The objective of the research was to establish anatomical variants of the external structure of the thyroid gland in human fetuses aged 4-6 months.
Material and methods of research. The study involved 37 specimens of human fetuses with 81.0-230.0 mm of the crown-rump length (CRL). The material was obtained in obstetrical departments of medical institutions in Chernivtsi and the corresponding region. Specimens of the fetuses weighing more than 500.0 grams were studied directly in Chernivtsi municipal institution “Department of morbid anatomy”. We only studied the cases where the cause of death had not been associated with thyroid pathologies (TP) and those of the organs and structures of the neck. We used the methods of ordinary and fine dissection controlled by means of binocular microscope MBS-10, morphometry and statistical analysis of the findings.
Results. 4 month-old fetuses’ thyroid was established to be shaped like the letter “H”. Isthmus of thyroid without clear boundaries entered the lateral glandular lobes, whose shape resembled a kind of edge pointed backwards and extended in the middle section. Thyroid lobes were almost symmetrical. The cross length of thyroid lobes in fetuses with 115.0-135.0 mm of CRL compared to those with 81.0-114.0 mm of CRL increased twice and their thickness – almost by four times.
By the 5th month of fetal growth (fetuses 136.0-185.0 mm of CRL) development of the lateral lobes of the thyroid and a clearer separation of the isthmus continued. We established both the variability of lateral lobes and the isthmus of the thyroid shapes, and their asymmetry. In 2.7% of cases the thyroid gland was butterfly-shaped and symmetric, while in 8.1% it was butterfly-shaped and asymmetric, yet in 10.8% the thyroid gland resembled a semicircle.
The fetuses at the age of 6 months (186.0-230.0 mm of CRL) had a slight increase in the length of their thyroid lobules. The shape of the thyroid gland was quite varied: horseshoe-shaped (5.4% of cases), butterfly-shaped symmetric (5.4% of cases) and asymmetric (8.1% of cases), semicircle-shaped (2.7% of cases), “H”-shaped (5.4% of cases) with elongated upper and lower poles.
- Intensive formation of structure and sizes of the thyroid gland, which in its shape usually resembles the letter “H” (84.6% of cases) occurred in the early fetal period.
- The structure of the thyroid gland in human fetuses at the age of 5-6 months was characterized by considerable individual anatomical variability, manifested in different shapes and topography of its parts. Variability of shapes of the thyroid gland can provide the following types: the letter “H” (37.93% of cases), butterfly-shaped symmetric (10.35% of cases) and asymmetric (20.69% of cases), semicircle-shaped (17.24% of cases) and the horseshoe-shape (13.79% of cases).
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