Femoral glands of the lizard, Crotaphytus collaris

The anatomy of the femoral glands in an iguanid lizard, Crotaphytus collaris collaris (Say), is described. The 48 lizards (including three embryos) from which glands were examined were obtained throughout their season of activity at one locality in Kansas. In animals of both sexes the glands lie in a linear series on the ventral aspect of each thigh. They are composed of branching tubes and tubules of epidermal and dermal origin. The row of femoral pores is the only external manifestation of the glands. Post hatching, the glands of males increase in size and complexity; little onto-genetic change occurs in the glands of females. The relative length of the glands appears to vary seasonally in adult males suggesting variation in their activity. The greatest relative sizes occur in the breeding season. At times a stratum corneum, continuous with the stratum corneum of the skin, occurs in the duct of the gland internal to part of the secretion plug. Formation of the stratum corneum seems to be initiated in the autumn prior to hibernation, and the stratum corneum removes the outer part of the secretion plug in the next ecdysis; meanwhile, production of a new secretion plug is initiated. The anatomy of the femoral glands in Crotaphytus is similar to that of the described glands of other species of lizards.     

Chemical signalling behaviour in intrasexual communication of lizards lacking femoral pores

Signals that are used in animal communication may have multiple sensorial channels and functions. Animal communication integrates very distinct mechanisms such as behaviour, morphology and physiological secretions. Chemical signals occur in several contexts and are known to have a role in sexual selection. In many lizards, pheromones secreted through femoral pores are used to attract females and demark territory dominance. In lizard species without femoral pores, however, study of chemical signalling is negligible. Lizards of the genus Tropidurus have no ventral pores, but express melanic patches in their ventral thighs and cloacae (body regions linked to chemical communication in other lizards), which may play a role in both visual signalling and chemical signalling. Here, we describe the occurrence of pelvic rubbing—a chemical signalling behaviour—in two Tropidurus species, displayed in intraspecific agonistic intrasexual staged encounters. In addition, we compile a list of currently reported species that display this behaviour, checking for its social contexts and presence/absence of secretion pores. We analysed behaviours in conspecific trials between males of Tropidurus semitaeniatus and of T. hispidus during their breeding season. In T. semitaeniatus, displays of pelvic rubbing elicited aggressive responses from the opponents. Tropidurus hispidus, however, did not react to these conspecific displays. Pelvic rubbings were also partially linked to defecation in both species, which is likely due to secretions from internal urodeal glands expelled during defecation. Also, high rates of tongue flick behaviours during the encounters support the hypothesis that these lizards make use of chemical communication. Our observations corroborate previous suggestions that glandular scales — scales covered by generation glands produced at the epidermis across the lizards’ shedding cycles — are present in their melanic ventral patches. Our work also highlights the potential of characterizing such ventral patches as multimodal signalling badges. Further, we investigated the contexts in which pelvic rubbing is displayed adding to our understanding of the role played by chemical signalling in lizards without femoral pores.     

Epidermal glands in squamata: Fine structure of pre-cloacal glands in Amphisbaena alba (Amphisbaenia,Amphisbaenidae)

The femoral or cloacal region in lizards and amphisbaenians displays epidermal glands; these are commonly used for purposes of systematics. In spite of being recognized as semiochemical sources (Maderson [1986] Plenum Press, pp. 13–25), their precise role remains uncertain. The glands of lizards are assumed to be principally associated with reproduction and the demarcation of territory. Their function in amphisbaenians remains unknown. The histology of these glands has only been described for lizards. There are no ultrastructural studies of glands of either type. This study concentrates on the fine morphology of the pre-cloacal glands in Amphisbaena alba using routine histological and ultrastructural techniques. The pre-cloacal glands of amphisbaenians are, like those of lizards (Chiu and Maderson [1975] J. Morphol. 147:23–40), made up by a layer of germinative cells and various layers of polyhedral cells. The latter display three well-characterized stages of differentiation. Granules form and pass through two distinct stages. Thereafter, the granules fuse in the third stage. The glandular secretion is formed by cellular units that constitute the plug. Comparison of these morphological data with those available for lizards allows speculation about the function of the glands in amphisbaenians. © 1994 Wiley-Liss, Inc.     

Epidermal glands in Squamata: morphology and histochemistry of the pre-cloacal glands in Amphisbaena alba (Amphisbaenia)

Summary Pre-cloacal glands occur in some species of amphisbaenians. Although these glands are important in systematics, their biology and chemistry are little known. The pre-cloacal glands of Amphisbaena alba are of the holocrine type. They are made up of a glandular body and a duct. The glandular body is conical to elongate and is formed of clongatc lobules separated one from another by collagen septa. Each lobule is composed, at its periphery, of germinative cells, and within of polyhedral secretory cells, of different degrees of differentiation. The germinative cells, set on a basal lamina, are basophilic and their cytoplasm is fairly electron dense. The polyhedral cells display bulky cytoplasm, filled with spherical granules, wrapped in membranes and differing in their electron densities. Towards the lumen of the gland, these granules are increasingly eosinophilic and have an affinity for orange G. The secretion is discharged into the duct leading to the pore, which is situated in the central region of the scale. This secretion shows positive histochemical results for mucopolysaccharides and proteins. The similarity between the epidermal glands of lizards and those of A. alba raises the suggestion that the glands have equivalent functions, possibly in the course of intra- or interspecific communication.     

Secretory and basal cells of the epithelium of the tubular glands in the male Mullerian gland of the caecilian Uraeotyphlus narayani (Amphibia: Gymnophiona)

Caecilians are exceptional among the vertebrates in that males retain the Mullerian duct as a functional glandular structure. The Mullerian gland on each side is formed from a large number of tubular glands connecting to a central duct, which either connects to the urogenital duct or opens directly into the cloaca. The Mullerian gland is believed to secrete a substance to be added to the sperm during ejaculation. Thus, the Mullerian gland could function as a male accessory reproductive gland. Recently, we described the male Mullerian gland of Uraeotyphlus narayani using light and transmission electron microscopy (TEM) and histochemistry. The present TEM study reports that the secretory cells of both the tubular and basal portions of the tubular glands of the male Mullerian gland of this caecilian produce secretion granules in the same manner as do other glandular epithelial cells. The secretion granules are released in the form of structured granules into the lumen of the tubular glands, and such granules are traceable to the lumen of the central duct of the Mullerian gland. This is comparable to the situation prevailing in the epididymal epithelium of several reptiles. In the secretory cells of the basal portion of the tubular glands, mitochondria are intimately associated with fabrication of the secretion granules. The structural and functional organization of the epithelium of the basal portion of the tubular glands is complicated by the presence of basal cells. This study suggests the origin of the basal cells from peritubular tissue leukocytes. The study also indicates a role for the basal cells in acquiring secretion granules from the neighboring secretory cells and processing them into lipofuscin material in the context of regression of the Mullerian gland during the period of reproductive quiescence. In these respects the basal cells match those in the epithelial lining of the epididymis of amniotes.     

Oviductal morphology and egg shelling in the oviparous lizards Crotaphytus collaris and Eumeces obsoletus

Morphological changes occurring in the oviduct and epithelial cells of the lizards Crotaphytus collaris and Eumeces obsoletus during the natural reproductive cycle were examined and quantified. Additionally, development of the eggshell at different stages of gravidity was described. The anterior uterus of each species has a distinct glandular type which differs between species: in E. obsoletus, the glands are tubular and in C. collaris, branched saccular. The branched saccular glands in the anterior uterus of C. collaris produce collagen-like material that forms the fibers of the shell membranes. However, fibers from the eggshell of E. obsoletus did not stain for collagen. The shell of both species is composed of a multilayered inner boundary covered externally by fibers of varying thickness. Initial layers are composed of thick fibers all lying along the same general axis. Outer layers of fibers are progressively thinner and an external surface layer composed of glycosaminoglycans (GAGs) is also present. In C. collaris, calcium, which is deposited in relatively small amounts on the shell surface, appears to be secreted by the epithelium of the anterior uterus. The nonciliated secretory epithelial cells covering the villi-like folds of the posterior infundibulum secrete GAGs. Epithelial cell height of the infundibular villi is greatest during early gravidity. A functional relationship may exist between luteal activity and oviductal secretory activity because the activity of the glandular epithelium varied as gravidity progressed.     

Cutaneous eccrine glands of the foot pads of the small Madagascan tenrec (<Emphasis Type="Italic">Echinops telfairi,</Emphasis> Insectivora,Tenrecidae): skin glands in a primitive mammal

In order to find correlations between skin gland morphology and specific ethological features, the cutaneous glands of the foot pads of the primitive mammal the Madagascan tenrec, Echinops telfairi, were studied by histological and various histochemical methods as well as by electron microscopy. In the foot pads specific eccrine skin glands occurred consisting of coiled ducts and tubular secretory portions, the lumina of which were considerably wider than in primate sweat glands. The secretory tubules were composed of branched myoepithelial cells and glandular cells. The latter contained abundant mitochondria, large amounts of glycogen particles and few secretory granules as well as individual heterolysosomes and myelin bodies. The lateral cell membrane was marked by extensive interdigitations. The apical membranes of all glandular cells contained proteoglycans with sulfated and carboxylated groups containing N-acetyl-glucosamine, N-acetyl-galactosamine, galactose and mannose. The expression pattern of cytokeratins of the glandular epithelium was variable and showed similarities to that of the human eccrine glands. Tubulin, vinculin and actin were expressed in the glandular epithelium. The secretory cells showed positive reactions with antibodies against antimicrobial peptides and IgA. A positive reaction was observed with antibodies against the androgen receptor. The PCNA and TUNEL reactions indicated that the tubular skin glands of Echinops are made up of a slowly renewing tissue. We conclude that the glands fulfill several functions: production of a fluid-rich secretory product, which may prevent slipping of the foot pads on the substrate during running or climbing, secretion of antimicrobial peptides and proteins, and playing a role in thermoregulation.We thank the Fendt Foundation for financial support     

An insight into the skin glands,dermal scales and secretions of the caecilian amphibian Ichthyophis beddomei

The caecilian amphibians are richly endowed with cutaneous glands, which produce secretory materials that facilitate survival in the hostile subterranean environment. Although India has a fairly abundant distribution of caecilians, there are only very few studies on their skin and secretion. In this background, the skin of Ichthyophis beddomei from the Western Ghats of Kerala, India, was subjected to light and electron microscopic analyses. There are two types of dermal glands, mucous and granular. The mucous gland has a lumen, which is packed with a mucous. The mucous-producing cells are located around the lumen. In the granular gland, a lumen is absent; the bloated secretory cells, filling the gland, are densely packed with granules of different sizes which are elegantly revealed in TEM. There is a lining of myo-epithelial cells in the peripheral regions of the glands. Small flat disk-like dermal scales, dense with squamulae, are embedded in pockets in the dermis, distributed among the cutaneous glands. 1–4 scales of various sizes are present in each scale pocket. Scanning electron microscopic observation of the skin surface revealed numerous glandular openings. The skin gland secretions, exuded through the pores, contain fatty acids, alcohols, steroid, hydrocarbons, terpene, aldehyde and a few unknown compounds.     

Histology and histochemistry of the accessory reproductive glands in the male hairy-nosed wombat (Lasiorhinus latifrons)

The accessory male reproductive glands of the hairy-nosed wombat, Lasiorhinus latifrons, are a prostate and three pairs of Cowper's glands. Component units of all are branched tubular structures of varying epithelial makeup and secretory content. The prostate has the carrotlike shape and three consecutive regions commonly found in marsupials. The regions differ in their tubular histology and histochemistry: all contain secretory globules in glandular lumina. Cowper's glands A and B are histologically identical except for the absence of interstitial mast cells from gland G: gland C is characterized by narrower tubules and larger epithelial cells. Histochemical tests for protein, carbohydrate and iron indicate that glycogen is a major secretory product of the prostate (largely posterior region), iron is also secreted (mainly posterior region) and a small quantity of acid mucin is produced (mainly central region). Glycogen is a feature also of anterior prostatic glandular epithelium and of the capping cells of the urethral transitional epithelium. Cowper's gland A has considerable protein in its secretion, gland B a neutral glycoprotein and gland C a sialomucin: the latter two also exhibit cytoplasmic glycogen in their secretory cells.     

Ultrastructure of the glands producing sex pheromones of the male Nauphoeta cinerea (Insecta,Dictyoptera)

Summary The abdominal glands described here play a decisive role in the typical sexual behavior of Nauphoeta cinerea. Unlike other cockroaches, the males of this species produce two successive chemical signals: the sex pheromone itself, produced by the sternal glands, attracts the female from a distance, and the aphrodisiacs, secreted by the tergal glands, are licked by the female who is thus in a favorable position for mating. The well developed glandular apparatus is composed of 5 sternal glands (St3 to St7) and 7 tergal glands (T2 to T8). These glands appear as a thickening of the epithelium without significant modification of the external cuticle. The glandular epithelium is made up of several kinds of cells: ordinary epidermal cells (which only exist in the sternal glands), cells with microtubules, type 2 cells (oenocytes), and especially type 3 glandular units (composed of a secretory cell and a canal cell). The products secreted by the sternal glands are chiefly volatile products and fatty acids and those secreted by the tergal glands are primarily fatty acids and proteins. In this work, the relationship between the cytology of the glandular cells and the nature of the secreted products is discussed.     

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.     

Chemical signalling in lizards: an interspecific comparison of femoral pore numbers in Lacertidae

Animals communicate via a variety of sensory channels and signals. Studies on acoustic and visual communication systems suggest that differences in the physical environment contribute to the variety of signalling behaviour, with species investing in those signals that are transmitted best under the local conditions. Whether or not environmental tuning also occurs in chemical communication systems has received much less attention. In the present study, we examined the effect of several aspects of the physical environment on the chemical communication system of lacertid lizards (family Lacertidae). The numbers of femoral pores are used as a proxy reflecting how much a particular species invests in and relies upon chemical signalling. Femoral pores are specialized epidermal structures that function as a secretion channel for the waxy substance produced by glands. In some lacertid species, the secretion carries infochemicals that play an important role in social communication. The number of femoral pores varies considerably among species. We have compiled data on femoral pore numbers for 162 species and tested for the effects of climate and substrate use. After correcting for body size and taking the phylogenetic relationships among the species into account, we found no effect of climate conditions or latitude on species pore numbers. Substrate use did affect pore numbers: shrub‐climbing species tended to have fewer femoral pores than species inhabiting other substrates. © 2014 The Linnean Society of London, Biological Journal of the Linnean Society, 2014, 114 , 44–57.     

Morphological, histochemical and immunohistochemical characterization of secretory production of the ciliary glands in the porcine eyelid

In addition to performing general histology and cytology of the ciliary glands of the miniature pig, we studied the localization of glycoconjugates and beta-defensins in these glands with the use of carbohydrate histochemical and immunohistochemical methods. The secretory cells of the glands were equipped with non-homogeneous secretory granules, a well-developed Golgi apparatus and rough endoplasmic reticulum. The secretory epithelium and luminal secretion of the glands contained large amounts of neutral and acidic glycoconjugates with various saccharide residues (alpha-L-Fuc, beta-D-Gal, alpha-D-GalNAc and sialic acid). The sebaceous glands and tarsal glands also exhibited positive reactions to most of the histochemical methods. Additionally, the antimicrobial peptide group of beta-defensins was demonstrated to be products of the ciliary glands, as well as the sebaceous glands and tarsal glands. The results obtained are discussed with regard to the specific function of the ciliary glandular secretions. These secretory products may be related to the moistening and general protection of the skin surface of the eyelid and ocular surface.     

Female genital system of the folding-trapdoor spider Antrodiaetus unicolor (Hentz, 1842) (Antrodiaetidae, Araneae): ultrastructural study of form and function with notes on reproductive biology of spiders

The genitalia of the female folding-trapdoor spider Antrodiaetus unicolor are characterized by two pairs of spermathecae that are arranged in a single row and connected to the roof of the bursa copulatrix. Each single spermatheca is divided into three main parts: stalk, bowl, and bulb, which are surrounded by the spermathecal gland. The epithelium of the spermathecal gland is underlain by a muscle meshwork and consists of different types of cells partly belonging to glandular cell units (Class 3 gland cells) that extend into pores in the cuticle of the stalk and bowl. Interestingly, the bulb lacks glandular pores and is characterized by a weakly sclerotized cuticle. This peculiarly structured bulb probably plays an important role in the discharge of the sperm mass. It is suggested that by contraction of the muscle layer the sperm mass may be squeezed out, when the bulb invaginates and expands into the spermathecal lumen, pushing the sperm to the uterus lumen. Each glandular unit consists of usually one or two central secretory cells that are for the most part surrounded by a connecting cell that again is surrounded by a canal cell. The canal cell, finally, is separated from the other epithelial cells (intercalary cells) located between the glandular units by several thin sheath cells that form the outer enveloping layer of the unit. The secretions are released through a cuticular duct that originates proximally between the apical part of the connecting cell and the apical microvilli of the secretory cells and runs into a pore of the spermathecal cuticle. The glandular products of the Class 3 gland cells likely contribute to the conditions allowing long-term storage of the spermatozoa in this species. Details regarding the ovary, the uterus internus, and the uterus externus are reported. Most of the secretion that composes the chorion of the egg is produced in the ovary. Glandular cell units observed in the uterus externus differ structurally from those in the spermathecae and likely play a different role. Finally, we briefly discuss our results on the female genitalia of A. unicolor in the light of knowledge about the reproductive biology of spiders.     

Silk Production after Mechanical Pulling Stimulation in the Ampullate Silk Glands of the Barn Spider, Araneus cavaticus

Synthesis of protein by the major ampullate silk glands in the barn spider, Araneus cavaticus was stimulated by depleting the storage of silk protein in the ampulla by mechanically pulling fiber from the spigot. After this treatment, fine structural changes of the glandular epithelium during silk production were examined using light and transmission electron microscopes. In the process of rapid production, major secretory silk was synthesized at the tail region via rER of glandular epithelial cells, and was transported into the ampulla region. The mature secretory product in glandular epithelium appears almost spherical vacuoles which were grown up by fusion with the surrounding small vesicles including the secretory silk. Unlike to a typical process of the secretion, the ampullate silk of tail region seems to bypass either concentrating or packaging steps by the Golgi apparatus. However there's no doubt that the Golgi apparatus also play an important role in the secretory process of the ampulla region. After mechanical pulling stimulation, both epithelia of ampulla and tail regions appeared as a thinner layer of columnar cells with less definitive cell membrane. There are few secretory droplets within these cells, thus causing this region to stain much lighter. It is obvious that the cell loses part of its cytoplasm in this process, and disorganization of the secretory product occurs when it is extruded from the cells by a apocrine release.     

Comparative analysis of the male reproductive accessory glands of bats Noctilio albiventris (Noctilionidae) and Rhynchonycteris naso (Emballonuridae)

In eutherian mammals, the male reproductive accessory glands (RAGs) comprise the prostate, bulbourethral glands, ampullary glands, and the seminal vesicles. Their composition, anatomy and function vary widely between species. This study aimed to characterize histologically and compare the RAGs of bats. The RAGs of Noctilio albiventris (Noctilionidae) and Rhynchonycteris naso (Emballonuridae) were studied using anatomical and histological methods, and were reconstructed three dimensionally. The RAGs of N. albiventris and R. naso are composed of a compact glandular complex that surrounds the urethra and a pair of bulbourethral glands, which are extra‐abdominally located in the inguinal region. In both species, the glandular complex is composed of two well‐defined prostatic regions (ventral and dorsal). The ventral region showed an atypical epithelium (holocrine), where no obvious cellular limits were observed, and PAS‐positive secretion. The dorsal region had a pseudostratified cuboidal epithelium, with basal and secretory cells, and PAS‐negative secretion. Noctilio albiventris also had urethral glands (Littre glands) surrounding the urethra, however, R. naso had only muscles. Both species had bulbourethral glands, with simple columnar epithelium and PAS‐positive secretion. In conclusion, the RAGs of N. albiventris and R. naso comprised a pair of bulbourethral glands and an intra‐abdominal complex, composed of a prostate with two different regions (ventral and dorsal), while the ampullary glands and seminal vesicles were missing in both species. This morphology was more closely related between N. albiventris and R. naso, and to species of the family Phyllostomidae than to families Molossidae and Vespertilionidae. J. Morphol. 277:1459–1468, 2016. © 2016 Wiley Periodicals, Inc.     

Fine structure of the external nasal gland of two lizards (Podarcis sicula campestris and Chalcides chalcides)

In this study, we describe the ultrastructural features of the external nasal gland in two lizards: ruin lizard (Podarcis sicula campestris) and seps (Chalcides chalcides). Two secretory cell types, which differ interspecifically, have been found in the secretory endpieces of the glandular tubules in both species examined. An unusual morphological observation was the presence of paracrystalline structures in the secretory granules of the seromucous cells of the external nasal gland of the seps. These structures may be related to the packaging mechanism of glycoproteins or to their macromolecular structure. They may also reflect segregation of heterogeneous subcomponents within the same secretory granule. The striated cells are located in the distal segment of the glandular tubules, and have the typical ultrastructural features of the cells which in some species of reptiles, but not in these two lizards, are known to be capable of elaborating a hyperosmotic saline solution.     

扬子鳄胚胎背腺的发生及退化

本文在１４例扬子鳄Ａｌｌｉｇａｔｏｒｓｉｎｅｎｓｉｓ胚胎中观察了背腺的发生及退化过程。孵化第２８天,背中线左右两侧第二行鳞片处的表皮内陷形成实心的背腺腺芽;第３８天,背腺腺泡明显,腺上皮为复层上皮;从第４６天开始,腺上皮出现明显的退化,大量增殖的腺管上皮细胞逐渐堵塞腺管及腺孔。扫描电镜观察表明,孵化第３２—３６天的胚胎背部第二行鳞的各列鳞片表面均有背腺腺孔,以后逐渐出现少数不规则的退化,孵化第５８天以后,绝大多数背腺腺孔消失。对扬子鳄背腺的发生及退化现象作了讨论。     

The structure of the salt gland of Aegiceras corniculatum

Summary The salt glands of Aegiceras corniculatum have been examined by light- and electron-microscope techniques. A gland consists of a large number of abutting secretory cells and a single, large basal cell. The secretory cells and basal cell are joined by well defined plasmodesmata. The glandular cuticle shows differences between the top and sides of the gland, which may indicate a variation in the nature or quality of wax deposited. These variations may be significant in the secretion process, in view of the lack of evidence for the presence of pores. In ultrastructure, the secretory cells are generally similar to others that have been described, though there is no evidence of any particular association of vacuoles within these cells.     

Ultrastructure of reproductive accessory glands in the female sandfly Phlebotomus perniciosus Newstead (Diptera : Psychodidae)

The paired female accessory glands of Phlebotomus perniciosus (Diptera : Psychodidae) were investigated by light microscopy, and by scanning and transmission electron microscopy. These glands undergo morphological and functional changes during oocyte development. After the blood meal, the monostratified glandular epithelium differentiates and starts to secrete. Well-developed rough endoplasmic reticulum, Golgi complexes, and membrane-bounded exocytic vesicles suggest that these secretory cells are involved in protein synthesis. As the secretory cells differentiate, the glandular lumen increases in size and fills with secretory material, consisting of globular granules of different sizes in an amorphous electron-dense matrix. The granules have an electron-translucent core and an electron-dense cortex. The morphological characteristics of the glandular epithelium and the functional role of the glands are discussed in relation to their possible contribution to the reproductive process.