The foregut glands of vermivorous cone shells

Journal of Molluscan Studies, 2015

The salivary glands of the cephalaspideans Philine quadripartita (Philinidae), Aglaja tricolorata (Aglajidae) and Haminoea navicula (Haminoeidae) were studied by light and electron microscopy to investigate relationships between diet, phylogeny and morphofunctional features of these glands. In herbivores such as H. navicula the posterior end of the long ribbon-shaped salivary glands is attached to the gizzard, whereas in P. quadripartita and A. tricolorata these glands are shorter and their posterior end is unattached. The salivary glands of the carnivorous cephalaspidean P. quadripartita contains three types of secretory cells. Granular mucocytes and vacuolated mucocytes, both secreting acid polysaccharides, were much more abundant than the granular cells secreting proteins associated with neutral polysaccharides. The same cell types were recognized in the salivary glands of H. navicula, but in this species the granular cells are much smaller and even less abundant. The salivary glands of A. tricolorata contain different secretory cells, which were named cells with dense vacuoles, alveolar cells and granular cells. The first two produce proteins and acid polysaccharides, while granular cells contain proteins and neutral polysaccharides. Based on these results and previously published data, it can be said that histologically the salivary glands of the carnivorous cephalaspidean P. quadripartita are much more similar to the salivary glands of herbivorous cephalaspideans (Bulla striata and H. navicula) and other herbivorous euopisthobranchs (Aplysia depilans), than to the salivary glands of aglajids (A. tricolorata and Philinopsis depicta) in which mucocytes are absent. Thus, having a herbivorous or a carnivorous diet by itself seems not to have been a major driving factor on the histology of salivary glands in cephalaspideans. The digestive system of aglajids differs from that of other carnivorous cephalaspideans, not only in the histology of salivary glands but also in other aspects such as absence of a gizzard, and the lack of a radula in all but one genus. Concerning the morphology of the digestive system, aglajids are highly derived cephalaspideans.

Acta Scientiarum. Biological Sciences, 2013

Procyon cancrivorus is a wild mammal from the Procyonidae family, being one of the least studied Brazilian carnivores. The aim of this study was to describe the morphological aspects of the salivary glands of Procyon cancrivorus, and to compare with literature data on the morphology of domestic animals and wilds animals, such as coatis and possums. Three adult animals were collected on highways (roadkilled), fixed 10% formaldehyde aqueous solution and submitted to desiccation. The salivary glands of the crab-eating raccoon are formed by the parotid, mandibular, sublingual and zygomatic glands. The parotid gland shows irregularly triangular shape with its respective duct. The mandible gland shows rounded outline surrounded by a fibrous capsule with its respective duct. The sublingual gland is divided into two parts: the caudal part, located in the occiptomandibular region of the digastric muscle and the rostral part between the tunica mucosa of the mouth and the mylohyoid muscle with its respective duct. The zygomatic gland is small and rounded, located in the rostral part of the pterygopalatine fossa with its respective duct. The morphology of the salivary glands of crabeating raccoon presents great similarity in shape and arrangement with the glands of dog, cat, coatis and possum.

Journal Molluscan Studies, 2004

A detailed morphological analysis of the salivary gland of adults of the freshwater snail Biomphalaria straminea was carried out by light and electron microscopy, complemented by the biochemical assay of key digestive enzymes in gland homogenates. The salivary gland is a paired tubular organ with the anterior portion (the tubular ducts) inserted into the buccal mass and the posterior region (the secretory portion) joined by their tips, forming a loop. The entire gland is made up of a simple columnar epithelium, resting on a thin connective tissue, and three regions can be recognized: the duct, the intermediary and the secretory regions. The duct is formed by a single cell type, the duct epithelial cell, covered apically by cilia and microvilli. The intermediary region presents two cell types: one similar to the duct cells and the other to the secretory cells found in the secretory region. Two cell types are also observed in the secretory region: the intercalary (non-secretory cells) and the secretory cells. The intercalary cells have many cilia and microvilli on their apical surface which, along with the cilia present in the duct epithelial cells, should act in mixing and propelling the salivary secretion in the gland lumen from the secretory region into the buccal cavity. According to the general cell morphology, size and secretory activity, five phases of differentiation (I-V) can be identified in secretory cells. Based on the ultrastructural aspect of the secretion vesicles and the rough endoplasmic reticulum, two cell sub-types can be further distinguished in secretory cells: L-cells and H-cells. The mechanism of elimination of secretion in secretory cells is initially apocrine (phases III-IV), ending as a holocrine mechanism in the final (phase V) steps of the secretory process. To detect the presence of digestive hydrolases in the salivary gland, five enzymes (amylase, cellulase, maltase, aminopeptidase and trypsin) were tested in gland homogenates. Except for trypsin, the other enzymes were found to be significantly active, indicating an important role of the salivary secretion in the initial digestion of food ingested by these animals.

Brazilian Archives of …, 2007

The aim of this work was to study the feeding habits of the predator Brontocoris tabidus (Heteroptera: Pentatomidae) analyzing the salivary gland complex (SGC). The SGC was dissected and subjected to histological analyses and biochemical assays. Results showed that a pair of bilobed principal salivary glands and one pair of tubular accessory salivary glands form the SGC and different parts of salivary gland synthesizes similar substances. Lipases, a-amylase and trypsin-like enzymes were detected at both lobes of the principal salivary gland. These data together with observations related to the predator's diet suggested that it could be considered an obligate zoophytophagous.

Tissue and Cell, 1979

The bilateral salivary glands, ducts, and nerves of the giant garden slug Lima maximus control the secretion of saliva and its transport to the buccal mass. Each salivary nerve, which originates at the buccal ganglion, contains over 3000 axon profiles. These axons innervate the musculature of the duct and branch within the gland. The salivary duct is composed of several muscular layers surrounding an epithelial layer which lines the duct lumen. The morphology of the duct epithelium indicates that it may function in ion or water balance. The salivary gland contains four major types of secretory cells. The secretory products are released from vacuoles in the gland cells, and are presumably transported by cilia in the collecting ducts of the gland into the larger muscular ducts.

Arthropod Structure & Development, 2003

The salivary glands of Culex quinquefasciatus female mosquitoes are paired organs composed of two lateral lobes with proximal and distal secretory portions, and a medial lobe. All portions comprise a simple epithelium that surrounds a salivary duct. In the apical portion of the medial lobe, non-secretory cells strongly resemble cells involved in ion and water transport.

Protoplasma, 2014

Podisus nigrispinus Dallas (Hemiptera: Pentatomidae) is a zoophytophagous insect with a potential for use as a biological control agent in agriculture because nymphs and adults actively prey on various insects by inserting mouthparts and regurgitating the contents of the salivary glands inside the prey, causing rapid paralysis and death. However, the substances found in saliva of P. nigrispinus that causes the death of the prey are unknown. As a first step to identify the component of the saliva of P. nigrispinus, this study evaluated the ultrastructure and cytochemistry of the salivary glands of P. nigrispinus. The salivary system of P. nigrispinus has a pair of principal salivary glands, which are bilobed with a short anterior lobe and a long posterior lobe, and a pair of tubular accessory glands. The principal gland epithelium is composed of a single layer of cells enclosing a large lumen. Epithelial cells of the principal salivary gland vary from cubic to columnar shape, with one or two spherical and well-developed nuclei. Cells of the anterior lobe of the principal salivary gland have an apical surface with narrow, short, and irregular plasma membrane foldings; apical and perinuclear cytoplasm rich in rough endoplasmic reticulum; and mitochondria with tubular cristae. The basal portion of the secretory cells has mitochondria associated with many basal plasma membrane infoldings that are short but form large extracellular canals. Secretory granules with electron-dense core and electron-transparent peripheral are dispersed throughout the cytoplasm. Cells of the posterior lobe of the principal salivary gland are similar to those of the anterior lobe, except for the presence of mitochondria with transverse cristae. The accessory salivary gland cells are columnar with apical microvilli, have welldeveloped nucleus and cytoplasm rich in rough endoplasmic reticulum, and have secretory granules. Cytochemical tests showed positive reactions for carbohydrate, protein, and acid phosphatase in different regions of the glandular system. The principal salivary glands of P. nigrispinus do not have muscle cells attached to its wall, suggesting that saliva-releasing mechanism may occurs with the participation of some thorax muscles. The cytochemical and ultrastructural features suggest that the principal and accessory salivary glands play a role in protein synthesis of the saliva.

Experimental Cell Research, 1970

Salivary glands from fourth-instar larvae, prepupae, and early pupae of Chironomus thummi were examined with light-and electron microscopes to determine whether developmental changes in the structure of the large polytenic gland cells might be correlated with the gland's secretory activity. It was found that the Golgi complexes, previously implicated in the production of dense "secretory" granules [13], are most extensively developed during mid-prepupal stages, when the glands are the largest, swollen with secretion and apparently at a peak of saliva production. In recently molted pupae, which appear inactive in the production of salivary secretion, the glands are smaller and display Golgi bodies that lack the dense secretory material found associated with Golgi complexes at earlier stages. Those dense secretory granules remaining in the cytoplasm of pupal glands are found no longer accumulated just beneath the secretory brush border, as in earlier stages, but rather aggregated in clusters within the endoplasm, apparently in preparation for autophagic digestion. Electron microscope radioautographs prepared from glands labeled with radioactive amino acids in culture have provided further evidence that the dense secretory granules are indeed composed, at least in part, of proteins synthesized de novo by ihe large gland cells.

Acta Scientiarum. Biological Sciences, 2013

Procyon cancrivorus is a wild mammal from the Procyonidae family, being one of the least studied Brazilian carnivores. The aim of this study was to describe the morphological aspects of the salivary glands of Procyon cancrivorus, and to compare with literature data on the morphology of domestic animals and wilds animals, such as coatis and possums. Three adult animals were collected on highways (roadkilled), fixed 10% formaldehyde aqueous solution and submitted to desiccation. The salivary glands of the crab-eating raccoon are formed by the parotid, mandibular, sublingual and zygomatic glands. The parotid gland shows irregularly triangular shape with its respective duct. The mandible gland shows rounded outline surrounded by a fibrous capsule with its respective duct. The sublingual gland is divided into two parts: the caudal part, located in the occiptomandibular region of the digastric muscle and the rostral part between the tunica mucosa of the mouth and the mylohyoid muscle with its respective duct. The zygomatic gland is small and rounded, located in the rostral part of the pterygopalatine fossa with its respective duct. The morphology of the salivary glands of crabeating raccoon presents great similarity in shape and arrangement with the glands of dog, cat, coatis and possum.