Remodeling of the postnatal mouse testis is accompanied by dramatic changes in stem cell number and niche accessibility

Little is known about stem cell biology or the specialized environments or niches believed to control stem cell renewal and differentiation in self-renewing tissues of the body. Functional assays for stem cells are available only for hematopoiesis and spermatogenesis, and the microenvironment, or niche, for hematopoiesis is relatively inaccessible, making it difficult to analyze donor stem cell colonization events in recipients. In contrast, the recently developed spermatogonial stem cell assay system allows quantitation of individual colonization events, facilitating studies of stem cells and their associated microenvironment. By using this assay system, we found a 39-fold increase in male germ-line stem cells during development from birth to adult in the mouse. However, colony size or area of spermatogenesis generated by neonate and adult stem cells, 2–3 months after transplantation into adult tubules, was similar (∼0.5 mm2). In contrast, the microenvironment in the immature pup testis was 9.4 times better than adult testis in allowing colonization events, and the area colonized per donor stem cell, whether from adult or pup, was about 4.0 times larger in recipient pups than adults. These factors facilitated the restoration of fertility by donor stem cells transplanted to infertile pups. Thus, our results demonstrate that stem cells and their niches undergo dramatic changes in the postnatal testis, and the microenvironment of the pup testis provides a more hospitable environment for transplantation of male germ-line stem cells.

Fauna hawaiiensis; being the land-fauna of the Hawaiian islands. by various authors, 1899-1913.

v. 2

1984 Men's Gymnastics Team

Back Row: head coach Bob Darden, Richard Landman, Stuart Downing, Mike McNelis, Gregory Nelson, captain Merrick Horn, Jonathan Ross, asst. coach Rick Kaufmann

Front Row: Gavin Meyerowitz, Bruce Bueno, Mitchell Rose, Thomas Alexander, Brock Orwig, Mike Spencer, Ari Golan

Missing: Paul Ingersoll

1986 Men's Gymnastics Team

Back Row: coach Bob Darden, trainer John McKinney, C.J. Bugyis, Scott Smith, Mark Wurfel, Tony Angelotti, Tim Devries, mngr. Scott Rosen, mngr. Jason Reis

Front Row: Greg Nelson, Mark Bonertz, Nick Lanphier, Gavin Meyerowitz, Craig Ehle, Scott Moore, Brock Orwig, Ken Haller, Paul Ingereoll, Steve Yuan, John Ross, captain Mitch Rose

Handbook of American sheet music; a catalog of sheet music. [1st ser.- ]

Mode of access: Internet.

Ethnology of Easter Island /

Bibliography : p. 421-429.

Insects of Micronesia.

Published by the Bernice P. Bishop Museum.

Guide to the birds of Samoa.

Bibliography: leaf 21.

Bulletin, ...

Mode of access: Internet.

References for teachers of English as a foreign language: a bibliography /

Mode of access: Internet.

Insects of Hawaii; a manual of the insects of the Hawaiian Islands, including an enumeration of the species and notes on their origin, distribution, hosts, parasites, etc.

Includes supplements to some of the vols.; suppl. to v. 1-5 in v. 6; suppl. to v. 11 published separately.

U.S. cotton textile imports : perspective on a complex problem /

Cover title.

Detroit tests of learning aptitude; a new instrument of mental diagnosis: examiner's handbook,

These tests were developed in the Detroit psychological clinic, a department of the Detroit public schools. cf. Pref.

Fauna Hawaiiensis, being the land-fauna of the Hawaiian Islands.

Each plate is accompanied by leaf with descriptive letter-press.