태아 및 배아 유선의 발달과정에 관한 관찰

Abstract

To evaluate the intra-uterine developmental process of the mammary gland, a microscopic observation was made using 38 normal human fetuses and 10 human embryos. Gestational ages were calculated based on the crown-rump lengths in the fetuses, and organ development (developmental horizons) in the embryos. Following observations were made: 1. The first sign of breast development is recognizable at the 4th gestational week, and was characterized by lens-like thickening of the epidermis and mesenchymal cell condensation. 2. Primordium of mammary gland becomes globoid by the tith gestational week and lobulated by the 7th week, which corresponds to the primary budding. 3. By the 18th week of gestation secondary buds grow downward from the primary buds and they start to branch by the 20th week. 4. The canalization of the lactiferous ducts is started from the 20th week and completed by the 30th gestational week. The secretory materials are first seen in the lumina of the glands by the 28th week of gestation. S. Lymphocytes start to gather around the duct from the 20th week and pronounced throughout the intra-uterine age until term. 6. There is no morphologic difference between male and female in regard to the breast development during the intrauterine life.