Talk:Testis Development: Difference between revisions
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==2010== | |||
===Drug transporters, the blood-testis barrier, and spermatogenesis=== | |||
J Endocrinol. 2011 Mar;208(3):207-23. Epub 2010 Dec 6. | |||
Su L, Mruk DD, Cheng CY. | |||
Source | |||
The Mary M Wohlford Laboratory for Male Contraceptive Research, Center for Biomedical Research, Population Council, New York, New York 10065, USA. | |||
Abstract | |||
The blood-testis barrier (BTB), which is created by adjacent Sertoli cells near the basement membrane, serves as a 'gatekeeper' to prohibit harmful substances from reaching developing germ cells, most notably postmeiotic spermatids. The BTB also divides the seminiferous epithelium into the basal and adluminal (apical) compartment so that postmeiotic spermatid development, namely spermiogenesis, can take place in a specialized microenvironment in the apical compartment behind the BTB. The BTB also contributes, at least in part, to the immune privilege status of the testis, so that anti-sperm antibodies are not developed against antigens that are expressed transiently during spermatogenesis. Recent studies have shown that numerous drug transporters are expressed by Sertoli cells. However, many of these same drug transporters are also expressed by spermatogonia, spermatocytes, round spermatids, elongating spermatids, and elongated spermatids, suggesting that the developing germ cells are also able to selectively pump drugs 'in' and/or 'out' via influx or efflux pumps. We review herein the latest developments regarding the role of drug transporters in spermatogenesis. We also propose a model utilized by the testis to protect germ cell development from 'harmful' environmental toxicants and xenobiotics and/or from 'therapeutic' substances (e.g. anticancer drugs). We also discuss how drug transporters that are supposed to protect spermatogenesis can work against the testis in some instances. For example, when drugs (e.g. male contraceptives) that can perturb germ cell adhesion and/or maturation are actively pumped out of the testis or are prevented from entering the apical compartment, such as by efflux pumps. | |||
PMID: 21134990 | |||
==2009== | ==2009== | ||
Revision as of 16:31, 3 May 2011
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Cite this page: Hill, M.A. (2024, April 24) Embryology Testis Development. Retrieved from https://embryology.med.unsw.edu.au/embryology/index.php/Talk:Testis_Development |
2010
Drug transporters, the blood-testis barrier, and spermatogenesis
J Endocrinol. 2011 Mar;208(3):207-23. Epub 2010 Dec 6.
Su L, Mruk DD, Cheng CY. Source The Mary M Wohlford Laboratory for Male Contraceptive Research, Center for Biomedical Research, Population Council, New York, New York 10065, USA.
Abstract
The blood-testis barrier (BTB), which is created by adjacent Sertoli cells near the basement membrane, serves as a 'gatekeeper' to prohibit harmful substances from reaching developing germ cells, most notably postmeiotic spermatids. The BTB also divides the seminiferous epithelium into the basal and adluminal (apical) compartment so that postmeiotic spermatid development, namely spermiogenesis, can take place in a specialized microenvironment in the apical compartment behind the BTB. The BTB also contributes, at least in part, to the immune privilege status of the testis, so that anti-sperm antibodies are not developed against antigens that are expressed transiently during spermatogenesis. Recent studies have shown that numerous drug transporters are expressed by Sertoli cells. However, many of these same drug transporters are also expressed by spermatogonia, spermatocytes, round spermatids, elongating spermatids, and elongated spermatids, suggesting that the developing germ cells are also able to selectively pump drugs 'in' and/or 'out' via influx or efflux pumps. We review herein the latest developments regarding the role of drug transporters in spermatogenesis. We also propose a model utilized by the testis to protect germ cell development from 'harmful' environmental toxicants and xenobiotics and/or from 'therapeutic' substances (e.g. anticancer drugs). We also discuss how drug transporters that are supposed to protect spermatogenesis can work against the testis in some instances. For example, when drugs (e.g. male contraceptives) that can perturb germ cell adhesion and/or maturation are actively pumped out of the testis or are prevented from entering the apical compartment, such as by efflux pumps.
PMID: 21134990
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 http://www.ncbi.nlm.nih.gov/pubmed/19136456
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2639084
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
2000
The testicular descent in human. Origin, development and fate of the gubernaculum Hunteri, processus vaginalis peritonei, and gonadal ligaments
Adv Anat Embryol Cell Biol. 2000;156:III-X, 1-98.
Barteczko KJ, Jacob MI.
Abteilung für Anatomie und Embryologie, Ruhr-Universität Bochum, Germany. klaus.barteczko@ruhr-uni-bochum.de
Testicular descent has to be divided into the turn-out of the testis and epididymis from the abdomen proper and an inner abdominal descent of genital organs. Both events are closely related to and depend on the development and reorganisation of ligaments, mainly the gubernaculum Hunteri. These seemingly unambiguous events are controversially described since the first description of the gubernaculum, and results and specifics of other species were intermingled with data from humans, thus giving more confusion than lucidity in this important step of gonadal development. Here, we concentrate on human embryos, chronologically investigated by serial sections, scanning electron microscopy, three-dimensional reconstructions, microdissection and immunohistochemistry. The first question to be answered was whether a real inner descent of gonads occurs. We demonstrated this inner descent by showing the relations of the gonads, mesonephros, cranial mesonephric ligament and the anlage of the diaphragm with the vertebral segments. No explosion-like increase in certain vertebral segments was observed which might simulate a gonadal descent. The inner descent is coupled with the growth of the gonad (ovary or testis), the involution of mesonephros, the descending septum transversum or the anlage of the diaphragm, and the intercalated cranial mesonephric ligament. This ligament always inserts medially at the border between the gonad and mesonephros in close relationship to the abdominal ostium of the müllerian duct, a region where hydatides often occur. In contrast to the testes, the ovaries arrive very early--20-25 mm CRL--at their definitive position of S2/3 (level of linea terminalis pelvis), yet, are transversally oriented. The cranial gonadal ligament does not exhibit notable increase in length during inner descent. It does not contain blood vessels. While regressing in both sexes, it will be replaced by the plica formed by the ovarian vessels, that is the suspensorium ligament of the ovary as known in adults. The second point to be investigated was the origin, development, structure and fate of the gubernaculum Hunteri as well as the processus vaginalis peritonei. Their arrangement and composition is crucial for testicular descent. We discriminated five phases of their development and differentiation. Phase I characterises the early development of the gubernaculum of stage 14 CC (5-7 mm CRL) embryos. It arises as conus inguinalis and connects the abdominal wall lateral to the umbilical artery with the caudal part of the mesonephric fold. It is in this early stage that the localisation of the inner inguinal ring is defined. In phase II, stage 20-23 CC (21-30 mm CRL), three parts of the gubernaculum--abdominal, interstitial and subcutaneous--can be distinguished. The processus vaginalis peritonei appears with its dorsal layer firmly adhering to the ventral side of the gubernaculum. The gubernaculum inserts cranially into the mesenchyme of the genital ducts at their crossing-over. Opposite to it, but at some distance, a ligament connects the caudal pole of the testis with the dorsal mesenchyme of the genital ducts. In female embryos, the analge of the ovarian ligament appears as a U-shaped, double peritoneal fold. Phase II is subdivided in phase IIa (32-55 mm CRL), characterised by an enormous increase in length and volume of the gubernaculum and also an enlargement of the processus vaginalis peritonei. In phase III, sex-specific differences in gonadal position and gubernacular structure can be observed for the first time. Testes increase in volume and come close to the mesenchyme of the genital ducts. The caudal pole of the testis overlaps both ducts. We also subdivide this phase into phase IIIa (about 100 mm CRL) where two very important events occur in male foetuses: 1, the swelling of the gubernaculum, and 2, the gliding of the testis across the genital ducts. This gliding is permitted by both, the regression of the müllerian duct and t
PMID: 11008363 http://www.ncbi.nlm.nih.gov/pubmed/11008363
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
