H-Y antigen expression in heterogametic males (XY) and females (ZW): a factor in reproductive strategy?

The cells of heterogametic females with ZW sex chromosomes express H-Y or H-W antigen. A hypothesis is formulated to explain why these animals are capable of 'practicing' amphigonia retardata, i.e., delay in actual fertilization of eggs by retaining viable sperm within the oviduct for a considerable time (several months).     

H-Y antigen expression in heterogametic males (XY) and females (ZW): a factor in reproductive strategy?

Summary The cells of heterogametic females with ZW sex chromosomes express H-Y or H-W antigen. A hypothesis is formulated to explain why these animals are capable of practicingamphigonia retardata, i.e. delay in actual fertilization of eggs by retaining viable sperm within the oviduct for a considerable time (several months).     

Parental care in terrestrial gastropods

Parental care in terrestrial gastropods includes the of oviposition sites, production of large, heavily-yolked eggs supplied with calcium carbonate, provisioning of hatchings with eggs in specis with facultative sibling cannibalism, egg retention, and ovoviviparity. Evidence for true viviparity is scarce in terrestrial gastropods, as it is for postlaying care of eggs, though external egg carrying on the shell occurs in a few species. Care of young has not been observed in any terrestrial gastropod species. Provisioning of eggs with nutrients and calcium carbonate might be the most common form of parental investment. Ovoviviparity allows terrestrial gastropods to persist in habitats otherwise unsuitable for oviparous species (e.g. exposed rock walls). An interspecific comparison demonstrates that egg-retaining and ovoviviparous species produce smaller clutches than oviparous species and suggests a cost of parental care.     

Oocyte maturation in vitro: contribution of the oviduct to total maturation in Xenopus laevis.

Contact of progesterone matured oocytes of Xenopus laevis with the oviduct reduces the time necessary to attain cleavage capacity from 24 h to 3 h. Full maturity has been demonstrated by normal development of the matured eggs after fertilization.     

Experimental studies on the symmetry reaction of axolotl oocytes and eggs: factors affecting the early appearance of the grey crescent following heat shock]

A heat-shock (36.8 degrees C for 10 min.) can induce the immediate appearance of the grey crescent in a high proportion of freshly laid fertilised or artificially activated Axolotl eggs, but only if that shock occurs within 1 h 30 min. following deposit of eggs (at 18 degrees C) and if eggs are not dejellied. On non-activated virgin eggs, the heat-shock is efficient during at least 3 hrs. This symmetry reaction can be induced on in vitro artificially matured oocytes, still protected by follicular cells. It is uncommon in oocytes taken from coelomic cavity or from the anterior part of the oviduct, but occurs with a high frequency as soon as the occytes are coated with the innermost and medium jelly layers.     

Oocyte maturation in vitro: Contribution of the oviduct to total maturation inXenopus laevis

Summary Contact of progesterone matured oocytes ofXenopus laevis with the oviduct reduces the time necessary to attain cleavage capacity from 24 h to 3 h. Full maturity has been demonstrated by normal development of the matured eggs after fertilization.     

Pregnancy following segmental isthmic reversal of the rabbit oviduct

Summary Microsurgical reversal of a segment of rabbit proximal tubal isthmus has been followed by normal pregnancy in the first two animals to undergo the procedure. Establishment of pregnancy despite radical modification of the oviduct furnishes the opportunity to gain new insights into the mechanisms controlling tubal ovum transport and emphasizes the evolving feasibility and importance of tuboplastic microsurgery both as a research tool and clinical procedure.This study was partly supported by an N.I.H. Institutional Research Grant.Supported by the Rockefeller Foundation.     

Über die Vermehrung der Polkörperchen während der Segmentation von Ratteneiern bei Vitamin-A-Mangel und -Überdosierung

Summary In the course of histochemical investigations on pre-implanted rat eggs it was found that eggs from animals with vitamin-A-deficiency or -overdosage show an increased number of polar bodies during the first 2 cleavages. Moreover, the polar bodies persist longer than normal.     

双离合器自动变速汽车换挡过程离合器模糊控制策略仿真研究

通过对装有双离合器自动变速系统汽车挟挡过程的分析,建立了双离舍器自动变速器的换挡过程的动力学方程。在分析双离合器自动变速汽车换挡品质影响因素的基础上,设计出两离合器分离、接合速度模糊控制器,并利用挡位传动比的变化对两离合器分离、接合速度模糊系统输出量进行量化修正。仿真结果表明,所设计的双离合器自动变速汽车换挡过程两离合器分离、接合速度模糊控制器较好地满足了汽车换挡平顺性和快速性的要求。     

Die Degenerationsraten präimplantierter Eier von Vitamin A-hyper- und avitaminotischen Ratten

Summary Comparing pre-implanted rat ova of animals suffering from Vitamin A deficiency or overdosage with normal ones, it was found that the amount of degenerated eggs was significantly higher in both the treated groups than in normal untreated animals. The mitotic stages of the segmentation steps prove to be highly sensitive to previous changes in the interior and exterior environment of the egg.     

Placental and fetal contraindications of dexamethasone administration to pregnant rats

Summary Dexamethasone (DEXA) given to pregnant rats for either the last 3 or 6 days of gestation lowered placental, fetal body and adrenal weights. Histologically, DEXA-treated placentas appeared smaller than controls and showed signs of necrosis and pyknosis. Treated animals that were permitted to carry their litters to term did not deliver naturally, and most of their fetuses were dead when excised 1 day postmaturely.     

Autoradiographic localization of RNA synthesis in vitro during oogenesis in Parascaris equorum]

Technical elaboration of in vitro incubation of Parascaris equorum gonads with 3H-Uridine has permitted, for the first time, the study of RNA synthesis during oogenesis along the whole gonadic tube. In germ cells, oocytes in diakinesis (oviduct) and in division of maturation (uterus) show no label. On the contrary oogonia and growing oocytes in ovary are labelled. RNA synthesis is always detected in all parietal cells but is more active in oviduct and uterus where the gonadic wall is particularly developed.     

Hymenolepis nana: Transfer of acquired immunity in mice through sensitized peritoneal exudate cells

Summary Sensitized peritoneal exudate cells from syngeneic donor Swiss albino mice infected with single and repeated doses of viable eggs ofHymenolepis nana produced a significant adoptive immunity in test mice when compared with animals which received non-sensitized (normal) cells. No significant difference was observed among the 2 recipient groups which received singly or repeatedly sensitized peritoneal exudate cells.Acknowledgment. We thank Professor B. M. Sinha for providing facilities and to the University Grants Commission, New Delhi for financial assistance.     

Hormonal facilitation in the release of sperm from the spermatheca of the red-spotted newt

Several neurotransmitters and hormones with potential to trigger a simultaneous contraction of the oviducts and the spermathecal myoepithelium were examined. Saline (0.05 ml), or 0.05 ml saline plus acetylcholine (9 mg), norepinephrine (50 micrograms), arginine-vasotocin (25 units), prostaglandin F2 alpha (3 micrograms) were injected into the spermathecal region of female newts (n = 24 per group). The numbers of sperm present in the cloacae of prostaglandin-injected animals (107 +/- 30 SEM) were significantly greater than the numbers detected in saline (27 +/- 5 SEM) and in uninjected (14 +/- 3 SEM) controls. Smaller and less consistent increases in the numbers of sperm were detected in the vasotocin- and norepinephrine-injected groups. Study of sections from ovulating female newts failed to produce evidence that pressure from the passage of ova through the posterior portion of the oviduct forced sperm from the spermatheca. Observations indicate an active role for the spermathecal myoepithelium in the discharge of stored sperm and of a role for prostaglandin F2 alpha in triggering that discharge.     

Mechanisms of sperm-egg interactions emerging from gene-manipulated animals

Untangling the molecular nature of sperm-egg interactions is fundamental if we are to understand fertilization. These phenomena have been studied for many years using biochemical approaches such as antibodies and ligands that interact with sperm or with eggs and their vestments. However, when homologous genetic recombination techniques were applied, most of the phenotypic factors of the gene-manipulated animals believed “essential” for fertilization were found to be dispensable. Of course, all biological systems contain redundancies and compensatory mechanisms, but as a whole the old model of fertilization clearly requires significant modification. In this review, we use the results of gene manipulation experiments in animals to propose the basis for a new vision. Received 26 January 2007; received after revision 7 March 2007; accepted 17 April 2007     

A malignant tumour in the female genital tract of Pachygnatha clercki Sundevall, 1823 (Arachnida, Araneae, Tetragnathidae)]

A first case of genuine neoplasm is reported in the order Araneida. This epithelial tumor, proceeding from oviduct ends, invades uterus; malignancy is strongly supported by cell structure and extensive local behavior.     

Morphology of the intercapsular segment of the oviduct in the golden hamster with special reference to ovumtransit from ruptured follicles to the ampulla

Summary The intercapsular segment of the oviduct in the golden hamster is not a simple duct which has constant outer and inner diameters. After penetrating the bursa ovarica the ICS has a circular constriction and the corresponding oviductal lumen is narrowed.     

Passive transfer of resistance in rabbits infested with adult Ixodes ricinus L: humoral factors influence feeding and egg laying.

Parital immunity against the bites of female I. ricinus was transferred to normal rabbits by inoculating immune serum from resistant animals. Transferred humoral factors diminished the weight of the ticks' blood meal by 29% and increased the feeding period by about 1 day in comparison with ectoparasites engorged on controls. They provoked also the failure of egg laying by female I. ricinus. Only 55% of ticks fed on treated rabbits laid eggs (94% on controls). The immunological state of immune serum donors or recipients was studied and the IgG and homocytotropic specific anti-I. ricinus antibodies were identified. The immediate hypersensitivity of rabbits' skin was also controlled.     

Ecdysteroid titre and caste determination in the ant,Pheidole pallidula (Nyl.) (Hymenoptera: Formicidae)

Summary In the antPheidole pallidula, ecdysteroid level is higher in worker-biased eggs than queen-biased eggs. Moreover queens laying worker-biased eggs exhibit a higher ecdysteroid level than queens laying queen-biased eggs.     

Failure of cilia of reprogram following segmental ampullary reversal of the rabbit oviduct

Summary Cilia exhibited unidirectional and coordinated movement within microsurgically reversed segments of rabbit ampulla when examined up to 13 months after surgery. The direction of ciliary beating was opposite that of the remainder of the oviduct.This research was supported in part by a grant (HD 09339-06) from the National Institutes of Health and the Bioassay and Smooth Muscle Core Laboratories (NIH grant P30 HD10202).