A pair of rosette glands in the embryo and zoeal larva of an estuarine crab Sesarma haematocheir, and classification of the tegumental glands in the embryos of other crabs

A pair of rosette glands (one of the tegumental glands in crustaceans) is present at the root of the dorsal spine of the thorax in mature embryos of the estuarine crab Sesarma haematocheir. Each rosette gland is spherical, 45-50 microm in diameter. This gland consists of three types of cells: 18-20 secretory cells, one central cell, and one canal cell. The secretory cells are further classified into two types on the basis of the morphology of secretory granules. There are 17-19 a cells, and only one b cell per rosette gland. An a cell contains spherical secretory granules of 2-3 microm in diameter. The granules are filled with highly electron-dense materials near the nucleus but have lower electron-density near the central cell. The secretory granules contained in the b cell have an irregular shape and are 1-1.5 microm in diameter. The density of the materials in the granules is uniform throughout the cytoplasm. The secretory granules contained in both the a and b cells are produced by the rough endoplasmic reticulum. Materials in the granules are exocytotically discharged into the secretory apparatus inside the secretory cell, sent to the extracellular channels in the central cell, and secreted through the canal cell. The rosette gland can be distinguished from the epidermal cells 2 weeks after egg-laying and the gland matures just before hatching. Materials produced by this gland are secreted after hatching and secretion continues through five stages of zoeal larvae. These rosette glands were never found in the megalopal larva. Rosette glands are found in the embryos of Sesarma spp. and Uca spp. In other crabs, tegumental glands are also found at the same position as in the embryo of S. haematocheir, but the fine structure of their glands is largely different from that of the rosette gland. On the basis of the morphology of secretory cells (a-g cell types), the tegumental glands of a variety of crab embryos can be classified into four types, including rosette glands (type I-IV). The function of these tegumental glands is not yet known, but different types of the gland seem to reflect the phylogeny of the crabs rather than differences of habitat.     

Secretion and stabilization of the layers of the egg capsule of the dogfish Scyuorhinus canicula

The egg capsule of the dogfish is a unique, collagcnous, layered structure secreted by the nidamental gland which has nine, remarkably discrete, transverse zones of tubular glands. The present paper traces the origin of the four layers of the capsule to particular zones within the gland. Evidence is presented for the existence of DOPA, DOPA oxidase. protein(s) rich in tyrosyl residues and a peroxidase within the same storage granules within the secretory cells of the C and E zones. It is suggested that these interact when secreted to cross-link the inner and outer surfaces of the egg capsule. Evidence is presented that the middle layer which forms the bulk of the thickness of the egg capsule and has the highest collagen content may be partly stabilized by the peroxidation of tyrosyl residues. The mechanical significance of crosslinking in this system and the possible cytological mechanisms involved in the secretion of the tanning agents and enzymes are discussed.     

Hatching glands in cephalopods – A comparative study

Hatching of embryos from their eggs involves either mechanical and/or chemical support. In particular enzymes are widely used in the animal kingdom to weaken the egg layers and facilitate the embryo's escape. Although numerous morphological and biochemical studies exist on the hatching glands of invertebrates (such as sea urchins, ascidians, insects) and vertebrates (teleosts, amphibians, and mammals), little is known about the morphology of the hatching glands (Hoyle organs) in cephalopod hatchlings.In this study, the internal gland structure and the external appearance of the Hoyle organ are compared among several cephalopod species (Idiosepius pygmaeus; Euprymna scolopes; Sepia officinalis; Loligo gahi; Sepioteuthis lessoniana; Architeuthis sp.; Octopus vulgaris; Tremoctopus gracilis; Argonauta hians). In almost all cases the glandular system is restricted to the posterior part of the dorsal mantle surface. Only Octopus and Argonauta lack a specific glandular structure in this body region and the animals apparently use other mechanisms to penetrate the egg layers.In all decapod species (Idiosepius; Euprymna; Sepia; Loligo; Sepioteuthis; Architeuthis) as well as in Tremoctopus only one specific cell type is present in the Hoyle organ, which synthesizes granular material. The secretory droplets are more or less uniform in electron density in Idiosepius, Euprymna and Tremoctopus but exhibit translucent inclusions in the other decapods. The time of gland development, first synthesis of secretory products and later degeneration after hatching vary between the species.The present study contributes to our knowledge of glandular systems in cephalopods and allows comparison with hatching structures in other invertebrates and vertebrates.     

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.     

Snythesis of mucoprotein secretion in the salivary glands of Drosophila melanogaster IIIrd instar larvae]

The process of mucoprotein (glue) accumulation is described. This substance is secreted by salivary glands of the III instar larvae of Drosophila melanogaster. Granules of the secretory substance appear in the glandular cells 90 hrs after egg laying. Its secretion takes place within 120 hrs. The template RNA of glue proteins appears to be synthesized within the range of 72-85 hrs since actinomycin treatment of larvae at this time suppresses the formation of secretory substance. The portion of secretory proteins amounts to 23-32% of the total gland protein. In a mutant, 13tl, deficient by the absence of pupation, no PAS-positive, staining of glands or secretory granules identified under the phase-contrast microscope was found. A possible participation of fat body in the formation of mucoprotein secretory substance is discussed.     

Functional morphology and neuronal innervation of the prothoracic defence gland in Timema

Timema is the most basal genus of Phasmatodea and the sister group to the remaining stick and leaf-insects (Euphasmatodea). An autapomorphy of all phasmids is the paired prothoracic exocrine defence glands. In this study, the anatomy and innervation of the defence glands in Timema petita and Timema chumash are described and compared with the data on Euphasmatodea. In all phasmids, the glands consist of a cuticular epithelium, a secretory epithelium and muscular fibres that compress the lumen. In Timematodea, the muscular part of the gland is less developed than in Euphasmatodea and the ejection of the defence secretion depends on the dorsal longitudinal neck muscles. On the neuroanatomical level, Timema petita and Timema chumash lack neurons that are involved in the independent contraction of the gland in euphasmids. In both studied species of Timema, neck muscles play an active role in the gland function which is not observed in any other phasmid. Considering the basal position of this genus, this supports the hypothesis that in euphasmids, the muscular part of the gland evolved from the dorsal longitudinal neck muscles. Additionally, the same nerves that innervate the dorsal longitudinal neck muscles in all Polyneoptera also innervate the defence glands in phasmids.     

Histology and histochemistry of the reproductive tract of the pulmonate snail,Bulinus truncatus,with observations on the effects of castration on its growth and histology

The reproductive tract of B. truncatus was investigated histologically in order to study possible effects of castration upon the accessory sex glands. In the female part of the reproductive tract—subdivided into albumen gland, oviduct, muciparous gland, oothecal gland, uterus, vagina and bursa copulatrix—13 histochemically different secretory cell types were distinguished. The majority produce different types of (acid) mucopolysaccharides. The roles of the various parts of the female tract in the production of an egg mass were elucidated by comparing the histochemistry of the egg mass to that of the female tract; the abundance and location of the cell types were also taken into account for this purpose.

The male part appeared to contain 12 histochemically different secretory cell types. These produce mainly (phospho lipoproteins together with some polysaccharides and neutral lipids.

Castration causes an acceleration of the growth of the snails. The volumes of female (albumen gland) and male (prostate gland) accessory sex glands were measured on histological sections. It appeared that growth of the albumen gland is not arrested by castration. This was not established beyond doubt for the prostate gland. The results suggest that the stimulating effects of the dorsal body hormone on the growth and synthetic capacity of the female accessory sex glands—such effects have been established for Lymnaea stagnalis—are not exerted via the ovotestis in B. truncatus.     

Ultrastructural changes in hatching-gland cells of pike embryos (Esox lucius L.) and evidence for their degeneration by apoptosis

Summary Around hatching, when the pike embryo sheds its acellular egg envelope, marked changes occur in the cellular covering of the embryo. This cellular covering consists of a peridermal layer and a mono-layered presumptive epidermis. The periderm begins to disintegrate shortly before hatching and is sloughed off in the first posthatching period. The cellular covering produces hatching enzyme, the protease that partly dissolves the zona radiata interna of the acellular envelope. By means of the peroxidase-anti-peroxidase staining method with antibodies against hatching enzyme the cells producing this enzyme (hatching gland cells, HGCs) could be identified ultrastructurally. They are interspersed as single cells between the periderm and the presumptive epidermis. The secretory cycle of the HGC was studied. Hatching enzyme is released by an exocytotic secretory process in which multiple secretion into a secretion vacuole predominates. Exocytosis into surrounding intercellular spaces also occurs. These results show that the HGCs are merocrine glands. The HGC also has some holocrine nature, however, in that only a single, massive release of its secretory product occurs. The death of the transitory HGCs in posthatching stages is characterized by condensation of the cell, formation of surface protuberances and splitting up into globular cell fragments. Eventually these fragments are ingested by epidermal cells and digested. These results lead to the conclusion that the pike HGCs degenerate by apoptosis, unlike true holocrine cells.     

Ultrastructure of esophageal glands and their secretory granules in the root-knot nematodeMeloidogyne incognita

Summary The dorsal and subventral esophageal glands and their secretory granules in the root-knot nematodeMeloidogyne incognita changed during parasitism of plants. The subventral esophageal glands shrank and the dorsal gland enlarged with the onset of parasitism. While secretory granules formed by both types of glands were spherical, membrane-bound, and Golgi derived, the granules differed in morphology and size between the two types of glands. Subventral gland extensions in preparasitic second-stage juveniles were packed with secretory granules which varied in diameter from 700–1,100 nm and had a finely granular matrix. Within the matrix of each subventral gland granule was an electron-transparent core that contained minute spherical vesicles. The size and position of the core varied within different granules. Few granules were present in the dorsal gland extension in preparasitic juveniles. The matrix of dorsal gland secretory granules formed during parasitism was homogeneous and more electron-dense than the matrix of subventral gland granules. Subventral gland secretory granules of parasitic juveniles and adult females appeared degenerate.     

A histochemical study of the secretions of reproductive glands and of the egg envelopes of Achatina fulica (Pulmonata: Stylommatophora)

Histochemical investigations of the secretions of reproductive glands—albumen gland, apical uterus, basal uterus and prostate gland—indicate the presence of galactogen in the albumen gland, acid mucopolysaccharide in the apical uterus, and lipoprotein in the basal uterus and prostate gland of A. fulica. The proteinaceous secretions produced by the glands do differ in their terminal reactive sites. Intense alkaline phosphatase reaction is found in albumen gland and apical uterus; carbonic anhydrase activity could be detected mainly in the uterine glands. The cyclical secretory activity of the reproductive glands has been studied preparatory to egg-laying and in the spent phase. Histochemical characteristics of the egg envelopes—albumen, shell membrane and egg-shell—suggest a possible sequential deposition of glandular products during the descent of eggs through the repv. ductive tract. The factors contributing to the stability and resistant nature of the egg envelopes, and the possible role of nutritive materials contained in reproductive gland secretions in the development of the embryo (even while the eggs are inside the uterus), are discussed.     

Development of female accessory glands of Chrysomya putoria (Wiedemann) (Diptera: Calliphoridae) during oogenesis

Females of Chrysomya putoria (Diptera: Calliphoridae) have two sexual accessory glands, which are tubular and more dilated at the distal extremity. The glands open independently into the common oviduct. Two morpho-physiological regions were distinguished in the longitudinal semi-thin sections of the glands. The secretory region is constituted by three layers: a cuticular intima, lining the lumen, followed by a layer of small cells, and then a layer of very large secretory cells. The ductal region of the gland presents only two layers: the cuticular intima and a cellular layer. In both regions a basement membrane is present. Each secretory cell has in its apical region a reservoir, which enlarges throughout oogenesis; in its basal region there is a large nucleus. The ductal cells are cylindrical and smaller than the secretory cells. The glandular secretion is synthesized in the cytoplasm of the secretory cells, stored and/or modified in the reservoir, then drained to the lumen through an end apparatus seen in the apical region of the secretory cell. Histochemical tests indicate that this secretion is a glycoprotein. Measurements of the glands from females at different physiological conditions and fed on different diets correlate with the results obtained for changes in the ovary during oogenesis. Cell number averaged 561.2 ± 77.54 per gland. There was no increase in cell number during oogenesis.     

Development and morphology of teratocytes in Encarsia berlesei and Encarsia citrina: first record for Chalcidoidea

In several species of hymenopteran parasitoids of the superfamilies of Ichneumonoidea and Platygastroidea, the membrane enveloping the parasitoid embryo dissociates at hatching into a number of cells, called teratocytes, which autonomously develop in the host haemolymph. In this work we report for Encarsia berlesei and Encarsia citrina (Hymenoptera: Chalcidoidea), the dissociation of the extraembryonic membrane into cells whose morphological and embryological features correspond to those of teratocytes. In E. berlesei the membrane dissociated at hatching into 4-9 larger cells (100 microm diameter) and about 10 smaller cells (60 microm), which scarcely doubled their size during maturation. In E. citrina the membrane dissociated into five large cells (250 microm) which did not grow appreciably. Ultrastructural investigation of the dissociated cells in E. berlesei revealed that their surface was covered by microvilli, whose density and length increased from the egg stage to the 12 h following hatching. During the same period, rough endoplasmic reticulum evolved from a parallel profile to that of the cisternal type, while abundant vesicles represented the dominant cytological feature. The ploidy level of these cells ranged between 8c and 140c at hatching, but increased to 40c-350c at maturation. These findings provide the first clear evidences for the presence of teratocytes in the superfamily Chalcidoidea.     

泥螺生殖系统的组织学

泥螺为雌雄同体。生殖系统包括交媾器和生殖器本部。交媾器包括刺激器、阴茎和摄护腺;生殖器本部主要包括两性腺、缠卵腺和蛋白腺。刺激器和阴茎都具有非常发达的肌肉组织,腔壁游离面具纤毛。阴茎腔壁为单层柱状细胞;摄护腺被膜为一层薄的肌纤维,里面具有许多分泌细胞;缠卵腺被膜为单层扁平上皮,下层为环肌,腺体组织由分泌小管构成。蛋白腺主要由皮质层和导管层组成,皮质层内充满了分泌细胞,导管层由许多分泌小管构成,管壁为柱状腺细胞。     

Morphophysiology of the paracloacal (scent) glands in females of the marsupial Metachirus nudicaudatus: action of estrogens

The histophysiology of both brown and yellow paracloacal glands of control animals from wild populations was analyzed in the breeding and non-breeding seasons and in oophorectomized animals. The effect of estrogens on the scent glands of female Metachirus nudicaudatus was investigated. Radioimmunoassay indicated that estradiol levels in the breeding season were high, while those in the non-breeding season and oophorectomized had minute amounts. No apparent change in gland volume was observed in the various animal groups. Light microscopy showed a wide variation in the number of layers of the holocrine secretory epithelium of the major (brown) gland between the breeding (1–7) and non-breeding season (8–19) and in oophorectomized (8–18) animals. The minor (yellow) gland showed the most evident variation: the holocrine epithelium was restricted to the basal layer in the breeding season, but was restored and exhibited up to eight layers in the non-breeding season and in oophorectomized females. The mean cellular area of the secretory holocrine epithelium in the breeding season was smaller than in the non-breeding period and in castrated animals. On the other hand, the mean cellular areas of tubular glands inserted in both yellow and brown glands in the breeding season were larger than those in the non-breeding season and after castration. The results consistently indicate that the glandular volumes of yellow and brown glands do not depend on estrogens, whereas the holocrine secretory epithelium and tubular glands of both are estrogenic modulation.     

The morphology of the club glands on the dorsal fin of mature male shannies, Lipophvys pholis (L.) (Blenniidae: Teleostei)

The pelvic, pectoral, anal and dorsal fins of mature male, female and immature male Lipophrys pholis (L.) were examined by light microscopy for the presence of club glands. All fins except the dorsal showed a highly stratified epidermis and a thick cuticle. Club glands were present on the dorsal fin of mature male fisH but only during the breeding season. The development and decline of the club glands corresponds to the period of gonadal build-up and spawnout. Each club gland comprises several thousand bundles ofcolumnar cells. The columnar cells surround acentral pore which opens to the outside through a layer of Malpighian cells. The substance produced by the gland includes mucopolysacchdride. The function of the secretion is unknown and is discussed in relation to studies on similar glands in several Mediterranean blenniids.     

A histochemical study of the secretory gland cells of Cercaria shikokuensis and their role during development from cercaria to metacercaria.

The roles of secretory glands during the developmental process from an immature cercaria to a metacercaria in Cercaria shikokuensis were studied. Four types of secretory cells were identified in this species. On maturation of the cercaria in redia, the products of ventral gland cells and mucoid gland cells formed a thick surface coat on the mature cercaria, and the products of cephalic gland cells also formed a thin cover on the surface coat. In the process leading to the formation of a metacercaria, the surface coat constituted the outer layer of the cyst, mucoid gland cells secreted mucous substances inside the wall, and then cystogenous gland cells discharged their products to the inner wall. The cyst wall was composed of four layers, and it was thought that the outermost surface layer helped the cyst wall to adhere to the matrix and the intermediate layers helped to put together outer and inner walls.     

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.     

Monoclonal Antibodies to Secretory Granules in Esophageal Glands of Meloidogyne Species

Monoclonal antibodies to secretory granules in the dorsal or subventral esophageal glands were generated by injecting BALB/c mice with immunogens from preparasitic second-stage juveniles (J2) of Meloidogyne incognita. Antibodies specific for secretory granules in the J2 subventral esophageal glands or the dorsal gland were identified by indirect immunofluorescence microscopy. Only antibodies that reacted with granules in the J2 dorsal gland reacted with the esophageal gland lobe ofM. incognita adult females. The antibodies also reacted with secretory granules in both types of esophageal glands in M. javanica and M. arenaria J2 but not with granules in esophageal glands of Heterodera glycines J2.     

Structure of the female genital glands of the oviduct in the opisthobranch mollusc, Runcina

Runcina is a small hermaphroditic opisthobranch which possesses a monaulic reproductive system. In previous studies the male copulatory apparatus, the structure of the spermatophore and also the process of oogenesis have been described. The present paper gives an account of the ultrastructure of the female genital glands of the oviduct. In Runcina the oviduct comprises three primary regions, the albumen gland, the egg capsule gland and the mucous gland. Eggs enter the fertilization chamber and as they pass the opening of the albumen gland they become surrounded by albumen or perivitelline fluid. The eggs appear to become encapsulated as they traverse the egg-capsule gland and are eventually stuck together by mucus to form an egg mass. The epithelial lining of the three glands consists of alternating ciliated and secretory cells. The characteristics in secretory products of the glandular cells are described, and are discussed with reference to the way they contribute to egg vestment.     

Mucus secretion from single submucosal glands of pig. Stimulation by carbachol and vasoactive intestinal peptide

Secretion rates of >700 individual glands in isolated tracheal mucosa from 56 adult pigs were monitored optically. "Basal" secretion of 0.7 +/- 0.1 nl x min(-1) gland(-1) was observed 1-9 h post-harvest but was near zero on day 2. Secretion to carbachol (10 microm) peaked at 2-3 min and then declined to a sustained phase. Peak secretion was 12.4 +/- 1.1 nl x min(-1) gland(-1); sustained secretion was approximately one-third of peak secretion. Thapsigargin (1 microm) increased secretion from 0.1 +/- 0.05 to 0.7 +/- 0.2 nl x min(-1) gland(-1); thapsigargin did not cause contraction of the trachealis muscles. Isoproterenol and phenylephrine (10 microm each) were ineffective, but vasoactive intestinal peptide (1 microm) and forskolin (10 microm) each produced sustained secretion of 1.0 +/- 0.5 and 1.7 +/- 0.2 nl x min(-1) gland(-1), respectively. The density of actively secreting glands was 1.3/mm(2). Secretion to either carbachol or forskolin was inhibited (approximately 50%) by either bumetanide or HCO(3)(-) removal and inhibited approximately 90% by the combined treatments. Mucus secreted in response to carbachol or forskolin was acidic by approximately 0.2 pH units relative to the bath and remained acidic by approximately 0.1 pH units after bumetanide. The strong secretory response to vasoactive intestinal peptide, the acidity of [cAMP](i)-stimulated mucus, and its inhibition by bumetanide were unexpected.