Hilbig, Brigitte and James A. Graff, J. Blake, J. I, with a reveiw of the literature for confirmed records. Dean, H. Doner, S. Orensky, L.
Fourth Edition. Chapter Volume 4. Series Editor B. Blake, James A. Maciolek, N. J, Blake, J.
Annelid sperm and fertilization biology | SpringerLink
Sene Silva, Gustaavo. Please report errors in award information by writing to: awardsearch nsf. Search Awards. A series of sections of the specimen shown in Fig.
We describe here the ovarian tissue first. Gross anatomy and morphology of Osedax females. The arrow marks opening of the oviduct to the sea. The oviduct moves inside at the beginning of the lower trunk arrow. Ovisac and lower trunk region of a female of O. Ovarian tissue with blood vessels is visible through the skin, as is the uterus region of the oviduct, which contains numerous presumably fertilized oocytes ready to be released to the sea through the anterior oviduct.
Osedax frankpressi lower trunk and ovisac region, with the ovisac epidermis and trophosome removed, showing ovarian tissue with developing oocytes and blood vessels. Osedax frankpressi lower trunk and anterior ovisac dissected open showing convoluted oviduct with oocytes arrow running in close association with the dorsal blood vessel. Near sagittal section of Osedax rubiplumus. Near sagittal section through entire body showing plume, upper trunk, lower trunk, and ovisac region filled with ovaries and developing eggs collected in the uterus.
Dashed lines mark areas shown in B and C. Detail of crown region showing palps and distal end of the oviduct filled with oocytes. Detail of A showing part of the upper trunk with the oviduct running exteriorly and the lower trunk with the oviduct located inside. The thin-walled nonciliated uterus is located further posteriorly. A different near sagittal section through the same O. The anterior part of the heart body in the dorsal vessel in the lower trunk is visible. Histology of lower trunk and ovisac region of female Osedax frankpressi.
Actual female specimen of O. Cross-section of lower trunk region showing large dorsal blood vessel filled with heart body, and nonciliated anterior oviduct asterisks. Cross-section of anterior ovisac region showing large dorsal blood vessel still filled with heart body, ovarian lobes, and oviduct asterisks. Cross-section of ovisac region more posterior to Fig. Cross-section of anterior ovisac region showing ovarian lobes separated by peritoneum, ovarian ducts asterisks , oviduct, and part of base of trunk with dorsal and ventral arrowhead blood vessel.
The transition between the uterus and anterior oviduct is boxed on the left and shown in F. Close-up of part of marked area in Fig. Cross-section of ovisac region more posterior than in Fig. Close-up of marked area in Fig. Cross-section of ovisac region further posterior than Fig.
Several ovarian ducts are indicated asterisks , as is the transition of the ovarian duct from the ovarian tissue to the uterus containing an oocyte in marked area shown in Fig. Close-up of area marked in Fig. The ovarian tissue lies in the coelom of the ovisac region and comprises a large proportion of the female body Fig. Proliferative germinal epithelia are scattered throughout the ovisac resulting in several ovarian lobes Figs.
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The discrete ovarian lobes were numerous, but could not be counted for this study Figs. It is not clear if the ovarian tissue represents multiple ovaries or a single large ovary. The germinal epithelium inside each ovarian lobe grows toward the lumen, forming several stalks Figs. Oocytes develop at the distal end of these stalks Fig. As the oocytes mature, with thin follicle cells surrounding them, they show yolk droplets and increase in size Fig. Mature oocytes lie at the distal end of the stalks and move into the ovarian ducts, which are present in each lobe Fig. Each ovarian lobe is surrounded by peritoneal tissue and shows intermingling connective tissue Fig.
The short ovarian ducts are composed of a thick-walled, single cell-layered, nonciliated epithelium surrounded by musculature and embedded in connective tissue Fig.
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The ovarian ducts lead to what we term here as a uterus, an enlarged, thin-walled proximal end portion of the terminal oviduct Figs. The uterus is not surrounded by musculature and lacks cilia. The uterus holds mature oocytes that are likely to be already fertilized Fig. From the uterus, the oocytes pass further along to a nonciliated part of the oviduct proper in the lower trunk Figs. As outlined above, the oviduct then emerges at the lower to upper trunk border at what we interpret as the gonopore, see Discussion and runs as the exterior oviduct, visible on the dorsal side of the upper trunk Figs.
The spatial relations of the ovarian lobes, the ovarian ducts, and the oviduct including the uterus region with each other, as well as their spatial relation with the dorsal and ventral blood vessels, are shown in a 3-D reconstruction Fig. Different sagittal views from this reconstruction illustrate the branching system of the reproductive ducts ovarian ducts, uterus, and oviduct Fig.
The female reproductive system only, with the vascular system removed, is shown in Fig. It resembles a bunch of grapes, with the ovarian lobes arranged on the periphery and the duct system, composed of the ovarian ducts, uterus, and oviduct in the center, corresponding to the stems of the grape cluster. Near sagittal section through the ovisac of O. The lobes contain developing oocytes and ensheathing follicle cells.
Note the uterus arrowheads with mature oocytes asterisks and several sections of ovarian ducts arrows. TEM of ovarian tissue of O. TEM of ovarian duct of O. Near sagittal section through 3D model of O. Dorso-lateral view of the ovisac region without the body wall, showing dorsal blood vessel and oviduct running in close association in the center and the ovarian tissue arranged in lobes on the periphery.
Oocytes yellow are passing from the ovarian tissue to the ovarian ducts. Sagittal section through 3D model of O. Late vitellogenic or mature oocytes, scattered through the ovarian tissue, are collected into the ovarian ducts.
Lateral view of the ovisac region of O. Note the oviduct running in the center, ovarian ducts leading to the uterus, and the ovarian tissue arranged in lobes on the periphery. In Osedax males, the sperm accumulate in a seminal vesicle at the anterior end of the body Fig. The sperm are densely packed in the seminal vesicle in a seemingly haphazard fashion Fig. They are clearly not bundled into spermatophores or spermatozeugmata Fig.
Phylogeny of Annelida (Lophotrochozoa): total-evidence analysis of morphology and six genes
When a mature male is slightly squeezed, a mass of individual sperm is emitted from the seminal vesicle in the head Fig. Squeezed O. Unpackaged mature sperm from seminal vesicle of O. Transmission electron micrograph TEM of a transverse section of the seminal vesicle of an O. TEM of sperm in seminal vesicle with random orientation and not bundled into spermatophores or spermatozeugmata. TEM of seminal vesicle male showing sperm in various cross-sections.
Interference contrast micrograph of mature sperm showing acrosome region, head comprised of the nucleus and mitochondrial complex, and the tail. TEM of a longitudinally sectioned sperm of O. The axoneme penetrates into the base of the sperm nucleus and emerges as a free flagellum. Note the small electron dense sheath behind the nucleus. TEM of longitudinal section through base of the acrosome vesicle and the thin nucleus. TEM of anchoring apparatus for the axoneme, which includes a single centriole. The mitochondrial spiral starts at the level of the anchoring apparatus of this sperm.
TEM of base of the head of another sperm from 5G showing the mitochondrial spiral starts past the anchoring apparatus. TEM of anterior tapering part of nucleus that lacks mitochondria, although still spiral. TEM showing the anterior tapering part of nucleus lacking mitochondria transitioning posteriorly to wider helically spiral nucleus occupied by mitochondria. TEM of the anteriormost part of nucleus capped by the acrosome.
TEM of a longitudinal section through longest section seen of tapered, thin anterior nucleus of the sperm head. TEM of a cross-section through the acrosome and nucleus. TEM of a cross-section through the tapered part of the nucleus, behind the acrosome. TEM of a cross-section through the wider helically spiral nucleus. TEM of a cross-section through the wider helically spiral nucleus and an occupying mitochondrion. TEM of a cross-section through the nucleus and the anchoring apparatus of the axoneme. TEM of a cross-section through the centriole, nucleus, and mitochondrion. TEM of a cross-section through axoneme and nucleus.
TEM of a cross-section through the flagellum in the region of the thickened plasma membrane just behind the thin electron dense sheath. Sperm ultrastructure is described for O. Mature sperm Fig.
Phylogeny and evolution of reproductive modes in Autolytinae (Syllidae, Annelida).
The head consists of a helical cylindrical nuclear and mitochondrial complex Fig. An anchoring apparatus and a flagellum are embedded basally Fig. The acrosome is a cap-like vesicle that tightly covers the apical part of the nucleus Fig. Although the full length of the acrosome was not measured, it is at least 2. No subacrosomal space could be seen.
The nucleus immediately proximal to the acrosome is a long uniform cylinder with a helical spiral 0. The longest section measured was 8. The wider to 0. The nucleus shows a deep helical groove that is filled with mitochondrial material, although it was not established if this was a single elongate mitochondrion or a series of mitochondria Fig. The mitochondrial spiral either terminated at the point of the nucleus where it is penetrated by the flagellum and anchoring apparatus Fig.
The basal part of the nucleus is penetrated by the flagellum and anchoring apparatus for about 4. The anchoring apparatus is comprised of a single centriole Fig. Dwarf males of Osedax Fig. The vast majority of males lie in the anterior third of the tube lumen, usually in close vicinity to the oviduct. In the tubes of some females of O. Observations of the interior of the oviduct along the trunk revealed no sperm. Similarly, no sperm were found stored in the uterus Figs. However, Hoechst nuclear staining on paraffin sections and TEM revealed many sperm throughout the ovisac of the investigated females Fig.
The sperm were associated with tissue near the ovarian ducts Fig. We were able to document the presence of sperm in the ovisac of females of O. Sperm located in the ovisac region of female Osedax spp. Sperm arrowheads in female O. Transmission electron micrographs of sperm arrowheads in connective tissue of ovisac region of O. Cross-section through sperm in connective tissue of O. Cross-section through connective tissue of O. While in some instances sperm tended to be located among the cells of the connective tissue, in other instances, the sperm seemed to be located in invaginations of such cells Fig.
In all cases, the sperm were always found in close vicinity to the oocytes Fig. Several spermatozoa occurred in close vicinity to each other and several such groups were found throughout the ovisac region of the females Fig. Rouse, Elena Kupriyanova and Eijiroh Nishi Blake In the Library Request this item to view in the Library's reading rooms using your library card. Details Collect From N Order a copy Copyright or permission restrictions may apply. We will contact you if necessary. To learn more about Copies Direct watch this short online video.
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