HORMONAL STORAGE PATTERNS AND MORPHOLOGICAL HETEROGENEITY OF PORCINE GONADOTROPE CELLS DURING POSTNATAL-DEVELOPMENT

Previous reports indicate that gonadotrope cells of the porcine pituit ary gland can be separated into three subpopulations of low- (1.049 g/ cm(3)), middle- (1.062 g/cm(3)) and high- (1.087 g/cm(3)) density in a continuous Percoll density gradient. The aim of this work was to stud y the hormonal storage patterns and morphological features of these su bpopulations at three representative ages of the postnatal development : neonatals (30-day-old animals), prepubertals (5-6-month-old animals) and matures (16-18-month-old animals). The low-density subpopulation, present at the three ages studied, was mainly composed of bihormonal LH/FSH cells in neonatal and monohormonal LH cells in prepubertal and mature animals. On the other hand, middle- (only present in prepuberta l and mature animals) and high-density subpopulations (only present in neonatal and prepubertal animals) were mainly composed of bihormonal LH/FSH gonadotropes. In ultrastructural terms, these subpopulations ex hibit a correlation between density and morphology irrespective of the animal's age. The low-density subpopulation was composed of poorly gr anulated cells with highly developed biosynthetic machinery (rough end oplasmic reticulum and Golgi complex), while high-density cells were o f opposite morphology, with a highly granulated cytoplasm and poorly d eveloped rough endoplasmic reticulum and Golgi complex. The middle-den sity subpopulation was composed of poorly granulated cells with scarce ly developed biosynthetic machinery. In conclusion, these results indi cate that porcine gonadotrope cells during postnatal development are c omposed of three subpopulations of different hormonal storage patterns and morphology. The presence of these subpopulations at the different stages of postnatal development strongly suggests that their proporti ons may play a major role in the endocrine control process.