It is now well established that certain chemical compounds, administered to animals in early pregnancy, can adversely influence the development of the fetus, resulting in congenital malformations. Recently, it bas been shown that thalidomide, a sedative drug, may induce skeletal defects in the offspring of treated females when administered in the early stages of pregnancy. McColl, Globus and Robinson (1963) reported that certain skeletal defects could be produced in the offspring of Sprague-Dawley rats following chronic oral administration of thalidomide. Notable among the defects produced were malfomations of the sternum. [...]

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Recently, the timing of oocyte loss during murine development has been brought into question as authors using mouse vasa homologue (MVH) as a germ cell marker did not observe a loss of oocytes during fetal life. Instead the major loss was observed in the days following birth, after chromosome pairing has occurred. / In this study the controversy was addressed by establishing a new and reliable method to quantify murine oocytes in meiotic prophase, as well as to determine the gestation age and meiotic prophase stage of oocyte loss. Earlier limitations were overcome through the use of Germ Cell Nuclear Antigen-1 (GCNA-1) antibody as a germ cell specific marker, and the novel addition of a cytospin centrifugation step to the method. Progress through meiotic prophase was examined in chromosome spread preparations where meiotic stages were assessed using an antiserum against synaptonemal complex (SC) proteins. Quantification was accomplished by counting the number of GCNA-1 immunoreactive cells in chromosome spread preparations and estimated in histological sections using the ratio estimation model. (Abstract shortened by UMI.)

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H1 histones are potentially significant to nuclear reprogramming during the oocyte-to-embryo transition. One characteristic distinguishing the H1 subtypes is that the somatic H1 histones are found primarily in dividing cells, whereas the H10 subtype is predominantly found in differentiated cells. The H1 complement in mouse oocytes and preimplantation embryos from wild-type and H10-/- animals was investigated. / Immunocytochemistry of wild-type cells demonstrated that H10 was predominant in oocytes while somatic H1 began accumulating in the 2-cell embryo. In H10-/- cells H10 was not detected, but, surprisingly, somatic H1 was detected beginning at the 1-cell stage. Radiolabeling of wild-type and H10-/- cells revealed that somatic H1 synthesis intensified after meiotic maturation, and therefore prior to its detection in embryos. The functional study found that loss of H10 impaired oogenesis but enhanced embryogenesis. The patterns of H1 immunodetection and synthesis are integrated, and the significance of H1 composition in development is discussed.

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Patterning of the body axes of the Drosophila embryo depends on maternally expressed genes, some of which function in the follicular epithelium of the developing egg chamber. Many such genes were identified in genetic screens for homozygous mutant females that produce abnormal embryos. However, mutations in zygotically required maternal effect genes are homozygous lethal, and therefore viable females cannot be recovered using this screening approach. This limitation can be overcome by generating homozygous mutant follicle cell clones in heterozygous females using a system that induces site-specific mitotic recombination events. However, to date, eggs produced from egg chambers with complete follicle cell clones cannot be directly identified. We have developed an eggshell marker for follicle cell clones using a dominant negative (DN) allele of the gene defective chorion (dec). Females with a single copy of this allele, decDN, lay collapsed eggs and are therefore sterile. Site-specific mitotic recombination events induced in females heterozygous for decDN and a mutation on the homologous chromosome arm result in homozygous mutant follicle cells that have lost decDN. Therefore, egg chambers with the entire follicular epithelium homozygous mutant generate intact eggs that can be unambiguously identified amongst otherwise collapsed eggs.