Secretory Acini Research Articles

Distribution of adrenergic nerves in the lacrimal glands of guinea-pig and rat

The distribution of adrenergic nerves in the ex- and intraorbital lacrimal glands of guinea-pig and rat was studied using the sucrose-potassium phosphate-glyoxylic acid (SPG) technique. Blood vessels and secretory acini of guinea-pig lacrimal glands were demonstrated as having a rich adrenergic innervation. Adrenergic fibers in the rat were, however, much more sparse, and most of them were seen in association with glandular blood vessels, with only a few being found between secretory acini. Pretreatment of animal with a monoamine oxidase inhibitor and l-dopa did not change the morphological distribution of catecholamine fluorescent fibers, although the treatment improved the fluorescence, especially in the rat. Extirpation of the ipsilateral superior cervical ganglion eliminated all the fluorescent fibers in both normal and pretreated animals. The presence of adrenergic innervation of the lacrimal glands, especially in close connection with secretory acini, supports the theory that catecholamine-containing nerves play a role in the regulation of lacrimal secretion.

Microscopic Anatomy and Enzyme Histochemistry of the Canine Anal Canal

AbstractThe microscopic anatomy of the anal canal was studied using routine histological methods and the light microscope in male and female dogs ranging from six months to 10 years of age. Precise anatomical boundaries were established for the zona columnaris, the zona intermedia, and the beginning of the zona cutanea. In an effort to clarify conflicting terminology concerning the anal canal, the term “anal sinus” (sinus anales) is applied to the shallow troughs located between the longitudinal mucosal ridges or columns (columnae anales) characteristic of the canine and human zona columnaris; and the term “anal crypt” is used to represent and distinguish the terminal blind pockets of anal sinuses which extend into the lamina propria of the zona intermedia.Anal glands were identified routinely in the z. columnaris and z. intermedia of the anal canal; dilated excretory ducts of the anal glands were frequently encountered, often filled with inflammatory cells. PAS‐positive but Sudan Black‐negative secretion was demonstrated in these ducts as well as within the secretory acini. Sebaceous, circumanal and apocrine sweat glands were restricted to the z. cutanea. Moderate to high alkaline phosphatase activity in the basement membrane of circumanal glands may suggest the presence of myoepithelial cells.

Hypercalcemia associated with an adenocarcinoma derived from the apocrine glands of the anal sac.

Clinical, gross, and light microscopic findings are described for 36 dogs, 33 females and three males, with adenocarcinomas arising from the apocrine glands of the anal sac. All tumors had light microscopic features of malignancy and 22 of 23 metastasized to iliac and lumbar lymph nodes. Nine dogs had disseminated metastases, but bone metastases were found in only one dog. Differentiated neoplasms formed secretory acini and tubules lined by tall columnar or cuboidal epithelium. Most neoplasms were histologically bimorphic, with glandular areas and solid nests. Parathyroid glands were atrophic. Hypercalcemia (mean = 16.1 mg/dl) was present in 20 of 22 dogs (90%) and hypophosphatemia (mean = 3.2 mg/dl) in 12 of 17 (71%). Remission of hypercalcemia by tumor ablation and recurrence of hypercalcemia with tumor regrowth suggested that the tumor produced a substance that caused hypercalcemia. This unique clinicopathologic syndrome is characterized by hypercalcemia in old, predominantly female, dogs with an adenocarcinoma arising from the apocrine glands of the anal sac.

The topography of rat submandibular gland parenchyma as observed with S.E.M.

The parenchymal components of rat submandibular gland were examined by scanning electron microscopy after removal of the stromal connective tissue by acid hydrolysis and/or enzymatic digestion. Secretory acini have polymorphous topographies but usually consist of three to five truncated lobes emanating from a common hilus. They have a mean volume of about 33,000 micrometers3. Myoepithelial cells are associated with the deeper acini of the gland where they cover congruent to 54% of the surface area of their allied acini. Each flattened myoepithelial cell has a central perikaryon that gives rise to four or five broad primary processes that bifurcate two or three times to produce a total complement of 20 to 40 terminal processes per cell, each 0.5 micrometer to 1.7 micrometers wide. The terminal processes of adjacent myoepithelial cells tend to slightly overlap and to attach to each other by desmosomes forming a network over adjacent acini. The components of the duct system are examined and each characterized by salient features as observed with the SEM.

Vasoactive Intestinal Polypeptide (VIP)-like immunoreactivity in salivary glands

VIP-like immunoreactivity was found in rat, cat and human salivary glands at a concentration of 17.0 – 29.3 pmol/g of tissue. The immunoreactivity was localised by immunocytochemistry in beaded nerve fibres which occurred in association with secretory acini, ducts, blood vessels and larger nerves. In salivary glands VIP may act as a neurotransmitter or neuromodulator involved in the regulation of blood flow and in the composition and volume of saliva.

Adrenergic and cholinergic nerves of bovine, guinea pig and hamster salivary glands. A light and electron microscopic study.

The distribution of formaldehyde-induced fluorescence and acetylcholine-esterase (AChE) activity was histochemically investigated in certain salivary glands of the cow (submandibular gland), guinea pig and hamster (submandibular and sublingual glands). Adrenergic nerves occur around the secretory acini of the bovine, guinea pig and hamster submandibular glands, as well as around those of the hamster sublingual gland. The mucous secretory acini of the guinea pig sublingual gland, however, seem to be devoid of adrenergic nerve supply. Except in the sublingual gland of the hamster, no adrenergic nerves occur in relation to duct cells.

Myoepithelial cells in the exorbital lacrimal and parotid glands of the rat in frozen-etched replicas.

AbstractLight and electron microscopy were combined with the technique of freeze‐etch to study myoepithelial cells. Myoepithelial cells of the rat exorbital lacrimal and parotid glands are found in relation both to secretory units and intercalated ducts. They lie within the basal laminae of secretory acini and intercalated ducts and do not protrude from the external surface. The myoepithelial cell consists of a central nucleus and surrounding cytoplasm with several cytoplasmic arms, the arms being less numerous in those cells associated with the ducts. The cytoplasm is filled with fine fibrils in parallel array. The interrelationship between myoepithelial cells and acinar or ductal cells is described with the aid of frozen‐etched replicas and the nature of the membrane surfaces is discussed. It is concluded that myoepithelial cells are contractile; their resemblance to smooth muscle is noted.

A histological and histochemical study of the development of salivary glands in the chick (Gallus domesticus).

The anterior submaxillary glands of the domestic fowl are paired, compound tubular glands. Each is divided into four lobes and each lobe is composed of branching lobules. Secretory acini are distributed along the lobules and each lobule drains into the oral cavity by a separate duct. The lobules originate as ingrowths of the oral epithelium at the 9-day incubation stage. These primordia later increase in number and length, and become branched. The secretory product is produced by both the acinar and duct cells and is demonstrable at the 14-day incubation stage. It is a mucous secretion containing sulfated mucopolysaccharides and mucoproteins. Sialomucin, if present, could not be demonstrated. The secretory product increases in amount within the cells and lumina during the prehatching period. The duct and acinar cells stain positively for ribonucleic acid and alkaline and acid phosphatase, and possess mitochondria and Golgi bodies. The evolution of these substances and organelles parallels cytogenesis and the rate of elaboration of the secretory product. Lipids are present only as components of the cell organelles.

HISTOCHEMICAL DEMONSTRATION OF NORADRENALINE IN RAT SALIVARY GLANDS

The localization of tissue noradrenaline in rat salivary glands has been studied by a fluorescence method for histochemical demonstration of catecholamines in combination with a pharmacological approach.In the submaxillary gland, noradrenaline fluorescence showed a fine network surrounding the secretory acini and the granular tubules, but there was no fluorescence in their cell bodies. The walls of arteries and arterioles were also surrounded by noradrenaline fluorescence but the intra- and interlobular excretory ducts were not. In the sublingual gland, noradrenaline fluorescence was present only in the walls of blood vessels and there was no fluorescence in the vicinity of the secretory acini and the excretory ducts. The localization of noradrenalide in the parotid gland was essentially similar to that of the submaxillary gland but somewhat weaker in intensity around the secretory acini. This indicates that the adrenergic innervation is predominant to the submaxillary and, to a lessor extent, parotid glands which are composed of serous cells and that there is no supply of adrenergic fibers to the mucous cells of the sublingual gland. The results of quantitative determination of noradrenaline with a biochemical method were well consistent with those of histochemical findings.In connection with the distribution of specific cholinesterase, the mode of double innervation of adrenergic and cholinergic fibers to the salivary glands are discussed.

The effect of postganglionic sympathectomy on the histochemical appearances of cholinesterase in the nerves supplying the submandibular and sublingual salivary glands of the rat.

1. The innervation of the submandibular and sublingual salivary glands of the rat has been studied histologically. A histochemical method for cholinesterase was used to demonstrate the nerve fibres. 2. The nerves were found to enter the glands as a series of intercommunicating trunks which accompanied and gave branches to the ducts and arteries. The nerves were seen to terminate by breaking up to form a network which surrounds the secretory acini. 3. In the submandibular gland the arrangement of the nerve net in the vicinity of the tropochrome and homeochrome cells was practically identical. In the sublingual gland fewer nerve fibres were visible and the concentration of cholinesterase within them was less. The arrangement of the nerve fibres in the region of the mucous and demilune cells appeared to be identical. 4. Postganglionic sympathectomy was found to have no effect on the distribution of the nerves within the glands. It was concluded that the nerves seen within the glands were parasympathetic although a few of the fibres might possibly have been sensory. 5. Some cholinesterase activity was found in the nuclei and cytoplasm of the duct cells. A small amount of enzyme activity was also seen in the walls of the tropochrome and homeochrome cells but more especially in the tropochrome cells. 6. The significance of these findings in relation to histological and physiological observations of past and present workers is discussed.