Summary Comparative data on the ultrastructure of spermiogenesis and spermatozoa of the Polyplacophora Acanthochitona crinita, Chaetopleura angulata and Callochiton septemvalvis are presented in this study. In contrast to what has been described for this and other classes of Mollusca, no acrosome is present in the spermatozoa of these Polyplacophora. The nucleus is extended by a long, thin apical point. In A. crinita and C. angulata the mitochondria are situated at the basal and lateral regions of the nucleus. They do not present a typical middle piece. These species present a pericentriolar process. In C. septemvalvis the mitochondria are situated at the base of the nucleus, surrounding the centrioles, which are orthogonally positioned in all species. The ultrastructural development during spermiogenesis is similar. In middle spermatids of A. crinita, the chromatin is arranged in fine filaments. In C. septemvalvis and C. angulata the chromatin filaments are thicker, forming coarse bands. In late spermatids elongation of the nucleus continues, it becomes rather electron-dense and the chromatin filaments are more condensed. Finally, the nucleus has a uniformly electron-dense appearance, with no signs of filamentous organization. Considering the ultrastructural modifications observed, the Polyplacophora spermatozoa could be included in a modified type. 相似文献
The structure of the spermatozoon of Acesta oophaga (Bivalvia) is described by transmission electron microscopy. This cold-seep species produces ect-aquasperm, confirming that it is a broadcast spawner. The head of the sperm consists of a small, rounded, electron-dense nucleus, capped by a short conical acrosome, the contents of which are differentiated. The mid-piece contains a pair of orthogonally arranged centrioles surrounded by five spherical mitochondria. The gonad of one individual contained eggs and sperm, which supports the hypothesis that A. oophaga is a sequential hermaphrodite. 相似文献
A simple trypan blue-neutral red-Giemsa staining procedure for simultaneous evaluation of acrosome, sperm head, and tail membrane integrity and morphology has been used to evaluate equine spermatozoa. Some special characteristics and problems have arisen in evaluating stallion semen. One problem was the differentiation of intact vs. damaged sperm tails primarily in frozen and thawed samples. After freezing and thawing, a high percentage of spermatozoa with an unstained head and stained tail were observed. These cells are considered immotile. Therefore, unambiguous differentiation of intact vs. damaged sperm tail membrane is very important for evaluating semen quality. The aim of our study was to develop a method especially for stallion sperm to distinguish more accurately the different cell types. We compared Chicago sky blue 6B (CSB) to trypan blue (TB) for viability staining. CSB/Giemsa staining showed good repeatability and agreement with TB/Giemsa measurements. For densitometry analysis, individual digital images were taken from smears stained by CSB/Giemsa and by TB/Giemsa. A red-green-blue (RGB) histogram for each area of spermatozoa was drawn. Differences of means of RGB values of live vs. dead tails and separate live vs. dead heads from each photo were used to compare the two staining procedures. CSB produced similar live/dead sperm head differentiation and better tail differentiation. TB can be replaced by CSB and this results in more reliable evaluation. After staining with 0.16% CSB and 4 min fixation, 2–4 h Giemsa staining at 25–40° C is recommended for stallion semen. 相似文献
The conchocelis cells of four strains of Porphyra yezoensis Udea and four other Porphyra species were cryopreserved in liquid nitrogen (LN) using a programmable freezer or a simple prefreezing system, which consisted of a styrofoam box and a deep-freezer at ?40° C. The cells differed in their freezing tolerance but survived maximally when prefrozen to ?40° C in a cryoprotective solution composed of 10% dimethylsulfoxide and 0.5 M sorbitol in 50% seawater. The cryopreservation was successfully performed by applying the simple prefreezing system as well as by a programmable freezer. Conchocelis cells thawed from the LN temperature formed colonies and retained the ability to form conchospores that grew into gametophytic thalli. This technique using a simple prefreezing system will accelerate the spread of Porphyra cryopreservation. 相似文献
Corneal cryopreservation requires that endothelial cells remain viable and intercellular structure be preserved. High viability
levels for cryopreserved endothelial cells have been achieved, but preserving intercellular structure, especially endothelial
attachment to Descemet's membrane, has proved difficult. Cell detachment apparently is not caused by ice, suggesting osmotic
or chemical mechanisms. Knowledge of the permeation kinetics of cryoprotectants (CPAs) into endothelial cells and stroma is
essential for controlling osmotic and chemical activity and achieving adequate tissue permeation prior to cooling. Proton
nuclear magnetic resonance (NMR) spectroscopy was used to assess the permeation of dimethyl sulfoxide (DMSO) into isolated
rabbit corneas. Corneas with intact epithelia were exposed to isotonic medium or 2.0 mol/L DMSO for 60 min and subsequently
transferred to 2.0 or 4.0 mol/L DMSO, respectively, at 22, 0, or −10°C. DMSO concentration in the cornea was measured vs time.
The Kedem-Katchalsky model was fitted to the data. Hydraulic permeability (m3/N·s) is 7.1×10−13+216%-11% at 22°C, 8.2×10−13+235%−21% at 0°C, and 1.7×10−14+19% −16% at −10°C. The reflection coefficient is 1.0+2%−1% at 22°C and 0°C, and 0.9±5% at −10°C. Solute mobility (cm/s) is
5.9×10−6+6%–11% at 22°C, 3.1×10−6+12%−11% at 0°C, and 5.0×10−8 cm/s+59%−40% at −10°C. 相似文献
The gametophytic cells of six species of Laminariales, Laminaria japonica Areschoug, L. longissima Miyabe, Kjellmaniella crassifolia Miyabe, Ecklonia stolonifera Okamura, E. kurome Okamura, and Undaria pinnatifida (Harvey) Suringar, were subjected to cryopreservation in liquid nitrogen. The cells were suspended in various cryoprotective solutions and slowly cooled to –40°C over a period of 4 h. After this slow cooling step, the suspensions were immediately immersed in liquid nitrogen. All the species of Laminariaceae used in the present study survived maximally in a mixture of ethylene glycol and proline. On the other hand, the gametophytic cells of Undaria pinnatifida, a member of the Alariaceae, survived maximally in the mixture of glycerol and proline. The viability of the thawed gametophytic cells decreased during postthawing incubation. The decrease in viability continued for 4–6 days, and the minimum levels ranged from 36.2% to 67.2%. After 4–6 days of incubation, the percentage viability of all strains began to increase due to the renewal of cell division. 相似文献
Routine infertility investigations in the male and female include imaging techniques such as ultrasonography and endoscopy (fertiloscopy). However, these techniques lack the resolution to localize vital sperm or to reveal detailed morphological analysis of the oviduct which is often the cause of infertility in females. Therefore we set out to evaluate the efficiency of optical coherence tomography (OCT) as a diagnostic imaging tool for micron‐scale visualization of the male and female genital tract. Using the bovine as a model, the optical features of the TelestoTM, GanymedeTM (both Thorlabs) and NirisTM (Imalux) OCT imaging systems were compared.
Comparative visualization of ex vivo bovine testicular tissue by the TelestoTM microscopic optical coherence tomography system (left) and corresponding H&E staining (right). 相似文献