Histochemical and ultrastructural study on the innervation of the byssus glands of Mytilus galloprovincialis

The aluminium-formaldehyde (ALFA) histofluorescence method reveals an extensive plexus of brilliant greenish monoaminergic elements in the glandular zones of the Mytilus foot, while only scanty nerve fibres are acetylcholinesterase-positive. By electron microscopy, bundles of nerve fibres can be seen i) in close connection with the intrinsic musculature located in the connective septa among the glands, and ii) near the cell bodies and necks of all the byssus glands. The nerve fibres show varicosities containing three types of vesicles: small clear (50-60 nm), small granular (80-90 nm), and large granular (160-200 nm). The regions of close apposition between nerve terminals and muscle or gland cells generally do not show typical pre- or postsynaptic specializations. Along the pedal groove, mainly in the proximal two thirds of the foot, peripheral bipolar neurons can be detected, both by fluorescence and electron microscopy.     

Morphological characterization of the glandular system in the salamander Plethodon shermani (Caudata,Plethodontidae)

Amphibians have evolved a wide variety of mechanisms that provide a certain degree of protection against predators, including camouflage, tail autonomy, encounter behavior and noxious or toxic skin secretions. In addition to these strategies, some amphibians release a glue-like secretion onto the surface of their skin when threatened. While some information regarding the origin and production of these adhesive secretions is available for frogs such as Notaden bennetti, these aspects are only partially understood in salamanders. We contribute to an earlier study and provide additional information regarding the origin, production, and characterization of the adhesive secretion in the red-legged salamander (Plethodon shermani) at a microanatomical level. When stressed, this salamander secretes a milky, viscous liquid from its dorsal and ventral skin. This secretion is extremely adhesive and hardens within seconds upon exposure to air. This study describes two cutaneous gland types (mucous and granular) in the dorsal and ventral epithelial tissue that differ considerably in their secretory content. While the smaller mucous glands contains flocculent to granular material, mostly acidic glycoproteins, the granular glands synthesize various granules of differing size and density that consist of basic proteinaceous material. The results strongly indicate that the secretions of both gland types from the dorsal as well as the ventral side form the adhesive mucus in Plethodon shermani, consisting of basic and acidic glycoproteins, glycoconjugates with mannose and α-l-fucose residues as well as lipid components.     

Observations on the Development of Babesia caballi (Nuttall) in the Tropical Horse Tick Dermacentor nitens Neumann

SYNOPSIS. The development of Babesia caballi (Nuttall) in Dermacentor nitens Neumann was studied in smear preparations and histologic sections of ticks infected with this protozoan parasite. A majority of the parasites in equine erythrocytes ingested by the adult ticks apparently were destroyed. Smal spherical bodies 4–6 μ in diameter were the 1st developmental stages of B. caballi observed in the gut contents of ticks infected with this parasite. These spherical bodies apparently gave rise to clavate (club-shaped) bodies 10–14 μ long by 4–6 μ wide. The latter developed into large round bodies 12–16 μ in diameter that segmented into vermicular-shaped parasites, about 8–12 μ long by 2–4 μ wide; some penetrated the gut wall, some invaded other cells of the tick.
In the cells of the Malpighian tubules, hemolymph, and ovaries, the vermicular parasites underwent a secondary cycle of multiple fission, forming vermicules similar to those occurring earlier in the gut. Vermicules that invaded the ova underwent a similar multiple fission cycle during the larval stage of the tick.
Vermicules from the multiple fission cycle that occurred during the period of larval feeding invaded the salivary glands. A multiple fission cycle of increase within these glands resulted in large numbers of small, oval and piriform parasites, 2.5–3 μ, maximum dimension. These parasites became mixed with the salivary secretions, and presumably are the forms injected into the horse by the nymphs as they feed. The small oval and piriform parasites therefore appear to be the infective stage for the horse.     

The anterior glands of adult Necator americanus (Nematoda: Strongyloidea)—I Ultrastructural studies

The ultrastructure of the amphidial, oesophageal and excretory glands of N. americanus is described. There are two amphidial glands, and each is attached to a lateral hypodermal cord. Anteriorly the glands become associated with the amphidial sense organs. The amphidial glands synthesize complex secretion granules which appear to release their contents into the sense organ. Secretions thus pass over the amphidial cilia and exit via the amphidial pore. It is suggested that the secretory activity of these glands is under direct nervous control. There are three oesophageal glands, and each synthesizes dense secretion granules. The secretions of the oesophageal glands are released into the lumen of the oesophagus and into the buccal capsule. The two excretory glands are ventral in position and connected to the tubular excretory system. These glands synthesize secretion granules of varying density. Secretions from the excretory glands may exit via the excretory pore, or pass back into the tubular excretory system, or both.     

The architecture of the accessory reproductive glands of the male desert locust: 1: types of glands and their secretions

The accessory reproductive glands of the male desert locust were studied by histological, histochemical, and phase-contrast techniques. It was found that the characteristics of the glandular epithelium and their corresponding secretions permit the division of the accessory glands into nine distinct types. Three types produce coarsely granular mucopolysaccharide secretions (glands 1, 11, and 12); three types produce finely fibrous mucopolysaccharide secretions (glands 2, 4, and 7-10, 13-15); one type produces a globular mucopolysaccharide or mucoproteinaceous secretion (gland 6); one type produces an acidic lipoprotein complex (glands 3 and 5); and one is the functional seminal vesicle (gland 16). Consequently, the various secretions are separated as a result of a vertical segregatign of the various cell types that are responsible for glandular activity.     

Anatomy and ultrastructure of the ventral pharyngeal organs of Saccocirrus(Saccocirridae) and Protodriloides(Protodriloidae fam. n.) with remarks on the phylogenetic relationships within the Protodrilida (Annelida: Polychaeta)

General anatomy and ultrastructure of the ventral pharyngeal organs were investigated in Succocirrus krusudensis, Protodriloides chaetifer and P. symbioticus. Succocirrus papillocercus, a species without a ventral pharyngeal organ, was included for comparison. The two genera show homologous similarities in their pharynges: bulbus muscle composed of transverse muscle fibres and interstitial cells, those cells with small cell bodies and processes containing prominent tonofilaments which are orientated dorsoventrally and connect the bulbus epithelium with the investing muscle; bulbus muscle fibres circomyarian with nuclei and mitochondria located basally, investing muscle also with interstitial cells, which lack tonofilaments; oesophagus surrounded by gland cells opening into the pharynx. Most likely, a ventral pharynx with these characters was already present in the stem species of Saccocirridae, Protodriloidae fam. n. and Protodrilidae and evolutionary processes led to several changes: a tongue-like organ with a prominent tip and supporting elements is a synapomorphic character of Protodrilus and Succocirrus; the pharyngeal organ is reduced to stomodeal pouches and salivary glands in S. papillocercus and completely lost in Asromus raenioides. These results and data from previous studies are summarized in a tentative phylogenetic dendrogram and allow the introduction of a new family, Protodriloidae.     

Distribution of FMRFamide-like immunoreactivity in the nervous system of the slug Limax maximus

Summary The distribution of FMRFamide-like immunoreactive neurons in the nervous system of the slug Limax maximus was studied using immunohistochemical methods. Approximately one thousand FMRFamide-like immunoreactive cell bodies were found in the central nervous system. Ranging between 15 m and 200 m in diameter, they were found in all 11 ganglia of the central nervous system. FMRFamide-like immunoreactive cell bodies were also found at peripheral locations on buccal nerve roots. FMRFamide-like immunoreactive nerve fibres were present in peripheral nerve roots and were distributed extensively throughout the neuropil and cell body regions of the central ganglia. They were also present in the connective tissue of the perineurium, forming an extensive network of varicose fibres. The large number, extensive distribution and great range in size of FMRFamide-like immunoreactive cell bodies and the wide distribution of immunoreactive fibres suggest that FMRFamide-like peptides might serve several different functions in the nervous system of the slug.     

Ultrastructural and histochemical study of the salivary glands of Aplysia depilans (Mollusca, Opisthobranchia)

The digestive system of the sea hare, Aplysia depilans , includes a pair of ribbon-shaped salivary glands. A central duct and a large blood vessel run close to each other along the length of these glands and both are surrounded by a layer of muscle cells. Three cell types form the glandular epithelium: granular cells, vacuolated cells and mucocytes. The granular cells possess cilia and spherical secretion granules, located primarily in the apical region. The granules of immature cells have a low electron density and are mainly formed by neutral polysaccharides with small amounts of proteins. The granules of mature cells are larger, have a high electron density and are mainly formed by proteins with lower amounts of neutral polysaccharides. Transition stages between immature and mature granular cells are observed. The vacuolated cells are large and frequently pyramidal in shape, but after the application of histochemical techniques almost all vacuoles remain uncoloured. The numerous vacuoles contain flocculent material in a clear background and the mitochondria possess large crystalline structures in the matrix. A pyramidal shape is also typical of the mucocytes, which are filled with vesicles containing granular masses surrounded by a network of secretion material. These large cells are strongly stained by Alcian blue, revealing the presence of acidic mucopolysaccharides. This is the first ultrastructural study of the salivary glands in opisthobranch gastropods.     

A histological and ultrastructural comparison of the male accessory reproductive glands of diapausing and non-diapausing adults in Bruchidius atrolineatus (Pic) (Coleoptera : Bruchidae)

Cytological variations of the median and the 2 lateral accessory glands of Bruchidius atrolineatus Pic (Coleoptera : Bruchidae) were examined as a function of age and the reproduction of the male. In sexually active virgin males, the secretory epithelium is columnar at emergence, but progressively flattens, and the secretions formed and stored by its cells are expelled by exocytosis into the glandular lumen. After 10 days, the male accessory glands exhibit a stage of repletion, characteristic of glands temporarily storing their secretions in their lumen. In diapausing males, the genital tract is relatively undeveloped and the accessory glands are reduced to tubules, whose lumen, surrounded by an epithelium composed of narrow cells, contains little secreted material. The presence of secretion aggregates in the secretory epithelial cells, the abundance of rough endoplasmic reticulum in them, and the release of a part of their secretions into the glandular lumen, indicate that reproductive diapause in B. atrolineatus is characterized by a decrease in the reproductive function. and not its total arrest.     

Integumentary structure and its relationship to wiping behaviour in the common Indian tree frog, Polypedates maculatus

Skin of the Indian tree frog, Polypedates maculatus (Rhacophoridae), was studied in the context of self-wiping behaviour which functions to expel and distribute cutaneous secretions recently shown to retard evaporative water loss. The secretions contain both mucus and lipids and are derived from a common gland considered to be homologous with characteristic anuran mucous glands. The glands are bipotent and secrete both mucus and lipoid products which are evidently mixed within the glandular lumen. Another type of gland resembling characteristic anuran serous (or granular) glands is found in dorsal but not ventral skin, whereas the lipid-secreting mucous glands are found in skin associated with all body surfaces. There is no distinct, lipid-secreting gland present in the skin of this species other than the mucous glands. These histochemical data complement the earlier finding that resistance to evaporative water loss in this species is relatively small compared with phyllomedusine 'waterproof frogs which also exhibit wiping behaviour associated with secretion of lipids. Thus, wiping behaviour may have evolved in association with mucous secretions before dominant lipoid secretions resulted from strong selection for water conservation.     

Ultrastructural and histochemical observations on secretory phenomena in the resting human mammary gland

Ultrastructure and histochemistry of clinically normal appearing tissue and secretions of non-lactating human mammary glands have been investigated in order to document and analyse secretory phenomena in the resting gland. The material studied originated from women of different ages (18-74 years) who underwent plastic surgery or surgery for various disorders of the breast. The epithelia of small ducts and of alveolar enlargements as well as acini contained moderate amounts of mitochondria and of cisterns of the rough endoplasmic reticulum; the transcisterns of the Golgi apparatus which were surrounded by smooth and coated vesicles, exhibited modest dilatations, the number of lysosomes increased with age; regularly glycogen particles and bundles of intracellular filaments (phi 5 nm) were to be observed. Typical casein vesicles and stages of apocrine secretion of milk fat globules were not seen. The following features indicated secretory activity: differently sized vesicles and granules with flocculent, dense, or light contents were regularly to be seen in the apical cytoplasm often immediately below the apical plasma membrane of the epithelia of the small ducts and even more frequently in the alveolar enlargements. Secretory products of fine granular or filamentous structure, probably containing proteins, were frequently found within the lumen. Different types of lipid and liposome-like particles were detected both in intracellular localization as well as in ductal lumina. As demonstrated by lectin histochemistry the secretory products also contained a considerable amount of carbohydrate components. The composition of the secretory products of the resting gland is of clinical interest since the chronical deposition of secretions, which among others possibly contain enzymes producing oxygen radicals, may lead to pathological changes of mammary gland tissue.     

Trypanosoma (Megatrypanum) megachiropterorum sp. n. from the Flying Fox, Pteropus tonganus Quoy & Gaimard

SYNOPSIS. Trypanosoma (Megatrypanum) megachiropterorum sp. n. from the flying fox, Pteropus tonganus Quoy & Gaimard, from the Kingdom of Tonga, is described. The trypomastigotes measure 32 ± 1.74 (here and below S.D.) (27–37.5) × 3.6 ± 0.23 (3–4.5) μm and has a flagellum averaging in length 6.4 ± 0.92 (4.5–10) μm. Their nuclear index is 1.2 ± 0.16 (0.7–1.6) and their kinetoplastic index equals 6.2 ± 0.32 (5.5–7.1). This is the first report of a member of the subgenus Megatrypanum from bats outside the American and African continents and also the first record of a trypanosome from bats in the Pacific area.     

Histologic study of the lumbar glands of Pleurodema thaul (Amphibia, Anura, Leptodactylidae)

Frogs of the Pleurodema thaul species have a pair of prominent elevated cutaneous glands dorsolaterally, just posterior to the sacrum, which are named lumbar glands. We have studied histologically these glands and found that their chromatophores are disposed mainly immediately under the epidermis structuring a dermal chromatophore unit. Similar to the other anuran macroglands, the lumbar glands are constituted basically by granular alveoli filled with secretion. The presence of these granular alveoli and the typical distribution of the dermal chromatophores to suggest a defensive role for the lumbar glands. In most of the amphibians granular alveoli contain secretions with toxicity for several vertebrates. On the other hand, chromatophores in this frog species, probably play an aposematic function, since their disposition on the skin permits that the lumbar glands might be taken for eyes, probably giving to an eventual predator the impression that it may be an animal of higher dimensions.     

Functional morphology of the mammiliform penial glands ofLittorina saxatilis (Gastropoda)

Summary The functional morphology of the mammiliform penial glands ofLittorina saxatilis has been investigated with both light and electron microscopy. These penial glands line the ventral edge of the penis and orient with the female mantle during copulation. Secretions are released from the penial glands to this interface where they probably function in adhesion. The penial gland secretions comprise heterogeneous granules as well as apocrine and mucous secretions. The heterogeneous granules are produced in separate multicellular glands arranged in a series of lobes that lie outside a thick smooth muscle layer enclosing the lumen. Each glandular lobe is surrounded by a thin layer of smooth muscle. Secretions are transported in individual cellular processes that pass through the thick smooth muscle layer and empty into the lumen. Surrounding the lumen is an epithelium containing apocrine secretory cells as well as occasional goblet-type, mucous cells. The combined action of the muscles forces secretions out of the lumen through the penial papilla, onto the external surface of the mammiliform penial gland. Longitudinal muscles extend into the penial papilla enabling its protrusion or retraction. Retraction of the penial papilla following secretion release is thought to create negative pressure beneath the penial gland producing suction adhesion. The visco-elastic properties of the penial gland secretion are qualitatively different from foot mucus and may represent specialization to an adhesive function.     

Golgi vesicles of uncommon morphology and wall formation in the red alga,Polysiphonia

Summary Golgi bodies of immature carposporangia ofPolysiphonia sp. are composed of a polarized stack of six to ten curved cisternae. The cisternae are surrounded by 50–200 nm diameter slightly granular vesicles.Hypertrophied, fibrillar Golgi cisternae occur in mature carposporangia. Secretory vesicles originate from ends of cisternae and by complete vesiculation of terminal cisternae; 0.6–1.2 m diameter, fibrous vesicles, many with electron dense nucleoids are abundant throughout the cytoplasm of mature sporangia. Vesicles expand, fuse with each other and cluster around starch granules. Some vesicles secrete their content into the spore wall. Morphological analyses of starch granules as well as topographical relations between vesicles, starch granules and the adjacent cytoplasm suggest that these Golgi vesicles function like lysosomes. The significance of these observations is discussed in relation to the composition of plant cell walls and cellular expansion.     

Non-resinous secretions of the lac insect Kerria lacca (Homoptera-Coccoidea)

The place of origin, sequence of appearance and the shape of various non-resinous secretions during the entire life cycle of both male and female lac insects, have been described here. Properties of the secretions found in the adult female are also given.
A total of 20 non-resinous secretions has been found in Kerria lacca . Fourteen of these secretions–dorsal relic, pencils, brachial mass, large anal hairs, short anal hairs, brachial core, major spiracular secretion, minor spiracular secretion, non-stalked girdle fibres, stalked girdle fibres, thin ventral patch, oral lobe secretion, brachial marginal secretion and cavaera secretion–are present both in male and female lac insects. Three secretions– opercular secretion, canella secretion and caudal filaments–occur only in the male while the remaining three–ventrolateral compact flat fibres, ventrolateral long coiled threads and perivaginal fine filaments–occur only in the female.
Two types of non-resinous secretions, 13 waxy and four non-waxy, occur in female K. lacca . The dorsal relic, pencils and their modifications (anal tubercular splint and anal tubercular shield), brachial mass, large anal hairs, short anal hairs, major spiracular secretion, minor spiracular secretion, non-stalked girdle fibres, thin ventral patch, oral lobe secretion, brachial marginal secretion, cavaera secretion and ventrolateral compact flat fibres are waxy in nature, whereas the brachial core, stalked girdle fibres, ventrolateral long coiled threads and perivaginal fine filaments are non-waxy.     

The structure and development of the spermatozoon of Heterakis gallinamm (Nematoda)

The structure and development of the spermatozoon of the nematode Heterakis gallinamm has been described. The spermatozoon is amoeboid. The centrioles have the unusual structure of nine single fibres. The nucleus has no limiting membrane and is surrounded by mitochondria and organelles, here called alpha bodies. These alpha bodies appear to arise from Golgi complexes in association with granular endoplasmic reticulum in the spermatocytes and have a fibrillar component which is released into the peripheral cytoplasm of the spermatid when the spermatozoon is formed. There is no refringent cone as in other ascaroid spermatozoa.     

Morphology and glycoconjugate histochemistry of the palpebral glands of the adult newt, Notophthalmus viridescens.

The eyelids of the newt were studied in 10 microns serial paraffin and 1-2 microns plastic sections using standard histological stains and special stains for glycoconjugates. The eyelids contain four different glands. Simple acinar serous and simple acinar mucous glands occur in the skin; unicellular mucous glands occur in the conjunctiva; and convoluted tubular seromucous glands are present in connective tissue beneath the conjunctiva. The first two are identical to cutaneous glands found elsewhere on the head and body. The simple acinar serous glands are surrounded by myoepithelial cells and release their secretion, which is composed largely of proteins with minimal glycoconjugate content, by a holocrine mechanism. The secretory product of the simple acinar mucous glands is composed of neutral glycoconjugates with a minor content of acidic glycoconjugates; the mucin exhibits strong PAS and PAPD staining and weak staining by AB and PAPS methods. The unicellular conjunctival mucous glands secrete both neutral and acidic glycoconjugates as shown by positive reactions with PAS, PAPD, PAPS, and AB methods. Convoluted tubular seromucous glands in the ventral eyelid synthesize both proteins and neutral glycoconjugates. The mucous secretions of the conjunctival glands probably provide lubrication and protection for the cornea.