BACKGROUNDFunctional male gametes are produced through complex processes that take place within the testis, epididymis and female reproductive tract. A breakdown at any of these phases can result in male infertility. The production of mutant mouse models often yields an unexpected male infertility phenotype. It is with this in mind that the current review has been written. The review aims to act as a guide to the ‘non-reproductive biologist’ to facilitate a systematic analysis of sterile or subfertile mice and to assist in extracting the maximum amount of information from each model.METHODSThis is a review of the original literature on defects in the processes that take a mouse spermatogonial stem cell through to a fully functional spermatozoon, which result in male infertility. Based on literature searches and personal experience, we have outlined a step-by-step strategy for the analysis of an infertile male mouse line.RESULTSA wide range of methods can be used to define the phenotype of an infertile male mouse. These methods range from histological methods such as electron microscopy and immunohistochemistry, to hormone analyses and methods to assess sperm maturation status and functional competence.CONCLUSIONWith the increased rate of genetically modified mouse production, the generation of mouse models with unexpected male infertility is increasing. This manuscript will help to ensure that the maximum amount of information is obtained from each mouse model and, by extension, will facilitate the knowledge of both normal fertility processes and the causes of human infertility.

ABSTRACT:The Sertoli cell ectoplasmic specialization (ES) is a specialized domain of the calcium-dependent Sertoli cell-spermatid junctional complex. Not only is it associated with the mechanical adhesion of the cells, but it also plays a role in the morphogenesis and differentiation of the developing germ cells. Abnormal or absent Sertoli ESs have been associated with step-8 spermatid sloughing and subsequent oligospermia. With a micropipette pressure transducing system (MPTS) to measure the force needed to detach germ cells from Sertoli cells, this study examined, for the first time, the strength of the junction between Sertoli cells and spermatids and between Sertoli cells and spermatocytes. The mean force needed to detach spermatocytes from Sertoli cells was 5.25 ϫ 10 Ϫ7 pN, prestep-8 spermatids from Sertoli cells was 4.73 ϫ 10 Ϫ7 pN, step-8 spermatids from Sertoli cells was 8.82 ϫ 10 Ϫ7 pN, and spermatids plus EDTA was 2.16 ϫ 10 Ϫ7 pN. These data confirm the hypothesis that step-8 spermatids are more firmly attached to Sertoli cells than are spermatocytes and pre-step-8 spermatids and that calcium chelation reduces binding strength between Sertoli cells and spermatids. The MPTS is a useful tool in studying the various molecular models of the Sertoli-germ cell junctional strength and the role of reproductive hormones and enzymes in coupling and uncoupling of germ cells from Sertoli cells.

ABSTRACT:The actin-based cell-cell adherens junction (AJ) between the Sertoli cell and the germ cell in the mammalian testis is important not only in mechanical adhesion of the cells, but in the morphogenesis and differentiation of the germ cells. The Sertoli ectoplasmic specialization (ES), a specialized type of AJ, is associated with Sertoli-spermatid binding and is important in cellcell adhesion in the seminiferous epithelium. Abnormal or absent Sertoli ESs have been associated with step-8 spermatid sloughing and oligospermia in conditions associated with reduced fertility potential. The reproductive hormones, follicle stimulating hormone (FSH), and testosterone (T) have also been shown to play a role in the regulation of binding of spermatids at the Sertoli-spermatid junctional complex (STJC). Adjudin [1-(2,4-dichlorobenzyl)-1H-indazole-3-carbohydrazide] is a potential male contraceptive and is thought to exhibit its contraceptive effects by interrupting the STJC. It has been shown that this compound induces reversible germ cell loss from the seminiferous epithelium, particularly elongating/ elongate/round spermatids and spermatocytes. Using a micropipette pressure transducing system (MPTS) to measure the force needed to detach step-8 spermatids from Sertoli cells, this study examined the strength of the STJC in Sertoli-spermatid cocultures in the presence of Adjudin (1 ng/mL, 50 ng/mL, 125 ng/mL, or 500 ng/mL in EtOH) and hormones [FSH (0.1 mg/mL, NIDDK-oFSH-20, AFP7028D, 175 6 NIH-FSH-S1), T (100 nM)] to optimize in vitro binding. The average forces required to detach the spermatids from the underlying Sertoli cells in the presence of 1 ng/mL, 50 ng/mL, 125 ng/mL, and 500 ng/mL Adjudin were 18.2 6 10 210 pN, 14.3 6 10 210 pN, 7.74 6 10 210 pN, and 6.51 6 10 210 pN, respectively. The average force required to detach step-8 spermatids in the presence of vehicle only (control) was 19.0 6 10 210 pN. A significant difference for Adjudin concentrations at or above 125 ng/mL was determined by one-way ANOVA (P , .05). These data confirm that Adjudin is effective in reducing the strength of the STJC, identifying Adjudin as a potential contraceptive agent in the male by inducing spermatid sloughing and therefore oligospermia.