European Journal of Molecular & Clinical Medicine

Abstract

Background: The thymus is the lymphoid organ of greatest importance. It is structurally separated lobules through the tissue of the connective septa. That lobule has a cortex and a medulla in it. Many studies of this organ related to the histology of early fetuses are focused on animals. The present study focuses on certain features relating to the histogenesis of the thymus and adolescent fetuses.
 
Materials and Methods: This is a prospective and observational study conducted in the Department of Anatomy, Ayaan Institute of Medical Sciences Teaching Hospital and Research Center has been undertaken on thymus specimens of 18 fetuses of different age corporations starting from the crown - rump length (CRL) of these fetuses have been to challenge to morphometry and histometry. The acquired fetuses were set in formalin of 10 per cent. They have been exposed to dissection after correct fixation. The specimens acquired had been processed through a well-known paraffin block making process. Sections were taken with haematoxylin & eosin, and painted. The stained sections had been tested using 40x and 100x optical magnifications and pictures taken under light microscopy.
 
Results:  The histometric analysis of parenchyma (cortex and medulla) and connective tissue indicates that there was no significant variation in their ratio. These corpuscles were frequently seen in thymuses of the early gestational period which were called as Solid Hassall Corpuscle (SHC) and were located at the periphery of the medulla within the age group of the present study. Their size ranged from 25-35 μm with a mean of 27.156 μm. This epithelial capsule was separated from the central mass by a subcapsular space that gave a cyst like an appearance hence named primary cystic Hassall’s corpuscle (CHC I). Their size varied from 35-70 μm with a mean of 48.153 μm thickness Externally the whole structure was surrounded by an epithelial capsule as found in CHC I, hence named as secondary cystic corpuscles (CHC II). They were mainly observed in the central core of the medulla. Their size ranged from 50-100 μm with a mean of 74.171 μm thickness late stages were noticed.
 
Conclusion: Thymus gland involution, pondered in its anatomy and histology, will serve as a basis for becoming conscious of pathological conditions. Within the first 18 weeks of gestation, all structural changes viz. cortico-medullary differentiation, lobulation, and maturity of the hassall's corpuscles happened.