Conclusions

Major progress has been achieved in spermatology in the last decade, including the successful transplantation of fresh (Brinster and Avarbock, 1994) and cryopre-served (Avarbock et al., 1996) testicular tissues, reported production of spermato-genic cells from stem cells (Geijsen et al., 2004; Toyooka et al., 2003), production of transgenic animals (Yanagimachi, 2005) and routine use of intracytoplasmic sperm injection (ICSI) in clinical practice. However, many challenges remain, including the development of reliable conditions for spermiogenesis in vitro, the complete, repeatable profiling of the spermatogenic transcriptome and proteome, identification of all major genes involved in the control of spermatogenesis and gene therapy of human male infertility. The development of more accurate methods for assessing spermatogenesis and human semen quality remains a major challenge, given the variability of human sperm morphology (Fig. 1.7), increased enrollment of patients in assisted reproduction programs and paucity of objective markers of semen quality and male infertility.

Figure 1.6 Irreversible changes of the sperm head structure during bovine fertilization.

Cross-section of an intact sperm head (A) shows the structure of the acrosome, which becomes vesiculated after sperm binding to egg zona pellucida (B). Figure (C) shows sperm penetration slit with a sagital sperm head section revealing the IAM and part of the ES and PAS. The ES of the sperm head binds first to oocyte microvilli during sperm-oolemma fusion (arrowheads) in the perivitelline space (D). Sperm plasma membrane is removed during sperm incorporation into ooplasm (E), at which time the layers of equatorial and postacrosomal PT dissolve in the ooplasm (F) and release the sperm borne factors that induce oocyte activation. For the purpose of illustration, the images in this figure plate were edited by Adobe Photoshop tools and merged together, while the structural information from the original TEM negatives has been retained. The process of sperm-ZP penetration and sperm incorporation into ooplasm is completed in most ova with first 8 hours after sperm addition during bovine fertilization in vitro

Figure 1.7 Ultrastructure and pathology of the human spermatozoa. (A) An unusual curvature of the AC (arrow), perhaps a consequence of aberrant chromatin condensation in the corresponding region of the nucleus, is observed in this otherwise normal spermatozoon. (B) Longitudinal section of the proximal centriole (asterisk) and proximal centriolar adjunct (arrow), an extension of the centriolar microtubule triplets often seen in human spermatozoa. (C) Cross-section of basal plate (arrowheads), proximal centriole (asterisk) and a striated column (arrows). (D) Abnormal spermatozoon with a connecting piece defect (arrow) and prominent nuclear vacuoles (arrowheads), containing trapped cytoplasm (see also Plate 1B). (E) Chromatin condensation defect combined with the presence of nuclear vacuoles

Figure 1.7 Ultrastructure and pathology of the human spermatozoa. (A) An unusual curvature of the AC (arrow), perhaps a consequence of aberrant chromatin condensation in the corresponding region of the nucleus, is observed in this otherwise normal spermatozoon. (B) Longitudinal section of the proximal centriole (asterisk) and proximal centriolar adjunct (arrow), an extension of the centriolar microtubule triplets often seen in human spermatozoa. (C) Cross-section of basal plate (arrowheads), proximal centriole (asterisk) and a striated column (arrows). (D) Abnormal spermatozoon with a connecting piece defect (arrow) and prominent nuclear vacuoles (arrowheads), containing trapped cytoplasm (see also Plate 1B). (E) Chromatin condensation defect combined with the presence of nuclear vacuoles

Pregnancy Guide

Pregnancy Guide

A Beginner's Guide to Healthy Pregnancy. If you suspect, or know, that you are pregnant, we ho pe you have already visited your doctor. Presuming that you have confirmed your suspicions and that this is your first child, or that you wish to take better care of yourself d uring pregnancy than you did during your other pregnancies; you have come to the right place.

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