Comparative anatomy and phylogeny of the cloacae of salamanders (Amphibia: Caudata). VI. Ambystomatidae and Dicamptodontidae.

Histology of the cloacae of Rhyacotriton olympicus and representative species from the genera Ambystoma and Dicamptodon was examined by light microscopy. Females of Ambystoma possess sperm storage glands, the spermathecae, as well as ventral glands and dorsal glands, both of uncertain function. Females of Ambystoma examined from the subgenus Linguaelapsus differ from those in the subgenus Ambystoma by possessing more extensive ventral gland clusters and a shorter cloacal tube. Females of Dicamptodon possess spermathecae and ventral glands, but differ in cloacal conformation from females of Ambystoma and lack the dorsal glands. Females of R. olympicus possess more extensive epidermal lining in the cloaca than that found in females of Ambystoma and Dicamptodon, and the only glands present are spermathecae, which cluster around a tube in the dorsal roof. Males of Ambystoma, Dicamptodon, and R. olympicus possess five types of cloacal glands (dorsal pelvic glands, lateral pelvic glands, anterior ventral glands, posterior ventral glands, and Kingsbury's glands) that function in spermatophore formation, and vent glands that may produce a courtship pheromone. In Ambystoma and Dicamptodon, vent glands secrete along the medial borders of the cloacal orifice. Males of A. opacum and A. talpoideum differ from males of other species examined from the two genera by possessing more extensive vent glands. Males of R. olympicus possess unique vent glands in which tubules secrete onto the surface of vent lobes lateral to the posterior end of the cloacal orifice, and distal ends of the glands pass anteriorly, superficial to the fascia enclosing the other cloacal glands. The results from analysis of cloacal anatomy support other data indicating that Ambystoma and Dicamptodon are sister groups, and that Rhyacotriton olympicus is not closely related to either of the other two genera and merits placement in a separate family.     

The morphology of the dorsal and ventral skin of Triturus karelinii (Caudata: Salamandridae)

In this study, for the first time, the morphology of the dorsal and ventral skin of Triturus karelinii using light microscopy through histochemical methods was described. The skin exhibited basic morphological characteristics of the other urodeles: the epidermis composed of keratinized stratified epithelium with numerous conical protrusions and the dermis subdivided into spongy and compact layers. In the spongious dermis, three distinct types of glands were observed, namely serous, mucous and mixed glands. These glands were alveolar and occurred in both males and females. The morphologies of all three skin glands differed from anurans and other urodeles, having peculiar characteristics. Serous glands exhibited three different appearances. An unusual finding in mucous glands was the different appearance of their granules, showing diverse density after staining with PAS and AB. The histochemical analysis clearly demonstrated the presence of neutral, acid and sulfated mucins in the adenocytes of mucous glands. Mixed glands formed by mucous and serous glands exhibited the same morphological traits of both types of glands. Light microscopic observations revealed that the dorsal and ventral skin showed structural similarities with some minor differences, possibly resulting from their functions.     

Foregut glands of Solenogastres (mollusca): anatomy and revised terminology

In the molluscan class Solenogastres, different types of foregut glands vary in number, structure, and location within the foregut. The present article describes their anatomy and cytology and intends to clarify their confused terminology. Pharyngeal glands, esophageal glands, and the more complex dorsal and ventrolateral foregut glands can be distinguished. The ventrolateral foregut glands (ventral foregut glandular organs, ventral salivary glands of auct.), in the literature subdivided previously into four types, are revisited here in the context of current vertebrate gland terminology. The results of recent investigations are added to earlier ones, and a classification system for these multicellular glands is proposed. This system is based on cytological characters of glandular cells (intra- or extraepithelial), characters of the associated musculature (inner or outer musculature), location of the gland relative to the pharynx epithelium (endoepithelial or exoepithelial), characters of the gland openings (paired or unpaired), morphology of the gland duct (simple or branched), and some additional features like the arrangement of glandular cells along the gland ducts. Gross morphology and anatomy of ventrolateral foregut glands constitute useful taxonomic characters in determining higher taxa (family level), and finer details of the anatomy and cytology are useful in determining lower levels (genus and species). Possible pathways for the evolution of the different gland types of Solenogastres in relation to foregut glands present in the other molluscan clades are presented. The importance of ventrolateral foregut gland characters for phylogenetic considerations within the Solenogastres is discussed.     

Morphology, and muscle- and papilla-volume ratios, of the tongue of Laudakia stellio (Agamidae, Squamata): a histological and stereological study

We examined the histological structure of the tongue of Laudakia stellio, the starred agama lizard (Agamidae, Squamata), under light microscopy. We also investigated the muscle and papilla volume ratios, with volumes of each aspect of interest estimated according to the Cavalieri method. The macroscopically short, thick and muscle-rich front tip of the tongue of L. stellio does not show any bifurcation, and under light microscopy, the oval-shaped papilla-free front tip was seen to be covered by keratinized stratified epithelium. The dorsal and ventral parts were different, with the former partially covered by keratinized stratified epithelium and rich in secretory glands and secretory cells. The ventral part, which contained keratinized stratified cells, had a flat surface with no papillae. The dorsal surface of the anterior and posterior parts contained fungiform papillae, with the apical parts of these papillae containing minimal keratin; the interpapillar space was covered by keratin-free squamous stratified epithelium. The middle section of the tongue contained cylindrical-type papillae, with serous and mucous secretory glands and ducts at their base. Finally, the frontal and middle parts of the ventral and dorsal surfaces did not contain any taste buds, although there were some in the hind part of the dorsal surface. As morphometric estimates of volumes of the muscles and papillae, the mean volume ratios (relative to total tongue volume)+/-standard deviation were 0.66+/-0.03 and 0.33+/-0.03, with mean coefficients of error of 0.02 and 0.03, respectively.     

Photoperiod affects amplitude but not duration of in vitro melatonin production in the ruin lizard (Podarcis sicula)

The pineal gland and its major output signal melatonin have been demonstrated to play a central role in the seasonal organization of the ruin lizard Podarcis sicula. Seasonal variations in the amplitude of the nocturnal melatonin signal, with high values in spring as compared to low values in summer and autumn, have been found in vivo. The authors examined whether the pineal gland of the ruin lizard contains autonomous circadian oscillators controlling melatonin synthesis and whether previously described seasonal variations of in vivo melatonin production can also be found in isolated cultured pineal glands obtained from ruin lizards in summer and winter. In vitro melatonin release from isolated pineal glands of the ruin lizard persisted for 4 days in constant conditions. Cultured explanted pineal glands obtained from animals in winter and summer showed similar circadian rhythms of melatonin release, characterized by damping of the amplitude of the melatonin rhythm. Although different photoperiodic conditions were imposed on ruin lizards before explantation of pineal glands, the authors did not find any indication for corresponding differences in the duration of elevated melatonin in vitro. Differences were found in the amplitude of in vitro melatonin production in light/dark conditions and, to a lesser degree, in constant conditions. The presence of a circadian melatonin rhythm in vitro in winter, although such a rhythm is absent in vivo in winter, suggests that pineal melatonin production is influenced by an extrapineal oscillator in the intact animal that may either positively or negatively modulate melatonin production in summer and winter, respectively.     

Localization of prolactin receptor in the dorsal and ventral skin of the frog (Rana ridibunda)

The dorsal and ventral skin in amphibians plays an important role in osmoregulation. Prolactin hormone is involved in regulation of amphibian skin functions, such as water and electrolyte balance. Therefore, amphibians may be useful as a model for determining the sites of the prolactin receptor. In this study, prolactin receptor was detected in frog dorsal and ventral skin using immunohistochemical staining method. Prolactin receptor immunoreactivity was localized in all epidermal layers except stratum corneum of dorsal skin epidermis, stratum germinativum layer of ventral skin epidermis, myoepithelial cells, secretory epithelium and secretory channel cells of granular glands in both skin regions. The mucous glands and secretory granules of granular glands did not show immunoreactivity for the prolactin receptor. According to our immunohistochemical results, the more widespread detection of prolactin receptor in dorsal skin epidermis indicates that prolactin is more effective in dorsal skin. Presence of prolactin receptors in epidermis points out its possible osmoregulatory effect. Moreover, detection of receptor immunoreactivity in various elements of poison glands in the dermis of both dorsal and ventral skin regions suggests that prolactin has a regulatory effect in gland functions.     

Morphological analysis of the male reproductive accessory glands of the bat Artibeus lituratus (Phyllostomidae: Chiroptera)

Bats are distributed worldwide from tropical to temperate regions. Despite their wide geographical radiation and advances in studies using evolutionary approaches, aspects related to the reproduction of these animals remain poorly explored, especially those related to the male reproductive accessory glands (RAGs). Thus, the aim of this study was to analyze the morphophysiology of the male RAGs in the bat Artibeus lituratus. The RAGs in A. lituratus are composed of a compact intra‐abdominal glandular complex, consisting of the prostate with two prostatic regions (ventral and dorsal), plus Littre glands and a pair of extra‐abdominal bulbourethral glands. The ventral region of the prostate has an epithelium with variable morphology, due to its holocrine type of secretion. In contrast, the dorsal region has a typical cubic‐to‐columnar pseudostratified epithelium. Both regions contain two cell types, basal and secretory cells. Similar to the epithelial morphology, the secretion also varies, with the ventral region containing numerous PAS‐positive globular vesicles, whereas the dorsal region has a more fluid, hyaline and PAS‐negative secretion. Littre glands are dispersed in the connective tissue of the urethra, while the bulbourethral glands are located in the penile root, both glands with cubic‐to‐columnar pseudostratified epithelium and globular PAS‐positive secretion. The results demonstrate that the RAGs of A. lituratus are composed of two prostatic regions, ventral and dorsal, and urethral and bulbourethral glands, with no seminal vesicles. Each prostatic region has unique and distinctive characteristics, with the ventral region presenting an exclusive holocrine nature and the dorsal region having similarities to the ventral prostate of rodents.     

PEDAL AND OPERCULAR SECRETORY GLANDS OF POMATIAS, BITHYNIA AND LITTORINA

The histochemical properties of the pedal and opercular glandcells of three prosobranchs from different habitats were examined.The suprapedal gland of Pomatias elegans contained 3 gland celltypes producing mucoprotein, protein and sulphated muco-polysaccharide.The ventral surfaces of the foot were devoid of gland cellsexcept in the median furrow in which two cell types producea neutral and a sulphated mucopolysacharide. The dorsal surfaceof the foot possesses 5 cell types which produce a variety ofmucosubstances. The anterior pedal gland of Bithynia tentaculata produces neutraland weakly acidic mucoprotein from one cell type. The ventralsurface of the foot is generally populated by gland cells oftwo types producing acid mucopolysaccharide and protein. A furthercell type producing carboxylated mucopolysaccharide is restrictedto a transverse band mid-way down the foot. The dorsal surfaceof the foot is covered by mucus from three cell types producinga variety of mucosubstances. The anterior pedal gland of Littorina littorea possesses twocell types both of which secrete mucoprotein. The ventral surfaceof the foot secretes sulphated and carboxylated mucopolysaccharideand a mucoprotein from three cell types which form a thick subepi-dermalglandular layer. The dorsal surface is lubricated by a sulphatedmucopolysaccharide and a mucoprotein. The secretory cells of the dorsal surface extend into the operculargroove and disc whose specialised cells generally secrete mucopolysaccharideand at least two differently staining proteins. ^*Present address: Department of Zoology, University of Durham,Durham City, U.K. (Received 19 August 1986;     

Histochemical study on the tongue of Rana ridibunda (anuran amphibian)

A structural and histochemical study of the tongue in the Anuran Amphibian Rana ridibunda was carried out. Histochemical analysis of the filiform and fungiform papillae of the dorsal epithelium has shown a variety of cellular types which may be characterized cytochemically. All of them, except the goblet cells, show a remarkable amount of neutral mucins. The intensity of histochemical positive reaction for sulphomucins, sialomucins and protein is variable according to the cell type. Other histochemical reactions show that the lingual glands are rich in neutral mucins, but not in sialomucins. Histochemically in the component the basic proteins with sulphydryl groups are demonstrated. This sulphydryl groups are more abundant in the glands located in the deep regions.     

Comparative anatomy and phylogeny of the cloacae of salamanders (Amphibia: Caudata). II. Cryptobranchidae,Hynobiidae, and Sirenidae

Cloacae were examined from salamanders representing the three families in which fertilization of eggs is known or inferred to occur externally. The cloacae of male and female sirenids are aglandular and lack cilia. Sexual dimorphism in sirenid cloacae occurs only in the extent of epithelial stratification in the cloacal chamber in females (entire chamber) versus males (posterior angle of the vent). Both male and female Cryptobranchus alleganiensis possess ventral glands that secrete an acid mucopolysaccharide and have ciliated cloacal linings. The ventral glands are more numerous and hypertrophied in breeding male than female C. alleganiensis, but in males, ventral glands secrete only onto the surface of the cloacal lips along the anterior three-fifths of the cloacal orifice, whereas in females, the glands secrete onto the border of the entire cloacal orifice. Except for male Onychodactylus japonicus, male and female hynobiids also possess only ventral glands and have ciliated cloacal linings. Hynobiid ventral glands secrete a glycoprotein. Much variation occurs, however, among these hynobiids in cloacal conformation, extent of epidermis into the cloaca, and anatomy of the ventral gland. Male O. japonicus possess an unciliated cloaca in which three types of cloacal glands occur, each giving unique reactions to tests for carbohydrates and proteins. The glands in male O. japonicus do not seem to be homologous to those found in spermatophore producing salamanders in the Salamandroidea, but this does not negate the possibility that O. japonicus makes spermatophores. Examination of cloacal characters in additional species of hynobiids may be useful in resolving intrafamilial phylogenetic relationships.     

Postembryonic development of the olfactory and vomeronasal organs in the frog Rana chensinensis

We studied by light microscopy the histological development of the olfactory and vomeronasal organ in tadpoles of the Chinese forest frog, Rana chensinensis, from postembryonic periods to the end of metamorphosis. Unlike Bufo americanus, the olfactory epithelium in larval R. chensinensis is not divided into dorsal and ventral branches in the rostral and mid-nasal regions. The olfactory epithelium in the dorsal portion of the buccal cavity in larval R. chensinensis may correspond to the ventral olfactory epithelium of Bufo, which has been argued to provide a chemosensory function in the tadpoles analogous to the role of taste buds in adults. Bowman's glands were present in the olfactory epithelium of R. chensinensis only after the appearance of the forelimbs during metamorphosis. The appearance of Bowman's glands in the olfactory epithelium at this time suggests that the nose first begins to detect odorants in the air, and this is thus also a metamorphic event. The vomeronasal epithelium appeared a little earlier than the vomeronasal gland in R. chensinensis, unlike in toads (bufonids). This study supports Eisthen's hypothesis that the most recent common ancestor to the tetrapods was aquatic and once had a vomeronasal organ, and that this has been lost in various evolutionary lineages.     

Histological and histochemical observations on the foot glands in some byssus-bearing bivalves of the Waltair coast

Summary The glands responsible for the formation of the byssus threads inArca symmetrica, Barbatia obliquata andSeptifer bilocularis are the white gland, phenol gland and enzyme gland. Besides these, mucous glands are also present in the sub-epithelia. The size and shape of the cells of these glands vary in one and the same species. From histochemical investigations it has been revealed that these glands contain 1,2-glycol groups in addition to disulphides and sulphhydryls. The white gland secretes a protein material and the phenol gland is rich in phenols. These two combine to form a phenolic protein which is acted upon by a polyphenol oxidase secreted by the enzyme gland and leads to the formation of a byssus thread. The mucous gland cells secrete acid mucopolysaccharides, neutral mucins and glycoproteins.     

The mucus producing glands and the distribution of the cilia of the pulmonate slug Limax pseudoflavus

The gross anatomy and histochemistry of the mucus-producing glands of Limax pseudoflavus Evans were investigated. The body mucus can be divided into three areas. The dorsal body surface is covered with a sulphated acid mucopolysaccharide/protein mixture secreted largely by five cell types. The pedal mucus is a mixture of neutral mucopolysaccharide from the suprapedal gland. The dorsal and pedal mucus sheets are separated by the peripodal groove whose cells secrete a weakly acid mucus. The duct of the suprapedal gland, the epidermis around the pneumostome, the ventral surface of the peripodal groove and the centre of the underside of the foot are ciliated. The dorsal and pedal mucus remain stationary relative to the body and the substrate respectively and the only rejection currents seen in the mucus are around the pneumostome.
It is suggested that the pedal mucus is formed by the mixture of the products of the suprapedal gland and the mucoprotein secreting gland in the leading edge of the foot, thus producing a mucus suitable for locomotion. Many areas of the animal (e.g. the head, pneumostome, sole and the leading edge of the foot) are capable of producing both a fluid (neutral or weakly acid) and a viscous (acid) mucus. It is postulated that such an arrangement allows for both adhesion and lubrication at different times.     

The epithelia of the protrusible tongue of Eurycea longicauda guttolineata (Hoolbrook 1838) (Urodela: Plethodontidae)

In this study the lingual and sublingual glands, the lingual stem and the epithelial surface of the protrusible secondary tongue were investigated by light, scanning and transmission electron microscopy. The quality of the secretions of the epithelia was characterized histochemically. The lingual epithelium is formed by superficial (pavement) and goblet cells and at the margin of the tongue pad are also regions covered by ciliated cells. On the dorsal part of the tongue there are goblet cells of type A with mainly acidic secretions and of type B containing neutral secretions. Most of the goblet cells on the ventral side of the tongue (hypoglottis) show a strong alcian blue/PAS positive reaction (type I) and some produce neutral secretions (type II). The glandular cells of the lingual gland react positively to alcian blue and PAS in the apical region of the gland. In contrast there is only alcian blue-positive staining in the basal part of the gland. The size and complexity of the inclusion bodies of the secretory granules increase in a basal direction. In addition, there are ciliated cells in the glandular epithelium. Although the epithelium of the lingual stem is thin, it is double-layered. The cell types observed in this region are identical to those of the ventral part of the protrusible tongue. At the margin of the sublingual gland are trough-like structures. In the center, tubular parts are observed. The cells of this gland are stain strongly with alcian blue (pH 1.0) mainly in the basal part of the gland. The results of this are compared to the tongue pad and the lingual gland of Salamandra salamandra and Ambystoma mexicanum.     

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.     

Release mechanism of sex pheromone in the female gypsy moth <Emphasis Type="Italic">Lymantria dispar</Emphasis>: a morpho-functional approach

A morpho-functional investigation of the sex pheromone-producing area was correlated with the pheromone release mechanism in the female gypsy moth Lymantria dispar. As assessed by male electroantennograms (EAG) and morphological observations, the pheromone gland consists of a single-layered epithelium both in the dorsal and ventral halves of the intersegmental membrane between the 8th and 9th abdominal segments. By using the male EAG as a biosensor of real-time release of sex pheromone from whole calling females, we found this process time coupled with extension movements of the ovipositor. Nevertheless, in females in which normal calling behavior was prevented, pheromone release was detected neither in absence nor in presence of electrical stimulation of the ventral nerve cord/terminal abdominal ganglion (TAG) complex. Tetramethylrhodamine-conjugated dextran amine stainings also confirm the lack of any innervation of the gland from nerves IV to VI emerging from the TAG. These findings indicate that the release of sex pheromone from the glands in female gypsy moths is independent of any neural control exerted by the TAG on the glands, at least by way of its three most caudally located pairs of nerves, and appears as a consequence of a squeezing mechanism in the pheromone-producing area.     

扬子鳄皮肤腺结构与发育的初步观察

扬子鳄有三种皮肤腺:背腺、泄殖腔麝腺和下颌腺。背腺位于背中线左右两侧第二行鳞片下方,其确切位置个体间差异很大,如表1。幼鳄背腺形态多种多样,但显示出是一种退化器官,未观察到腺开口,也未观察到半成鳄和成鳄的背腺,因此扬子鳄背腺可能不具功能。泄殖腔麝腺位于泄殖腔腹唇内,梨形,腺管开口于泄殖腔腹壁,成体腺腔很大,腺的底部壁较厚,腺细胞明显地分成若干小叶,其它部位壁较薄,小叶不明显,属全泌腺,分泌油脂物,繁殖期特别发达,但性未成熟个体亦具功能,是一种信息素下颌腺位于下颌后方两侧皮肤内,圆柱状,脉管开口于下颌腹侧皮肤表面,成体腺腔不规则,腺壁厚,从包囊到腺腔,腺细胞可明显地分成三个区,属全泌腺,分泌油脂物,在繁殖期特别发达,此腺到性成熟才具功能。     

Morphology, histology and histochemistry of the ventral buccal salivary glands of the Arabian camel (Camelus dromedarius)

Morphometric, histological and histochemical investigations were carried out on the ventral buccal salivary glands of the Arabian camel ( Camelus dromedarius ). The ventral part (inferior molar gland) is composed of serous acini with abundant myoepithelial cells and the dorsal part of the gland comprises mucoserous acini. The serous acini are devoid of any type of mucosubstances while the mucoserous cells of the dorsal part show neutral glycoproteins and sialomucins but neither glycogen nor sulfomucins. The histoenzymological tests employed have detected alkaline phosphatase, adenosine triphosphatase, succinic dehydrogenase, non-specific esterases and α-amylase but no activities for aminopeptidase, lipase, cholinesterases and β-glucuronidase.     

Cultures of human tracheal gland cells of mucous or serous phenotype

There are two main epithelial cell types in the secretory tubules of mammalian glands: serous and mucous. The former is believed to secrete predominantly water and antimicrobials, the latter mucins. Primary cultures of human airway gland epithelium have been available for almost 20 yr, but they are poorly differentiated and lack clear features of either serous or mucous cells. In this study, by varying growth supports and media, we have produced cultures from human airway glands that in terms of their ultrastructure and secretory products resemble either mucous or serous cells. Of four types of porous-bottomed insert tested, polycarbonate filters (Transwells) most strongly promoted the mucous phenotype. Coupled with the addition of epidermal growth factor (EGF), this growth support produced “mucous” cells that contained the large electron-lucent granules characteristic of native mucous cells, but lacked the small electron-dense granules characteristic of serous cells. Furthermore, they showed high levels of mucin secretion and low levels of release of lactoferrin and lysozyme (markers of native serous cells). By contrast, growth on polyethylene terephthalate filters (Cyclopore) in medium lacking EGF produced “serous” cells in which small electron-dense granules replaced the electron-lucent ones, and the cells had high levels of lactoferrin and lysozyme but low levels of mucins. Measurements of transepithelial resistance and short-circuit current showed that both “serous” and “mucous” cell cultures possessed tight junctions, had become polarized, and were actively secreting Cl.