摘要:

AbstractThe mature spermatozoa of four species of European decapod crabs(Clibanarius erythropus, Maja squinado, Cancer pagurusandPotamon fluviatile)have been investigated using indirect immuno‐fluorescence techniques for the presence of the cytoskeletal proteins actin and tubulin. Indirect immunofluorescence labelling with monoclonal anti‐actin antibody and three different monoclonal anti‐tubulin antibodies indicate that actin is present in the spermatozoa of all four species, but tubulins are restricted to the two species with microtubular arms,ClibanariusandMaja.The pattern of actin fluorescence varies between the spermatozoa of the four species, withMajaandCancershowing intense fluorescence in the acrosome vesicle and in elements of the sperm cell involved in the acrosome reaction. The spermatozoon of each species is described ultrastructurally using transmission electron microscopy and correlations made between observed patterns of fluorescence and the cellular components described. No obvious filamentous actin (F‐actin) is visible in the electron micrographs of the spermatozoa of any of the species. In most cases the fluorescence is sufficiently specific to indicate in which region of the mature sperm cell the actin and tubulin occurs. Actin is acrosomal inMaja, CancerandPotamonbut appears to be cytoplasmic inClibanarius, while the tubulins appear only to be present in the cytoplasm ofClibanarius, Majaan

ISSN:0001-7272    

DOI:10.1111/j.1463-6395.1994.tb00964.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

AbstractSpermiogenesis and spermatozoa were studied by transmission and scanning electron microscopy inTroglocaridicolasp., a scutariellid epizoic on a cavernicolous freshwater shrimp. Spermiogenesis involves elongation of the spermatid in which the nucleus elongates, but remains close to the common cytoplasmic mass. Flagella first grow in opposite direction and at a right angle to the cytoplasmic shaft, and centrioles show associate structures. Later, the two centrioles rotate and the flagella emerge parallel, but still perpendicular to the shaft. An apical process elongates at the extremity of the spermatid shaft. The spermatozoon shows active flagellar beating and undulations of the sperm body. The spermatozoon comprises an anterior ‘corkscrew’ region, the flagellar insertion region, a cytoplasmic region and a posterior nuclear region. The corkscrew contains an electron dense structure, not membrane‐bound, originating from the apical process of the spermatid. The flagella show the 9+‘1’ pattern, usual in Platyhelminthes. The cytoplasmic and nuclear regions show a cortical row of about 50 twisted longitudinal microtubules surrounding a row of electron dense, and not membrane‐bound, 25‐nm granules. These granules are original structures and seem to be known only in a few Platyhelminthes species in which a non‐flagellar movement of the spermatozoon occurs. Thus, it is hypothesised that the 25‐nm granules play a role in cellular motility. Sperm ultrastructure inTroglocaridicolashows major differences to that in the temnocephalids. It is therefore concluded that the phylogenetic position of the scutariellids within the Temnocephalidea should

ISSN:0001-7272    

DOI:10.1111/j.1463-6395.1994.tb00965.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

AbstractA morphological study was carried out on thefournaupliar stages ofSacculina carciniusing mainly scanning electron microscopy. Frontal horns were present and throughout development the typical nauplius limbs remained simple and gnathobases were lacking. Such features are characteristic of other lecithotrophic barnacle nauplii. The presence of a vestigial ventral thoracic process was evident on the stage III nauplius and was even more prominent on the stage IV nauplius. These observations confirm that the rhizocephalan nauplius is close to the thoracican nauplius form and lend strong support for the retention of the Rhizocephala within the Cirripedia.

ISSN:0001-7272    

DOI:10.1111/j.1463-6395.1994.tb00966.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

AbstractThe present paper deals with the morphology of the luminous organ of the squidLoligo duvauceli, caught in the sea off Indonesia and Thailand. Two luminous organs are situated on the ventral surface of the ink sac, near the anus. Each organ consists of a luminous sac divided into numerous discrete chambers containing bacteria. On the ventral side the organ is bordered by a lens‐like structure, consisting of muscle cells. On the remaining sides the bacterial chambers are limited by a cup‐shaped reflector layer with numerous parallel lamellae. The reflector separates the bacterial chamber from the ink sac. A ciliated channel connects the interior of the bacterial chamber with the mantle cav

ISSN:0001-7272    

DOI:10.1111/j.1463-6395.1994.tb00967.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

AbstractThe morphology and fine structure of femaleIntoshia variabili, new combination forRhopalura variabiliAlexandrov&Sljusarev, 1992, were studied with transmission electron microscopy. The body surface is covered with a 3‐layered cuticula, under which is a layer of ciliated + non‐ciliated cells arranged in alternating rings around the body. Ciliated cells have lateral extensions that intercalate with the non‐ciliated cells. The kinetosome of each cilium has two longitudinally oriented cross‐striated rootlets. The outer surface of the ciliated cells is covered with small tubercles, and the cytoplasm of these cells contains granules, vacuoles, mitochondria, fibrillar structures and lamellary bodies. A band of dense fibrils passes through the upper part of each ring of cells, going from one cell junction to another, encircling the entire body. Between the layer of ciliated + non–ciliated cells and the oocytes, elongated contractile cells from 4–5 longitudinal columns and 1 ring, the latter at the level of ciliated rings 7–9. The contractile cells contain thick and thin longitudinally oriented fibrils. The oocytes contain a large nucleus, numerous mitochondria, electron–dense granules and 1–2 spherical structures. An anteriorly situated, ciliated goblet–like receptor, not described for any other orthonectids, consists of three closely apposed cells, the upper part of which contains densely packed cilia. The genital pore opens through a non–ciliated cell and is surrounded by severa

ISSN:0001-7272    

DOI:10.1111/j.1463-6395.1994.tb00968.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

AbstractThis paper investigates whether elastic fibre‐like structures are present in the ventral aorta of hagfishes and lampreys. Fibres, which are morphologically similar to the elastic fibres of gnathostomatous (jawed) vertebrates, are shown to be present in the ventral aorta of the hagfishParamyxine atami, and also, but to a lesser extent, the dorsal aorta of this species and the ventral aorta of another hagfish,Eptatretus stouti.The ‘elastic’ tissue formed irregular sheet‐like aggregates, comprising well‐defined amorphous material surrounded by tubular microfibrils, whose diameters ranged from 10 to 15 nm. While this tissue was most abundant in the same region of the aortae as that occupied by the elastica interna in the blood vessels of gnathostomes, it was also found deeper in the wall of these blood vessels. Although tubular microfibrils were found in the ventral aorta of the hagfishMyxine glutinosaand the lampreyGeotria australis, these were never associated with well–defined, amorphous material. This parallels the results of previous studies onMyxine glutinosaand another species of lamprey,Petromyzon marinus.Thus, the elastic fibre–like tissues found in the ventral aortae ofP. atamiandE. stoutiprovide the first examples of such structures in this region in agnatha

ISSN:0001-7272    

DOI:10.1111/j.1463-6395.1994.tb00969.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

AbstractThe pectoralis muscle (M. pectoralis) of many premier soaring birds contains a smaller, accessory, deep belly in addition to the much larger superficial belly found in all flying birds. Here we describe the muscle fiber types in both the superficial and deep bellies of the pectoralis of one such adept soaring species, the white pelican(Pelecanus erythrorhynchos).Histochemical techniques are used to demonstrate both nicotinamide adenine dinucleotide (reduced) and myofibrillar adenosine triphosphatase activities within the muscle fibers. Immunocytochemical methods employing several monoclonal antibodies, each directed against a different myosin heavy chain epitope of the chicken, are also used to characterize the fibers. While the superficial belly of the muscle consists entirely of fast‐twitch oxidative‐glycolytic fibers, the deep belly is composed exclusively of slow fibers. These slow fibers are labelled by two different antibodies specific for chicken slow myosin. We suggest that the fibers of the superficial belly are best suited to flapping flight, and that the fibers of the deep belly would be recruited only during soaring flight. Furthermore, we hypothesize that the deep belly found in the pectoralis of soaring species probably evolved from a deep neuromuscular compartment of the superficial be

ISSN:0001-7272    

DOI:10.1111/j.1463-6395.1994.tb00970.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

AbstractThe morphology and setation of mouth appendages (trophi) are investigated with scanning electron microscopy in the balanomorph barnaclesSemibalanus balanoides, Balanus balanusandB. nubilusand in the pedunculate barnaclesPollicipes polymerus, P. cornucopiaandLepas anatifera.It is difficult to uphold a clearcut distinction between denticles and setae and several types of setae also intergrade with each other. The trophi ofPollicipes polymerusandP. cornucopiahave the most ‘generalized’ morphology. The palps ofPollicipesandL. anatiferaare simpler than those in balanomorphs and carry a single type of seta. InL. anatiferathe mandibles and maxillules are adapted to a semi‐predatory feeding habit by carrying large, pointed teeth, but this species lacks the foliate‐serrate setae which populate the palps in the other species studied. Compared withPollicipesandLepas, the three balanomorphs have palps with a complex setation. The trophi inS. balanoidesdiffer from the two species ofBalanusin numerous features of setation and denticulation, notably in having the palps populated by plumodenticulate setae homologous to purely denticulated types inBalanus.It is suggested that SEM studies of barnacle trophi will provide characters of use in estimating ph

ISSN:0001-7272    

DOI:10.1111/j.1463-6395.1994.tb00971.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

AbstractIn cetaceans, each otic capsule is bound anteriorly to the remainder of the endocranium by an aliform structure called the supracochlear lamina. This lamina has been established here as the homologue of the sphenocochlear commissure of other mammals. Most researchers believe that these two structures arose within mammals. However, a comparative study involving data from both extant and extinct craniates suggests that the supracochlear lamina and the sphenocochlear commissure have a long premammalian history. The conclusion is that the lower of the two pharyngeal segments at the upper end of the mandibular branchial arch first became incorporated in the endocranium, constituting the cartilago trabecularis in the embryos of jawed craniates. The distal, or posterior, extremity of the trabecular cartilage projected outwardly to form the basitrabecular process. This process, which when ossified is called the processus basipterygoideus, functioned as a jaw support. Later, one more jaw support, termed the basivincular, evolved immediately in front of the basipterygoid process. Both these supports for the upper jaw existed in the piscine forerunners of the tetrapods. Subsequently, in the lineages leading to mammals, the basivincular jaw support became the processus alaris to which is attached an upper jaw endoskeletal remnant, called the ala temporalis. The basipterygoid jaw support, however, vanished as a consequence of the evolution of an exoskeletal joint system for the jaws of mammals. Yet the basipterygoid process persisted and as the sphenocochlear commissure or the supracochlear lamina assumed the new function of supporting the cochlear part of the auditory capsule.

ISSN:0001-7272    

DOI:10.1111/j.1463-6395.1994.tb00972.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

AbstractA morphological and functional study was made of the hepatic region in four enteropneust hemichordates:Schizocardiumsp.,Ptychodera flava, Ptychodera bahamensis, and an undescribed ptychoderid from Maui, Hawaii, using light and electron microscopy. The hepatic region of these enteropneusts, as well as others, is characterized by a brown‐green color and the presence of numerous caeca which represent dorsal extensions of the gut. These caeca extend above the dorsal surface of the worm and are organized into bilateral rows. Species‐specific differences were noted in the organizational pattern of the sacculations within rows and the morphology and histology of individual sacculations. Numerous brown‐green vesicles were discovered in both the epithelial cells and lumen of sacculations. Transmission electron microscopy revealed these bodies to be heterophagic vacuoles and residual bodies. Morphological evidence suggests that hepatic caeca are involved in intracellular digestion. Once endocytosed food particles are packaged as heterophagic vacuoles, and digestion has been completed, the residual bodies are packaged together and exuded from the cell in a spherule of cyto

ISSN:0001-7272    

DOI:10.1111/j.1463-6395.1994.tb00973.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY