Morphological and functional characteristics of peritoneal mast cells from young rats

To study why neonatal and young rats are resistant to the effects of some secretagogues, such as compound 48/80 and 2.5-S nerve growth factor, we examined peritoneal mast cells from 14–15-day-old rats (young rats) and compared them to peritoneal mast cells from adults. Peritoneal mast cells from young rats contain approximately one-tenth of the amount of histamine observed in adult peritoneal mast cells. However, both cell populations contained similar low levels of the mucosal mast cell-associated protease rat mast cell protease II. Histochemical analysis of peritoneal mast cells from young rats using safranin O and berberine sulphate suggested that only a portion of the granules of these cells contained heparin. At an ultrastructural level the young rat peritoneal mast cell contains relatively few granules. The majority of mast cells from young rats have a bilobed or indented nucleus which is only rarely observed in adult cells. Functionally, the young rat peritoneal mast cell demonstrates a significantly reduced histamine release in response to the connective tissue mast cellspecific secretagogues compound 48/80 and 2.5-S nerve growth factor. In contrast, the percent histamine release in response to the neurotransmitter substance P, which degranulates both connective tissue mast cells and intestinal mucosal mast cells, was similar in the adult cells and the young rat cells. This study demonstrates substantial differences between the young rat and adult peritoneal mast cells which may explain the ability of very young animals to withstand large doses of certain secretagogues.     

Immunohistochemical Localization of α-Mannosidase During Postnatal Development of the Rat Cerebellum

The localization of alpha-D-mannosidase in the rat cerebellum was studied by using indirect immunohistochemistry at both optical and electron microscopic levels. In the adult the enzyme is particularly concentrated in the dendrites and cell bodies of Purkinje cells, basket cells, and Golgi neurons in the cerebellar cortex and in the cytoplasm and dendrites of deep nuclei neurons. The cytoplasm of granule cells is poorly stained, whereas parallel fibers, white matter, Bergman fibers, and Golgi epitheloid cell perikarya show virtually no staining. Electron microscopy suggests that most of the staining is found in the cytosol, although some staining is found in the postsynaptic densities of the synapses between parallel fibers and Purkinje dendrites. The pattern of staining was followed throughout the postnatal development of the rat cerebellum. At bith an intense and diffuse staining is found in all cells except those of the external germinative layer. At the 6th postnatal day, Purkinje cell bodies and apical cones are strongly labeled. From the 13th day on the pattern is very similar to that found in the adult. However, at the 18th postnatal day (when compared with the other structures), the staining of Purkinje cell dendrites seems to be higher than at all other ages. These data are correlated with biochemical studies and discussed in relation to the possible role of this enzyme during the postnatal development of the rat cerebellum.     

Ultrastructural relation between cortical efferents and terminals containing enkephalin-like immunoreactivity in rat neostriatum

The interrelationships between cortical efferents and terminals containing enkephalin-like immunoreactivity (ELI) were examined by combining anterograde degeneration with electron microscopic immunocytochemistry in the adult rat neostriatum. Two days following unilateral removal of the cerebral cortex, the brains were fixed by aortic arch perfusion, then sectioned and processed for the immunocytochemical localization of an antiserum directed against methionine (Met5)-enkephalin. The observed relationships between the degenerating cortical efferents and immunocytochemically labeled terminals were of two types. In the first, the degenerating and ELI containing terminals converged on the same unlabeled dendrite or dendritic spine. In the second, terminal and preterminal axons of the ELI containing neurons had one surface directly apposed to the plasma membrane of a degenerating axon terminal. These findings support the concept that neurons containing opioid peptides and cortical efferents modulate the output of common recipient neurons and may also directly interact with each other through presynaptic axonal mechanisms in the rat neostriatum.     

Neuronal distribution and subcellular localization of HCNP-like immunoreactivity in rat small intestine

A novel peptide, hippocampal cholinergic neurostimulating peptide (HCNP), originally purified from young rat hippocampus, affects the development of specific cholinergic neurons of the central nervous system in vitro. In this study, HCNP-like-immunoreactive nerve processes and nerve cell bodies were identified by electron microscopic immunocytochemistry in the rat small intestine. Labeled nerve processes were numerous in the circular muscle layer and around the submucosal blood vessels. In the submucosal and myenteric plexuses, some HCNP-like-immunopositive nerve cell bodies and nerve fibers were present. The reaction product was deposited on the membranes of various subcellular organelles, including the rough endoplasmic reticulum, Golgi saccules, ovoid electron-lucent synaptic vesicles in axon terminals associated with submucosal and myenteric plexuses, and the outer membranes of a few mitochondria. The synaptic vesicles of HCNP-like-positive terminals were 60–85 nm in diameter. The present data provide direct immunocytochemical evidence that HCNP-like-positive nerve cell bodies and nerve fibers are present in the submucosal and myenteric plexuses of the rat small intestine. An immunohistochemical light microscopic study using mirror-image sections revealed that in both the submucosal and myenteric ganglia, almost all choline acetyltransferase (ChAT)-immunoreactive neurons were also immunoreactive for HCNP. These observations suggest (i) that HCNP proper and/or HCNP precursor protein is a membrane-associated protein with a widespread subcellular distribution, (ii) that HCNP precursor protein may be biosynthesized within neurons localized in the rat enteric nervous system, and (iii) that HCNP proper and/or HCNP precursor protein are probably stored in axon terminals.     

Phylogenic study of calcitonin gene-related peptide-immunoreactive structures in the pancreas

 The immunohistochemical localization of calcitonin gene-related peptide was examined, at both light and electron microscopic levels, in the pancreas of various vertebrates, including the eel, bullfrog, turtle, chicken, mouse, rat, guinea pig, dog, monkey, and human. Immunoreactive staining was observed in nerve fibers in every animal species examined, but positive endocrine cells were limited to the rat, monkey, and human. The density of the positive endocrine cells varied considerably among the three species (monkey > rat > human). Positive nerve fibers were distributed throughout the parenchyma, being particularly rich around pancreatic ducts, and near large or small blood vessels. In four species (eel, mouse, rat, and dog), positive nerve fibers formed a dense network in the islet region. There were positive varicose nerve fibers around exocrine cells. These fibers, varying in density in different species (relatively high in the eel, bullfrog, and rat), were sometimes adjacent to acinar cells. At the electron microscopic level, positive nerve terminals were often demonstrated in close apposition to the outer membrane of acinar cells. The eel pancreas revealed an exceptional pattern of staining in neuronal cell bodies that were scattered in the interlobular connective tissue. Despite these anatomical differences, the omnipresence of this peptide suggests its essential role(s) in the pancreas. Accepted: 12 June 1997     

异丙肾上腺素对心内神经节中肽能递质VIP影响

异丙肾上腺素是临床常用的心脏骤停的抢救药物。为了研究该药对心内神经节中肽能递质的影响,本文在大鼠皮下注射异丙肾上腺素５ｍｇ／ｋｇ,连续三天,后固定取心房后壁,用免疫组化结合图像分析,观察心内神经节中肽能递质ＶＩＰ的变化。对照组大鼠心内神经节中含有ＶＩＰ免疫反应（ＶＩＰ－ＩＲ）阳性神经纤维和胞体;实验组大鼠心内神经节中含有ＶＩＰ－ＩＲ阳性神经纤维和胞体呈不同程度增多。其中ＶＩＰ－ＩＲ阳性神经纤维积分光密度较对照组增加２５．３％,而神经胞体积分光密度只增加８．１％。结果提示：１．大鼠心内神经节中ＶＩＰ－ＩＲ阳性神经纤维可能有两个来源：即心内ＶＩＰ－ＩＲ阳性神经节细胞和心外副交感神经元;２．异丙肾上腺素对心脏的作用并非单一的直接作用,其中部分是通过影响心内神经节中肽能递质的变化而发挥间接作用。     

Neurofilament-like and glial fibrillary acidic protein-like immunoreactivities in rat and guinea-pig sympathetic ganglia in situ and after perturbation

Summary The presence of neurofilament (NF)-like and glial fibrillary acidic protein (GFAP)-like immunoreactivities was studied in sympathetic ganglia of adult rats and guinea pigs during normal conditions and after perturbation. In the superior cervical ganglion (SCG) of normal rats, many ganglion cells and nerve fibers show NF immunoreactivity. Some of these nerve fibers disappear after preganglionic decentralization of SCG; this indicates the presence of a mixture of preand postganglionic NF-positive nerves in the ganglion. Cuts in both preand postganglionic nerves result in a marked increase in GFAP immunoreactivity in SCG, whereas NF immunoreactivity increases in nerve cell bodies after preganglionic cuts. Only a few ganglion cells show NF immunoreactivity in the normal SCG of guinea pig. All intraganglionic NF-positive nerves are of preganglionic origin; decentralization abolishes NF immunoreactivity in these nerve fibers. The inferior mesenteric ganglion, the hypogastric nerves and colonic nerves in guinea pigs contain large numbers of strongly NF-immunoreactive nerve fibers.When the SCG of adult rat is grafted to the anterior eye chamber of adult rat recipients, both ganglionic cell bodies and nerve fibers, forming on the host iris from the grafted ganglion, are NF-positive. As only the perikarya of these neurons normally exhibit NF immunoreactivity, and the terminal iris arborizations are NF-negative, it appears that the grafting procedure causes NF immunoreactivity to become more widespread in growing SCG neurons.     

Synaptic regulation of paraventricular arginine vasopressin-containing neurons by neuropeptide Y-containing monoaminergic neurons in rats

Summary Synaptic regulation of arginine vasopressin (AVP)-containing neurons by neuropeptide Y (NPY)-containing monoaminergic neurons was demonstrated in the paraventricular nucleus of the rat hypothalamus. NPY and AVP were immunolabeled in the pre- and the post-embedding procedures, respectively, and monoaminergic fibers were marked by incorporating 5-hydroxydopamine (5-OHDA), a false neurotransmitter. The immunoreaction for NPY was expressed by diaminobenzidine (DAB) chromogen, and that for AVP by gold particles. The DAB chromogen was localized on the surface of the membrane structures, such as vesicles or mitochondria, and on the core of large cored vesicles. Gold particles were located on the core of the secretory granules within the AVP cell bodies and processes. The incorporated 5-OHDA was found as dense cores within small or large vesicular structures. From these data, three types of nerve terminals were discernible: NPY-containing monoaminergic, NPY-containing non-aminergic, and monoaminergic fibers. The AVP cell bodies appeared to have synaptic junctions formed by these nerve terminals as well as by the unlabeled nerve terminals which have small clear vesicles and large cored vesicles. These different types of nerve terminals were frequently observed in a closely apposed position on the same AVP cell bodies. The functional relationships of these three types of neuronal terminals are discussed.     

The development of histochemically demonstrable cholinesterases in the rat neostriatum in vivo and in vitro

The development of acetylcholinesterase (AChE) and non-specific cholinesterase (NsChE) activity was studied in the rat neostriatum by the light and electron microscope using three thiocholine methods. The AChE activity was first demonstrable only in the lateral parts of the nucleus, and during the early postnatal development the most intense activity was in the cell bodies, whilst the typical intense staining of the neuropil of adult animals was seen in two-week-old rats. Two types of AChE-containing cells were observed in the neostriatum of rats younger than two weeks and in cultures of newborn rat neostriatal cells. The neuropil of the cultures showed weak activity in the membranes of thin preterminal processes. In the neuropil of old rats, NsChE activity was present in the membranes of nerve cell processes. The capillary endothelial cells of newborn rats contained both AChE and NsChE. During subsequent development, the AChE activity disappeared, whilst for NsChE no change was seen in the distribution of activity seen in newborn or young adult rats less than three months old.     

The development of histochemically demonstrable cholinesterases in the rat neostriatum in vivo and in vitro

Summary The development of acetylcholinesterase (AChE) and non-specific cholinesterase (NsChE) activity was studied in the rat neostriatum by the light and electron microscope using three thiocholine methods. The AChE activity was first demonstrable only in the lateral parts of the nucleus, and during the early postnatal development the most intense activity was in the cell bodies, whilst the typical intense staining of the neuropil of adult animals was seen in two-week-old rats. Two types of AChE-containing cells were observed in the neostriatum of rats younger than two weeks and in cultures of newborn rat neostriatal cells. The neuropil of the cultures showed weak activity in the membranes of thin preterminal processes. In the neuropil of old rats, NsChE activity was present in the membranes of nerve cell processes. The capillary endothelial cells of newborn rats contained both AChE and NsChE. During subsequent development, the AChE activity disappeared, whilst for NsChE no change was seen in the distribution of activity seen in newborn or young adult rats less than three months old.     

COMPARATIVE ANALYSIS OF THE FINE STRUCTURE OF YOUNG AND ADULT INDIVIDUALS OF DUNALIELLA SALINA (POLYBLEPHARIDACEAE,CHLOROPHYCEAE) WITH EMPHASIS ON THE FLAGELLAR APPARATUS1

Individuals of Dunaliella salina (Dunal.) Teod. change their shape during ontogenesis. Here we describe the fine structure of this species with emphasis on distinctions between young and adult individuals. The cell coat is present at early stages of cell development and may be synthesized by vesicles of nuclear membrane-associated endoplasmic reticulum. Scanning electron microscopical observations show differences in the surface pattern of the cell coat in young and adult cells. The nucleus of young cells is more or less spherical, whereas that of adult cells is pyriform. The Golgi apparatus is positioned immediately under the basal bodies and consists of three dictyosomes in young cells and six to eight dictyosomes in adult cells. The flagellar apparatuses of young and adult cells have a 1/7 o'clock (i.e. clockwise) displacement of basal bodies and are grossly similar, but there are subtle differences between specific components. Two non-axonemic basal bodies (1′, 2′) appear in a plane perpendicular to that determined by the flagella-bearing basal bodies (1, 2). The cruciate microtubular rootlet system has a 4–2–4–2 alternation pattern. In adult cells, rhizoplasts emerge from each terminal body and run parallel to the four rootlets.     

Synaptic relationships in the plexiform layers of carp retina

Summary The synaptic contacts made by carp retinal neurons were studied with electron microscopic techniques. Three kinds of contacts are described: (1) a conventional synapse in which an accumulation of agranular vesicles is found on the presynaptic side along with membrane densification of both pre- and postsynaptic elements; (2) a ribbon synapse in which a presynaptic ribbon surrounded by a halo of agranular vesicles faces two postsynaptic elements; and (3) close apposition of plasma membranes without any vesicle accumulation or membrane densification.In the external plexiform layer, conventional synapses between horizontal cells are described. Horizontal cells possess dense-core vesicles about 1,000 Å in diameter. Membranes of adjacent horizontal cells of the same type (external, intermediate or internal) are found closely apposed over broad regions.In the inner plexiform layer ribbon synapses occur only in bipolar cell terminals. The postsynaptic elements opposite the ribbon may be two amacrine processes or one amacrine process and one ganglion cell dendrite. Amacrine processes make conventional synaptic contacts onto bipolar terminals, other amacrine processes, amacrine cell bodies, ganglion cell dendrites and bodies. Amacrine cells possess dense-core vesicles. Ganglion cells are never presynaptic elements. Serial synapses between amacrine processes and reciprocal synapses between amacrine processes and bipolar terminals are described. The inner plexiform layer contains a large number of myelinated fibers which terminate near the layer of amacrine cells.This work was supported by an N.I.H. grant NB 05404-05 and a Fight for Sight grant G-396 to P.W. and N.I.H. grant NB 05336 to J.E.D. The authors wish to thank Mrs. P. Sheppard and Miss B. Hecker for able technical assistance. P.W. is grateful to Dr. G. K. Smelser, Department of Ophthalmology, Columbia University, for the use of his electron microscope facilities.     

First visualization of dopaminergic neurons with a monoclonal antibody to dopamine: a light and electron microscopic study

A monoclonal antibody recently synthesized against dopamine (DA) was tested in rat and mouse brain sections after further treatment by PAP immunocytochemistry at the light and electron microscopic levels. Distribution of DA-immunoreactive cell bodies was examined in the substantia nigra (sn), the ventral tegmental area (vta), and the raphe nuclei. DA-immunoreactive fibers were investigated in two DA projection systems, the striatum and the septum. Many dopaminergic cell bodies were found in the sn and the vta. Some scattered DA neurons were encountered in the pars reticulata of the sn. The dorsal raphe and linearis raphe nuclei displayed sparse immunoreactive neurons and a dense plexus of DA fibers. Immunoreactive fibers were observed in the entire striatum, more dense in the ventral part. In the septum, immunonegative neurons were outlined by thin DA fibers in synaptic contact with their somata or dendrites. According to our observations, this DA monoclonal antibody seems to be a selective and sensitive tool for studying the dopaminergic neuronal circuitry at both histological and ultrastructural level.     

Catecholaminergic innervation of pyramidal and GABAergic nonpyramidal neurons in the rat hippocampus. Double label immunostaining with antibodies against tyrosine hydroxylase and glutamate decarboxylase

This study describes the catecholaminergic innervation of rat hippocampal neurons at the electron microscopic level by using an antibody against tyrosine hydroxylase (TH) and immunocytochemical techniques. In a first series of experiments, the course and distribution as well as the synaptic contacts of TH-immunoreactive fibers were analyzed with the peroxidase-antiperoxidase (PAP) method. Next, peroxidase immunostaining of TH fibers was combined with glutamate decarboxylase (GAD) immunostaining, using avidinated ferritin as a second electrondense marker. Our results demonstrate that TH-immunostained terminals establish asymmetric synaptic contacts with spines of pyramidal neurons, and symmetric synaptic contacts with cell bodies and dendritic shafts of ferritin-labeled GAD-immunoreactive nonpyramidal cells.     

Immunocytochemical studies of quaking mice support a role for the myelin-associated glycoprotein in forming and maintaining the periaxonal space and periaxonal cytoplasmic collar of myelinating Schwann cells

The myelin-associated glycoprotein (MAG) is an integral membrane glycoprotein that is located in the periaxonal membrane of myelin-forming Schwann cells. On the basis of this localization, it has been hypothesized that MAG plays a structural role in (a) forming and maintaining contact between myelinating Schwann cells and the axon (the 12-14-nm periaxonal space) and (b) maintaining the Schwann cell periaxonal cytoplasmic collar of myelinated fibers. To test this hypothesis, we have determined the immunocytochemical localization of MAG in the L4 ventral roots from 11-mo-old quaking mice. These roots display various stages in the association of remyelinating Schwann cells with axons, and abnormalities including loss of the Schwann cell periaxonal cytoplasmic collar and dilation of the periaxonal space of myelinated fibers. Therefore, this mutant provides distinct opportunities to observe the relationships between MAG and (a) the formation of the periaxonal space during remyelination and (b) the maintenance of the periaxonal space and Schwann cell periaxonal cytoplasmic collar in myelinated fibers. During association of remyelinating Schwann cells and axons, MAG was detected in Schwann cell adaxonal membranes that apposed the axolemma by 12-14 nm. Schwann cell plasma membranes separated from the axolemma by distances greater than 12-14 nm did not react with MAG antiserum. MAG was present in adaxonal Schwann cell membranes that apposed the axolemma by 12-14 nm but only partially surrounded the axon and, therefore, may be actively involved in the ensheathment of axons by remyelinating Schwann cells. To test the dual role of MAG in maintaining the periaxonal space and Schwann cell periaxonal cytoplasmic collar of myelinated fibers, we determined the immunocytochemical localization of MAG in myelinated quaking fibers that displayed pathological alterations of these structures. Where Schwann cell periaxonal membranes were not stained by MAG antiserum, the cytoplasmic side of the periaxonal membrane was "fused" with the cytoplasmic side of the inner compact myelin lamella and formed a major dense line. This loss of MAG and the Schwann cell periaxonal cytoplasmic collar usually resulted in enlargement of the 12-14-nm periaxonal space and ruffling of the apposing axolemma. In myelinated fibers, there was a strict correlation between the presence of MAG in the Schwann cell periaxonal membrane and (a) maintenance of the 12-14-nm periaxonal space, and (b) presence of the Schwann cell periaxonal cytoplasmic collar.(ABSTRACT TRUNCATED AT 400 WORDS)     

Calcitonin gene-related peptide: detailed immunohistochemical distribution in the central nervous system

With the use of an antiserum generated in rabbits against synthetic human calcitonin gene-related peptide (CGRP) the distribution of CGRP-like immunoreactive cell bodies and nerve fibers was studied in the rat central nervous system. A detailed stereotaxic atlas of CGRP-like neurons was prepared. CGRP-like immunoreactivity was widely distributed in the rat central nervous system. CGRP positive cell bodies were observed in the preoptic area and hypothalamus (medial preoptic, periventricular, anterior hypothalamic nuclei, perifornical area, medial forebrain bundle), premamillary nucleus, amygdala medialis, hippocampus and dentate gyrus, central gray and the ventromedial nucleus of the thalamus. In the midbrain a large cluster of cells was contained in the peripeduncular area ventral to the medial geniculate body. In the hindbrain cholinergic motor nuclei (III, IV, V, VI, VII XII) contained CGRP-immunoreactivity. Cell bodies were also observed in the ventral tegmental nucleus, the parabrachial nuclei, superior olive and nucleus ambiguus. The ventral horn cells of the spinal cord, the trigeminal and dorsal root ganglia also contained CGRP-immunoreactivity. Dense accumulations of fibers were observed in the amydala centralis, caudal portion of the caudate putamen, sensory trigeminal area, substantia gelatinosa, dorsal horn of the spinal cord (laminae I and II). Other areas containing CGRP-immunoreactive fibers are the septal area, nucleus of the stria terminalis, preoptic and hypothalamic nuclei (e.g., medial preoptic, periventricular, dorsomedial, median eminence), medial forebrain bundle, central gray, medial geniculate body, peripeduncular area, interpeduncular nucleus, cochlear nucleus, parabrachial nuclei, superior olive, nucleus tractus solitarii, and in the confines of clusters of cell bodies. Some fibers were also noted in the anterior and posterior pituitary and the sensory ganglia. As with other newly described brain neuropeptides it can only be conjectured that CGRP has a neuroregulatory action on a variety of functions throughout the brain and spinal cord.     

Distribution of serotonin-immunoreactive nerve cells and fibers in the rat gastrointestinal tract

 The distribution of serotonin-immunoreactive (5HT-IR) nerve cells and fibers was thoroughly investigated immunohistochemically in the rat stomach, duodenum, jejunum, ileum, and colon. The immunoreactivity of the 5HT neurons was compared between non-treated controls and animals treated with colchicine, colchicine plus 5-hydroxytryptophan (5HTP), colchicine plus pargyline, and reserpine. The intensity of immunoreactivity in nerve fibers as well as nerve cell bodies was enhanced mostly in colchicine plus pargyline treated animals, therefore these animals were used for an observation of precise localization of 5HT in the rat gastrointestinal (GI) tract. Immunoreactivity in the nerve cell bodies and fibers was completely abolished in the GI tract of reserpine treated animals. The pattern of localization and projection of 5HT-IR neurons was similar in all segments of the rat GI tract. 5HT-IR nerve cell bodies were located in the myenteric plexus and showed the distinctive features of Dogiel type I neurons. Prominent bundles of varicose fibers traversed the myenteric ganglia and some of them surrounded the cell bodies of immunopositive and immunonegative neurons. 5HT-IR nerve fibers were located in the submucous plexus, densely entwined about the submucosal blood vessels. Most characteristically, 5HT-IR nerve fibers invaded the lamina propria of mucosa where they underlay the crypt epithelium. In conclusion, the present study showed that 5HT-IR neurons located in the myenteric plexus projected fibers widely in the rat GI tract. The localization of fibers in the lamina propria of mucosa implies that this neuron may exert an important role in the epithelial function of the GI tract. Accepted: 8 October 1996     

DIFFERENTIATION AND DEDIFFERENTIATION OF RAT LENS EPITHELIAL CELLS IN SHORT- AND LONG-TERM CULTURES

The crystallin synthesis of rat lens cells in cell culture systems was studied in relevance to their terminal differentiation into lens fibers. SDS-gel electrophoresis combined with several immunological techniques showed that γ-crystallin is a fiber-specific lens protein and is not localized in the epithelium of either newborn or adult lenses. When lens epithelial cells of newborn rats were cultured in vitro , α-crystaIlin was detected in many, but not all, of cells cultured for 10 days. Cells with α-crystallin gradually changed their shape into a flattened filmy form and finally differentiated into lentoid bodies. The differentiation of lentoid bodies was also found in cultures of epithelial cells obtained from adult lenses. The molecular constitution of lentoid bodies was the same as that of lens fibers in situ . The differentiation of lentoid bodies occurred successively for 5 months in cultures of lens epithelial cells. Most of the proliferating cells, however, lost α-crystallin during the culture period. Thereafter, they did not show any sign of further differentiation into lens fibers. Four clonal lines were established from these cells. One protein which is specific to the lens epithelium and the neural retina in situ (tentatively named as β_u-crystallin) was maintained in all lines, suggesting that some specific properties of ocular cells remain in the lined cells.     

Stimulation of rat Sertoli cell secretory activity in vitro by germ cells and residual bodies

The direct influence of germ cells and residual bodies on Sertoli cell basal and FSH-stimulated secretion of androgen-binding protein (ABP) was studied using Sertoli cells, recovered from 20-day-old rats, cultured alone or cocultured with a crude germ cell preparation from adult rats or with pachytene spermatocytes, round spermatids or populations of residual bodies enriched by centrifugal elutriation. The effect of a rat liver epithelial cell line (LEC) on Sertoli cell function was also tested. Addition of a crude germ cell preparation increased basal and FSH-stimulated ABP secretion. Pachytene spermatocytes and residual bodies adhered to the Sertoli cell monolayer to a much greater extent than did round spermatids. Addition of pachytene spermatocytes markedly enhanced basal and FSH-stimulated ABP secretion over 12 days of culture. Round spermatids and residual bodies stimulated ABP secretion although to a lesser extent than did spermatocytes. Furthermore, the increase of FSH-stimulated ABP levels was not maintained after 4 or 8 days of culture. LEC also enhanced basal and FSH-induced ABP levels but the increase of FSH-induced ABP production was only observed until Day 8 of culture. The influence of LEC on Sertoli cell secretion could be mediated through the production of an extracellular matrix. It is concluded that germ cells, particularly pachytene spermatocytes, can directly stimulate Sertoli cell secretory activity in vitro.     

Transient involvement of enkephalins in both the sympathetic and parasympathetic innervations of the submandibular gland of rats

Summary A time course study with enkephalin(Enk)-like immunoreactivity has revealed that nerve fibers intensely immunoreactive for Enk-8 appeared transiently only during the postnatal week 2 and 4 within the acini as well as in the inter- and intralobular connective tissues of the submandibular gland of rats. At these stages numerous nerve fibers immunoreactive for tyrosine hydroxylase (TH) appeared also in the inter- and intralobular connective tissues and within the acini. Coincidently with these postnatal stages, abundant Enk-immunoreactive principal ganglion cells appeared in the superior cervical ganglion. These were not immunoreactive for neuropeptide tyrosine (NPY). A substantial number of Enk-immunoreactive ganglion cells were also present in the submandibular ganglia at these younger postnatal stages. Superior cervical ganglionectomy at these stages resulted in a marked decrease in number of the inter- and intralobular Enk-immunoreactive nerve fibers, a slight decrease in number of the intraacinar Enk-immunoreactive nerve fibers, and almost complete disappearance of intraglandular TH-immunoreactive nerve fibers. Immuno-electron-microscopic analysis revealed that Enk-immunoreactive nerve fibers in the submandibular gland were identified as electron-dense neuronal profiles enclosed by Schwann cells in the inter- and intralobular connective tissues and those directly apposed to secretory cells within the acini. They contained small clear vesicles mixed with some large granular vesicles. After postnatal week 6, no Enk-immunoreactive nerve fibers were detected in the submandibular gland, and no TH-immunoreactive nerve fibers were seen within the acini, while TH-immunoreactive nerve fibers remained numerous in the inter- and intralobular connective tissues. These findings indicate that both sympathetic and parasympathetic nerve fibers exhibit Enk-like immunoreactivity transiently during postnatal weeks 2 and 4. It is further indicated that the inter- and intralobular nerve fibers lose Enk-like immunoreactivity while the intraacinar fibers disappear at the adult stage.