bluuebunny/crossref_metadata_2025_split huggingface dataset:
Ultrastructure of mature sperm and eggs of the brooding hermaphroditic chiton, Lepidochitona fernaldi Eernisse 1986, with special reference to the mechanism of fertilization
Authors: Buckland‐Nicks John A. , Eernisse Douglas J. 
Published: June 2005

AbstractMost chitons are gonochoric and free spawning with fertilization occurring in seawater. Brooding hermaphroditic chitons retain their embryos in the pallial groove but whether the eggs are fertilized internally in the female genital tract or externally in the pallial groove was not previously known. Furthermore, the transition to this mode of reproduction could be expected to involve other changes in the functional morphology of eggs and sperm. We describe for the first time observations on live spawning, as well as the ultrastructure of sperm and eggs, in the brooding hermaphrodite, Lepidochitona fernaldi.Sperm and eggs are spawned through common gonoducts and the eggs are self‐fertilized in the pallial groove. Sperm structure is unmodified from that typical of other Lepidochitonidae, which suggests that the medium filling the pallial groove is seawater and not some more viscous fluid. The egg hull is reduced in this species to a series of flattened hexagonal plates that block access to sperm. Sperm must, therefore, penetrate the egg in between hull plates. In this region are located numerous micropores that provide more direct access to the vitelline layer beneath the hull. This region also overlies an area of the egg membrane that is rich in microvilli. The biological significance of these results is discussed with reference to the evolution of self‐fertilization. © 1993 Wiley‐Liss, Inc.
Distribution of lectin binding sites in the oviducts of cycling and hormone‐treated pigs
Authors: Raychoudhury S. S. , Suarez S. S. , Buhi W. C. 
Published: June 2005

AbstractGamete transport, fertilization, and early embryonic development take place in different regions of the oviduct and under different hormonal conditions. The objective of this study was to use lectins to detect variation in the distribution of glycosylated molecules on the surface of the epithelia that influence these events. Oviducts were collected from gilts on day 1 (estrus) and day 16 (diestrus) of the estrous cycle, and from gilts that were bilaterally ovariectomized on day 4 of the estrous cycle, and were subsequently treated with estradiol valerate (100 μg/day), progesterone (200 mg/day), or corn oil vehicle for 11 days. Six biotinylated lectins, Triticum vulgaris (WGA), Arachis hypogaea (PNA), Ulex europeus (UEA‐I), Dolichos biflorus (DBA), Ricinus communis (RCA‐I), and Canavalia ensiformis (Con A), were used to probe tissue from the isthmus and ampulla using peroxidase‐conjugated avidin as the marker. In cyclic gilts, WGA and DBA stained more strongly in the isthmus than the ampulla on both cycle days. Staining with PNA was patchy, but greater on the apical surface of isthmic epithelium on day 16 than day 1. With UEA‐I, staining was more intense in the ampulla on day 16 than day 1. Staining by PNA and UEA‐I was suppressed in both the ampulla and isthmus with estradiol treatment. DBA staining was suppressed in the isthmus with both estradiol and progesterone treatments. Cilia were labelled by all lectins except WGA and PNA. Thus glycosylation patterns vary in the porcine oviduct with region and hormonal state, reflecting the variety of events that may be influenced. © 1993 Wiley‐Liss, Inc.
Temperature‐dependent sex determination in the leopard gecko, Eublepharis macularius
Authors: Viets Brian E. , Tousignant Alan , Ewert Michael A. , Nelson Craig E. , Crews David 
Published: June 2005

AbstractThe leopard gecko, Eublepharis macularius, has temperature‐dependent sex determination (TSD). Previous reports have shown that females are produced predominately at cool incubation temperatures and males are produced predominately at warm incubation temperatures (Pattern Ib). We report here that incubation at even higher temperatures (34 and 35°C) produces mostly females (Pattern II). The lethal maximum constant incubation temperature for this species appears to be just above 35°C. Although a previous study indicated that females from a warm incubation temperature (32°C) failed to lay eggs, we found that 12 of 14 mature females incubated at 32.5°C, and 5 of 6 mature females incubated at 34°C produced fertile eggs and viable hatchlings. © 1993 Wiley‐Liss, Inc.
Regulation of hepatic vitellogenin synthesis in the little skate (Raja erinacea): Use of a homologous enzyme‐linked immunosorbent assay
Authors: Perez Lorelei E. , Callard Ian P. 
Published: June 2005

AbstractAn enzyme‐linked immunosorbent assay (ELISA) was developed to detect vitellogenin in skates. The antibody raised against the yolk protein lipovitellin was shown to recognize a sexspecific, estrogen‐inducible 205 kD protein in plasma, previously identified in skate as vitellogenin. The detection limit of the assay was 31.3 ng/ml, similar to that of radioimmunoassays for vitellogenin detection in other species. Using the assay, vitellogenin levels were shown to be highest (241.8 ± 26.5 ug/ml) in the ovarian follicular phase, decreasing approximately 1‐2 days before ovulation to a low (173.1 ± 22.9 ug/ml) during the luteal phase. Vitellogenin levels increased again approximately 1‐2 days before oviposition to 259.8 ± 38.8 ug/ml.The effects of estrogen and progesterone on hepatic vitellogenin production in normal and hypophysectomized male skates were also investigated. Plasma vitellogenin was not detectable in either intact or hypophysectomised male skates, but increased with estradiol treatment (intact: 48.2 ± 4.9 ug/ml vs. hypophysectomised 252 ± 10.6 ug/ml at day 8). Progesterone treatment significantly (P < .01) attenuated the effect of estrogen on plasma vitellogenin levels in both intact (17 ± 2.1 ug/ml) and hypophysectomized (44.0 ± 9.4 ug/ml) male skates. © 1993 Wiley‐Liss, Inc.
Movement of spermatozoa and changes in micropyles during fertilization in medaka eggs
Authors: Iwamatsu Takashi , Ishijima Sumio , Nakashima Seiko 
Published: June 2005

AbstractIn the medaka, movement of spermatozoa and changes in the egg micropyles during fertilization were observed through a video camera and recorded with a video recorder to analyse sperm movement. Movement of spermatozoa as they entered micropyles in both intact and isolated chorions was compared before and after fertilization of the eggs. The inner one third of the micropyle was completely closed and the micropylar vestibule became shallow by 5 min after sperm attachment. Spermatozoa did not increase in swimming speed in the vicinity of the micropyle and were not attracted to it. The majority of spermatozoa entering the micropyle were rotating at an average frequency of 8 Hz in the right‐hand direction. The rotation direction did not correspond to the left‐hand spiral structure of the micropylar wall, though a small amplitude of the beating sperm flagellum corresponded with the narrow micropylar canal. The frequency of sperm entry into the micropyle decreased significantly in intact eggs and isolated chorions following fertilization, independent of artificial occlusion of the micropylar canal. Moreover, in isolated chorions before fertilization, spermatozoa rarely entered the micropylar canal from its inner aperture. The present data suggest the existence of some substance in the micropyle which guides spermatozoa into the micropylar canal, although the perimicropylar depression might also play a role in the guidance of spermatozoa. © 1993 Wiley‐Liss, Inc.
Effects of epidermal growth factor, insulin‐like growth factor‐I, and dialyzed porcine follicular fluid on porcine oocyte maturation in vitro
Authors: Reed Michael L. , Estrada Jose L. , Illera Maria J. , Petters Robert M. 
Published: June 2005

AbstractUndefined follicular factors that may influence nuclear maturation and/or cytoplasmic maturation are required during in vitro maturation of pig oocytes. Epidermal growth factor (EGF), insulin‐like growth factor‐I (IGF‐I), and dialysed porcine follicular fluid (dpFF) were evaluated for their effects on porcine oocyte nuclear maturation in vitro. In Experiment I, eight different maturation media were made in a split‐plot factorial design with dpFF (0% vs. 10% v/v dialyzed pFF) as the whole plot component, and EGF (0.0 vs. 50 ng/ml) and/or IGF‐I (0.0 vs. 100 ng/ml) as the factorial subplot component. Experiment II was a complete factorial design with dpFF and EGF. Pig follicular granulosa‐cumulus‐oocyte complexes (GCOC) were obtained from slaughterhouse ovaries, washed, and cultured at 38.5°C in a humidified incubator with 5% CO2 in air for 42 h. Following culture, GCOC were mechanically stripped of granulosa‐cumulus cells and evaluated for nuclear maturation by light microscopy. In Experiment I, the percentage of Metaphase II oocytes for control, IGF‐I, EGF, and IGF‐I + EGF treatments without pFF were 50.7%, 52.6%, 80.9%, and 84.3% (control and IGF‐I groups significantly less, P<.001). The same treatments in the presence of pFF were similar and high (84.2, 84.9, 82.1, and 86.8%, respectively). Experiment II gave similar results. These results demonstrate that EGF, in the absence of pFF, promotes a similar level of oocyte nuclear maturation as does pFF alone or pFF with EGF and/or IGF‐I. IGF‐I does not appear to influence nuclear maturation of GCOC. © 1993 Wiley‐Liss, Inc.
Possible involvement of pertussis toxin‐sensitive GTP‐binding protein in the α2‐adrenoceptor‐mediated melanosome‐aggregation response of goldfish melanophores
Authors: Morishita Fumihiro , Hashito Katsuhiko , Fujimoto Masaaki , Yamada Koji 
Published: June 2005

AbstractThe signal‐transduction system involving α‐adrenoceptors, which controls the aggregation of melanosomes, was investigated in the melanophores of the black‐moor goldfish, Carassius auratus.The order of effectiveness of α‐subtype‐specific agonists and antagonists indicated that the major subtype of α‐adrenoceptor in these cells is α2. After a 12‐hr treatment, pertussis toxin markedly attenuated the melanosome‐aggregation response to norepinephrine (NE), but it failed to inhibit the Li+ ‐induced aggregation of melanosomes.Pertussis toxin catalyzed the [32P]‐ADP‐ribosylation of a 43‐kDa protein in a crude preparation of membranes from the goldfish melanophores. The radioactivity incorporation into the protein was much reduced by the presence of an analog of GTP, guanosine‐5′‐(3‐O‐thio)‐triphosphate, in the presence of NE. When the membranes were prepared from cells that had been pretreated with pertussis toxin, [32P]‐ADP‐ribosylation of the protein was not observed. These observations indicate that the 43‐kDa protein is the α subunit of a regulatory GTP‐binding protein, and that pertussis toxin inhibits the action of NE on the cells via ADP‐ribosylation of the protein.From these results, it is concluded that stimulation of α2‐adrenoceptors of goldfish melanophores induces the aggregation of melanosomes in a process mediated by a pertussis toxin‐sensitive GTP‐binding protein. © 1993 Wiley‐Liss, Inc.
Novel female protein with biological activities of C‐reactive protein and lectin in a viviparous rockfish, Sebastes taczanowskii
Authors: Takemura Akihiro , Nunomura Wataru , Takano Kazunori , Hirai Hidematsu 
Published: June 2005

AbstractA novel sex‐limited protein (FS3) was purified from the serum of female viviparous rockfish, Sebastes taczanowskii, and its physicochemical properties and biological activities were investigated. By using a phosphorylcholin (PC)‐Sepharose column, two types of FS3 could be isolated. Their molecular weights were estimated to be 160,000 and 152,000 by gel filtration. Subunits of 30,000 and 26,000 were found on SDS‐PAGE. Each fragment was glycosylated. In the presence of Ca2+, FS3 agglutinated Streptococcus pneumoniae and rabbit red blood cells (rRBC). The agglutinating activity against the bacteria was inhibited with PC or EDTA, and that of rRBC was inhibited with some sugars. The results indicate that FS3 shares activities of both C‐reactive protein and lectin. FS3 was induced in the serum of males by estrogen administration. The serum levels in the females during the vitellogenic and gestation periods were about 1,000 times higher than those in the normal males. Therefore, the appearance of FS3 is correlated with the active reproductive periods of the female fish and may be related to the peculiar reproductive systems of this species, such as the deposition of spermatozoa and/or developing embryos in the ovary. © 1993 Wiley‐Liss, Inc.
Effects of prolactin, growth hormone, and triiodothyronine on prolactin receptors in larval and adult tiger salamanders (Ambystoma tigrinum)
Authors: Bres Odd , Nicoll Charles S. 
Published: June 2005

AbstractThe effects of porcine growth hormone (pGH) or ovine prolactin (oPRL) alone and in combination with triiodothyronine (T3) on renal PRL receptors were determined in both pre‐ and post‐metamorphic tiger salamanders (Ambystoma tigrinum). The protein hormones were given at a dose of 1.0 μg/gm body weight/day and the T3 was given at 10.0 ng/gm body weight/day. The duration of treatment was 7 days. Effects on growth, and plasma thyroid hormone levels were also determined. Ovine PRL increased growth in both larvae and adults and reversed metamorphic changes. Administration of T3 increased the plasma T3 concentration, as measured by radioimmunoassay, and when given alone caused weight loss at both stages. The GH decreased plasma T4 and increased plasma T3 concentrations, indicating that it caused an increase in T4 deiodination. In adults the renal PRL receptor affinity of 2.9 ± 0.7 × 1010 L/mol and capacity of 160 ± 22 fmol/mg protein were higher than the corresponding values of 1.8 ± 0.3 × 1010 L/mol and 29.2 ± 3.8 fmol/mg in larvae. In adults only, there is an additional low‐affinity, high capacity PRL binding site. The oPRL treatment decreased the binding capacity to 33.2 ± 1.2 and 5.9 ± 4.9 fmol/mg in adults and larvae, respectively. By contrast, pGH increased the capacities to 249 ± 18 and 62.1 ± 6.8 fmol/mg in adults and larvae, respectively. Treatment with T3 alone doubled the oPRL binding capacity to 58.3 ± 4.7 fmol/mg in larvae, but there was no effect in adults. In both developmental stages the effects of oPRL and pGH on the receptors were not changed by the simultaneous T3 treatment. Porcine GH treatment both with and without T3 reduced the PRL binding affinity, but the effect was significant only in larvae. The effect of oPRL on binding affinities could not be determined, because the binding capacity was so low. In adults the low‐affinity site was detectable in all treatment groups, but none of the treatments caused the appearance of the low‐affinity binding site in larval kidneys, even when they increased the binding capacity to adult levels (T3, pGH, or both together). It therefore seems likely that some other factors are involved in the development of the adult binding pattern. The increased oPRL binding capacity caused by pGH in larvae and adults may be secondary to its effect on serum T3 levels. However, the reduction in Ka values in the larvae may be caused by GH itself, possibly due to an increase in the number of the low‐affinity sites. © 1993 Wiley‐Liss, Inc.
Chorioallantoic placentation in squamate reptiles: Structure, function, development, and evolution
Authors: Blackburn Daniel G. 
Published: June 2005

AbstractAllantoplacentae in lizards and snakes form during the evolution of viviparity through apposition of the chorioallantois and a vestige of the shell membrane to the uterine lining. Generalized squamate allantoplacentae are epitheliochorial, diffuse, adeciduate, and highly vascular, accomplish maternal‐fetal gas exchange, and possibly transfer small quantities of organic and inorganic nutrients. Placental gas exchange presumably is enhanced by the thinning of tissues lying between fetal and maternal capillaries, a progressive increase in placental vascularity, and in some species, by differences in oxygen affinity of fetal and maternal blood. A few saurian genera (e.g., Chalcides, Mabuya, and Pseudemoia) include species with specialized placentae that transfer large quantities of nutrients. Specializations of the allantoplacentae of these lizards include interdigitating, hypertrophied uterine and chorioallantoic tissues, and enlarged absorptive chorionic epithelia. South American Mabuya are further specialized by the presence of chorionic areolae and a distinctive placentome. Weekes' 1935 classification of placental morphotypes is reviewed, and a few minor modifications are proposed, in addition to recognition of a fourth morphotype. Phylogenetic analyses suggest that placental organs have originated on more than 100 occasions among squamate reptiles, and indicate that three separate lineages have converged on substantial placentotrophy through the evolution of specialized histotrophic placentae. © 1993 Wiley‐Liss, Inc.
Yolk sac placentation in reptiles: Structural innovation in a fundamental vertebrate fetal nutritional system
Authors: Stewart James R. 
Published: June 2005

AbstractThe extraembryonic membranes of amniote vertebrates are shared structures that have a brief, yet substantive role in the ontogeny of the organism. The yolk sac, which is the first of these structures to develop, has an important function in regulation and mobilization of nourishment to embryos of oviparous species and additionally contributes to maternal‐fetal exchange in many viviparous species. Yolk sac placentation has been described in all major taxa of viviparous amniotes. The yolk sac of viviparous reptiles contributes to three categories of placentation, the choriovitelline placenta, which also occurs in marsupial and eutherian mammals, and the omphaloplacenta and omphalallantoic placenta, which occur only among squamate reptiles (lizards and snakes). The fetal contribution to the omphaloplacenta includes a structure termed the isolated yolk mass, which forms in all Squamata independent of reproductive mode, and is produced by a morphogenesis of extraembryonic mesoderm that is unique to this reptilian order. For some viviparous squamates, the allantois contributes to the inner margin of the isolated yolk mass and this structural arrangement constitutes the omphalallantoic placenta. The isolated yolk mass is bordered externally by a bilaminar omphalopleure. Epithelial cells of the bilaminar omphalopleure of the omphaloplacenta and omphalallantoic placenta are hypertrophied. The apposed uterine epithelium likewise contains enlarged cuboidal or columnar shaped cells and the underlying lamina propria is richly vascularized. This epithelial cell structure suggests that the region of the isolated yolk mass is a site of placental specialization in viviparous reptiles. Further, since these features of omphaloplacentation or omphalallantoic placentation commonly occur in species without apparent morphological specialization in other areas of fetal‐uterine contact, it is likely that the bilaminar omphalopleure of the isolated yolk mass is evolutionarily the initial site of placental specialization among viviparous reptiles. © 1993 Wiley‐Liss, Inc.
Diapause, pregnancy, and parturition in Australian marsupials
Authors: Renfree Marilyn B. 
Published: June 2005

AbstractMarsupial pregnancy is characterised by a long lactation and a relatively short gestation. Marsupials have, in effect, exchanged the umbilical cord for the teat. However, gestation can be extended for up to 11 months by the imposition of a period of developmental arrest known as embryonic diapause. Diapause may be under either lactational or seasonal control, and in the kangaroos and wallabies these effects are mediated by prolactin and melatonin, respectively. At the other end of gestation, namely parturition, it appears that marsupials are fairly typical mammals and require all the same physiological and behavioural cues essential for the delivery of a viable young. Parturition depends on a synchronised cascade of hormonal events triggered by the fetus itself. Prostaglandin and prolactin concentrations pulse around the time of birth and progesterone falls. Successful parturition also depends on the adoption of the appropriate behaviour and birth posture by the mother. Despite the fact that the entire period of gestation is accomplished in such a short time, the neonate has perfectly adapted its growth and development to influence its mother's physiology to induce the change from nurturing the young in its uterus via a placenta, to a precise synchronisation of the birth process resulting in completion of its growth within the pouch sustained by a milk tailor‐made for each developmental stage. © 1993 Wiley‐Liss, Inc.
Implantation and decidualization in rodents
Authors: Abrahamsohn Paulo A. , Zorn Telma M. T. 
Published: June 2005

AbstractThis article reviews the main events of embryo‐implantation and decidualization in rodents. In common laboratory rodents the embryo attaches to the uterine epithelial lining, usually on days 4 to 6 of pregnancy. A progressive degree of proximity between trophoblast and epithelium occurs until the epithelial cells undergo apoptosis and detach from the basement membrane. During the attachment stage, the spindle‐shaped connective tissue cells that underlie the epithelium next to the embryos transform into polyhedral and closely packed decidual cells. Following the epithelial detachment and the breaching of the basement membrane the embryo is thus in direct contact with decidual cells. These cells accumulate organelles associated with synthesis of macromolecules, intermediate filaments, and eventually lipid droplets and glycogen. Another remarkable feature of decidual cells is the establishment of gap and adherens intercellular junctions. Differentiation of fibroblasts into decidual cells advances antimesometrially and mesometrially, creating in the endometrium several regions of cells with different morphology. The whole phenomenon of decidualization which is normally triggered by the embryo can be artificially induced in pseudopregnant or hormonally‐prepared animals with the use of diverse stimuli. The uterine epithelium is probably responsible for the transduction of the initial stimulus. Prostaglandins have been shown to be important in the induction of decidualization. More recently other substances such as leukotrienes, platelet‐activating factor (PAF), and transforming growth factor (TGF) have been thought to play a role in induction. Much evidence points to prostaglandin production by the decidual cells. New proteins such as a luteotropic factor, desmin, and other molecules were shown to be produced after rat stromal cells undergo decidual transformation. The extracellular matrix of the mouse decidua contains very thick collagen fibrils. Mouse decidual cells are also very active in phagocytosing the thick fibrils, contributing to the remodeling and involution of the decidua that accompanies embryonic growth. Radioautographic data indicates that mouse decidual cells produce and secrete collagen and sulfated proteoglycans. © 1993 Wiley‐Liss, Inc.