Finger-like Process Research Articles

A new pattern of dendrobranch gill within the family Solenoceridae (Crustacea: Decapoda: Dendrobranchiata).

Mostly, gills are simple lamellate structures, but in decapods they can assume three elaborate morphologies: trichobranchiate, phyllobranchiate and dendrobranchiate. The dendrobranchiate gill, typically found among the suborder Dendrobranchiata, primarily consists of a long central axis, from which arises a series of paired secondary branches. Each secondary branch is subdivided into smaller fingerlike tertiary processes, and each fingerlike process is also branched (dendritic). The family Solenoceridae is known for having the dendrobranchiate type. Examen of 50 species of Solenoceridae from all nine genera, revealed a new pattern to the classic dendrobranchiate type in 14 species of Solenocera and in Mesopenaeus tropicalis. This new pattern consists of the flattening of the secondary and tertiary processes, with tertiary processes also having a wide, flattened, lamella-like base. This new pattern is herein described as a dendrolamellate gill.

A new lizard (Reptilia: Squamata) from the Lower Cretaceous Yixian Formation of China, with a taxonomic revision of Yabeinosaurus

Yabeinosaurus was the first lizard genus described from the Early Cretaceous Jehol Biota of China. The holotype of the type species, Y. tenuis, is an immature skeleton but it has been lost for decades. A second species, Y. youngi, was erected based on another immature skeleton and is distinguished by its longer, more gracile limbs. In 2001, a juvenile skeleton from the Jingangshan locality of Liaoning was designated as the neotype for Y. tenuis. Subsequently, several further specimens from other localities, juvenile and adult, have been attributed to this species. Here we describe a second lizard specimen from the neotype locality. In anterior tooth shape, finger-like mandibular angular process, cranial sculpture, maxilla shape, and short, robust humerus, the new specimen resembles adult and subadult material currently attributed to Y. tenuis, but it differs in having bicuspid posterior teeth and a straight rather than a hooked angular process of the mandible. We propose a new species (Y. bicuspidens sp. nov.) for this specimen which represents the first occurrence of bicuspid teeth in an Early Cretaceous lizard from China. However, the recognition of a second species at the neotype locality raises a taxonomic problem. Due to the immaturity of the designated holotype and neotype of Y. tenuis, they cannot be coded for the jaw and dental characters that distinguish the two robust-limbed species. This renders Yabeinosaurus tenuis a nomen dubium. Here we propose that Yabeinosaurus tenuis should be treated as a historic taxon, permitting retention of the generic name under ICZN rules, and erect a second new species (Y. robustus sp. nov.) for the principal robust-limbed morphotype in the Jehol Biota with monocuspid posterior teeth and a hooked angular process.

A new species of the genus Hermanella Needham & Murphy (Ephemeroptera: Leptophlebiidae) from Northeastern Brazil.

Hermanella angeli sp. nov. (Holotype male deposited in MZUSP: Itacaré municipality, Cachoeira Bom Sossego, 14°20'05.2"S, 39°01'27.4"W, 31.VII.2012, Mariano, R, Almeida, E & Costa, S. leg.) is described based on imagos and nymphs from the State of Bahia, Brazil. The new species can be distinguished by the following combination of characteristics, in male imagos: (1) costal and subcostal area of forewing brown (Fig. 5b); (2) thorax and abdominal terga predominantly brown (Fig. 2-3); (3) penes divided in apical 1/8 (Fig. 8); (4) penis lobe with ventral, long, curved spine (Fig. 7); (5) prosternum narrow (Fig. 1). In nymphs: (1) tarsal claws with 2-3 accessory denticles (Fig. 19); (2) mandible without setae near basal articulation (Fig. 13a); (3) prostheca of left mandible with spines on inner margin (Fig. 13b); (4) plate-like gills terminated in a finger-like process (Fig. 11).

A new sauropod dinosaur from the Late Jurassic of China and the diversity, distribution, and relationships of mamenchisaurids

ABSTRACT—Qijianglong guokr, gen. et sp. nov., represents a mamenchisaurid eusauropod from the Late Jurassic of southern China. The holotype consists of an incomplete skull, partly articulated axial skeleton, and fragmentary appendicular skeleton. A well-preserved braincase and skull roof provide rare insights into the poorly known neurocranial anatomy of mamenchisaurids and reveal a unique combination of characters such as an accessory tuber at the base of planar basipterygoid process and parietal excluding frontal from the anterior margin of the supratemporal fenestra. The cervical vertebrae have a distinct finger-like process extending from the postzygapophyseal process beside a zygapophyseal contact. Qijianglong is the first mamenchisaurid from the Late Jurassic of China that is definitively distinct from Mamenchisaurus, indicating greater morphological and taxonomic diversity of the poorly represented Late Jurassic mamenchisaurids. The occurrence of Qijianglong is consistent with a scenario in which mamenchisaurids formed an endemic sauropod fauna in the Late Jurassic of Asia. Phylogenetically, Qijianglong represents a relatively plesiomorphic mamenchisaurid lineage. The mamenchisaurids form an ancient clade of basal eusauropod dinosaurs that likely appeared in the Early Jurassic. A cladistic analysis highlights the interrelationships of mamenchisaurids and suggests guidelines for mamenchisaurid taxonomic revision. It may be desirable to restrict generic names to the type species in order to avoid confusion.http://zoobank.org/urn:lsid:zoobank.org:pub:F93276CF-71FE-472E-9114-68294547C2A9SUPPLEMENTAL DATA—Supplemental materials are available for this article for free at www.tandfonline.com/UJVP

One new and two known species of Aporcelinus Andrássy, 2009 and a new species of Coomansinema Ahmad & Jairajpuri, 1989 (Nematoda: Dorylaimida)

Coomansinema istvani sp. n. is described from Ecuador, and is characterised by its relatively small size (L = 0.95-1.51 mm), lip region almost continuous with body profile with partly amalgamated lips, odontostyle slightly sinuate, with wide lumen, 20-27 μm long, female reproductive apparatus didelphic, vulva transverse, pre-rectum very short, mainly in female, 8-9 weakly developed, spaced, ventral pre-cloacal supplements, tail short (c′ = 0.6-1.0), tail convex-conoid in male and cupola-shaped, with a short finger-like process dorsally oriented in female. An updated list of the species of Coomansinema and a key to their identification is also provided. In addition, one new and two known species of Aporcelinus are reported. Aporcelinus altitudinalis and A. seychellensis are described on the basis of more numerous specimens and the male of A. seychellensis is described for the first time; it is similar to the female in general morphology and is characterised by a series of 7-9 spaced ventromedian supplements in addition to the cloacal pair with two supplements in the range of the spicules. Aporcelinus reyesi sp. n. is characterised by a 1.69-1.92 mm long body, lip region truncate, set off by a constriction, lips distinct with prominent papillae, odontostyle straight, with wide lumen, 29-36 μm long, female genital system didelphic-amphidelphic, uterus tripartite, containing up to five small eggs, vulva transverse, 13 male supplements, the last three in the range of the spicules. Tail 1.0-1.5 anal body diam. long, conical with acute tip, ventrally slightly convex, dorsally first convex and then concave, often appearing bent dorsad.

New Records of Acanthocephalans from Birds in the Philippines with a Description of a NewPorrorchisSpecies and Identification Keys for the Genus

Three acanthocephalan species, Sphaerirostris turdi from the island thrush (Turdus poliocephalus), and Porrorchis centropusi and Porrorchis kinsellai n. sp., both from Philippine scops owls (Otus megalotis), are reported from Aurora Province, Luzon Island, Philippines. Porrorchis kinsellai n. sp. can be readily differentiated from previously known members of the genus by an almost perfectly spherical proboscis and presence of a characteristic finger-like process at the female posterior end, among other features. Porrorchis centropusi and Porrorchis hylae are regarded as synonyms by some authors, but based on several morphological features, they are considered separate species here. A key to the identification of all known species of Porrorchis (other than insufficiently described Porrorchis brevicanthus) is provided.

Structure and formation of the twisted plywood pattern of collagen fibrils in rat lamellar bone

This study was designed to elucidate details of the structure and formation process of the alternate lamellar pattern known to exist in lamellar bone. For this purpose, we examined basic internal lamellae in femurs of young rats by transmission and scanning electron microscopy, the latter employing two different macerations with NaOH at concentrations of 10 and 24%. Observations after the maceration with 10% NaOH showed that the regular and periodic rotation of collagen fibrils caused an alternation between two types of lamellae: one consisting of transversely and nearly transversely cut fibrils, and the other consisting of longitudinally and nearly longitudinally cut fibrils. This finding confirms the consistency of the twisted plywood model. The maceration method with 24% NaOH removed bone components other than cells, thus allowing for three-dimensional observations of osteoblast morphology. Osteoblasts extended finger-like processes paralleling the inner bone surface, and grouped in such a way that, within a group, the processes arranged in a similar direction. Transmission electron microscopy showed that newly deposited fibrils were arranged alongside these processes. For the formation of the alternating pattern, our findings suggest that: (1) osteoblasts control the collagen fibril arrangement through their finger-like process position; (2) osteoblasts behave similarly within a group; (3) osteoblasts move their processes synchronously and periodically to promote alternating different fibril orientation; and (4) this dynamic sequential deposition of fibrils results in the alternate lamellar (or twisted plywood) pattern.

Two new species of harpacticoid copepods from anchialine caves in karst area of North Vietnam

Two new harpacticoid species belonging to the genera Microarthridion Lang, 1944 (Tachidiidae) and Nitocra Boeck, 1864 (Ameiridae) are recorded from underground caves in the karst area of Ninh Binh Province, North Vietnam. Microarthridion thanhi n. sp. is distinguished from congeneric species by the number of setae on the antennary exopod, the structure of leg 5 in both sexes, and the finger-like process modified from an outer distal pinnate seta of the third endopodal segment of leg 2 in the male. Nitocra vietnamensis n. sp. has the character combination of six setae on the ellipsoidal exopod of leg 5 in both sexes, the first endopodal segment of leg 1 shorter than the whole exopod, the seta/spine armature of an inner seta of P2-P4 enp-1 and four elements on P2 enp-3, and the reduction of the proximal endite to a seta on the maxillary syncoxa.

Studies on Oemopteryx vanduzeea (Claassen, 1937) and a new species in the O. vanduzeea species group (Plecoptera: Taeniopterygidae) from the Pacific Northwest, USA

The Holarctic genus Oemopteryx is represented in the Nearctic region by three species groups, including the far western O. vanduzeea group. In this paper, we redescribe and illustrate O. vanduzeea (Claassen, 1937) and describe O. leei sp. n. from California and Oregon, USA. The new species is distinguished in the male from O. vanduzeea by the epiproct complex having a tongue-shaped prong that is hood-like at the apex, by the sleeve containing a filament that bears a terminal hook, and by a ventral, elongate, finger-like process that inserts into the apex of the prong. The female of O. leei sp. n. exhibits a large, wide subgenital plate that terminates in a narrow notched apex, whereas the subgenital plate is smaller and trapezoidal, with a flat, truncate margin in O. vanduzeea.

Two new species of Thyridosmylus Kruger (Neuroptera: Osmylidae) from China

The genus Thyridosmylus Krüger (Neuroptera: Osmylidae) belongs to the subfamily Spilosmylinae based on the type species Osmylus langii Mclachlan 1870 (Krüger 1913). The genus has 19 species mainly distributed in Asia, especially in China where there are 14 species: Thyridosmylus polyacanthus sp. nov., Thyridosmylus trimaculatus sp. nov., Thyridosmylus minoroides Yang, 1987, Thyridosmylus laetus Yang, 1988, Thyridosmylus pulchrus Yang, 1988, Thyridosmylus medoganus Yang, 1988, Thyridosmylus similaminor Yang, 1992, Thyridosmylus trifasciatus Yang, 1993, Thyridosmylus triypsiloneurus Yang, 1995, Thyridosmylus maolanus Yang, 1993, Thyridosmylus qianus Yang, 1993, Thyridosmylus fuscus Yang, 1999, Thyridosmylus vulgatus Yang, 1999 and Thyridomsylus pallidius Yang, 2002. Three species are described from India (Thyridosmylus langii (McLachlan 1870), Thyridosmylus perspicillaris (Gerstaecker, 1885), Thyridosmylus pustulatus Kimmis 1942) while another two species are known from Madagascar (Thyridosmylus marmoratus Fraser, 1955 and Thyridosmylus punctulatus (Navás, 1933)). Gerstaecker (1885) described one subspecies Thyridosmylus perspicillaris perspicillaris Gerstaecker and Kimmins (1942) erected three additional subspecies, Thyridosmylus langii angustus Kimmins, 1942, Thyridosmylus perspicillaris fenestratus Kimmins, 1942, Thyridosmylus perspicillaris minor Kimmins, 1942. However due to rampant variation in colouration and venation, the valid status of these subspecies is doubted and they are provisionally treated as synonyms herein. Thyridosmylus is characterised by fuscous and maculate forewings and largely hyaline hind wings, moderately sized and usually ochreous body, costal cross-veins simple and radial field with numerous cross veins (not including gradates). In the male genitalia, the anal plate generally elevates into a fingerlike process on the dorsal margin, and parameres are commonly arcuate in lateral view. Female genitalia usually have a broad anal plate, while the gonapophysis lateralis is finger-like or coniform in lateral view. In this paper, two new species are described from China. Terminology follows Tjeder (1957) and New (1986). All the type specimens are deposited in the Entomological Museum of China Agricultural University (CAU), Beijing.

Ultrastructural changes at the myotendinous junction induced by exercise

BackgroundAlthough exercise is believed to reduce the risk of rupture of the myotendinous junction, exercise-induced structural changes in this region have not been studied. We examined exercise-induced ultrastructural changes in the myotendinous junction of the lower legs in rats. MethodsTen adult male LETO rats were used. Five rats were randomly placed in the Exercise group; the remaining five were used as controls and placed in the non-Exercise group. Running exercise was performed every day for 4 weeks. The tibialis anterior and gastrocnemius muscles were then removed from both legs from each animal in the two groups. The specimens were subsequently examined by transmission electron microscopy (TEM). Numerous finger-like processes were observed at the myotendinous junction. The changes in frequency of branching of the finger-like process (the number of times one finger-like process branched) and the direction of the processes (the angle of the major axis of a finger-like process to the longitudinal direction of the muscle fiber) were studied. To evaluate the two indicators above, each 10 finger-like process was randomly and separately selected from the tibialis anterior and gastrocnemius muscles of rats, providing 50 finger-like processes of both muscles for evaluation per group. ResultsIn terms of the frequency of branching of the finger-like processes, the mean values obtained in the non-Exercise group were 0.04 and 0.18 times, respectively, in the tibialis anterior and gastrocnemius muscles and were 0.38 and 1.16 times, respectively, in these two muscles in the Exercise group. Regarding the direction of the finger-like processes, the values were 4.1° and 3.6°, respectively in the non-Exercise group and 10.4° and 14.5°, respectively in the Exercise group. The differences between the two animal groups were significant. ConclusionsMorphological changes in the myotendinous junction occurred as an adaptation to tension increased by exercise.

Description of a New Species of Cephalocarida, Sandersiella Kikuchii, and Redescription of S. Acuminata Shiino Based upon the Type Material

A new species of cephalocarid, Sandersiella kikuchii, is described from central Japan, 300 m depth. It differs from congeners primarily based on the following points: 5-9 hooks on each ventrolateral side of cephalon; exopod proximal segment of thoracopod 6 with long finger-like lateral process (with narrow base) on the dorsal margin; exopodal distal segment of thoracopod 6 pointed distally, not divided into 2 lobes; exopodal proximal segment and pseudopipod of thoracopod 8 furnished with 2 and 2-3 setae respectively. Sandersiella acuminataShiino, 1965 is redescribed and illustrated based on the holotype.

Caridina longiacuta, a new species of freshwater atyid shrimp (Decapoda, Atyidae) from Hunan Province, China

A new atyid species, Caridina longiacuta, is described and illustrated from Hunan Province, China. Caridina longiacuta is characterized by its long rostrum, long finger-like process on the anterolateral angle of basal antennular segment, the narrow scaphocerite, the segmental ratios of third maxilliped, the shape and spination of its posterior telsonic margin, and small eggs. Also, Caridina cantonensis Yu, 1938 is reported from Hunan Province for the first time.

Life cycle of Brachylaima mascomai n. sp. (Trematoda: Brachylaimidae), a parasite of rats in the Llobregat delta (Spain).

The terrestrial triheteroxenous life cycle of Brachylaima mascomai n. sp. (Trematoda: Brachylaimidae) is elucidated. Operculated, assymetric, embryonated eggs (25.4 x 12.7 microm) are passed with feces of the natural (Rattus norvegicus and R. rattus) and experimental (albino and wild mice, albino rats, Apodemus sylvaticus, Mus spretus [Muridae] and the golden gerbil) definitive hosts and ingested by the helicid gastropod Pseudotachea splendida, the only natural and experimental first intermediate host. Microcaudate cercariae harbored in branched sporocysts in the digestive gland emerge from this snail and contact P. splendida, Otala punctata, Theba pisana, and Helix (C.) aspersa snails developing into unencysted infective metacercariae in the kidney. Definitive hosts are infected by ingestion of infected snails; the adult parasites inhabit the small intestine. Chaetotaxic cercarial pattern specific at acetabular (S(II) 8-10 papillae) and cephalic (C(III) 13-15 papillae, H 16 papillae) levels. Three types of cercarial papillae are observed by scanning electron microscopy (SEM) and their arrangement is correlated with chaetotaxy for the first time in trematodes: argentophilic papillae with fingerlike process (cephalic, body, and acetabular levels), argentophilic papillae with opening (2 papillae in the M body level), and nonargentophilic dome-shaped papillae (alternated with argentophilic S(II) papillae on the ventral sucker). SEM detected interlacing network of ridges covering the metacercarial body. Adults with multidigitate tegumentary spines were observed by SEM. Subequal suckers; the acetabulum located in the posterior part of anterior fifth of body. Vitellaria extend from between middle level and anterior margin of anterior testis to between middle level and posterior margin of acetabulum. Uterus almost reaches the intestinal bifurcation.

Comparative Observations on Cercariae and Metacercariae of Echinostoma trivolvis and Echinoparyphium sp.

Comparative observations were made on cercariae of Echinoparyphium sp. from Physa gyrina in Charlie's pond, Stokes County, North Carolina and cercariae of Echinostoma trivolvis from Helisoma trivolvis in Northampton County, Pennsylvania. The cercaria of Echinoparyphium sp. has 43 collar spines, lacks penetration and paraesophageal glands, and has a conical tail without fin folds. The cercaria of E. trivolvis has 37 collar spines, penetration and paraesophageal glands, a finger-like process at the tip of the tail and fin folds. The length of the cercarial body and tail of E. trivolvis was significantly greater than that of Echinoparyphium sp. Cercariae of both species encysted in Biomphalaria glabrata snails in single and concurrent infections. In concurrent infections with a single cercaria of each species, 2 encysted metacercariae were adjacent to each other in the saccular kidney of the snail at 24 hr postinfection. The diameter of encysted metacercariae of E. trivolvis was significantly greater than that of Echinoparyphium sp. Echinoparyphium sp. metacercariae excysted at 39 C in an alkaline trypsin-bile salts medium used previously to excyst E. trivolvis. The length of excysted metacercariae of E. trivolvis was significantly greater than that of Echinoparyphium sp.

The Glaphyromorphus isolepis Species Group (Lacertilia: Scincidae): Diagnosis of the Taxon and Description of a New Species from Timor

The Glaphyromorphus isolepis Species Group (Lacertilia: Scincidae): Diagnosis of the Taxon and Description of a New Species from Timor

The apical structure in Perophora annectens (tunicate) spermatozoa: fine structure, differentiation and possible role in fertilization.

The apical structure in Perophora annectens spermatozoa is approximately 4 micron in length and it is helically coiled. Its major component is a striated structure, which may be analogous to a perforatorium. The plasmalemma enclosing the anterior quarter of the apical structure is covered by extracellular materials, the anterior ornaments. During spermiogenesis, the apical structure is first recognized as a small blister of the plasmalemma at the apex of the young spermatid. It develops into a conical protrusion and then into a finger-like process (approximately 1 micron in length). This process is transformed into an elongated process (approximately 4 micron in length) with electron-dense material in its core. Finally, the elongated process is helically coiled to form an apical structure in which electron-dense material forms dense striations. Vesicles (50-70 nm in diameter), presumably derived from the Golgi apparatus, have been recognized in the blisters of younger spermatids, and can be followed through to the finger-like process. In the finger-like process these vesicles are transformed into smaller vesicles (20-30 nm in diameter), which probably fuse with the anterior plasmalemma of the finger-like process. This suggests that chorion lysin(s) is associated with the anterior membrane enclosing the apical structure in these spermatozoa.

CLINICAL AND PATHOLOGICAL STUDY OF ORAL LICHEN PLANUS

The clinical and pathological observation has been carried out in 59 cases of oral lichen planus examined by our department and results are as follows.1) Patients were 16 males and 43 females, and predilection was observed in females in their fifties.2) Within 6 months sized with subjunctive symptom, many of them visited our hospital as their chief complaint was pain.3) Focus appeared at buccal mucous membrane bilaterally in most cases, then at tongue and then at mucobuccal fold. At buccal mucous membrane a great many reticular patterns appeared but incidence of the pattern except reticular pattern was observed a little and also the difference in disease pattern by site was observed a little. These disease patterns accompanied with erosion were observed in 35 cases. With or without erosion can be considered to be an important index on degree of lesion and presence of secondary lesion, and in this report the cases were classified into erosive pattern and nonerosive pattern regardless of the disease pattern described above.4) In the investigation on past history and life history 2 cases of oral lichen planus seemed to be drug eruption were experienced. And 1 case grown at buccal mucous membrane developed into squamous cell carcinoma. These cases were all erosive patterns.5) Investigating the relationship between oral lichen planus and metal prosthesis with referring to patch test, positive percentage was markedly lower compaired with the past reports. In 4 cases progress was observed after metal prosthesis was removed, but since improvement of symptom was recognized only in 1 case, the influence by metal prosthesis is considered to be comparatively small.6) In the results of glucose tolerance test the incidence of diabetes mellitus pattern or junction pattern showed high (93%), especially in erosive pattern many diabetes mellitus patterns were observed. The possibility that oral lichen planus indicates the early stage of diabetes mellitus is clear.7) Amount of serum immunoglobulin (IgG, IgA, IgM) ranged within the normal values.8) In histological studies appearance of granular cell layer at mucoepithelium and acceleration of keratinization were seen in a few cases. Squamous cell layer thickened, prolongation and acumination or rete ridges and enlargement of inter-cellular space were shown. And in basal cell degeneration necrosis of cell, liquefaction degeneration and appearance of hyaline body were observed. At subepithelial tissue zonal inflammatory cellular infiltration was present and infiltrate cell was mainly lymphocyte.In electron microscopic findings inter-cellular space at epithelial layer enlarged, intrusion of amorphous flocculent material was often seen, and numbers of finger-like process and desmosome decreased. Basement membrane was not uniform in thickness and disposition, and duplication, winding and discontinuities were present. The cell infiltrated to sub-epithelial tissue was considered to be lymphocyte but cell-organell was scanty and cluster dense body was not present.9) With direct immunofluorescence method comparing with cutaneous lichen planus, less cases of immunoglobulin and deposition of complement were observed, but deposition of fibrinogen was observed at high percentage mainly at basement membrane, and in erosive pattern this tendency was shown evidently. With indirect immunofluorescence method serum antibody exhibited negative.10) Although the author may not conclude on etiology, it was assumed that degeneration of mucoepithelial basal cell and submucosal lymphocyte infiltration were the basis for lesion morphologically, and involvement of mechanism of cellular immunity in epithelial connective layer junction played an important role in pathological process of this disease.

Ultrastructural and time-lapse studies of primary mesenchyme cell behavior in normal and sulfate-deprived sea urchin embryos

The mechanism of primary mesenchyme cell migration in the sea urchin, Lytechinus pictus, was studied in normal embryos and in sulfate-deprived embryos in which primary mesenchyme cells do not migrate. Based on scanning electron microscopy (SEM), cell processes were classified into six morphological types. Time-lapse cinematographic studies showed that two types of cell processes, a short finger-like process and a long process which accounted for 40 and 30% of the cell processes formed, respectively, in normal embryos, functioned as kinetic appendages during cell migration. Although the short finger-like process was formed to some extent in sulfate-deprived embryos, these processes were not able to attach to the ectodermal basal lamina, which is the migratory substratum. The long type of cell process was not observed at all in sulfate-deprived embryos. Transmission electron microscopy (TEM) demonstrated that cell processes in normal embryos were associated with 30 nm diameter granules in the basal lamina. Because these granules were absent in sulfate-deprived embryos, it is suggested that a specific component of the basal lamina substratum can be a limiting factor in cell migratory behavior.

The spermatozoa and spermiogenesis of Perophora formosana (ascidia) with special reference to the striated apical structure and the filamentous structures in the mitochondrion

The spermatozoon of Perophora formosana is approximately 140 μ m long. It contains an extremely elongated filiform nucleus (ca. 90 μ m in length) and a single long mitochondrion (ca. 80 μ m in length) which is loosely wound around the nucleus as a lateral body. The anterior third of the head is coiled in a helical configuration. Filamentous structures approximately 10 nm thick are observed exclusively in the mitochondrial matrix. They are arranged parallel to one another along the long axis of the mitochondrion (lateral body). During spermiogenesis, they appear in the mitochondria of spermatids as the mitochondrion begins to elongate into the lateral body. They occur regularly aligned in a row in the matrix just beneath the inner membrane in the elongating region of the mitochondrion. They are first recognized as an accumulation of moderately electron-dense material. Possible functions for these filamentous structures in producing and maintaining mitochondrial shape changes are discussed. A striated apical structure, about 2 μ m in length, is found at the anterior end of the spermatozoon. It is composed of an electron-opaque substance in the form of dense striations. Each striation is approximately 7 nm thick. During spermiogenesis, an electron-dense material is deposited to form striated structures in the finger-like process at the apex of spermatids at almost the same stage that the filamentous structures appear in the mitochondrion. The role of the apical structure in the process of fertilization has not been determined.