Morphology and ultrastructure of the venom glands of the northern pacific rattlesnake Crotalus viridis oreganus

The venom gland of Crotalus viridis oreganus is composed of two discrete secretory regions: a small anterior portion, the accessory gland, and a much larger main gland. These two glands are joined by a short primary duct consisting of simple columnar secretory cells and basal horizontal cells. The main gland has at least four morphologically distinct cell types: secretory cells, the dominant cell of the gland, mitochondria-rich cells, horizontal cells, and “dark” cells. Scanning electron microscopy shows that the mitochondria-rich cells are recessed into pits of varying depth; these cells do not secrete. Horizontal cells may serve as secretory stem cells, and “dark” cells may be myoepithelial cells. The accessory gland contains at least six distinct cell types: mucosecretory cells with large mucous granules, mitochondria-rich cells with apical vesicles, mitochondria-rich cells with electron-dense secretory granules, mitochondria-rich cells with numerous cilia, horizontal cells, and “dark” cells. Mitochondria-rich cells with apical vesicles or cilia cover much of the apical surface of mucosecretory cells and these three cell types are found in the anterior distal tubules of the accessory gland. The posterior regions of the accessory gland lack mucosecretory cells and do not appear to secrete. Ciliated cells have not been noted previously in snake venom glands. Release of secretory products (venom) into the lumen of the main gland is by exocytosis of granules and by release of intact membrane-bound vesicles. Following venom extraction, main gland secretory and mitochondria-rich cells increase in height, and protein synthesis (as suggested by rough endoplasmic reticulum proliferation) increases dramatically. No new cell types or alterations in morphology were noted among glands taken from either adult or juvenile snakes, even though the venom of each is quite distinct. In general, the glands of C. v. oreganus share structural similarities with those of crotalids and viperids previously described.     

Evidence for an exocrine function of theAplysia atrial gland

Summary The fact that the atrial gland ofAplysia californica contains peptides that will induce egg laying when injected into mature animals prompts consideration of the role played by the gland in the normal physiology of the animal. We have approached this consideration with a combination of morphologic and physiologic investigations. Morphologic study reveals the gland as a stratified epithelium comprised of three cell types. The only evidence for secretory activity was seen in the columnar epithelial cells containing large vesicular inclusions. These cells appear to discharge their secretory product into the lumen of the large hermaphroditic duct. While we cannot specify the contents of the secretion from the columnar cells, perfusate of the duct lumen contained bioassay active material only when the duct was exposed to depolarizing conditions. Though additional experiments in which exogenously administered atrial gland peptides were found to initiate egg laying in animals from which the source of the egg laying neurohormone had been extirpated, it appears likely that the atrial gland substances are not endocrine factors. Instead, their function must be sought among the exocrine products of the duct epithelium.Abbreviations FWS filtered artificial sea water - LHD large hermaphroditic duct Technical assistance for these studies was ably provided by Eugene Dannen and Gary Whitney. The surgical procedures were developed by Greg Thayer. Funding for the work was provided by NIH grant NS 11149 to S.A.     

Venom and Dufour's glands of the emerald cockroach wasp Ampulex compressa (Insecta,Hymenoptera, Sphecidae): Structural and biochemical aspects

The digger wasp species Ampulex compressa produces its venom in two branched gland tubules. They terminate in a short common duct, which is bifurcated at its proximal end. One leg is linked with the venom reservoir, the other one extends to the ductus venatus. Each venom gland tubule possesses, over its entire length, a cuticle-lined central duct. Around this duct densely packed class 3 gland units each composed of a secretory cell and a canal cell are arranged. The position of their nuclei was demonstrated by DAPI staining. The brush border of the secretory cells surrounds the coiled end-apparatus. Venom is stored in a bladder like reservoir, which is surrounded by a thin reticulated layer of muscle fibres. The reservoir as a whole is lined with class 3 gland units. The tubiform Dufour's gland has a length of about 350 μm (∅ 125 μm) only and is surrounded by a network of pronounced striated muscle fibres. The glandular epithelium is mono-layered belonging to the class 1 type of insect epidermal glands. The gland cells are characterized by conspicuous lipid vesicles. Secretion of material via the gland cuticle into the gland lumen is apparent. Analysis of the polypeptide composition demonstrated that the free gland tubules and the venom reservoir contain numerous proteins ranging from 3.4 to 200 kDa. The polypeptide composition of the Dufour's gland is completely different and contains no lectin-binding glycoproteins, whereas a dominant component of the venom droplets is a glycoprotein of about 80 kDa. Comparison of the venom reservoir contents with the polypeptide pattern of venom droplets revealed that all of the major proteinaceous constituents are secreted. The secreted venom contains exclusively proteins present in the soluble contents of the venom gland. The most abundant compound class in the Dufour's gland consisted of n-alkanes followed by monomethyl-branched alkanes and alkadienes. Heptacosane was the most abundant n-alkane. Furthermore, a single volatile compound, 2-methylpentan-3-one, was identified in various concentrations in the lipid extract of the Dufour's gland.     

Morphology and ultrastructure of a secretory region enclosed by the venom reservoir in social wasps (Insecta,Hymenoptera)

The morphology and ultrastructure of the convoluted gland inside the venom reservoir of four species of social Vespidae are described. The cells of the venom gland (including the convoluted gland) can be divided into six groups: (1) epithelial cells, (2) glandular cells with the end apparatus secreting into the tubule inside the convoluted gland (internal or embedded tubule), (3) a continuous arrangement of glandular cells with the end apparatus secreting directly into the venom reservoir, (4) glandular cells that are loosely dispersed along the tubule lumen between the free tubules and the embedded tubule of the convoluted gland, (5) secretory cells of the free tubules and (6) duct cells. One kind of secretory cell, hitherto unknown and described in this paper (group 3), is characterized by the presence of a well-developed end apparatus, usually with enlarged extracellular spaces, but lacking the normally associated duct cells. The secretory cells contain several stacks of granular endoplasmic reticulum, but these are mainly concentrated in the middle of the cell. The basal half of the cells contains many lipid droplets. Although the function of the convoluted gland is not yet understood, an hypothesis is related to what is known of the function of reservoir secretory cells in solitary wasps. All wasp species studied showed the same organization of the convoluted gland, which clearly distinguishes their venom gland from that of Sphecidae.     

腰带长体茧蜂毒液器官和卵巢的形态学及其超微结构

应用超薄切片和电镜技术,观察内寄生蜂腰带长体茧蜂Macrocentrus cingulum Brischke毒液器官和卵巢的形态结构。腰带长体茧蜂毒液器官由1个毒囊和2条毒腺组成,毒腺接于毒囊的顶端。毒腺由单层分泌细胞、退化的外胚层细胞和环腔的内膜构成,分泌细胞主要由1个明显的细胞核和1个较大囊状细胞器构成,囊状细胞器的功能是分泌毒液。毒囊由肌肉鞘和扁平细胞层构成,但没有分泌细胞。腰带长体茧蜂卵巢1对,每个卵巢由10条左右卵巢小管组成,与侧输卵管相接处略微膨大形成卵巢萼区。2条侧输卵管在产卵管基部会合形成1条总输卵管与产卵管相接。毒液器官通过毒囊的毒液导管附着在总输卵管上。对寄生蜂毒液器官的生物学、细胞学及在分类进化上的意义进行研究。     

Venom apparatus and toxicity of the centipede Ethmostigmus rubripes (Chilopoda, Scolopendridae)

The venom apparatus of Ethmostigmus rubripes, a generalized predator, consists of the telopodites of the postcephalic segment, the basal article of w which contains the venom gland. Within the gland, venom granules are concentrated in intracellular secretory granules, from which they are discharged into vacuoles in the cytoplasm of the secretory cells and thereafter by exocytosis into the lumen of the gland. A venom duct carries venom to the venom claw, which introduces it into prey via a subterminal pore on the outer curvature of the claw. Pits containing pegs, presumed to be sensory, are concentrated near grooves leading to a cutting ridge proximal to the point of the claw. The venom is toxic both to mammals and insects.     

The male reproductive system and mechanism of sperm transfer in Argulus japonicus (Crustacea: Branchiura)

The histomorphology of the male reproductive system and surface morphology of the “peg-and-socket” in Argulus japonicus are described from serial sagittal and transverse sections and scanning electron micrographs. The prostate complex consists of a glandular part, a reservoir for storing the secretion, and an efferent duct opening into the ejaculatory duct. The openings of both the vas deferens and the prostate duct into the ejaculatory duct are guarded by sphincters. The ejaculatory ducts, which are lined by tall columnar epithelial cells, do not open into the cuticle-lined genital atrium but are blind-ending tubes. This observation and results obtained from observing live specimens, as well as the fact that no spermatophores are formed, suggest that semen could leave the ejaculatory duct only after puncturing of its walls. It is suggested that sperm transfer is accomplished in the following manner: during copulation contraction of the muscular walls of the vas deferens and prostate duct causes semen to be pumped into the ejaculatory duct, which is then closed off by sphincters and a high internal pressure is developed. When a spermathecal spine penetrates the walls of the ejaculatory duct, semen flows from the ejaculatory duct into the spermathecal vesicle due to the higher pressure in the ejaculatory duct. This mechanism is analogous to the sucking up of fluid with a hypodermic syringe. © 1993 Wiley-Liss, Inc.     

Ultrastructure of the venom gland of the scorpion,Centruroides sculpturatus (Ewing)

The venom apparatus of the scorpion, C. sculpturatus (Ewing) was studied with light and electron microscopy. Each of the paired glands is lined by secretory epithelium made up of a single layer of columnar cells. Extensive folding in the epithelial layer creates a primitive acinar gland. The secretory products are either membrane-bound or unbound vesicles with discrete morphologies and are observed in the extruded venom, within the lumen of the gland, and within single secretory cells. The venom apparatus, including connective tissues, nerve cells, and muscle tunic is described and correlations are made with observations in other Athropods.     

Venom gland of the digger wasp Liris niger: morphology, ultrastructure, age-related changes and biochemical aspects

Females of the parasitoid digger wasp species Liris niger hunt crickets as food for their future brood. The wasps paralyse the prey by injecting their venom directly into the CNS. The venom is produced in a gland consisting of two ramified glandular tubules terminating in a common reservoir. The reservoir contents enter the sting bulb via a ductus venatus. Secretory units of dermal gland type III line the two free gland tubules, the afferent ducts to the reservoir and the cap region within the reservoir. Secretion products of tubules reach the reservoir through the cuticle-lined central funnel. Secretory cells in the distal and middle parts of the tubules contain extensive rough endoplasmic reticulum and numerous electron-dense vesicles, whereas secretory cells of the afferent ducts and the cap region of the reservoir lack electron-dense vesicles and the endoplasmic reticulum is poorly developed. The secretory apparatus undergoes age-related changes. The secretory units in the venom gland tubules and inside the reservoir complete differentiation 1 day after imaginal ecdysis. After 30 days, massive autolytic processes occur in the secretory cells and in the epithelial cells of the reservoir. Analysis of the polypeptide composition demonstrates that the venom reservoir contains numerous proteins ranging from 3.4 to 200 kDa. A dominant component is a glycoprotein of about 90 kDa. In contrast the polypeptide composition of Dufour's gland is completely different and contains no glycoproteins. Comparison of the venom reservoir contents with the polypeptide pattern of venom droplets reveals that all of the major proteinaceous constituents become secreted. Thus the secreted venom contains exclusively proteins present in the soluble contents of the venom gland.     

The venom apparatus of the globiferous pedicellariae of the toxopneustid Sphaerechinus granularis (Echinodermata,Echinoida): Fine structure and mechanism of venom discharge

Summary Globiferous pedicellariae of Sphaerechinus granularis are venomous defensive appendages consisting of a stalk bearing a head made of three movable jaws. Each jaw is supported by a calcareous valve ending with a terminal grooved tooth. A venom apparatus is located in each jaw and consists of a venom gland surrounded by a muscular envelope and terminating in a duct which completely encircles the terminal tooth of the valve. Contrary to previous statements, the duct does not lie inside the groove of the terminal tooth. In mature pedicellariae, the venom is stored in intracellular vacuoles of highly differentiated cells which are no longer active. The cells fill the whole space of the venom gland which is without a lumen; they are segregated into two types that occur in distinct regions and differ from each other by morphological and staining properties of their secretions. Upon contraction of the muscular envelope, the venom is released via a holocrine mechanism and infiltrates the predator's tissues through the wound inflicted by the three calcareous teeth of the valves. In no case is the venom emitted through the tooth groove.     

Virus-like particles in venom of Meteorus pulchricornis induce host hemocyte apoptosis

Ultrastructural studies on the reproductive tract and venom apparatus of a female braconid, Meteorus pulchricornis, revealed that the parasitoid lacks the calyx region in its oviduct, but possesses a venom gland with two venom gland filaments and a venom reservoir filled with white and cloudy fluid. Its venom gland cell is concaved and has a lumen filled with numerous granules. Transmisson electron microscopic (TEM) observation revealed that virus-like particles (VLPs) were produced in venom gland cells. The virus-like particle observed in M. pulchricornis (MpVLP) is composed of membranous envelopes with two different parts: a high-density core and a whitish low-density part. The VLPs of M. pulchricornis is also found assembling ultimately in the lumen of venom gland cell. Microvilli were found thrusting into the lumen of the venom gland cell and seem to aid in driving the matured MpVLPs to the common duct of the venom gland filament. Injection of MpVLPs into non-parasitized Pseudaletia separata hosts induced apoptosis in hemocytes, particularly granulocytes (GRs). Rate of apoptosis induced in GRs peaked 48h after VLP injection. While a large part of the GR population collapsed due to apoptosis caused by MpVLPs, the plasmatocyte population was minimally affected. The capacity of MpVLPs to cause apoptosis in host's hemocytes was further demonstrated by a decrease ( approximately 10-fold) in ability of host hemocytes to encapsulate fluorescent latex beads when MpVLPs were present. Apparently, the reduced encapsulation ability was due to a decrease in the GR population resulting from MpVLP-induced apoptosis.     

Excurrent duct system of the male turtle Chrysemys picta

The epididymis and efferent duct system of the turtle Chrysemys picta were examined. Seminiferous tubules are drained by a series of ducts that form a rete exterior to the tunica albuginea. The rete is located lateral to the testis and consists of anastamosing tubules of varying diameters, lined by a simple epithelium consisting of squamous to cuboidal cells. The rete is highly vascularized. A series of tubules (efferent ductules) connect the rete to the epididymis proper. The efferent ductules are highly convoluted, running between the epididymal tubules and are of varying diameters. The simple columnar epithelium lining these tubules possesses tight junctions, with every third or fourth cell possessing long cilia that protrude into the lumen. The cytoplasm of these epithelial cells contains abundant mitochondria. In the central portion of the efferent ductule, epithelial cells possess granules that appear to be secreted into the lumen by an apocrine process. The epididymis proper is a single, long, highly convoluted tubule that receives efferent ductules along its entire length. It is lined by a pseudostratified epithelium containing several cell types. The most abundant cell (vesicular cell) lacks cilia, but has a darkly staining apical border due to numerous small vesicles immediately beneath the luminal membrane. The small vesicles appear to fuse with each other basally to form larger vesicles. These cells appear to have an absorptive function, and occasionally sperm are embedded in their cytoplasm. The second-most abundant cell is a basal cell found along the basement membrane. The number of these cells fluctuates throughout the year, being most abundant in late summer and early fall. A small narrow cell with an oval nucleus and darkly staining cytoplasm, extending from the basement membrane to the apical surface, is present in small numbers, particularly in the caudal regions of the epididymis. This cell is frequently found in association with another narrow cell having a rounded nucleus and abundant mitochondria in its cytoplasm.     

Ultrastructure and histochemistry of the testicular efferent duct system and spermiogenesis in Opistognathus whitehurstii (Teleostei, Trachinoidei)

 Testis organization and spermatogenesis, with the emphasis on spermiogenesis, in Opistognathus whitehurstii are described by ultrastructural and histochemical methods. The germinal epithelium is extremely reduced and restricted to the periphery of the testis, while most of the organ is occupied by a highly developed system of testicular efferent ducts. A semicystic type of spermatogenesis is observed and in the germinal epithelium spermatogenesis occurs only until the spermatidal stage. Young spermatids are released into the lumen of the testicular lobules and mature to sperm within the efferent duct system. The epithelial cells of these ducts are involved in protein and glycogen secretion and in phagocytosis of degenerating germ cells and residual bodies cast off by developing spermatids. On the basis of these functions, the testicular efferent duct system cells are considered to be homologous to the Sertoli cells. A correlation between a highly developed testicular efferent duct system and semicystic spermatogenesis is examined and a possible functional meaning of this apparently unusual mode of sperm production is proposed. Accepted: 18 March 1997     

管氏肿腿蜂毒液器官超微结构观察

应用透射电镜技术,观察了管氏肿腿蜂Scleroderma guani毒液器官的超微结构.毒腺由基膜层、分泌细胞层、导管细胞层和内膜层构成,分泌细胞内含内质网、末端附器、分泌囊泡、分泌颗粒、液泡等细胞器,其内合成的毒液由末端附器输送至毒腺的腔体.毒囊由肌肉鞘层、上皮细胞层和内膜层组成,肌肉鞘内的肌纤丝规则排列不交错,上皮细胞层内细胞器稀少,内膜层呈波浪状均匀加厚.     

Morphologic analysis of the venom gland of Apis mellifera L. (Hymenoptera: Apidae) in populations of Mato Grosso do Sul, Brazil

In Apis mellifera L. the venom gland (also called acid gland) is composed of secretory cells that surround a channel that opens into a reservoir devoid of musculature. This gland can present apical branching. In this study the frequency of branched venom glands in Africanized honeybee workers (A. mellifera) from eleven localities in the state of Mato Grosso do Sul was recorded. The relations among the length of the main duct, the length of the duct from the reservoir to the beginning of branching, the length of the branched segment (when present) and the total length of the gland were also analyzed. The frequency of branched glands varied from 50% to 83% in the workers, indicating that this characteristic is primitive in those bees. The results of the Analysis of Discriminant Functions indicated significant differences in the morphometrical segments of the venom gland (Wilks Lambda = 0.092; F (40, 55) = 3.43; P < 0.001), and permitted a differentiation of the populations studied. Using the Mantel test we verified that there does not exist a significant correlation between the morphologic characteristics and the geographical distance between the localities evaluated (Mantel r = -0.006, P = 0.48). The high frequency of workers with large venom gland in all the apiaries considered makes viable the development of a selection program in order to obtain bees with longer venom glands, aimed at the commercial production of venom by the beekeepers of those localities of Mato Grosso do Sul.     

Ultrastructure of the cardiac and pyloric glands of the gastric mucosa of the South African hedgehog,Atelerix frontalis

The cardiac and pyloric glands in the gastric mucosa of the South African hedgehog, Atelerix frontalis, are described. The cardiac area of the stomach contains proper cardiac glands and lacks undifferentiated fundic glands. The cardiac glands are simple tubular, coiled, and lined with columnar cells ultrastructurally similar to those of the gastric surface epithelium. Secretory granules with varying electron densities fill the apical cytoplasm of these cells. In contrast to other mammals, these glands lack mucous neck cells. The neck of the pyloric glands contains only a single cell type, whereas the basal regions of these glands contain “light” and “dark” cells. The secretory granules in the “dark” cells and the pyloric neck cells have a moderate electron density and often contain an electron dense core. An electron-lucent cytoplasm with numerous polysomes is characteristic of the “light” cells. Some “light” cells contain electron-dense granules in the apical cytoplasm. The presence of only neutral mucins in the cardiac gland cells denotes the absence of mucous neck cells. The acidic mucins within the pyloric neck cells seem to indicate that these cells are mucous neck cells, whereas the neutral mucins within the basally located pyloric gland cells show at least a partial functional difference from the pyloric neck cells. © 1993 Wiley-Liss, Inc.     

Dufour gland of the digger wasp<Emphasis Type="Italic"> Liris niger:</Emphasis> structure and developmental and biochemical aspects

The tubiform Dufour gland in the digger wasp species Liris niger is about 1.0 mm long ( 0.15 mm). An alternating arrangement of longitudinal and circumferential bundles of striated muscle fibers surrounds the gland. The Dufour gland, together with the venom gland, enters the sting base and terminates in the sting. The glandular epithelium is monolayered. Glands about 3 day after imaginal ecdysis have an empty lumen but a thick lining epithelium. The gland cells are characterized by a well-developed vesicular smooth endoplasmic reticulum, sparse rough ER and numerous free ribosomes. They also exhibit several electron-lucent vesicles and autophagic vacuoles. Secretion of electron-dense material via the gland cuticle into the gland lumen is apparent. Glands more than 20 days after imaginal ecdysis display a large lumen and a thin epithelium. The cells show signs of degeneration with numerous cytolytic inclusions. Dufour gland liquid contains numerous polypeptides of molecular weights ranging from 14 to about 200 kDa. In addition the secretion consists predominantly of straight-chain hydrocarbons, accompanied by small amounts of esters. The major hydrocarbons are pentadecane and (Z)-8-heptadecene. Dufour gland secretion may have several functions: (1) the polypeptides might be involved in the gluing process of the eggs, while (2) the hydrocarbon oils may function as lubricants for the lancets and (3) might soften the secretion, thus allowing easier application of the glue. The lipophilic volatile material (4) might also be involved in pheromonal signaling.     

Immunocytochemical localization and secretion process of the toxin CSTX-1 in the venom gland of the wandering spider Cupiennius salei (Araneae: Ctenidae)

Fluorescein and horseradish peroxidase-labeled monoclonal antibodies were used to localize the predominant toxic peptide CSTX-1 in the venom gland of the spider Cupiennius salei. There was no polarity of CSTX-1 expression in repleted glands, whereas the glands of previously milked spiders showed a decreasing immunofluorescent response from the distal to the proximal portion. Detailed investigation revealed a new structure in the venom-secreting epithelium, which is postulated to be an evolutionary adaptation to increasing gland volume. CSTX-1 was found to be synthesized and stored as a fully active toxin within complex units, composed of long interdigitating cells running perpendicular to the muscular sheath and extending into the central lumen of the gland. These venom-producing units were found in all sectors of the gland, including the transitional region between the main gland and the venom duct. The venom is liberated from the venom-producing units into the glandular lumen following the contraction of the surrounding muscle layer. Free nuclei or other cellular fragments, which would have provided evidence for a holocrine secretion process, were not found in the glandular lumen or in the crude venom obtained by electrical stimulation. The fine regulation of the spider's venom injection process is postulated to be the function of the bulbous ampulla, situated in the anterior third of the venom duct.     

Morphology and ultrastructure of the Dufour gland in workers of social wasps (Hymenoptera, Vespidae)

The Dufour gland in workers of vespine wasps appears as an unpaired tubiform gland that opens in close proximity to the sting base. The epithelial cells that line the central reservoir are characterized by apical microvillus-like projections and deep basal invaginations. Their cytoplasm contains a well-developed Golgi apparatus, numerous mitochondria, as well as strands of smooth endoplasmic reticulum. The Dufour gland duct occurs ventrally to the venom gland duct, and bends downward near the sting base to open in the dorsal vaginal wall. In this region, the duct is dorsoventrally flattened, and shows conspicuous bundles of parallel microtubules in the epithelial cells, that transmit the pulling forces of the myofilaments of the underlying muscular supply to the cuticle. This results in an active opening mechanism regulated by muscular contraction, while passive closure probably results from the return of the cuticular intima to a rest position.     

Ejaculatory duct of the migratory grasshopper,Melanoplus sanguinipes (fabr.) (Orthoptera : Acrididae): A histological and ultrastructural analysis

The ejaculatory duct of the migratory grasshopper (Melanoplus sanguinipes [Fabr.]) (Orthoptera : Acrididae) is divisible into 3 regions: upper ejaculatory duct (UED) into whose anterior end the accessory glands and vasa deferentia empty; the funnel characterized by its slit-like lumen; and the lower ejaculatory duct (LED). Anteriorly, the UED has a keyhole-shaped lumen surrounded by a thin intima and highly columnar epithelial cells whose most conspicuous feature is massive aggregations of microtubules. More posteriorly, the UED lumen differentiates into dorsal and ventral chambers, the former having a thick cuticular lining armed with spines. In the hindmost part of the UED, the ventral chamber expands to obliterate the dorsal chamber; its cuticular lining thickens, and conspicuous lateral evaginations develop. The thick cuticle includes 3 distinct layers and on its surface carries numerous spatulate processes. In this region, the epithelial cells develop numerous short microvilli beneath which are many mitochondria. As the funnel is reached, the intima becomes extremely thick, and the epithelial cells lack microvilli and most microtubules. Within the funnel, a new, very distinct form of cuticle appears, which is in “units”, each associated with an epithelial cell and having a rounded epicuticular cap. The new cuticle arises ventrally but rapidly spreads to encircle the entire lumen, at which point the LED is considered to begin. Beneath this new cuticle, the epithelial cells are columnar, have long microvilli, numerous mitochondria in the apical cytoplasm, and rough endoplasmic reticulum basally. Apically, adjacent cells are tightly apposed; however, prominent intercellular channels develop more basally. The ejaculatory duct's features are briefly discussed in terms of its role in spermatophore formation.