INTRODUCTION Primordial germ cells have an extra-gonadic origin in the chick embryo. They may be found in the primitive streak or head-process stage, in an area known as the germinal crescent, located in the endoderm anterior and antero-lateral to the primitive streak at the junction of the area opaca and area pellucida (Swift, 1914; Willier, 1937; Reynaud, 1967; Clawson & Domm, 1969). Primordi...

INTRODUCTION Primordial germ cells have an extra-gonadic origin in the chick embryo. They may be found in the primitive streak or head-process stage, in an area known as the germinal crescent, located in the endoderm anterior and antero-lateral to the primitive streak at the junction of the area opaca and area pellucida (Swift, 1914; Willier, 1937; Reynaud, 1967; Clawson & Domm, 1969). Primordi...

The C. elegans germ line proliferates from one primordial germ cell (PGC) set aside in the early embryo to over a thousand cells in the adult. Most germline proliferation is controlled by the somatic distal tip cell, which provides a stem cell niche at the distal end of the adult gonad. The distal tip cell signals to the germ line via the Notch signaling pathway, which in turn controls a networ...

The female germline comprises a reserve population of primordial (non-growing) follicles containing diplotene oocytes arrested in the first meiotic prophase. By convention, the reserve is established when all individual oocytes are enclosed by granulosa cells. This commonly occurs prior to or around birth, according to species. Histologically, the 'reserve' is the number of primordial follicles...

During the peri-implantation development of the mouse embryo from the blastocyst through gastrulation, Pou5f1 (OCT-4) down-regulation is closely linked to the initial step of lineage allocation to extraembryonic and embryonic somatic tissues. Subsequently, differentiation of the lineage precursors is subject to inductive tissue interactions and intercellular signalling that regulate cell prolif...

STUDY QUESTION How do apoptosis-related BCL2 and BAX genes, known to regulate death or survival of germ cells in fetal and adult life, and germ-cell-specific VASA protein behave from birth to puberty in the human ovary? SUMMARY ANSWER In resting primordial follicles in both infant and pubertal ovaries, BCL2 family members and germ-cell-specific VASA behave as in fetal life. After birth, once ...

Testicular germ cell tumors of adolescents and adults (TGCTs; the so-called type II variant) are the most frequent malignancies found in Caucasian males between 20 and 40 years of age. The incidence has increased over the last decades. TGCTs are divided into seminomas and nonseminomas, the latter consisting of the subgroups embryonal carcinoma, yolk-sac tumor, teratoma, and choriocarcinoma. The...

We established a database to study germ cells during the early developmental stage in the chicken. The ChickGCE database provides integrated expressed sequence tag (EST) data from chicken testis, ovary, embryonic gonads, and primordial germ cells. We gathered data on 10,294 ESTs from approximately 1000 embryonic gonads, and we experimentally determined 10,851 ESTs from primordial germ cells pur...

A number of environmental factors (e.g. toxicants) have been shown to promote the epigenetic transgenerational inheritance of disease and phenotypic variation. Transgenerational inheritance requires the germline transmission of altered epigenetic information between generations in the absence of direct environmental exposures. The primary periods for epigenetic programming of the germ line are ...

Social insects are characterized by the development of castes in which some colony members reproduce whereas others function as altruistic helpers. The conditional switch controlling caste formation usually involves environmental stimuli that act on processes that regulate development of individuals. Unlike other social species, embryos of polyembryonic wasps develop clonally to produce large n...