Volume 14, Issue 2: 2024 - Article 167

Abstract
The Nigerian indigenous chicken (NIC) is a hardy breed that has been widely reported to be very resistant to diseases. Though the thymus and spleen are functionally very significant in the chicken, their morphological development in the NIC has not been reported. The present study histologically evaluated the morphological development of the thymus and spleen of light ecotype Nigerian indigenous chicken. Fifteen fertile eggs of the light ecotype NIC (Group A) and 15 light ecotype NICs (Group B) were used for the study. The eggs were sampled on embryonic days (ED) 14 and 19, and post-hatch day (PD) 1, while the chickens were chronologically sampled according to the following groupings: B1 (3 – 6 months of age; 210 – 250 g; n = 5), B2 (6 – 9 months of age; 400 – 600 g weight; n = 5), and B3 (12 – 18 months of age; 900 – 1200; n = 5). Samples of the thymus and spleen were collected at the specified time points, processed and stained for histological evaluation following standard procedures. Results of the histological evaluation showed that the thymus at ED 14 contained loose connective tissue areas with numerous islands of nascent thymic tissues. At ED 19, the thymic lobules showed large cortical areas with small medulla, whereas, the thymus at PD 1 had distinctly demarcated parenchymal areas. The thymus of 3 – 18 months old birds showed extensive medullary area that contained diffusely distributed Hassall’s corpuscles and necrotic foci. The spleen, at ED 14, contained red pulp areas with cords of Billroth and occasional shallow sinusoids. Wide splenic sinusoids containing numerous red blood cells occurred at ED 19. However, at hatch, the splenic parenchyma had clearly demarcated red and white pulps with predominance of white pulp areas in the spleen of older birds. It was concluded that the thymus of the light ecotype Nigerian indigenous chicken is structurally mature in the late embryonic and early post-natal life, with regressive changes occurring around 3 months of age, but the spleen may predominantly perform hematopoietic function during embryonic life, with the predominant role of immune function ensuing after hatch.

Keywords: Embryonic development; Morphology; Histology; Nigerian indigenous chicken; Spleen; Thymus.

How to cite this article:
Udoumoh AF and Nwosu FE (2024). Histological evaluation of the development of the thymus and spleen in the light ecotype Nigerian indigenous chicken (Gallus gallus domesticus). Journal of Veterinary and Applied Sciences, 14(2): 809 – 819.

* Correspondence: Anietie F. Udoumoh; Email: HYPERLINK "mailto:anietie.udoumoh@unn.edu.ng"anietie.udoumoh@unn.edu.ng; Phone: +2348030996966

*Correspondence: E-mail:     aniete.udoumoh@unn.edu.ng      Phone: +2348030996966

Histological evaluation of the development of the thymus and spleen in the light ecotype Nigerian indigenous chicken (Gallus gallus domesticus)

Anietie F. Udoumoh ^* and Frank E. Nwosu
Department of Veterinary Anatomy. Faculty of Veterinary Medicine. University of Nigeria, Nsukka, Enugu State, Nigeria.

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