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We measured cord blood levels of calcium-regulating hormones and osteocalcin in 34 premature infants of various gestational ages. 1,25(OH)2D levels were low in mid-gestation and increased with advancing gestation. Parathyroid hormone levels were low, and calcitonin levels were high in mid-gestation. Both of them declined with advancing gestation. Osteocalcin levels were high in mid-gestation. They increased from 22 weeks through 27 weeks of gestational age, and decreased thereafter. Circulating osteocalcin is considered as a clinical marker of bone turnover. However, cord blood osteocalcin decreased between 27 and 36 weeks of gestation during which period calcium accumulation by the fetus increases. Therefore, cord blood osteocalcin does not appear to reflect fetal bone formation.

Recently, several reports have demonstrated the presence of oxytocin (OT) in the corpus luteum of mammalian species. However, the biological role of ovarian OT remains obscure. This study was performed to examine OT gene expression in cumulus cells of mice and humans, and in human corpus luteum, and the role of OT in early embryogenesis. OT gene and OT mRNA were analyzed by reverse transcription-polymerase chain reaction, with single-strand-conformation polymorphism and heteroduplex procedures. OT-treated in-vitro-fertilized mouse oocytes were cultured and the rate of blastocyst development estimated. An immunohistochemical study was also carried out to detect OT on the surface of the mouse oocytes.

Oxytocin (OT) has been detected in mammalian granulosa-luteal cells during the early stages. The purpose of this study was to explore gene expressions of OT and OT receptor (OTR) in human cumulus cells. Cumulus cells enclosing a mature oocyte were obtained from 6 women undergoing clinical in vitro fertilization and embryo transfer programs. OT and OTR gene expressions were investigated by employing reverse transcription polymerase chain reaction and reverse transcription polymerase chain reaction/single-strand conformation polymorphism methods. OT gene expression in the cumulus cells was positive in 5 women and weakly positive in the remaining patient. The structure of OT mRNA in the cumulus cells was equivalent to that in human hypothalamus. OTR gene expression was also observed in the cumulus cells. This study is the first to describe the simultaneous expression of both OT and OTR genes in human cumulus cells. It is suggested that local OT plays some important roles in fertility through modification of the micro-environment around the oocyte.

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