Summary
Thyroid glands from 40 human fetuses ranging from 30 to 175 mm in length were examined by electron microscopy. At the 30 mm stage, the cells are arranged in cords or clusters and contain numerous free ribosomes. The rough-surfaced endoplasmic reticulum (RER) is poorly developed and the Golgi complex consists of saccules, smooth and coated vesicles. Mitochondria, microfilaments, glycogen particles, occasional lysosome-like structures, and single cilia are observed. At sites of incipient follicle formation, intercellular clefts containing interdigitating microvilli, delimited by junctional complexes, are evident. In addition, the apical region of some cells contains vacuoles. At the 50-mm stage, intercellular clefts are more apparent, some of them organized into small follicles through the enlargement of the lumen, the incorporation of additional cells, and the formation of a basal lamina. With increasing gestational age, more follicles are established. The lumina vary from round to clover-leaf shaped and have an electron-dense content. Cisternae of RER are dilated and contain flocculent material. The Golgi complex is more extensive, and lysosome-like structures are more numerous. By the 100-mm stage, the follicular cells appear morphologically well differentiated. The results demonstrate an extracellular origin of the follicular lumen in the human fetal thyroid.
References
Calvert R, Pusterla A (1973) Formation of thyroid follicular lumina in rat embryos studied by serial fine sections. Gen Comp Endocrinol 20:584–597
Cau P, Michel-Béchet M, Fayet G (1976) Morphogenesis of thyroid follicles in vitro. Adv Anat Embryol Cell Biol 52:1–66
Ericson LE (1979) Intracellular lumens in thyroid follicle cells of thyroxine-treated rats. J Ultrastruct Res 69:297–305
Garcia-Bunuel R, Anton E, Brandes D (1972) The development of lysosomes in the human fetal thyroid in correlation with the onset of functional maturation. Endocrinology 91:438–449
Hilfer SR (1964) Follicle formation in the embryonic chick thyroid. I. Early morphogenesis. J Morphol 115:135–151
Hilfer SR (1979) Follicle formation in the embryonic chick thyroid. III. Initiation of follicle formation. Tissue Cell 11:727–740
Lietz H, Wöhler J, Pomp H (1971) Zur Entwicklung und Ultrastruktur der embryonalen Schilddrüse des Menschen. Z Zellforsch 113:94–110
Olin P, Ekholm R, Almqvist S (1970) Biosynthesis of thyroglobulin related to the ultrastructure of the human fetal thyroid gland. Endocrinology 87:1000–1014
Rémy L, Michel-Béchet M, Cataldo C, Bottini J, Hovsepian S, Fayet G (1977) The role of intracellular lumina in thyroid cells for follicle morphogenesis in vitro. J Ultrastruct Res 61:243–253
Rémy L, Michel-Béchet M, Athouel-Haon AM, Magre S, Cataldo C, Jost A (1980) Development of the thyroid gland in the rat fetus in vivo. An ultrastructural and radioautographic study. Arch Anat Microsc 69:91–108
Reynolds ES (1963) The use of lead citrate at high pH as an electron-opaque stain in electron microscopy. J Cell Biol 17:208–212
Shepard TH (1967) Onset of function in the human fetal thyroid: biochemical and radioautographic studies from organ culture. J Clin Endocrinol Metab 27:945–958
Shepard TH (1968) Development of the human fetal thyroid. Gen Comp Endocrinol 10:174–181
Shepard TH, Anderson H, Anderson HJ (1964) Histochemical studies of the human fetal thyroid during the first half of fetal life. Anat Rec 149:363–380
Sugiyama S, Taki A, Nakano A, Sugiyama N, Yamamoto Y (1959) Histological studies of the human thyroid gland in middle and late prenatal life. Okajimas Folia Anat Jpn 33:75–84
Takashima R, Hara S (1934) Über die Entwicklung der Schilddrüse beim Japaner. Z Anat EntwGesch 102:409–423
Taki A (1959) Histological studies of the prenatal development of the human thyroid gland. Okajimas Folia Anat Jpn 32:65–85
Tice LW, Carter RL, Cahill MC (1977) Tracer and freeze fracture observations on developing tight junctions in fetal rat thyroid. Tissue Cell 9:395–417
Author information
Authors and Affiliations
Additional information
Supported by a grant from the National University of Singapore
The technical assistance of Chan Heng Leong, Yick Tuck Yong and Carolyne Wong is gratefully acknowledged
Rights and permissions
About this article
Cite this article
Chan, A.S. Ultrastructural observations on the formation of follicles in the human fetal thyroid. Cell Tissue Res. 233, 693–698 (1983). https://doi.org/10.1007/BF00212236
Accepted:
Issue Date:
DOI: https://doi.org/10.1007/BF00212236