Beyond the Mouse Monopoly: Studying the Male Germ Line in Domestic Animal Models

Abstract

Spermatogonial stem cells (SSCs) are the foundation of spermatogenesis and essential to maintain the continuous production of spermatozoa after the onset of puberty in the male. The study of the male germ line is important for understanding the process of spermatogenesis, unravelling mechanisms of stemness maintenance, cell differentiation, and cell-to-cell interactions. The transplantation of SSCs can contribute to the preservation of the genome of valuable individuals in assisted reproduction programs. In addition to the importance of SSCs for male fertility, their study has recently stimulated interest in the generation of genetically modified animals because manipulations of the male germ line at the SSC stage will be maintained in the long term and transmitted to the offspring. Studies performed mainly in the mouse model have laid the groundwork for facilitating advancements in the field of male germ line biology, but more progress is needed in nonrodent species in order to translate the technology to the agricultural and biomedical fields. The lack of reliable markers for isolating germ cells from testicular somatic cells and the lack of knowledge of the requirements for germ cell maintenance have precluded their long-term maintenance in domestic animals. Nevertheless, some progress has been made. In this review, we will focus on the state of the art in the isolation, characterization, culture, and manipulation of SSCs and the use of germ cell transplantation in domestic animals.

TALEN‐mediated gene targeting in porcine spermatogonia

“…The targeting efficiency in primary germ cells achieved in the current study was similar to that reported for rodent SSCs (Chapman et al, 2015;Fanslow et al, 2014). (Gonzalez & Dobrinski, 2015).…”

Testes of DAZL null sheep lack spermatogonia and maintain normal somatic cells

“…Sheep, mouse 3 Cleavage normalised on nIVC. 4 Blastocyst development normalised on ≥ 2-cell embryos. 5 Proportion of grade 1-2 blastocysts normalised on total number of blastocysts.…”

“…To create such sterile hosts, local testes irradiation has successfully depleted germ cells in sheep 2 and cattle 3 . However, this method requires general anaesthesia and access to expensive specialist equipment 4 . Depending on the radiation dose and animal's age at time of radiation, it may also leave some endogenous germ cells intact 2 , compromise testicular somatic cells [5][6][7] , slow down recovery of spermatogenesis and even reduce libido 7 .…”

Multispecies Purification of Testicular Germ Cells

“…As a proof of principle, our work has major implications for several types of studies in developmental biology. First, it provides the tools to investigate the dynamics of germ cell development in different species individually, which would benefit research of understudied mammalian species such as domesticated animals [35]. Furthermore, using the same experimental procedure in different species reduces noise and eliminates sources of variables that often challenge comparative studies.…”