Mistakes in chromosome segregation lead to aneuploid cells. In somatic cells, aneuploidy is associated with cancer but in gametes, aneuploidy leads to infertility, miscarriages or developmental disorders like Down syndrome. Haploid gametes form through species-specific developmental programs that are coupled to meiosis. The first meiotic division (MI) is unique to meiosis because sister chromat...

We have examined the regulation of maturation-promoting factor (MPF) activity in the mitotic and meiotic cell cycles of Xenopus laevis eggs and oocytes. To this end, we developed a method for the small scale extraction of eggs and oocytes and measured MPF activity in extracts by a dilution end point assay. We find that in oocytes, MPF activity appears before germinal vesicle breakdown and then ...

Follicle-stimulating hormone (FSH) in the organism together with LH is responsible for follicular growth and maturation of eggs. If the ovaries are not working, FSH levels rise. The most common reason for high serum FSH concentration is in a female who is undergoing or has recently undergone menopause. High levels of follicle-stimulating hormone indicate that the normal restricting feedback fro...

Down-regulation of MAP kinase (MAPK) is a universal consequence of fertilization in the animal kingdom, although its role is not known. Here we show that MAPK inactivation is essential for embryos, both vertebrate and invertebrate, to enter first mitosis. Suppressing down-regulation of MAPK at fertilization, for example by constitutively activating the upstream MAPK cascade, specifically suppre...

Investigations in the rat model of pregnancy indicate an important role for the corpus luteal (CL) hormone relaxin in the maternal circulatory and osmoregulatory changes in pregnancy, which are epitomized by profound vasodilation and modest hypoosmolality, respectively. In a pilot study of infertile women who became pregnant through donor eggs, in vitro fertilization, and embryo transfer, the g...

Sexual reproduction of the coral Diploria labyrinthiformis was studied for the first time. Monthly histological analyses at the Corales del Rosario National Park (Colombian Caribbean) from May 1997 to April 1998 show that D. labyrinthiformis is a hermaphroditic broadcasting species. It presents an annual gametogenic cycle with a 10-11 month period for gonad investment, in which oogenesis begins...

Follicle-stimulating hormone (FSH) in the organism together with LH is responsible for follicular growth and maturation of eggs. If the ovaries are not working, FSH levels rise. The most common reason for high serum FSH concentration is in a female who is undergoing or has recently undergone menopause. High levels of follicle-stimulating hormone indicate that the normal restricting feedback fro...