Chemical coding of sympathetic neurons controlling the tarsal muscle of the rat.

Sympathetic axons in the upper eyelid and in tissues in the superior retro-orbital space were examined for NPY immunoreactivity. Sympathetic nerve terminals containing co-localised NPY were associated with blood vessels, the conjunctiva and the Meibomian glands. The acini of the Harderian gland completely lacked sympathetic innervation. Sympathetic axons lacking NPY were only found in the tarsal muscle. In addition, a minority of terminals, located in the more proximal part of the tarsal muscle, contained weak immunoreactivity to NPY. Injections of the retrograde tracer, Fast Blue, into the eyelid or retro-orbital space labelled postganglionic somata in the superior cervical ganglion. While many retrogradely labelled somata were immunoreactive for NPY, around half lacked NPY immunoreactivity and so are likely to project to the tarsal muscle. Most of the retrogradely labelled postganglionic somata lacking NPY were surrounded by terminals immunoreactive for met-enkephalin, leu-enkephalin and met-enkephalin arg-gly-leu which were all found to be present in the same nerve terminals. Sectioning the cervico-sympathetic trunk eliminated all enkephalin-immunoreactive pericellular baskets. Many enkephalin-immunoreactive pericellular terminals contained co-localised VAChT, calretinin and calbindin immunoreactivity, but completely lacked nitric oxide synthase immunoreactivity. A second population of nerve terminals that were immunoreactive for nitric oxide synthase also surrounded tarsal muscle-projecting neurons, but these terminals lacked immunoreactivity to enkephalin. Thus, postganglionic neurons projecting to the tarsal muscle are of at least two chemical phenotypes (with or without NPY) and they receive convergent input from at least two populations of preganglionic neurons with distinctive chemical phenotypes.

A parasympathetic ganglion innervating the harderian gland and lacrimal gland of the musk shrew (Suncus murinus): fluorescent tracing and immunohistochemical studies.

A small ganglion, named the peri-trigeminal ganglion (PTG), was found in the ventromedial border of the rostral half of the trigeminal ganglion (TG) in the musk shrew (Suncus murinus). In frontal sections, the PTG was semicircular or elliptical in shape. Most of the neurons constituting this ganglion were round in shape and much smaller than those of the TG. The retrograde fluorescent tracer fluoro-gold was injected into various regions of the face in order to investigate innervation by the PTG neurons. When the tracer was injected subcutaneously around the external acoustic meatus and around the circumference of the orbit, a number of labeled neurons were seen not only in the TG but also in the PTG. After applying the tracer to the lacrimal gland (LG) and the harderian gland (HG), numerous labeled neurons were detected only in the PTG. A few labeled neurons were found in the PTG after injection into the palatoglossal arch. Immunohistochemically, most of the neurons constituting the PTG were positive for vasoactive intestinal polypeptide (VIP) antiserum. And a moderate number of somatostatin (SOM)-immunoreactive neurons and a small number of leucine-enkephalin (L-ENK)-immunoreactive neurons were detected. Numerous substance P-immunoreactive nerve fibers and varicosities were found in the PTG, and fewer L-ENK-, SOM- and VIP-immunoreactive fibers were observed. The present results suggest that the PTG is an autonomic ganglion that resembles in part the pterygopalatine ganglion in other species, and mainly innervates the HG and LG.

An ultrastructural study of myoepithelium maturation during postnatal development of the hamster Harderian gland.

This study reports the ultrastructural cell modifications in the myoepithelium of the Harderian gland during the postnatal development of the Syrian hamster. Tissues were obtained from male and female hamsters at days 1, 3, 5, 7, 10, 12, 15, 17, 20, 27, 37, 46 and 90 after birth, and processed for transmission electron microscopy. Electron microscopy was coupled with point counting methods to quantitate changes in several subcellular organelles during the course of myoepithelial cell maturation. The myoepithelial cells in this gland remained immature at birth. The earliest age of development when organized bundles of microfilaments were observed was 7 days. By the 12th day, the myoepithelial cells had developed most of their specific characteristics and resembled the mature form. Myoepithelial cells mature synchronously with each other and with the secretory cells. No undifferentiated myoepithelial and myoepithelial cells, the secretory endpieces of the adult hamster Harderian gland contain a third cell type which resembles the myoepithelial cell in shape and has an extremely electron-lucent cytoplasm lacking microfilament bundles.

Lymphoid cells in the harderian gland of the rodent Octodon degus.

The Harderian gland of the degu (Octodon degus) is composed of tubulo-alveolar secretory units that share most of morphological features found in the Harderian glands of other rodents. However, a peculiar characteristic observed in the glands of female degus is the existence of lymphoid cell clusters within the connective tissue surrounding the secretory adenomeres. Lymphocytes and lymphoblasts are found associated with blood vessels and especially with nerve bundles in the medullary region of the gland. Occasionally, macrophages and plasma cells are also observed. Although the Golgi apparatus appears well developed, the ultrastructural characteristics of most of these lymphoid elements correspond to those of inactive lymphocytes. Unmyelinated fibers containing clear and dense-core vesicles are found closely related to lymphocytes. On some occasions, lymphocytes present extensive areas of apposition with structures resembling intercellular junctions. The analogy of the lymphoid clusters reported in this study with those described in the avian Harderian gland is discussed.

Ultrastructural observations on myoepithelial cells and nerve terminals in the camel Harderian gland.

The myoepithelial cells and the nerve terminals of the Harderian gland in the one-humped camel were examined by using the transmission electron microscope. The myoepithelial cells are well developed, and composed of a cell body containing the nucleus, and many cytoplasmic processes. The cytological features are consistent with the function of the myoepithelial cell mainly as a contractile element, and possibly as a regulator for fluid transport. They are attached to the glandular cells of the end-pieces with desmosomes and interdigitating cytoplasmic processes. Densely packed myofilaments fill most of the cytoplasm, and micropinocytosis vesicles on the inner and outer borders are prevalent. The glandular end-pieces are innervated with unmyelinated nerve terminals which have been observed in the interstitial connective tissue. Nerve terminals without neurolemmal sheath penetrating the basal lamina and forming a direct neuroglandular contact with the glandular cells were observed. These intraglandular nerve terminals were found in direct contact with the myoepithelial cells, and contained small clear vesicles and a few larger dense granules.

Neuropeptides and the innervation of the avian lacrimal gland.

The chicken Harderian gland, the major lacrimal gland, has two major cell populations: a cortical secretory epithelium and a medullary interstitial cell population of lymphoid cells. There is an extensive acetylcholinesterase (AChE) network throughout the gland, as well as catecholamine positive fibers among the interstitial cells. There are substance P-like (SPLI) and vasoactive intestinal polypeptide-like (VIPLI) immunoreactive fibers throughout the gland. These fibers are particularly dense and varicose among the interstitial cells. The adjacent pterygopalatine ganglion complex has neuronal somata that exhibit VIPLI and were AChE-positive. This ganglion complex also contains SPLI and catecholamine-positive fibers. In regions of the ganglion, the somata appear surrounded by SPLI varicosities. Surgical ablation of the ganglion eliminated or reduced the VIPLI, AChE and catecholamine staining in the gland. The SPLI was reduced only in some regions. Ablation of the superior cervical ganglion or severance of the radix autonomica resulted in the loss of catecholamine staining in the pterygopalatine ganglion and the gland. Severance of the ophthalmic or infraorbital nerves had no effect on the VIPLI or the SPLI staining pattern in the gland.

Characterization of beta-adrenoceptors in the Syrian hamster Harderian gland: sexual differences and effects of either castration or superior cervical ganglionectomy.

Scatchard analysis of saturation isotherms of [125I]-iodopindolol was used to characterize beta-adrenoceptor density (Bmax) and affinity constant (Kd) in female and male hamster Harderian glands. Single-point experiments were also completed in intact females, intact males, and castrated or superior cervical ganglionectomized males. Scatchard analysis described a single population of binding sites with a Bmax of 292.2 +/- 45.1 fmol/mg protein (X +/- SEM, n = 6) in females and 18.2 +/- 3.0 fmol/mg protein (n = 6, P less than .001) in males. The affinity also varied significantly (P less than .05) with a Kd of 1.08 +/- 0.18 versus 0.26 + 0.05 nM (n = 6) in the Harderian gland of females and males, respectively. Single-point [125I]-IPIN (400 pM) binding values in females were 67.3 +/- 4.0, in intact males were 12.8 +/- 3.2, and in castrated males were 31.2 +/- 4.2 fmol/mg protein (n = 7-9). Superior cervical ganglionectomy induced no significant changes in receptor binding. The results indicate pronounced sexual differences in the density and affinity of beta-adrenoceptors in the hamster Harderian gland, which may be sex hormone dependent.

Sexual dimorphism in the cholinergic innervation of the hamster (Mesocricetus auratus) harderian glands.

We study the cholinergic innervation of the Harderian gland in male and female golden hamsters. There is a clear sexual dimorphism in the cholinergic innervation between both sexes. The Harderian gland from male animals contain much more nervous fibers with acetylcholinesterase (AChE) positive reaction than in female. The nervous fibers containing AChE activity are surrounding the acini and blood vessels.

Peptidergic innervation of the rat Harderian gland.

The immunohistochemical localization of vasoactive intestinal polypeptide (VIP), Neurotensin (NT), cholecystokinin (CCK), Neuropeptide Y (NPY), and calcitonin-gene-related peptide (CGRP) in rat Harderian glands was examined. Numerous VIP- and CCK-like immunoreactive nerves were found in close apposition to the acini. Sparse numbers of NT-, NPY-, and CGRP-like immunoreactive nerves were observed in close proximity to the acini and blood vessels. Some VIP-like immunoreactive nerves were shown to be co-localized with acetylcholinesterase-positive cholinergic nerves.

A fine structural study of the turkey harderian gland.

The ultrastructure of the turkey Harderian gland is described and the findings support previous histological descriptions of the gland. The gland is a compound tubulo-acinar structure composed of characteristic bipolar epithelial cells providing a predominantly merocrine secretion to the lumina. In the basal aspect of the cell, aggregations of non-secretory lipid-like droplets were evident and apically, the secretion was mucoid. The cells had abundant mitochondria, granular endoplasmic reticulum, ribosomes and a complex network of Golgi elements. In the subepithelial regions, myoepithelial cells and large numbers of plasma cells were seen. Within the granular endoplasmic reticulum cisternae of the epithelial cells, fibrillary or crystalline rods in some instances measuring up to 10 micron in length, with a 7.0 nm repeat pattern, were frequently seen.

Catecholamine-containing neurons and lymphoid cells in a lacrimal gland of the pigeon.

The Harderian gland of birds, a major lacrimal gland, contains a large population of lymphoid cells that produce IgA, a significant component of tears. Using histochemical techniques, we have examined the innervation of the gland. There was an extensive acetylcholine-esterase positive fiber network throughout the gland. However, catecholamine positive fibers were seen mainly associated with peripheral blood vessels and the lymphoid cell population which contained autofluorescent plasma cells. Ultrastructural examination showed that vesicle filled nerve varicosities were often seen near plasma cells and that some of these varicosities reacted positively for catecholamines. These anatomical data suggest that the lymphoid cell population may be affected by the autonomic nervous system.

Vasoactive intestinal peptide nerves in ocular and orbital structures of the cat.

Vasoactive intestinal polypeptide (VIP), a neuronal peptide of ubiquitous occurrence in the body, is known to have strong vasodilatory effects and to promote secretion from many exocrine glands. Nerves displaying VIP immunoreactivity (VIP nerves) were detected in several orbital structures of the cat. Such nerves were numerous in the lacrimal glands and somewhat less numerous in the Harderian glands and the tarsal glands. The nerves surrounded glandular acini and small blood vessels. Intraocularly, VIP nerves were seen in the ciliary processes, in the posterior third of the ciliary muscle, and around small to medium-sized blood vessels in the posterior uvea. VIP nerve fibers were absent from vessels in the anterior uvea. This distribution may explain why intracranial stimulation in the oculomotor nerve exit region dilates the vessels of the choroid but not those of the iris. A large number of VIP-immunoreactive nerve cell bodies were observed in the pterygopalatine ganglion. Extirpation of this ganglion resulted in the disappearance of VIP nerves from the intraocular structures and from the lacrimal and Harderian glands. Removal of the superior cervical ganglion and the ciliary ganglion did not affect the VIP nerve supply. The results suggest that the VIP nerves originate in the pterygopalatine ganglion.

Ultrastructure of the harderian gland in male albino rats.

Harderian glands of adult male albino rats were examined by light and transmission electron microscopy. The animals were divided into the following experimental groups: (1) castrated only, (2) castrated with testosterone replacement and (3) sham operated controls. Two types of secretory cells, designated as A and B, comprise the glandular epithelium and are distinguished on the basis of morphologic differences in the following cellular components: cytoplasmic secretory vacuoles, mitochondria and smooth endoplasmic reticulum (SER). Cell type A is more numerous and contains larger secretory vacuoles than cell type B which is characterized by the presence of large numbers of mitochondria and packet-like arrangement of SER profiles. The glandular secretion appears to be elaborated via merocrine mechanisms and consists primarily of lipids and a fibrogranular substance. The latter component may consist of porph,yrin compounds. Nerve endings are found in the connective tissue interstices of the gland. Direct synapses were not observed in association with either gland cells or myoepithelial cells. Castration did not produce significant alterations in the morphology of the glandular epithelium. Results of the investigation suggest that the rat Harderian gland may serve as a useful model for the study of cellular mechanisms involved in the production of human porphyrias.

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.