Histology and ultrastructure of male mullerian gland of Uraeotyphlus narayani (Amphibia: Gymnophiona)

This study reports the anatomy, histology, and ultrastructure of the male Mullerian gland of the caecilian Uraeotyphlus narayani, based on dissections, light microscopic histological and histochemical preparations, and transmission electron microscopic observations. The posterior end of the Mullerian duct and the urinogenital duct of this caecilian join to form a common duct before opening into the cloaca. The boundary of the entire gland has a pleuroperitoneum, followed by smooth muscle fibers and connective tissue. The Mullerian gland is composed of numerous individual tubular glands separated from each other by connective tissue. Each gland has a duct, which joins the central Mullerian duct. The ducts of the tubular glands are also surrounded by abundant connective tissue. The tubular glands differ between the column and the base in regard to the outer boundary and the epithelial organization. The basement membrane of the column is so thick that amoeboid cells may not penetrate it, whereas that around the base of the gland is thin and appears to allow migration of amoeboid cells into and out of the basal aspect of the gland. The epithelium of the column has nonciliated secretory cells with basal nuclei and ciliated nonsecretory cells with apical nuclei. In the epithelium of the base there are secretory cells, ciliated cells, and amoeboid cells. The epithelium of ducts of the tubular glands is formed of ciliated dark cells and microvillated light cells. The epithelium of the central duct is formed of ciliated dark cells also possessing microvilli, ciliated light cells also possessing microvilli, and microvillated light cells that lack cilia. It is regressed during March to June when the testis lobes are in a state of quiescence. The Mullerian gland is active in secretion during July to February when the testis is active in spermatogenesis.     

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.     

Fine Structure of Female Accessory Reproductive Gland in the Mealworm Beetle, Tenebrio molitor

ABSTRACT The fine structure of female accessory reproductive gland (FARG) of the adult mealworm beetle, Tenebrio molitor is studied with light and electron microscopes. The FARG is a simple tubular organ that composed of two kinds of cells-secretory epithelial cells and duct forming cells. The lumen of FARG is lined with a thin cuticle and filled with secretory materials. Each secretory epithelial cell has its peculiar end apparatus in addition to well-developed rough endoplasmic reticulum (rER), mitochondria, and secretory vesicles. They are forming basal infolding along the plasma membrane. Along the inner surface of the plasma membrane, numerous secretory vesicles are seen. The glandular secretions of the epithelial secretory cells are synthesized via rER to Golgi apparatus, and are stored in the extracellular cavity in the epithelial cell. These secretions are drained to the lumen through the end apparatus and this type of glandular secretion in the insects is type III. Histochemical reactions reveal the major component of these glandular secretions is an acid mucopolysaccharide.     

The fine structure of the coxal glands in Myobia murismusculi (Schrank) (Acari: Myobiidae)

The coxal glands of M. murismusculi consist of the proximal tubular portion (tubulus), the distal glandular sac and the terminal excretory duct. The tubulus comprises looped proximal and distal tubes that run in close association with each other. The cells of the proximal tube form numerous short protrusions that project into the neighbouring organs through the pores in their basal lamina. The sac is a distal part of the gland and so it cannot be considered as a homologue of the proximal filter sacculus of other arthropods. A large number of pinocytotic vesicles and lysosome-like bodies in the epithelial lining of the sac imply that the main functions of this organ may be the absorption of substances from the lumen of the gland and their subsequent intracellular transformation. In addition the sac of females was shown to produce dense secretory granules. The ultrastructural features of the glands are discussed and compared to other representatives of Acari.     

Ultrastructure of the male reproductive accessory glands in the medfly Ceratitis capitata (Diptera: Tephritidae) and preliminary characterization of their secretions

The morphology and the ultrastructure of the male accessory glands and ejaculatory duct of Ceratitis capitata were investigated. There are two types of glands in the reproductive apparatus. The first is a pair of long, mesoderm-derived tubules with binucleate, microvillate secretory cells, which contain smooth endoplasmic reticulum and, in the sexually mature males, enlarged polymorphic mitochondria. The narrow lumen of the gland is filled with dense or sometimes granulated secretion, containing lipids. The second type consists of short ectoderm-derived glands, finger-like or claviform shaped. Despite the different shape of these glands, after a cycle of maturation, their epithelial cells share a large subcuticular cavity filled with electron-transparent secretion. The ejaculatory duct, lined by cuticle, has epithelial cells with a limited involvement in secretory activity. Electrophoretic analysis of accessory gland secretion reveals different protein profiles for long tubular and short glands with bands of 16 and 10 kDa in both types of glands. We demonstrate that a large amount of accessory gland secretion is depleted from the glands after 30 min of copulation.     

Early changes in the dog prostate after castration. An ultrastructural study

Using electron microscopic techniques the prostate glands of male Beagle dogs were studied 3 days after castration. At this time marked differences in the extent of alterations of the glandular epithelium were observed: Whereas several acini showed only minor changes with reduction of epithelial height and diminution of secretory granules, many acini were severely affected with pronounced alteration of cellular structure and accumulation of large lipid droplets. A constant feature was the stimulation of the basal cells of the grandular epithelium. Additionally, in some areas of the gland aggregations of stimulated basal cells forming an acinus-like structure with a slit-like lumen were found. Our study shows that castration leads to marked alterations of prostatic epithelium within a short time. Androgen deprivation causes regressive changes of secretory epithelial cells, but clearly stimulates the basal cell population.     

Ultrastructure of male accessory glands in the scorpionfly Sinopanorpa tincta (Navás, 1931) (Mecoptera: Panorpidae)

The ultrastructure of male reproductive accessory glands was investigated in the scorpionfly Sinopanorpa tincta (Navás, 1931) (Mecoptera: Panorpidae) using light and transmission electron microscopy. The male accessory glands comprise one pair of mesodermal glands (mesadenia) and six pairs of ectodermal glands (ectadenia). The former opens into the vasa deferentia and the latter into the ejaculatory sac. The mesadenia consist of a mono-layered elongated columnar epithelium, the cells of which are highly microvillated and extrude secretory granules by means of merocrine mechanisms. The epithelium of ectadenia consists of two types of cells: the large secretory cells and the thin duct-forming cells. These two types of cells that join with a cuticular duct constitute a functional glandular unit, corresponding to the class III glandular cell type of Noirot and Quennedey. The cuticular duct consists of a receiving canal and a conducting canal. The secretory granules were taken up by the receiving canal and then plunged into the lumen through the conducting canal.     

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

Summary 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 B: 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.     

The morphology of the mucous gland and its responses to prolactin in the skin of the red-spotted newt

The mucous gland of the red-spotted newt, Notophthalamus viridescens viridescens, Rafinesque was examined by histochemical and ultrastructural techniques and its cytological responses to various hormonal conditions were studied. Its secretory epithelial cells produce and release in merocrine fashion a neutral, unsulphated mucosubstance. The secretory epithelium is bounded peripherally by a thin, but apparent non-functional, myo-epithelium. The duct of this mucous gland consists of a single keratinized tubular cell that extends from the neck region of the gland to the surface of the epidermis. Mucous secretion is absent or greatly reduced on the skins of newts maintained under laboratory conditions for a few weeks but reappears after injection of ovine prolactin. Mucous glands in laboratory conditioned animals show a 4-fold increase in volume brought about by the engorgement of their epithelial cells with secretory granules. Ovine prolactin reduces the volume of the glands to unconditioned levels with a corresponding reduction in granular content, suggesting that prolactin functions in the release of the granules. This view is reinforced by the findings that autotransplantation of the pituitary gland prevents the conditioning effect and that glandular volume increases in auto-transplanted animals given ergocornine. Granular accumulation begins also in hypophysectomized newts but ceases after a week, indicating the need for some hypophyseal factor in the synthesis as well as the release of the granules. Ovine prolactin restores mucous glands of hypophysectomized newts to the unconditioned state. Contrary to earlier findings, ovine prolactin induces a reduction in the volume of the mucous gland in thyroidectomized newts.     

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.     

Fine structure of the spermatheca and of the accessory glands in Orchesella villosa (Collembola, Hexapoda)

The spermatheca and the accessory glands of the collembolan Orchesella villosa are described for the first time. Both organs exhibit ultrastructural differences, according to the time of the intermolt in which the specimens were observed. A thick cuticular layer lines the epithelial cells of the accessory glands. In the reproductive phase, they are involved in secretory activity; a moderately dense secretion found in the apical cell region opens into the gland lumen. Cells with an extracellular cistern are intermingled with the secretory cells. These cells could be involved in fluid secretion, with the secretory product opening into the cistern which is filled with an electron-transparent material. After the reproductive phase, the gland lumen becomes filled with a dense secretion. The accessory gland secretion may play a protective role towards the eggs. The spermatheca is located between the accessory glands; its epithelium is lined by a thin cuticle forming spine-like projections into the lumen and consists of cells provided with an extracellular cistern. Secretory cells, similar to those seen in the accessory glands, are missing. Cells with a cistern could be involved in the production of a fluid secretion determining sperm unrolling and sperm motility.     

Ultrastructure of the tubular accessory gland in Haemaphysalis longicornis (Acari: Ixodidae)

The paired tubular accessory glands in Haemaphysalis longicornis open at the junction of the cervical and the vestibular parts of vagina via short and narrow ducts. The pseudostratified columnar glandular epithelium covered by the muscle layer consists of both secretory and supporting cells. As feeding proceeds, the secretory cells increase in volume. In ovipositing females, well-developed rough endoplasmic reticulum, the Golgi complex, and membranebound granules that are undergoing exocytosis suggest that the secretory cells are involved in protein synthesis. However, in virgin females that fed 10 days, only small dense granules and no secretion activity were observed. The secretions from the tubular accessory gland may be released into the genital tract during the egg passage through the vagina. However, the supporting cells located between the secretory cells become slender during feeding, cohere to each other at the luminal side, and have a very narrow attachment at the basement membrane. Supporting cells probably help maintain secretory cell shape especially during granular discharge into the lumen. © 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.     

The effects of adrenalectomy on the harderian gland of the Wistar albino rats

Harderian glands of the Wistar albino rats normal and adrenalectomized were investigated by light microscopy. In normal, these glands have a tubuloalveolar structure. The gland is located in the medio posterior aspect of the orbit. It is lobulated and appears homogeneous in colour and texture. Harderian gland consist of tubules with wide lumina lined by a single layer of columnar epithelial cells surrounded by myoepithelial cells within their basal lamina. It contains porphyrin pigment which is stored as solid intraluminal deposits. The glandular epithelium possesses two cell types, termed A and B. Type A cells are more numerous. The single excretory duct of the gland is directly continuous with endpieces at the hilus and opens nasally and ventrally to the third eyelid. The excretory duct is accompanied by many acini of small serous glands around it. The tubuloalveoli of the gland is not divided into lobules. There is no branched duct system within the gland. The secretion seems to be associated with porphyrins, is essentially released by exocytosis, but holocrine secretion also occurs. The single excretory duct is lined by a stratified epithelium. The gland is surrounded by a collagenous capsule. The adrenalectomy, caused degenerative changes in the glands. Epithelial height was lower than in normal gland epithelium. Most of the acini were completely disorganised. The acinar lumina were filled with porphyrin debris. The results suggest that rat harderian glands are sensitive to adrenal androgen changes in both male and female rats.     

Fine structural studies of rat seminal vesicle in castrated and intact animals following estrogen treatment.

The effect of estradiol and/or testosterone upon secretion by seminal vesicle in castrated and intact rats was assessed in young adult Sprague-Dawley rats, using light microscopy (LM), transmission (TEM) and scanning (SEM)electron microscopy. Hormones were injected daily for ten days beginning ten days after castrations were performed. The normal rat seminal vesicle, as revealed by SEM, was characterized by a large saccular lumen with highly folded walls. Cell surfaces were covered with microvilli, or occasionally displayed a protruding, ruffled surface, sparsely covered with short microvilli. Cytology was normal in testosterone-treated animals. Estradiol treatment of castrated animals stimulated secretion by seminal vesicle epithelial cells as evidenced by the presence of normal secretory bodies, the presence of RER, and moderately hypertrophied Golgi complexes. These glands were not heavier than were glands from castrated, untreated animals, although the epithelial cells were significantly taller. Secretion was maintained in intact animals treated with estradiol, although glands were smaller and epithelial height was reduced. Estradiol and testosterone treatment in combination did not appear to have an additive effect on secretion, weight of the gland, or epithelial height. The following results support the hypothesis that estrogen-induced prolactin synthesis and release may be involved in the mechanism by which estradiol effected stimulation of seminal vesicle epithelium. Prolactin-treated, castrated animals exhibited focal areas of stimulated epithelium. In hypophysectomized animals (untreated controls), the seminal vesicle epithelium retained some secretory bodies and secretory fluid in the glandular lumen; epithelial height was taller than that in castrated controls. Estrogen treatment reduced the epithelial height to that of castrated controls; there was no evidence of secretion. This suggests that in the absence of anterior pituitary hormones, including prolactin, the stimulatory effect of estradiol on seminal vesicle epithelium was nullified. In adrenalectomized/castrated animals, estradiol treatment stimulated secretion in seminal vesicle epithelium just as in non-adrenalectomized/castrated animals. This indicates that the adrenal gland plays a non-essential role in the action of estrogen on seminal vesicle epithelium.     

Ultrastructural changes in the oviductal mucosa throughout the sexual cycle in Bufo arenarum

In Bufo arenarum the oviduct exhibits conspicuous changes throughout the sexual cycle. In the present study, we analyzed the optical and ultrastructural characteristics of the oviductal pars convoluta mucosa, the portion responsible for jelly secretion, during both the preovulatory and postovulatory periods. Secretory epithelial cells, ciliated cells, basal cells, and glandular cells are described. Secretory epithelial cells are characterized by the presence of secretory granules, the size, shape and electron density of which vary markedly. Their contents are mainly released by exocytosis into the oviductal lumen. Moreover, in the preovulatory period, apocrine, and holocrine secretion processes frequently occur. During the postovulatory period, these cells exhibit a marked diminution of secretory granules. Ciliated cells show a typical ultrastructural organization. Basal cells are distinguished in the lower part of the epithelium by their heterochromatic nuclei and electron‐lucent cytoplasm. These cells, to the best of our knowledge, are reported for the first time in Amphibia. Glandular cells exhibit oval, round, or polyhedric granules, most of them with one or more cores. Our results indicate that the contents of epithelial and glandular secretory cells are partially secreted during the preovulatory period. Additional secretion occurs during the transit of the oocytes. J. Morphol. 239:61–73, 1999. © 1999 Wiley‐Liss, Inc.     

CHANGES IN FINE STRUCTURE DURING SILK PROTEIN PRODUCTION IN THE AMPULLATE GLAND OF THE SPIDER ARANEUS SERICATUS

The ampullate silk gland of the spider, Araneus sericatus, produces the silk fiber for the scaffolding of the web. The fine structure of the various parts of the gland is described. The distal portion of the duct consist of a tube of epithelial cells which appear to secrete a substance which forms the tunica intima of the duct wall. At the proximal end of the duct there is a region of secretory cells. The epithelium of the sac portion contains five morphologically distinct types of granules. The bulk of the synthesis of silk occurs in the tail of the gland, and in this region only a single type of secretory droplet is seen in the epithelium. Protein synthesis can be stimulated by the injection of 1 mg/kg acetylcholine into the body fluids. 10 min after injection, much of the protein stored in the cytoplasm of the epithelial cells has been secreted into the lumen. 20 min after stimulation, the ergastoplasmic sacs form large whorls in the cytoplasm. Protein, similar in electron-opacity to protein found in the lumen, begins to form in that portion of the cytoplasm which is enclosed by the whorls. The limiting membrane of these droplets is formed by ergastoplasmic membranes which lose their ribosomes. No Golgi material has been found in these cells. Protein appears to be manufactured in the cytoplasm of the tail cells in a form which is ready for secretion.     

An ultrastructural analysis of the salivary system of the terrestrial mollusc, Limax maximus.

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

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.     

Peculiar salivary glands in a silk‐producing mite Bakericheyla chanayi (Cheyletidae)

This is the first ultrastructural investigation of salivary glands in the family Cheyletidae. In both sexes of Bakericheyla chanayi, paired acinous salivary glands and tubular coxal glands were shown to be united into the common podocephalic system. The secretory portion of the salivary gland includes medial and lateral lobes composed of the five and two cells, respectively, with clearly distinct ultrastructure. The cytoplasm of the cells is occupied by the secretory granules containing fine fibrous material. The fine structure of both cell types suggest a proteinaceous nature of their secretions. A single central process extending from the apical face of each secretory cell passes through the common acinar cavity to enter the conducting duct. A pair of intercalary cells at the base of the conducting duct links it with the secretory portion of the gland. Extending towards the acinar cavity, protrusions of intercalary cells alternate the apical regions of the secretory cells and form with them highly‐specialized contacts characterized by the apical network of microtubules and microfilaments. Two possible ways of secretion are suggested: 1) exocytosis into the acinar cavity and 2) direct passage via the central processes. The detection of axon profiles in the gland body suggests a neural control for the glandular cell function. In tritonymphs, neither secretion nor large lateral lobe cells were observed up to the pharate stage when the lateral lobe undergoes rapid differentiation. The arrangement of the acinous gland is compared to that of other arthropods. Its composition appears to be close to the class three of insect glands. The involvement of the lateral lobe cells in silk production is discussed. J. Morphol. 276:772–786, 2015. © 2015 Wiley Periodicals, Inc.