Endocrine‐like cells in human fetal lungs: An electron microscopic study

This study of primitive bronchial epithelium in human fetuses revealed cells of distinctive ultrastructural appearance. These cells contained cytoplasmic granules similar to neurosecretory‐type granules and are termed fetal Kultschitzky‐type cells (K‐type cells) of lung. The fetal K‐type cells appear similar to certain cells in mature lungs and in other tissues that have an endocrine function. The advanced cytoplasmic differentiation and large numbers of K‐type cells in early stages of fetal development suggests that these cells might also have an important, probably endocrine function.