Femtosecond mode-locked Nd(3+)-doped Ba(Zr,Mg,Ta)O(3) ceramic laser.

We have demonstrated continuous wave (CW) laser operation and the first, to the best of our knowledge, sub-200 fs mode-locked laser operation of Nd(3+)-doped Ba(Zr,Mg,Ta)O(3) ceramic. Its disordered crystalline nature exhibits a broad gain bandwidth of 30 nm with a high-emission cross section. It also has higher thermal and mechanical properties than Nd:glass. In CW operation, a maximum output power of 1.5 W under 6.2 W of absorbed pump power was obtained. In mode-locked operation, a pulse duration of 196 fs with an average power of 60 mW was successfully achieved. The laser spectrum straddled both fluorescence peaks of A-site and B-site Nd(3+) ions.

Serum concentrations of soluble Fas antigen and soluble Fas ligand in mother and newborn.

We measured soluble Fas antigen and soluble Fas ligand, which are considered to be an apoptotic substance, in maternal serum, umbilical cord serum and amniotic fluid during cesarean section at full term pregnancy. Seventeen healthy parturients with no fetal distress were studied. Soluble Fas antigen showed no different levels between these measurement sites. Soluble Fas ligand showed a difference, in which umbilical serum level was significantly higher than maternal serum and amniotic fluid levels. The present results suggest high serum levels of soluble Fas ligand in newborn. However, the reason for this evidence is entirely unknown.

Analysis of mouse oocyte activation suggests the involvement of sperm perinuclear material.

The mouse oocyte can be activated by injection of a single, intact mouse spermatozoon or its isolated head. Isolated tails are unable to activate the oocyte. Active sperm-borne oocyte-activating factor(s) (SOAF) appears during transformation of the round spermatid into the spermatozoon. The action of SOAF is not highly species-specific: mouse oocytes are activated by injection of spermatozoa from foreign species, such as the hamster, rabbit, pig, human, and even fish. Some SOAF can be extracted by simple freeze-thawing of (hamster) spermatozoa; additional SOAF is obtained by sequential treatment of spermatozoa with Triton X-100 and SDS. Electron microscopic examination of sperm heads during SOAF extraction suggests that the relatively insoluble SOAF is associated with perinuclear material. When microsurgically injected into oocytes, Triton X-100-treated sperm heads (with perinuclear material, but without any membranes) can activate the oocytes, leading to normal embryonic development. Whereas perinuclear components have been believed to play a purely structural role, these data suggest an additional function for them in oocyte activation.

Behavior of transgenic mouse spermatozoa with galline protamine.

General morphology, physical and chemical stability of nuclei, and postfertilization behavior of spermatozoa from transgenic mice [TgN (Prml Gal) 223 Bri] containing nuclear avian protamine (galline) were compared to those in the spermatozoa of wild-type (Wild) mice. Galline to protamine I ratios in spermatozoal nuclei of transgenic mice, strains 3175 (T75) and 3177 (T77), were 1.94 and 5.62, respectively. Live T75 and T77 spermatozoa were indistinguishable in their gross morphology from Wild spermatozoa. However, unlike Wild and T75 spermatozoa, T77 spermatozoa were vulnerable to mechanical handling, as about 40% of heads and tails were separated after gentle pipetting in suspension. Motility of T77 spermatozoa was markedly inferior to that of T75 and Wild. Chromatin heterogeneity and instability of transgenic spermatozoal nuclei were evident by transmission electron microscopy, staining reaction to Giemsa, and, as apparent by both light microscopy and flow cytometry, reaction to SDS detergent. Wild and T75 spermatozoa fertilized 90% and 60% of zona-intact oocytes in vitro, respectively. T77 spermatozoa completely failed to fertilize and bound to zona surfaces very weakly, and none of them inserted their heads into the zona. Although inefficiently, T77 spermatozoa could fertilize zona-free oocytes in vitro, indicating some ability to undergo capacitation and spontaneous acrosome reaction in vitro. After microsurgical injection into oocytes, the rate of nuclear decondensation was the greatest in rooster spermatozoa, followed by T77, T75, and Wild spermatozoa.

Mouse primary spermatocytes can complete two meiotic divisions within the oocyte cytoplasm.

This study was undertaken to determine whether primary spermatocyte nuclei can complete meiosis after transfer into maturing or mature oocytes and can participate in normal embryogenesis. When injected into maturing mouse oocytes at prometaphase of the first meiotic division, spermatocyte chromosomes became arranged on a first meiotic metaphase (Met-I) spindle. Thus, oocytes contained two sets of Met-I chromosomes. When these oocytes were matured in vitro and artificially activated, pronuclei and polar bodies of both maternal and paternal origin were formed, and zygotes began development. When single spermatocyte nuclei were injected into fully mature oocytes at metaphase of the second meiosis (Met-II), the spermatocyte nuclei transformed into a Met-I configuration, resulting in the formation of oocytes with both maternal (Met-II) and paternal (Met-I) chromosome complements. After activation of these oocytes, half of each chromosome set was separated into polar bodies. Transfer of nuclei from polar bodies of "paternal" origin into other Met-II oocytes resulted in the formation of oocytes with two sets of Met-II chromosomes, one maternal and one paternal in origin. When activated, two pronuclei and two polar bodies were formed and zygotes began development. It is concluded that nuclei of primary spermatocytes are able to undergo two successive meiotic divisions within oocyte cytoplasm. Thus, factors that drive chromosome condensation, organization of metaphase, and chromosome separation at anaphase in oocytes can drive these same maturation processes in primary spermatocyte nuclei. When a total of 258 two-cell embryos were transferred to foster mothers, only two live pups were born to two mothers. One died shortly after birth and the other 3 wk after birth. The reasons for poor embryonic and neonatal development remain to be determined.

Fertilization and development of mouse oocytes injected with isolated sperm heads.

To determine whether spermatozoa must be structurally intact before microsurgical injection into oocytes for normal fertilization, intact spermatozoa, as well as sperm heads separated from tails by sonication, were individually injected into oocytes. When whole spermatozoa were injected immediately after their immobilization, the majority of the oocytes were fertilized and developed normally. Sonication in the presence or absence of Triton X-100 decapitated more than 95% of spermatozoa. Although all decapitated spermatozoa were diagnosed as "dead" by live/dead sperm staining, separated sperm heads (nuclei) could participate in normal embryo development when injected into the oocytes. The ability of isolated sperm heads (nuclei) to participate in normal embryo development was maintained under cryopreservation conditions that were not suitable for the survival of plasma membrane-intact spermatozoa. These results indicate that 1) spermatozoa do not need to be structurally intact for intracytoplasmic injection, 2) the plasma and acrosomal membranes and all tail components are not essential for normal embryo development, at least in the mouse, and 3) the cryopreservation conditions required for maintenance of the genetic integrity of sperm nuclei are less stringent than those necessary for keeping plasma membrane-intact spermatozoa alive.

Inadequate function of sterile tw5/tw32 spermatozoa overcome by intracytoplasmic sperm injection.

Mice carrying two t complementary haplotypes (tw5/tw32) are totally sterile. Their spermatozoa have poor motility and fertilize neither zona-intact nor zona-free oocytes, even though they are structurally indistinguishable from control (wild-type) spermatozoa. However, when injected directly into oocytes, these infertile spermatozoa are able to participate in normal development. This suggests that infertility of tw5/tw32 male (spermatozoa) is more likely to be due to poor sperm-oocyte interaction than to genetic incompetence of sperm nuclei.