Round spermatids from hybrid sterile mice can initiate normal embryo development

Intracytoplasmic sperm injection in assisted reproductive technology: an evaluation

Since the first reports of successful pregnancies in humans after treatment with intracytoplasmic sperm injection (ICSI), intensive investigations have focused on several important aspects of this form of assisted reproductive technology. In addition to the technical development of ICSI and increasing understanding of the biochemical and biophysical processes involved during fertilization after injection of an immobilized sperm, studies have aimed to define the indications for patients for a first-line ICSI treatment. One of the major concerns is of course the safety of the technique in terms of the health and reproductive life of the babies born after ICSI. The rhesus monkey is an excellent model to investigate all aspects of this micromanipulation technique. This article provides an evaluation of ICSI.

Progression to the blastocyst stage of embryos derived from testicular round spermatids

Progression to the blastocyst stage of embryos derived from testicular round spermatids in men with non-obstructive azoospermia was studied. A total of 56 men were studied in whom partial spermatogenesis failure had occurred where only very few spermatozoa (fewer than the number of oocytes retrieved) were extracted from multiple testicular biopsy specimens. Oocytes remaining after intracytoplasmic injection of testicular spermatozoa (group 1) were injected with round spermatids (ROSI, group 2). Only embryos derived from group 1 were transferred. Remaining embryos were observed under culture for 8 days and their progression to the blastocyst stage was recorded. Of the 546 oocytes injected with testicular spermatozoa, 404 (73.9%) showed evidence of 2-pronuclear (2PN) fertilization. Injection of testicular round spermatids resulted in 2PN fertilization rate of 50% (P < 0.05). Using a four-point grading system, 53% of the good quality embryos (grade 1 or 2) in group 1 reached the blastocyst stage compared with 25% in group 2 (P < 0.05). The rate of progression to the blastocyst stage of grade 3 and grade 4 embryos was 46 and 8.5% in the two groups respectively (P < 0.05). Using a different three-point grading system for the blastocysts, 75.3% of the blastocysts in group 1 were either grade 1 or grade 2 and 24.7% were grade 3. However, in group 2 all blastocysts were grade 3. All embryos observed in group 1 reached the blastocyst stage by day 5 or 6 compared with 25% of the embryos reaching the blastocyst stage by this time in group 2. While 31.2% of the blastocysts in group 1 showed evidence of spontaneous hatching in vitro, none of the blastocysts in group 2 hatched. In conclusion, progression to the blastocyst stage occurred at a much lower and slower rate in embryos derived from testicular round spermatids. Furthermore, all blastocysts resulting from ROSI were of poor quality and none showed spontaneous hatching. These results may explain the dismal outcome associated with ROSI.

The Golgi apparatus segregates from the lysosomal/acrosomal vesicle during rhesus spermiogenesis: structural alterations

The acrosome is an acidic secretory vesicle containing hydrolytic enzymes that are involved in the sperm's passage across the zona pellucida. Imaging of the acrosomal vesicle and the Golgi apparatus in live rhesus monkey spermatids was accomplished by using the vital fluorescent probe LysoTracker DND-26. Concurrently, the dynamics of living spermatid mitochondria was visualized using the specific probe MitoTracker CMTRos and LysoTracker DND-26 detected the acrosomal vesicle from its formation through spermatid differentiation. LysoTracker DND-26 also labeled the Golgi apparatus in spermatogenic cells. In spermatocytes the Golgi is spherical and, in round spermatids, it is localized over the acrosomal vesicle, as confirmed by using polyclonal antibodies against Golgin-95/GM130, Golgin-97, and Golgin-160. Using both live LysoTracker DND-26 imaging and Golgi antibodies, we found that the Golgi apparatus is cast off from the acrosomal vesicle and migrates toward the sperm tail in elongated spermatids. The Golgi is discarded in the cytoplasmic droplet and is undetectable in mature ejaculated spermatozoa. The combined utilization of three vital fluorescent probes (Hoechst 33342, LysoTracker DND-26, and MitoTracker CMTRos) permits the dynamic imaging of four organelles during primate spermiogenesis: the nucleus, the mitochondria, the acrosomal vesicle, and the Golgi apparatus.