Seasonal lectin binding variations of thumb pad in the frog (Pelophylax ridibundus)

The thumb pad is one of the most common secondary sexual characteristics in frogs. Although it is known that amphibian skin has affinity for several lectins, there is no report regarding lectin‐binding affinity of the thumb pad or its structural components. This study investigated localization and seasonal variation of specific carbohydrate moieties of glycoconjugates in both the epidermal and dermal components of the frog thumb pad at the light microscopic level using lectin histochemistry. The study consisted of four seasonal groups of the frog species, Pelophylax ridibundus (Synonym of Rana ridibunda): active, prehibernating, hibernating and posthibernating. Four horseradish peroxidase conjugated lectins were employed. It was found that dolichos biflorus agglutinin (DBA), wheat germ agglutinin (WGA), and ulex europaeus (UEAI) gave positive reactions in both epidermal layers and breeding glands. These three lectins bound specific secretory cells in the breeding glands, and the distribution of the cells and epithelial lectin reactions exhibited seasonal changes. In addition, UEA‐I and peanut agglutinin (PNA) showed an affinity in granular glands and the granular zone of mixed glands. Generally, epidermal lectin binding showed dense affinity during the posthibernation period. DBA, UEA‐I, and WGA‐specific cells in the mucous gland decreased gradually until the posthibernation period. These findings suggest that differences of lectin binding in the thumb pad may be related to functional activities and, thus, seasonal adaptations. Moreover, the presence of specific lectin‐binding cells in the breeding glands indicated that they consisted of heterogeneous secretory cell composition or that the cells were at different secretory stages. J. Morphol. 275:76–86, 2014. © 2013 Wiley Periodicals, Inc.     

Little-known accessory glands in female Zygaena moths (Lepidoptera, Zygaenidae)

In the female genital system of Zygaena moths, an additional pair of accessory glands is present besides the Y-shaped sebaceous gland. The term 'Petersen's glands' is proposed for these organs. Anatomy, histology, histochemistry and cytology of Petersen's glands of Zygaena trifolii are described. The sac-like glands, situated in the extreme dorsocaudal part of the abdomen, can be divided into a purely secretory part consisting of acini with large pear-shaped gland cells and a reservoir part with combined secretory and storage function. The secretory cells of the acini are penetrated by long curved ductules or secretory end apparatuses having feltwork consisting of very fine filaments. The cytoplasm is characterized by abundance of smooth tubular endoplasmic reticulum (ATER) and the presence of peroxisomes. This cytoplasmic organization is in accordance with the chemical composition of the sticky secretion, which evidently consists completely of lipids. The ultrastructure of the epithelium lining the reservoir of the glands has both traits of secretory and of transporting epithelia. Besides contributing to the secretion, it may be involved in absorption of residual aqueous phase from the contents of the reservoir.     

Significance of saliva for the denture‐wearing population

This paper summarises a series of studies already published in German and presents new data related to the aetiology of the dry mouth' and its associated problems. Aims: to study factors affecting mucous and serous salivary gland secretion, the aetiology of the ‘dry mouth’ and its associated problems, causative factors for hyposalivation and it's treatment Setting : two university dental hospitals. Subjects: 587 denture wearers and 521 control subjects, and autopsy material Interventions : exercise, chewing, water, oestrogen, pilocarpine, and anetholtrithion theiapy, biopsy of the minor glands Main outcome measures : Palatal secretion (PAL, μL/cm²/min) and parotid salivary flow (PAR), subjective complaints and clinical findings. Results: resting flow rates for PAL between 0 and 65 μl/cm²/min were seen in every age group. The flow rates of PAR (0 to 3.7 ml/10 min) were not correlated with PAL. Most patients with a resting flow rate of PAL≤6.0 μl/cm² suffer from a ‘dry mouth’ and Burning Mouth Syndrome (BMS) or oral dysaesthesia (OD) with or without chronic lesions of the oral mucosa. Etiological factors for the incidence of reduced PAL and associated problems include xerostomic drugs, oestrogen deficiency, ladiotherapy, thyroid dysfunction, smoking or continuous wearing of complete upper dentures. PAL also correlated with the retention of upper complete dentures. PAL was correlated with the water content of epithelial tissues. PAL and PAR were both increased by drinking ample fluid, improving their circulation by physical exercises, chewing intensively, or taking oestrogens, pilocarpine, anetholtrithion. Conclusions: Variation in palatal salivary secretion occurs and is clinically important.     

Egg envelopes of Streptocephalus dichotomus Baird: A structural and histochemical study

The origin, ultrastructure and histochemical properties of the egg membranes in the South Indian anostracan, Streptocephalus dichotomus have been studied. The egg morphology and the ultrastructure of the tertiary membrane of this phyllopod crustacean have been examined both by scanning and transmission electron microscopy. Scanning electron microscopic observations on the egg surface reveal the characteristic ridges on the egg surface with pores. Similarly, the tertiary egg shell of S. dichotomus consists of two distinct layers, an outer cortex and an inner alveolar layer. There are specific differences in the structure and in the relationship of one layer to the other. The alveolar layer is characterised by large lipid droplets and an alveolar mesh. These two layers termed as tertiary layers are secreted by maternal shell glands. The outer tertiary egg layers are phenolically tanned, the precursor materials for tanning being derived from shell gland secretions.     

Fine structural aspects of silk secretion in a spider. II. Conduction in the pyriform glands

The excretory duct of pyriform glands in Araneus diadematus is connected to the secretory sac through an intermediary cell ring. Apices of these cells bear thick, long microvilli and cytoplasmic extensions containing microtubules in bundles, some of which are derived from normal basal bodies. These finger-like extensions lie between the cuticular intima and the secretory product; they are thought to protect the intima and to initiate moulding of the silk thread. Structural features of the duct cells suggest that the latter play a role in the control of the water content of the silk glue which is restricted to the last portion of the duct where numerous nerve endings are inserted between cells. It is evident that duct structure and chemical and physical characteristics of silk are correlated in all spider silk glands.     

Male insect accessory glands: Functions and control of secretory activity

Summary

Paralleling the diversity of the class Insecta, the male accessory glands (MAG) exhibit a wide range of form, and their secretion serves a variety of functions, including spermatophore and mating plug formation, sperm activation, provision of nutrients to females, and, through production of fecundity-enhancing and/or receptivity-inhibiting substances, modification of female reproductive behavior. In most insects, juvenile hormone (JH) is important in the regulation of MAG secretory activity; specifically, JH controls the production of particular proteins in the secretion. However, the production of some proteins appears not to be influenced by JH; rather, their synthesis is regulated by ecdysteroids. During sexual maturation, JH and ecdysteroids seem to interact to bring about a specified temporal sequence of protein synthesis in the MAG.     

Effect of essential fatty acid deficiency on G-proteins, cAMP-dependent protein kinase activity and mucin secretion in the rat submandibular salivary glands

Studies were conducted to determine whether β-adrenergic cell signalling is altered in submandibular salivary glands (SMSG) is essential fatty acid (EFA) deficiency. Three groups of rats were fed diets which were deficient in EFA (EFAD), marginally deficient in EFA (MEFAD) or contained sufficient amount of EFA (Control). Rats were killed after 20 wk on diets, SMSG were dissected out and cyclic AMP-dependent protein kinase (PKA) activity was measured. The specific enzyme activities were higher in the homogenates and supernatant fractions of the gland from EFAD and MEFAD rats compared with the controls. The relative levels of guanine nucleotide-binding regulatory proteins (Gs and Gi) were also measured in the SMSG membranes of rats fed the 3 diets. The levels of Gs were significantly higher in the EFAD and MEFAD groups than in the controls. No significant differences were observed in the secretion of trichloroacetic acid-phosphotungstic acid (TCA-PTA) precipitable glycoproteins from the SMSG slices among the 3 dietary groups.