Talk:Testis Development

2009

New insights into epididymal biology and function

Hum Reprod Update. 2009 Mar-Apr;15(2):213-27. Epub 2009 Jan 8.

Cornwall GA. Department of Cell Biology and Biochemistry, Texas Tech University Health Sciences Center, Lubbock, 79430, USA. gail.cornwall@ttuhsc.edu

Abstract BACKGROUND: The epididymis performs an important role in the maturation of spermatozoa including their acquisition of progressive motility and fertilizing ability. However, the molecular mechanisms that govern these maturational events are still poorly defined. This review focuses on recent progress in our understanding of epididymal function including its development, role of the luminal microenvironment in sperm maturation, regulation and novel mechanisms the epididymis utilizes to carry out some of its functions. METHODS: A systematic search of Pubmed was carried out using the search term 'epididymis'. Articles that were published in the English language until the end of August 2008 and that focused on the specific topics described above were included. Additional papers cited in the primary reference were also included. RESULTS: While the majority of these findings were the result of studies in animal models, recent studies in the human epididymis are also presented including gene profiling studies to examine regionalized expression in normal epididymides as well as in those from vasectomized patients. CONCLUSIONS: Significant progress has been made in our understanding of epididymal function providing new insights that ultimately could improve human health. The data also indicate that the human epididymis plays an important role in sperm maturation but has unique properties compared with animal models.

PMID: 19136456

Background reading

• Aging of the human ovary and testis. Perheentupa A, Huhtaniemi I. Mol Cell Endocrinol. 2009 Feb 5;299(1):2-13. Epub 2008 Nov 18. Review. PMID: 19059459
• Epithelial-mesenchymal crosstalk in Wolffian duct and fetal testis cord development. Archambeault DR, Tomaszewski J, Joseph A, Hinton BT, Yao HH. Genesis. 2009 Jan;47(1):40-8. Review. PMID: 18979542
• Mixed signals: development of the testis. Cool J, Capel B. Semin Reprod Med. 2009 Jan;27(1):5-13. Epub 2009 Feb 5. Review. PMID: 19197800

Posttesticular development of spermatozoa of the tammar wallaby (Macropus eugenii)

J Anat. 1997 Feb;190 ( Pt 2):275-88.

Setiadi D, Lin M, Rodger JC. Department of Biological Sciences, University of Newcastle, NSW, Australia.

Abstract Tammar wallaby spermatozoa undergo maturation during transit through the epididymis. This maturation differs from that seen in eutherian mammals because in addition to biochemical and functional maturation there are also major changes in morphology, in particular formation of the condensed acrosome and reorientation of the sperm head and tail. Of spermatozoa released from the testes, 83% had a large immature acrosome. By the time spermatozoa reached the proximal cauda epididymis 100% of sperm had condensed acrosomes. Similarly 86% of testicular spermatozoa had immature thumb tack or T shape head-tail orientation while only 2% retained this immature morphology in the corpus epididymis. This maturation is very similar to that reported for the common brush tail possum, Trichosurus vulpecula. However, morphological maturation occurred earlier in epididymal transit in the tammar wallaby. By the time spermatozoa had reached the proximal cauda epididymis no spermatozoa had an immature acrosome and thumbtack orientation. Associated with acrosomal maturation was an increase in acrosomal thiols and the formation of disulphides which presumably account for the unusual stability of the wallaby sperm acrosome. The development of motility and progressive motility of tammar wallaby spermatozoa is similar to that of other marsupials and eutherian mammals. Spermatozoa are immotile in the testes and the percentage of motile spermatozoa and the strength of their motility increases during epididymal transit. During passage through the caput and corpus epididymis, spermatozoa first became weakly motile in the proximal caput and then increasingly progressively motile through the corpus epididymis. Tammar wallaby spermatozoa collected from the proximal cauda epididymis had motility not different from ejaculated spermatozoa. Ultrastructural studies indicated that acrosomal condensation involved a complex infolding of the immature acrosome. At spermiation the acrosome of tammar wallaby spermatozoa was a relatively large flat or concave disc which projected laterally and anteriorly beyond the limits of the nucleus. During transit of the epididymal caput and proximal corpus the lateral projections folded inwards to form a cup like structure the sides of which eventually met and fused. The cavity produced by this fusion was lost as the acrosome condensed to its mature form as a small button-like structure contained within the depression on the anterior end of the nucleus. During this process the dorsal surface of the immature acrosome and its outer acrosomal membrane and overlying plasma membrane were engulfed into the acrosomal matrix. This means that the dorsal surface of the acrosomal region of the testicular tammar wallaby sperm head is a transient structure. The dorsal acrosomal surface of the mature spermatozoon appears ultrastructurally to be the relocated ventral surface of the acrosomal projections which previously extended out beyond the acrosomal depression on the dorsal surface of the nucleus of the immature spermatozoon. PMID: 9061449