title: Neonatal gonocyte differentiation in Mongolian gerbil Meriones unguiculatus involves asynchronous maturation of seminiferous cords and rapid formation of transitional cell stage.
abstract: This study describes the neonatal differentiation of the Mongolian gerbil gonocytes, focusing on the relationship between its relocation to the basement membrane, apoptosis and postrelocation changes and also the distribution of androgen receptors (AR). Testes of gerbils from 1 to 35 days of age (d) were examined by high resolution light microscopy and immunocytochemistry for proteins PCNA, VASA, and AR as well as by the TUNEL method. Gonocytes were quantified according to degree of relocation into nonrelocated, relocating and relocated. Most of them were found in the center of seminiferous cords at 1 d but a small number of relocating and relocated gonocytes were already visible in the first postnatal day. After relocation, gonocytes change phenotypically to a transitional stage designated herein prospermatogonia. Both gonocyte relocation and transformation into spermatogonial lineage occur asynchronously in the seminiferous cords, mainly after 7 d. Gonocyte proliferation began before but peak after their relocation to basement membrane at the prospermatogonia stage. Higher levels of gonocyte apoptosis were found at 7 d and 21 d. From this time onward gonocytes were not found. Gonocytes and prospermatogonia showed high amounts of AR in their cytoplasm contrary to spermatogonial subtypes, indicating a possible AR inactivation in these cells. In conclusion, the process of gonocyte relocation in the gerbil extends until the second postnatal week, leads to their rapid differentiation into prospermatogonia and occurs simultaneously with the loss of androgen sensitivity. Differently from other laboratory rodents, the events regarding gonocyte maturation in the gerbil last longer and occur asynchronously in seminiferous cords.
authors.affiliation: Department of Cell Biology, Institute of Biology, State University of Campinas-UNICAMP, Campinas, São Paulo, Brazil.
authors.forename: Maria Etelvina
authors.initials: ME
authors.lastname: Pinto
authors.forename: Lívia Silva
authors.initials: LS
authors.lastname: Botta
authors.forename: Sebastião Roberto
authors.initials: SR
authors.lastname: Taboga
authors.forename: Rejane Maira
authors.initials: RM
authors.lastname: Góes
mesh_terms: D000367:Age Factors; D000375:Aging; D000818:Animals; D000831:Animals, Newborn; D017209:Apoptosis; D002454:Cell Differentiation; D019070:Cell Lineage; D002465:Cell Movement; D049109:Cell Proliferation; D053487:DEAD-box RNA Helicases / Q000378:metabolism; D005849:Gerbillinae; D007150:Immunohistochemistry; D008297:Male; D008940:Mitotic Index; D010641:Phenotype; D018809:Proliferating Cell Nuclear Antigen / Q000378:metabolism; D011944:Receptors, Androgen / Q000378:metabolism; D012671:Seminiferous Tubules / Q000166:cytology / Q000254:growth & development* / Q000378:metabolism / Q000648:ultrastructure; D012708:Sertoli Cells / Q000502:physiology; D013093:Spermatogonia / Q000254:growth & development* / Q000378:metabolism / Q000648:ultrastructure
chemical_list: D018809:Proliferating Cell Nuclear Antigen; D011944:Receptors, Androgen; D053487:DEAD-box RNA Helicases