起,是开放连接的重要形式特点。     

气管的器官内淋巴管

本文应用淋巴管间接注射法以及光镜和电镜观察的方法,对家兔气管的器官内淋巴管进行了研究。在气管粘膜层仅见到毛细淋巴管,彼此吻合成网。气管与喉的粘膜层毛细淋巴管存在吻合,但数量较少。在气管粘膜下层、肌层及外膜层则见到毛细淋巴管和淋巴管。气管毛细淋巴管的超微结构可见,管壁厚薄不均,内皮的多数细胞核向管腔内突出,基膜不完整,无孔窗,无周细胞,壁外有大量纤维束伴行。内皮间连接较复杂,归纳可分为端端连接、重叠连接和嵌合连接。内皮间连接处有粘着装置(如粘着带、粘着斑或桥粒),但较薄弱,有的连接呈开放状态(>30nm)。毛细淋巴管内皮的胞浆内有大量囊泡,其分布无一定规律,有的囊泡与内皮细胞质膜融合或呈开放状态,形成质膜内陷。囊泡形态大小不等,有的体积较大且内部充满颗粒状不均匀物质,有的囊泡外包有电子密度较高的外衣,有些则不明显。     

An ultrastructural analysis of the developing enteric nervous system of the guinea-pig small intestine

Summary The developing enteric nervous system of the guinea-pig has been analysed ultrastructurally. In addition, electron microscope autoradiography, following incubation with tritiated 5-hydroxytryptamine ([³H]5-HT) or tritiated norepinephrine ([³H]NE) was used to locate the developing axons of enteric serotoninergic and adrenergic neurons respectively. Observations have been correlated with previous studies of the development of the various types of enteric neuron and the onset of intestinal neuromuscular function. Prior to 25 days of gestation no neurons can be recognized morphologically. Neurons first appear at 25 days' gestation, together with a primitive neuropil in neural islands within the outer gut mesenchyme. Ganglion cell precursors are primitive at first and resemble the cells in the surrounding mesenchyme. Growth cones are abundant but there are no terminal varicosities or synapses. The circular muscle also begins to form at this time. At 32 days' gestation the longitudinal layer of smooth muscle can be discerned and, within the myenteric plexus, terminal axonal varicosities appear containing small (about 50 nm in diameter) electron-lucent synaptic vesicles. The submucosal plexus appears to be derived from neurons and neurites that reach it from the earlier-developing myenteric plexus. The submucosal plexus can be recognized at 38 days of gestation but is not well developed until day 42. Synapses on ganglion cell somata first appear in the myenteric plexus on gestational day 38 and are numerous on day 42 when the first axo-dendritic synapses can be seen. Between days 42 and 48 the developing neural tissue and growing smooth muscle cells interdigitate but after day 48, the plexus becomes ensheathed by supporting cells and connective tissue and this interdigitation is lost. Prior to day 48 most varicosities contain small electron-lucent synaptic vesicles; however, after this time a variety of terminals appears. Between days 48 and 53 of gestation evidence of degenerating neuronal processes is common, indicating that cell death may occur. Electron microscopic autoradiography with [³H]5-HT reveals labelling of axons in the neuropil of the myenteric plexus at day 32 of gestation. Some primitive appearing cell bodies, however, are also labelled and these cells seem to be entering the myenteric plexus from the surrounding mesenchyme. After 42 days of gestation [³H]5-HT labels only axons of both nerve plexuses. Often, labelled terminals are apposed to ganglion cells or dendrites. In contrast, significant labelling by [³H]NE is not found until gestational day 48. Axons are labelled by [³H]NE and these tend to be located at the interface between the myenteric plexus and the surrounding connective tissue.     

Adrenergic and Cholinergic Nerves of the Human Urethra and Urinary Bladder. A Histochemical Study

The occurrence and distribution of adrenergic and acetylcholine esterase (AChE) positive nerves in the human urethra and urinary bladder were studied histochemically with the fluorescence method of Falck and Hillarp, and the copper thiocholine method of Koelle and Friedenwald. Both types of nerves were mainly confined to the layers of smooth muscle cells in the walls of the organs. In all parts of the urethra, there was a scanty supply of adrenergic nerves. Few adrenergic nerves were also found in the urinary bladder, except in the trigone area, where they were abundant. AChE-positive nerves were uniformly and richly distributed in the urinary bladder. Throughout the urethra the distribution of AChE-positive nerve fibres was uniform, but the number was clearly less than in the urinary bladder. No intramurally located adrenergic or AChE-positive ganglion cells could be demonstrated.     

Postnatal development of the ovarian bursa of the golden hamster (Mesocricetus auratus): Its complete closure and morphogenesis of lymphatic stomata

The golden hamster ovarian bursa was studied by light and electron microscopy to clarify the process of its complete closure and the development of lymphatics that leads to morphogenesis of stomata. The results were as follows. (1) The bursa completely closed at 9 days of age primarily due to development of the mesotubarium superius. (2) With the closure, the ovary and bursa became closely apposed, and most of the original bursal cavity disappeared. (3) Between 9 and 12 days of age U-shaped folds of the bursal mesothelium began to invade the connective tissue of the bursa. (4) Widening of the internal angle of the U-shaped folds contributed to reappearance of the bursal cavity, and thus separation of the bursa from the ovary. It also contributed to future geometrical proximity of lymphatics to the cavity of the bursa. (5) The separation of the bursa from the ovary began as early as 12 days of age in the cephalic half of the bursa. It occurred remarkably late in the caudal half. Juxtaposition of the window portion of the bursa to the ovary remained in some adult animals. (6) Development of lymphatics in the cephalic half of the bursa was divided into two stages, before and after days 21–24 of life. In the first stage, lymphatics grew in the submesothelial connective tissue, and the framework of lymphatics was formed. In the second stage, lymphatics extended small branches to form the submesothelial plexus or lymphatic lacuna. (7) Intercellular junctions between contiguous lymphatic endothelial cells were mostly tight and desmosomelike. Open junctions were, if they occurred at all, rare. (8) A smooth-surfaced area lined with the lymphatic endothelium was found in the bursa on day 27 of life, before the initiation of ovulation. Valvelike stomal orifices were absent before the initiation of ovulation and extremely rare even after the first ovulation. They were commonly present in the bursae after the fourth ovulation, however. The process of complete closure of the ovarian bursa is very complex and may be related to the later development of the bursal mesothelium and lymphatics. Some liplike stomal orifices are of purely developmental origin. However, all valvelike stomal orifices are assumed to be formed as a result of damage to the bursal mesothelium, as well as to the submesothelial connective tissue and lymphatics, by repetition of ovulation. It is possible that liplike stomal orifices may be formed in the process of repairing the damage.     

Postinflammatory changes of the diaphragmatic stomata

Numerous investigations concerning the fine morphology of diaphragmatic stomata have been performed, but its ultrastructural changes in experimental conditions remain unclear. The present study demonstrates the peritoneal side of the diaphragm in adult Wistar rats by transmission electron microscopy. Ten experimental animals were observed 5 and 8 days after Pseudomonas aeuriginosa instillation (PI) into the peritoneal cavity. A control group of 6 rats showed flat mesothelial covering on basal lamina (BL) and connective tissue layer, as well as cubic mesothelial cells, single stomata over underlying lymphatic lacunae (LL). Five days after PI the mesothelial cells had more numerous microvilli, microvesicles, vacuoles, lysosomes and a lesser number of specialized contacts. The multiplication of the extravasal cells and larger intercellular spaces lead to thickenings of the connective tissue around LL. LL were larger and located in close proximity of the mesothelium. Intercellular spaces in the mesothelial layer and different types of contacts between mesothelial cells and endothelial protrusions of LL (with common BL or without BL) were encountered. Eight days after PI the mesothelium, endothelium of LL, their BL and surrounding connective tissue were interrupted and structurally modified to form typical new channels--stomata. The larger portion of the channels were formed of mesothelial cells, while the endothelial cells participated in the submesothelial part. LL were more numerous than in the previous period, and were arranged in groups. LL increased their vertical (50.59 microm) and horizontal (155.57 microm) diameter, as compared with control animals (respectively 12.37 microm and 74.08 microm). Neighbouring LL were separated by thin or thick septae. Peristomatal mesothelial cells or more rarely endothelium formed valve- or bridge-like structures. Valves on the opposite side of LL were observed. Groups of electron-dense bodies characterized some tall endothelial cells of LL. Cubic mesothelium, endothelium of the LL, both BL, the cell connections that formed new stomata, LL and surrounding connective tissue underwent rapid and parallel changes after PI. Among these elements of the lymphatic regions mentioned above, the mesothelium and endothelium of LL had a main role in experimental conditions.     

Innervation of the rat harderian gland by adrenergic and cholinergic nerve fibres

The innervation of the rat Harderian gland was studied using histochemical methods for catecholamines and acetylcholinesterase (AChE). Selective denervations were performed to investigate the neural connections of this gland with various ganglia. Light microscopically the AChE-positive nerves seemed to run as thick bundles in the intertubular connective tissue. These bundles sent finer branches around the acini. The blood vessels, localized in the connective tissue septa, were surrounded by a dense plexus of AChE-containing fibres. By electron microscopy, the AChE-positive fibres were seen to terminate near the myoepithelial cells surrounding secretory cells. These fibres were also observed in contact with the blood vessels and occasionally close to the secretory cells. Fluorescent adrenergic nerves surrounded the blood vessels. Some fibres were also observed in the interlobular tissue. All the AChE-containing nerves degenerated after cutting the zygomatic nerve. On the other hand, removal of the ciliary ganglion or the superior cervical ganglion, or stereotactic coagulation of the ophthalmic nerve did not affect these nerves. The fluorescent adrenergic fibres disappeared following both removal of the superior cervical ganglion and coagulation of the ophthalmic nerve. These fibres were intact after removal of the ciliary ganglion.     

The autonomic innervation of the human urinary bladder,bladder neck and urethra: A histochemical study

The autonomic innervation of smooth muscle in fresh biopsy specimens of the human urinary bladder, bladder neck and urethra has been examined using specific neurohistochemical techniques. Acetylcholinesterase-containing nerve fibers have been demonstrated amongst the smooth muscle cells in all the biopsy samples. Enzyme-positive fibers formed a plexus, the density of which varied dependent upon the region from which the biopsy material was obtained. Catecholamine (noradrenaline)-containing autonomic nerve fibers were observed amongst smooth muscle cells of the vesico-urethra junction; other than for perivascular nerve plexuses. Noradrenergic fibers were absent from biopsy samples of other regions. Juxtamural, acetylcholinesterase-positive neurones were present in some samples, and a proportion of these cell bodies were closely related to noradrenergic nerve terminal regions. These findings are discussed in relation to those of other workers who have examined the innervation of the mammalian lower urinary tract.     

家兔回肠淋巴管三维结构的扫描电镜观察

目的　探讨回肠淋巴管的三维结构及流注关系。方法　将Mercox注入家兔回肠壁内制成淋巴管铸型 ,在扫描电镜下观察回肠各层淋巴管的三维结构。结果　回肠的粘膜层、粘膜下层、肌层和浆膜层都有毛细淋巴管网及淋巴管。在小肠绒毛内存有中央乳糜管 ,铸型样品上可见其立体结构 ,可见中央乳糜管注入粘膜层和粘膜下层的毛细淋巴管网 ,该网汇合而成的淋巴管穿过肌层进入浆膜层 ,之后以淋巴集合管的形式入肠系膜淋巴管而离开回肠。铸型标本可见淋巴管呈串珠状外观 ,管壁表面有双凹切迹 ,相当于淋巴管瓣膜的部位。铸型表面还可见淋巴管内皮细胞的椭圆形压迹 ,光镜下可见粘膜下与肌层之间存有三角形间隔 ,其内动脉与两条淋巴管并行。结论　中央乳糜管注入粘膜下毛细淋巴管网 ,该网与粘膜下淋巴管网相连 ,此淋巴管再穿肌层入浆膜层后离开回肠 ,并见淋巴通道存在于中央糜管周围。     

Demonstration of the intralobular lymphatics in the guinea pig pancreas by an enzyme-histochemical method

Intralobular lymphatics in the guinea pig pancreas were demonstrated enzyme-histochemically showing the extent, distribution and fine structure by combined light and transmission electron microscopy. 5'-nucleotidase(5'-Nase)-positive lymphatic vessels were present throughout the pancreas. Intralobular lymphatics among the acini were comparatively rare and generally independent of the blood capillaries, pancreatic ducts and acini. These lymphatics revealed the usual structural features, such as typical intercellular junctions and very tenuous vascular walls without continuous basal laminae. Fine precipitates of the cerium-based reaction product for 5'-Nase activity were found to be associated with cell membranes of the lymphatic endothelium and pinocytotic vesicles. Lymphatics were not closely related to the endocrine islets, although alkaline phosphatase(ALPase)-positive blood capillaries were well developed. Collecting lymphatic vessels with valves with weaker 5'-Nase activity were also detected in the interlobular connective tissue. ALPase activity, absent in the lymphatics, was positive in the blood capillaries, suggesting that it is also a useful way of demonstrating, histochemically, the blood capillaries in the guinea pig pancreas.