Morphology and Histogenesis of Human Fetal and adult Thyroid Gland

P Vahini^*

^*Correspondence: P Vahini, Department of Anatomy, Sree Balaji Medical College & Hospital Affiliated to Bharath Institute of Higher Education and Research, India, Email:

Author info »

Introduction

Thyroid hormones are necessary for regulating the body metabolic rate, body temperature, calcium metabolism, somatic and circadian rhythm. The organogenesis of thyroid gland in human is often disturbed, leading to a variety of morphological variations such as hypoplasia, ectopy, agenesis etc. These anomalies may lead to various thyroid illnesses and clinical disorders [1-4]. Congenital hypothyroidism is the most common disorder of the endocrine system among new-borns. We intend to study the morphological changes of the thyroid gland at different gestational weeks in human foetuses and in adult and also to document the microscopic structure of thyroid gland at different gestational age groups and also in adult.

Materials and Methods

Thirty three human foetuses (16 males and 17 females) of different age groups ranging from 10 to 39th gestational week. Morphological parameters such as length, width and size were ascertained and also the histopathological studies were done on the collected samples.

Results

The morphological studies revealed that level of superior poles of thyroid lobe were located between the upper ½ and lower ½ of the thyroid cartilage in group 1 samples. Thyroid gland was found to be normal in position and dimensions in group 2 cases. In the group 3 category the distance between superior poles of thyroid gland and the hyoid bone increases throughout the fetal period as depicted in Figure 1.

Figure 1: Comparisons of dimensions of the lobes of thyroid gland and isthmus.

The histopathological results explains that human fetal thyroid (12wks) showing pheriperal differentiation of the follicles with increase vascularity in group 1 (a) and in group 2 samples it was seen that thick connective septa along with blood vessels invading the glands in 20weeeks also increase in size of the follicles (Group 2A & 2B).

Matured thyroid follicle filled colloid and increased vascularity seen in 30 weeks also with densely stained colloid was seen in group 3 cases.

Figure 2: Histological observations.

Discussion and Conclusion

The study of morphology and Histogenesis of human fetal thyroid gland gives us insight into the growth and differentiation of the gland and for better understanding of the developmental anomaly. Anomalies of thyroid gland like agenesis of isthumus can be diagnosed via CT, MRI and ultrasound [3-10]. Proper identification of vessels is very important in order to avoid major complications. Hence a thorough knowledge of the thyroid anatomy and its associated anatomical variations is very much essential, so these anomalies are not overlooked in the different diagnosis. This analysis could be of great importance for the radiologists to prevent both maternal and fetal complications to avoid further invasive procedures.

References

1. Patel J, Landers K, Li H, et al. Thyroid hormones and fetal neurological development. J Endocrinol 2011; 209:1.
2. Morreale de Escobar G. The role of thyroid hormone in fetal neurodevelopment. J Pediatr Endocrinol Metabol 2001; 14:1453-62.
3. Klein A, Agustin A, Foley JR T. Successful laboratory screening for congenital hypothyroidism. Lancet 1974; 304:77-9.
4. Olivieri A, Stazi MA, Mastroiacovo P, et al. A population-based study on the frequency of additional congenital malformations in infants with congenital hypothyroidism: Data from the Italian Registry for congenital hypothyroidism (1991–1998). J Clin Endocrinol Metabol 2002; 87:557-62.
5. Bocian-Sobkowska J, Wozniak W, Malendowicz LK. Morphometric studies on the development of the human thyroid gland. II. The late fetal life. Histol Histopathol 1997.
6. Sophia MM, Kalpana R. Morphological and histological features of human fetal thymus gland. Int J Scient Study 2016; 4:187-91.
7. Lee J, Yi S, Kang YE, et al. Morphological and functional changes in the thyroid follicles of the aged murine and humans. J Pathol Translational Med 2016; 50:426.
8. Morreale de Escobar G, Jesús Obregón M, Escobar del Rey F. Is neuropsychological development related to maternal hypothyroidism or to maternal hypothyroxinemia?. J Clin Endocrinol Metabol 2000; 85:3975-87.
9. Polak M. Hyperthyroidism in early infancy: Pathogenesis, clinical features and diagnosis with a focus on neonatal hyperthyroidism. Thyroid 1998; 8:1171-7.
10. Taki A. Histological studies of the prenatal development of the human thyroid gland. Okajimas Folia Anatomica J 1958; 32:65-85.