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Gross morphology and topographical relationships of the hyobranchial apparatus and laryngeal cartilages in the ostrich (Struthio camelus)
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The ostrich hyobranchial apparatus consists of the centrally positioned paraglossalia and basiurohyale and paired caudo‐lateral elements (horns), each consisting of the ceratobranchiale and epibranchiale. The paraglossalia lie within the tongue parenchyma and consist of paired, flat, caudo‐laterally directed cartilages joined rostrally. The basiurohyale forms a single dorso‐ventrally flattened unit composed of an octagonal‐shaped body from which extend rostral (the rostral process) and caudal (the urohyale) projections. The laryngeal skeleton consists of cricoid, procricoid and paired arytenoid cartilages. The large ring‐shaped cricoid cartilage displays a body and paired wings which articulate with each other and with the procricoid. The blunt, ossified, rostral projection of the cricoid and the scalloped nature of the arytenoid cartilages are unique to the ostrich. The procricoid is a single structure which links the paired arytenoids and wings of the cricoid. The hyobranchial apparatus is firmly attached to the tongue parenchyma and to the larynx and proximal trachea. In contrast to previous reports in this species, the horns of the hyobranchial apparatus are not related to the skull. Ossification of the body of the basihyale, the ceratobranchials and the rostral process and body of the cricoid cartilage of the larynx lends stability to these structures. 相似文献
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Ragnar Kinzelbach 《Zoology in the Middle East.》2013,59(1):20-21
Spermatogenesis in the Caspian Bent-toed Gecko, Cyrtopodion caspium, was studied in Mazandaran Province, northern Iran. Sampling took place periodically every 15 days during the activity period of this species at night, from 5 April to 20 October 2011. In total, 70 adult males were captured by hand. Testes were removed and processed for histological and morphometric studies. The results show that spermatogenesis begins in early April, reaches its peak in late May and early June, and ends in early to mid August. The maximum level of sperm production occurred in early June. The minimum diameter, weight and volume of testes were observed in early August. Three phases were observed during the activity period for spermatogenesis in C. caspium: active, transitional and inactive phases. Spermatogenesis of C. caspium in Iran is seasonal and alternate. 相似文献
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Carles G. Simeó Kathryn Kurtz Manel Chiva Enric Ribes Guiomar Rotllant 《Journal of morphology》2010,271(4):394-406
This study describes spermatogenesis in a majid crab (Maja brachydactyla) using electron microscopy and reports the origin of the different organelles present in the spermatozoa. Spermatogenesis in M. brachydactyla follows the general pattern observed in other brachyuran species but with several peculiarities. Annulate lamellae have been reported in brachyuran spermatogenesis during the diplotene stage of first spermatocytes, the early and mid‐spermatids. Unlike previous observations, a Golgi complex has been found in mid‐spermatids and is involved in the development of the acrosome. The Golgi complex produces two types of vesicles: light vesicles and electron‐dense vesicles. The light vesicles merge into the cytoplasm, giving rise to the proacrosomal vesicle. The electron‐dense vesicles are implicated in the formation of an electron‐dense granule, which later merges with the proacrosomal vesicle. In the late spermatid, the endoplasmic reticulum and the Golgi complex degenerate and form the structures–organelles complex found in the spermatozoa. At the end of spermatogenesis, the materials in the proacrosomal vesicle aggregate in a two‐step process, forming the characteristic concentric three‐layered structure of the spermatozoon acrosome. The newly formed spermatozoa from testis show the typical brachyuran morphology. J. Morphol., 2010. © 2009 Wiley‐Liss, Inc. 相似文献
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The ultrastructure of the testes in two representatives of the enigmatic taxon Nemertodermatida was studied using transmission
electron microscopy. Nemertoderma westbladi has paired testes, which are delineated by lining cells. Within each testis, different follicles, each surrounded by a membrane-like
structure, are found. Flagellophora apelti has genuinely follicular testes, consisting of several follicles, each containing a certain stage of spermatogenesis. As
the gametes are not enclosed by a structure that can be called a true gonad, the structure of the testes differs from most
bilaterian animals, but resembles the organization of gametogenic areas of ctenophores. Each stage of spermatogenesis in F. apelti is described, enabling the inference of the origin of the structures seen in mature spermatozoa. The overall structure of
the mature spermatozoa is similar in all nemertodermatids and unique within the Metazoa: an elongated head containing the
nucleus; a middle piece containing an axoneme, mitochondrial derivatives and in F. apelti granular derivatives; and a flagellar tail. 相似文献
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André L.B. Magalhães Nilo Bazzoli Gilmar B. Santos Elizete Rizzo 《Environmental Biology of Fishes》2004,70(4):415-425
We analysed the reproductive biology of the dogfish characid, Galeocharax knerii, by histological and ultrastructural techniques during two consecutive annual cycles at the Furnas and Itumbiara reservoirs, upper Paraná River basin, Southeastern Brazil. We classified the ovaries as cystovarian with asynchronous oocyte development and the testes as anastomosing tubular and unrestricted spermatogonial. Spermatogenesis is cystic and the spermatozoa have a rounded head, short middle piece and a long tail that contains microtubules in a 9 + 2 axonemal arrangement. Oogenesis occurs in ovigerous lamellae that project into the ovarian cavity. Vitellogenic oocytes possess a zona pellucida that is folded around the micropyle in an arrangement that facilitates fertilisation and which is also seen in other characids. Although the reservoirs of Furnas and Itumbiara have similar geomorphology and ichthyofauna, the biological parameters (e.g., gonadosomatic index) indicated more favourable conditions for reproduction of G. knerii in Itumbiara. An extended reproductive period, multiple spawnings and continuous spermatogenesis were the main reproductive characteristics of this species. We conclude that G. knerii has an opportunistic reproductive strategy, characterised by absence of parental care, early maturation and continuous reproduction, that also occurs in other neotropical characids, and allows them to rapidly colonise most of the reservoirs of the Southeastern Brazil. 相似文献
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SALMFamide2 and serotonin immunoreactivity in the nervous system of some acoels (Xenacoelomorpha)
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Isabel L. Dittmann Thomas Zauchner Lucy M. Nevard Maximilian J. Telford Bernhard Egger 《Journal of morphology》2018,279(5):589-597
Acoel worms are simple, often microscopic animals with direct development, a multiciliated epidermis, a statocyst, and a digestive parenchyma instead of a gut epithelium. Morphological characters of acoels have been notoriously difficult to interpret due to their relative scarcity. The nervous system is one of the most accessible and widely used comparative features in acoels, which have a so‐called commissural brain without capsule and several major longitudinal neurite bundles. Here, we use the selective binding properties of a neuropeptide antibody raised in echinoderms (SALMFamide2, or S2), and a commercial antibody against serotonin (5‐HT) to provide additional characters of the acoel nervous system. We have prepared whole‐mount immunofluorescent stainings of three acoel species: Symsagittifera psammophila (Convolutidae), Aphanostoma pisae, and the model acoel Isodiametra pulchra (both Isodiametridae). The commissural brain of all three acoels is delimited anteriorly by the ventral anterior commissure, and posteriorly by the dorsal posterior commissure. The dorsal anterior commissure is situated between the ventral anterior commissure and the dorsal posterior commissure, while the statocyst lies between dorsal anterior and dorsal posterior commissure. S2 and serotonin do not co‐localise, and they follow similar patterns to each other within an animal. In particular, S2, but not 5‐HT, stains a prominent commissure posterior to the main (dorsal) posterior commissure. We have for the first time observed a closed posterior loop of the main neurite bundles in S. psammophila for both the amidergic and the serotonergic nervous system. In I. pulchra, the lateral neurite bundles also form a posterior loop in our serotonergic nervous system stainings. 相似文献
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Xin-Jie Zhuang Wen-hao Tang Chang-yu Liu Jin-liang Zhu Xue Feng Jie Yan Ying Lian Ping Liu Jie Qiao 《PloS one》2015,10(6)
Background
Spermatogenesis is the complex process by which diploid stem cells generate haploid germ cells in gamete production. Members of the Xlr (X-chromosome linked, lymphocyte regulated) superfamily play essential roles in spermatogenesis. The expression, localization and role in spermatogenesis of one such member, Xlr5c, has not been reported previously.Methodology/Principal Findings
Xlr5c mRNA and protein levels in murine testes and other tissues were investigated using RT-PCR and Western blotting. Xlr5c was abundantly transcribed in mouse testes, particularly during the early stages of spermatogenesis and throughout prophase I in the nuclei of spermatocytes. Xlr5c was specifically localized at synaptonemal complexes(SCs) region in preleptotene and pachytene spermatocytes, as was the homologous Xlr protein Sycp3.Conclusions/Significance
These results suggest that Xlr5c was abundantly transcribed in germ cells, localized at SCs region, where it may play a potential role during the early stages of spermatogenesis. Identification and characterization of this novel testis protein may offer a new perspective for understanding of the molecular mechanisms involved in germ cell differentiation. 相似文献11.
Aarón Torres-Martínez Liliana Ruiz de Dios Arlette Hernández-Franyutti Mari Carmen Uribe Wilfrido Contreras Sánchez 《Journal of morphology》2019,280(10):1537-1547
We describe the histological characteristics of the testis and spermatogenesis of the cave molly Poecilia mexicana, a viviparous teleost inhabiting a sulfur spring cave, Cueva del Azufre, in Tabasco, Southern Mexico. P. mexicana has elongate spermatogonial restricted testes with spermatogonia arranged in the testicular periphery. Germ cell development occurs within spermatocysts. As spermatogenesis proceeds, the spermatocysts move longitudinally from the periphery of the testis to the efferent duct system, where mature spermatozoa are released. The efferent duct system consists of short efferent duct branches connected to a main efferent duct, opened into the genital pore. Spermatogenesis consisted of the following stages: spermatogonia (A and B), spermatocytes (primary and secondary), spermatids, and spermatozoa. The spermatozoa are situated within spermatocysts, with their heads oriented toward the periphery and flagella toward the center. Once in the efferent duct system, mature spermatozoa are packaged as unencapsulated sperm bundles, that is, spermatozeugmata. We suggest that the histological characteristics of the testis and spermatogenesis of P. mexicana from the Cueva del Azufre, and the viviparous condition where the spermatozoa enter in the female without been in the water, have allowed them to invade sulfurous and/or subterranean environments in Southern Mexico, without requiring complex morphofunctional changes in the testis or the spermatogenetic process. 相似文献
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Gonad development and sex differentiation from embryos to 594‐day‐old individuals were investigated in farmed Acipenser naccarii using light and transmission electron microscopy. The migrating primordial germ cells first appear along the dorsal wall of the body cavity in embryos 1.5 days before hatching. The gonadal ridge, containing a few primary primordial germ cells (PGC‐1) surrounded by enveloping cells, appears in 16‐day‐old larvae. At 60 days, the undifferentiated gonad is lamellar and PGC‐1 multiply, producing PGC‐2. In 105‐day‐old juveniles, a distinct germinal area with advanced PGC‐2 appears on the lateral side near the mesogonium and the first blood vessels are visible. At 180 days, putative ovaries with a notched gonadal epithelium and putative testes with a smooth one appear, together with adipose tissue on the distal side. In 210‐day‐old juveniles, active proliferation of germ cells begins in the putative ovaries, whereas putative testes still contain only a few germ cells. The onset of meiosis and reorganization of stromal tissue occurs in ovaries of 292‐day‐old individuals. Ovaries with developed lamellae enclosing early oocyte clusters and follicles with perinucleolar oocytes occur at 594 days. Meiotic stages are never found, even in anastomozing tubular testes of 594‐day‐old individuals. Steroid producing cells are detected in the undifferentiated gonad and in the differentiated ones of both sexes. Anatomical differentiation of the gonad precedes cytological differentiation and female differentiation largely precedes that of the male. Gonad development and differentiation are also associated with structural changes of connective tissue, viz. collagen‐rich areas are massive in developing testes and reduced in ovaries. J. Morphol., 2008. © 2008 Wiley‐Liss, Inc. 相似文献
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Johan C. De W. Kruger 《Journal of morphology》1991,210(2):163-174
Spermatogenesis and sperm ultrastructure were studied by transmission electron microscopy (TEM) and scanning electron microscopy (SEM) in the longidorid Xiphinema theresiae. All germ cell stages, except spermatogonia, are present in the testes of young adult males. The nonflagellated, slightly elongated sperm displays little intraspecific variation and, although never polarized into a head and tail region, has a remarkably precise form, with a high degree of internal organization. Incipient fingerlike pseudopodia appear in the young spermatid and increase to such an extent that the adult sperm has a conspicuous “woolly” appearance. Microfilament bundles encircle the perinuclear mitochondria in the spermatid, and seem to be closely associated with the evaginated plasma membrane, especially in the spermatozoon. A large nucleus with nuclear envelope is prominent in the spermatocyte, but the envelope is absent in the young spermatid. Mitochondria are present in all germ cell stages and undergo certain morphological changes (e.g., in size and number, presence or absence of cristae), as well as changes in intracellular movements during spermatogenesis. Membranous organelles are prominent in the spermatocyte, but disappear in the older spermatid. Annulate lamellae and a residual body (i.e., cytophore) are conspicuous in the spermatocyte and spermatid, respectively; the spermatozoon clearly lacks a refringent body (i.e., acrosome). 相似文献
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Summary
Typosyllis pulchra reproduces by the production of three to four gamete-bearing stolons (schizogamy) during consecutive 30-day periods. Although gonads are found in a large number of segments, only those in the posterior-most segments produce gametes and become incorporated into the developing stolon. The more anterior gonads remain undifferentiated and probably sexually undetermined until they are needed in future stolonizations. Gonial cells, which will eventually become either male or female, are ultrastructurally identical at the onset of each stolonization period. Spermatogenesis is marked by a short proliferative period followed by differentiation and spermiogenesis. The first ultrastructural signs of spermatogenesis were found in coelomic spermatogonia on day 10 of stolon formation. Spermatogonia are joined by intercellular bridges, which are maintained until the early spermatid stage. Synaptonemal complexes mark the onset of meiosis, which is apparently synchronized in the syncytial clusters of primary spermatocytes. Spermiogenesis occurs during the final 10 days of stolonization and a variety of stages is present within a single animal. All sperm mature by the time the stolon detaches. Acrosome formation and nuclear condensation are described in addition to the ultrastructure of mature sperm. 相似文献
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Raissa A. Araújo Beatriz D. Amaro Sônia A. Talamoni Hugo P. Godinho 《Journal of morphology》2013,274(11):1230-1238
With a nearly global distribution the vespertilionid bat Myotis represents one of the most exceptional examples of adaptive radiation among mammals. We investigated the reproductive activity of the vespertilionid bat yellowish myotis, Myotis levis, from a highland area in Southeastern Brazil. The data were obtained through histological analyses of the male and female genital systems from February 2010 to May 2011. The testes of the adult yellowish myotis showed seasonal morphological characteristics which were categorized in the following stages: rest, maturing, mature, and mating. Rest and maturing males were recorded throughout the rainy season (October‐March). In the rest stage no spermatogenesis was observed and the epididymal duct was devoid of spermatozoa. Maturing individuals had started spermatogenesis and few spermatozoa were found in the epididymal duct. Mature males were found toward the end (February‐March) of the rainy season, when full spermatogenic activity was recorded and spermatozoa were packed in the epididymal duct. Although not recorded, mating probably occurred in the middle of the dry season (April–September) when the cauda epididymis was enlarged and packed with sperm. The spermatozoa remained stored in the cauda epididymis for at least three months when the testes entered into regression. The ovaries showed all types of ovarian follicles throughout the study period except mature follicles which were registered only in July (mid‐dry season). Lactating females were captured in the beginning of the rainy season. The seasonal reproductive characteristics of the yellowish myotis from this Neotropical highland area were similar those of epididymal sperm‐storing temperate vespertilionids. J. Morphol. 274:1230–1238, 2013. © 2013 Wiley Periodicals, Inc. 相似文献
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Peter Michalik Martín J. Ramírez Christian S. Wirkner Elisabeth Lipke 《Invertebrate Biology》2014,133(2):180-187
The male reproductive systems of spiders are highly diverse in structure across all major spider taxa. Little is known about this organ system in basal araneomorph spiders, especially Austrochiloidea; such knowledge is necessary for a more complete understanding of the evolutionary morphology of the male reproductive system in spiders. In the present study, we describe the male reproductive system of an austrochilid spider, the enigmatic troglophilic Tasmanian cave spider Hickmania troglodytes, using light and electron microscopic techniques. The male reproductive system consists of tubular testes leading into convoluted deferent ducts, which are fused close to the genital opening to an unpaired ejaculatory duct. Spermatogenesis occurs only in the subadult testes, whereas adult testes showed neither spermatogenic stages nor any generative tissue in all investigated specimens. The testes of adult males are drastically reduced in size compared with those of subadult males, but the deferent ducts are filled with large numbers of mature spermatozoa. Thus, our data suggest that males of H. troglodytes are sperm‐limited, but not necessarily sperm‐depleted as described for certain orb‐weaving spiders. Due to the absence of generative tissue, limited sperm production is permanent (PSL) and probably has an influence on the reproductive strategies in this species. As nearly no data are available on the life history of H. troglodytes, and in particular information on the phenology of males is lacking, implications of the evolution of PSL in this species are unclear. Nonetheless, our data on other representatives of Austrochilidae (Austrochilus forsteri, Thaida chepu) and Gradungulidae (Progradungula otwayensis) suggest that PSL evolved within Austrochiliodea only in H. troglodytes and might be an adaptation to its troglophilic lifestyle. 相似文献
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Spermatogenesis is a complex series of processes that involves (1) the maintenance of a renewable pool of diploid stem cells within a niche, (2) the mitotic expansion of a subpopulation of stem cells committed to the spermatogenic pathway, and (3) the differentiation of diploid cells into highly specialized, haploid spermatozoa through meiotic and post-meiotic cellular transformations. Drosophila melanogaster is a desirable model for studying spermatogenesis, as similarities exist between mammalian and fly spermatogenesis. Like mammals, flies maintain a spermatogenic stem cell niche; the steps involved in mammalian spermatogenesis are mimicked in flies, with the main difference being that fly sperm develop within cysts rather than an epithelial cell layer. Here, we report a reliable robust system for culturing whole testes and individual spermatogenic cysts obtained from mid- to late-pupal stages of Drosophila pseudoobscura. D. pseudoobscura testes can be easily distinguished in later pupal stages because of their intense red pigmentation and are easily handled because of their simple ellipsoidal morphology. Cultured cysts are comparable in length to cysts obtained from adult flies, and motility is consistently achieved in vitro. This system not only offers a method for dissecting the mechanisms involved in meiotic and post-meiotic cellular transformations, but also can be used for the study of signaling during spermatogenesis. 相似文献
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Summary Spermatogenesis inHydra carnea was investigated. The cell proliferation and differentiation kinetics of intermediates in the spermatogenesis pathway were determined, using quantitative determinations of cell abundance, pulse and continuous labelling with3H-thymidine and nuclear DNA measurements. Testes develop in the ectoderm of male hydra as a result of interstitial cell proliferation. Gonial stem cells and proliferating spermatogonia have cell cycles of 28 h and 22 h, respectively. Stem cells undergo four, five or six cell divisions prior to meiosis which includes a premeiotic S+G2 phase of 20 h followed by a long meiotic prophase (22 h).Spermatid differentiation requires 12–29 h. When they first appear, testes contain only proliferating spermatogonia; meiotic and postmeiotic cells appear after 2 and 3 days, respectively and release of mature sperm begins after 4 days. Mature testes produce about 27,000 sperm per day over a period of 4–6 days: about 220 gonial stem cells per testis are required to support this level of sperm differentiation. Further results indicate that somatic (e.g. nematocyte) differentiation does not occur in testes although it continues normally in ectodermal tissue outside testes. Our results support the hypothesis that spermatogenesis is controlled locally in regions of the ectoderm where testes develop. 相似文献
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Ultrastructural organization of the genital tracts in amphigonic females of Euceraphis betulae Koch (Aphididae: Calaphidinae)
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The ultrastructure of the genital tracts in amphigonic females of Aphidoidea is described for the first time, using Euceraphis betulae Koch (Aphididae: Calaphidinae) as a representative. The female reproductive apparatus consists of two ovaries, each one with three/four meroistic telotrophic ovarioles; two sac‐like accessory glands lie laterally to a sac‐like seminal receptacle, opening into the dorso‐medial part of the common oviduct by means of a spermathecal duct. A marked secretory activity takes place in the epithelial cells of all the investigated tracts as shown by ultrastructural observation of many organelles involved in this process. No evident golgian area was observed in the cytoplasm of these cells. Extensive smooth endoplasmic reticulum, whose probable role is here discussed, was observed in epithelial cells of the wall of the accessory gland. Spermathecal duct and seminal receptacle had peculiar features that could be related to different secretory activities carried out by these two parts of the spermatheca. 相似文献
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Tian L Ji BZ Liu SW He CL Jin F Gao J Stanley D Li S 《Archives of insect biochemistry and physiology》2010,75(4):275-286
We report on juvenile hormone (JH) biosynthesis from long‐chain intermediates by specific reproductive tissues and the corpora allata (CA) prepared from adult longhorned beetles, Apriona germari. The testes, male accessory glands (MAGs), ovaries, and CA contained the long‐chain intermediates in the JH biosynthetic pathway, farnesoic acid (FA), methyl farnesoate (MF), and JH III. The testes and ovaries, but not CA, produced radioactive JH III after the addition of 3H‐methionine and, separately, unlabeled methionine, to the incubation medium. We inferred that endogenous FA is methylated to MF in the testes and ovaries. Addition of farnesol led to increased amounts of FA in the testes, MAGs, ovaries, and CA, indicating oxidation of farnesol to FA. Addition of FA to incubation medium yielded increased JH III, again indicating methylation of FA to MF in the testes, MAGs, ovaries, but not CA. Addition of MF to incubation medium also led to JH III, from which we inferred the epoxidation of MF to JH III. JH biosynthesis from farnesol in the testes, MAGs, and ovaries of A. germari proceeds via oxidation to FA, methylation to MF, and epoxidation to JH III. This is a well‐known pathway to JH III, described here for the first time in reproductive tissues of longhorned beetles. © 2010 Wiley Periodicals, Inc. 相似文献