Surfing the wave, cycle, life history, and genes/proteins expressed by testicular germ cells. Part 1: Background to spermatogenesis, spermatogonia, and spermatocytes
Article first published online: 25 NOV 2009
Copyright © 2009 Wiley-Liss, Inc.
Microscopy Research and Technique
Special Issue: Strategic Aspects of Spermatogenesis and the Maturation of Spermatozoa. Part III. Surfing the Wave, Cycle, Life History, and Genes/Proteins Expressed by Testicular Germ Cells
Volume 73, Issue 4, pages 241–278, April 2010
How to Cite
Hermo, L., Pelletier, R.-M., Cyr, D. G., Smith, C. E. (2010), Surfing the wave, cycle, life history, and genes/proteins expressed by testicular germ cells. Part 1: Background to spermatogenesis, spermatogonia, and spermatocytes. Microsc. Res. Tech., 73: 241–278. doi: 10.1002/jemt.20783
- Issue published online: 15 MAR 2010
- Article first published online: 25 NOV 2009
- Manuscript Accepted: 14 AUG 2009
- Manuscript Received: 24 JUN 2009
- stem cell renewal;
- sex body;
- synaptonemal complex;
Spermatogenesis, a study of germ cell development, is a long, orderly, and well-defined process occurring in seminiferous tubules of the testis. It is a temporal event whereby undifferentiated spermatogonial germ cells evolve into maturing spermatozoa over a period of several weeks. Spermatogenesis is characterized by three specific functional phases: proliferation, meiosis, and differentiation, and it involves spermatogonia, spermatocytes, and spermatids. Germ cells at steps of development form various cellular associations or stages, with 6, 12, and 14 specific stages being identified in human, mouse, and rat, respectively. The stages evolve over time in a given area of the seminiferous tubule forming a cycle of the seminiferous epithelium that has a well-defined duration for a given species. In this part, we discuss the proliferation and meiotic phase whereby spermatogonia undergo several mitotic divisions to form spermatocytes that undergo two meiotic divisions to form haploid spermatids. In the rat, spermatogonia can be subdivided into several classes: stem cells (As), proliferating cells (Apr, Aal), and differentiating cells (A1–A4, In, B). They are dependent on a specific microenvironment (niche) contributed by Sertoli, myoid, and Leydig cells for proper development. Spermatogonia possess several surface markers whereby they can be identified from each other. During meiosis, spermatocytes undergo chromosomal pairing, synapsis, and genetic exchange as well as transforming into haploid cells following meiosis. The meiotic cells form specific structural entities such as the synaptonemal complex and sex body. Many genes involved in spermatogonial renewal and the meiotic process have been identified and shown to be essential for this event. Microsc. Res. Tech., 2010. © 2009 Wiley-Liss, Inc.