The fine structure of the human corpus luteum of term pregnancy

Abstract

The fine structure of human corpora lutea from term pregnancies is described following preservation in formaldehyde-glutaradehyde fixatives containing trinitrophenol. The morphology of human corpora lutea of term pregnancy is compared with recently published observations of lutein tissue taken during early gestation. Granulosa lutein cells at term resemble granulosa lutein cells taken during early pregnancy with respect to nuclear morphology, the nature and amount of both granular and agranular endoplasmic reticulum, the presence of fine filaments, and cell surface modifications. These observations are correlated with recent data on progesterone secretion by corpora lutea of term pregnancy and support the concept that such corpora are functional. At the same time, differences in the nature or number of mitochondria, Golgi complex, lipid droplets, and microtubules distinguish granulosa lutein cells obtained at different stages of pregnancy. These differences are correlated with published data on serum titers of gonadotrophins which vary during the course of gestation. Possible reasons for the persistence of functional corpora lutea throughout human pregnancy are discussed with respect to relaxin secretion, absence of a uterine luteolytic factor, and serum titers of placental hormones.