Sexual reproduction in flowering plants is unique in multiple ways. Distinct multicellular gametophytes contain either a pair of immotile, haploid male gametes (sperm cells) or a pair of female gametes (haploid egg cell and homodiploid central cell). After pollination, the pollen tube, a cellular extension of the male gametophyte, transports both male gametes at its growing tip and delivers the...

Ascidians are basal chordates that have become increasingly important for understanding chordate evolution. They comprise three orders. In the orders Phlebobranchia and Stolidobranchia, most species freely spawn eggs and sperm, whereas members of the order Aplousobranchia form colonies that brood their eggs and broadcast sperm. In the two free spawning orders, eggs and sperm are easily obtained...

The feasibility of achieving viable embryos, developing to term after transfer into the uterus, by fertilizing oocytes with spermatids has been demonstrated both in animal studies and in preliminary human clinical trials. Here we review the current clinical indications of spermatid conception and discuss the predictable success rates associated with each of these indications. Potential health h...

ne of the most significant findings in recent stem cell research is the establishment of the induced pluripotent stem (iPS) cells, because they could have critical implications in both regenerative and reproductive medicine. Male gametes play a crucial role in transmitting genetic information to subsequent generations, and notably there are more and more patients with azoospermia, due to geneti...

Rapid development in assisted reproductive techniques along with relieving the pain of childlessness has brought new ethical and policy dilemmas. Posthumous assisted reproduction is the most challenging, difficult and sensitive issue to be discussed ethically and religiously. In this paper the acceptability of the posthumous reproduction in Islamic contexts is evaluated and major concerns like ...

The ultrastructure of 18 metaphase-II oocytes after intracytoplasmic sperm injection (ICSI) was analysed from 30 min to 8 h following the microinjection. Three control metaphase-II oocytes were not injected. The 21 oocytes were embedded individually and examined in serial pole-to-pole sections. Seventeen oocytes had been matured in vitro from the germinal vesicle stage and showed ultrastructura...

Sperm and eggs are essential cells for reproduction and fertility in mammals. Lack of sperm production is one of the leading causes of infertility, a major and growing problem in the developed world affecting 13 to 18% of reproductive-age couples. The birth of the first test tube baby by in vitro fertilization marked an advance in infertility treatment. Later on, several important new technique...

activities of the two enzymes recorded in Table 1 for various animals cannot be compared with each other since the supernatants of the homogenates contain only a portion of the total content of the respective hexosaminidases and since the instability of serylA-acetylgalactosaminidase3 may vary with the source. The relatively high specific activity of serylA-acetylgalactosaminidase of the oviduc...