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Histological Observations of Thyroid Glands at Prepubertal, Pubertal and Castrated Adult Indigenous Bulls (bosindicus)

GN Adhikary*
Departmentof Anatomy and Histology, Sylhet Agricultural University, Sylhet-3100, Bangladesh

SK Chowdhury
Departmentof Pathology, Sylhet Agricultural University, Sylhet-3100, Bangladesh

S Sarkar
Departmentof Anatomy and Histology, Sylhet Agricultural University, Sylhet-3100, Bangladesh

B Paul
Departmentof Anatomy and Histology, Sylhet Agricultural University, Sylhet-3100, Bangladesh

KM Islam
Departmentof Parasitology, Sylhet Agricultural University, Sylhet-3100, Bangladesh

M N Islam
Departmentof Anatomy and Histology, Sylhet Agricultural University, Sylhet-3100, Bangladesh

Abstract/ Executive Summary:

The experiment was conducted to elucidate the histomorphology of thyroid gland of prepubertal, pubertal and castrated adult indigenous bulls (Bos indicus) using Hematoxyline and Eosin (H&E) during July 2013 to June 2014. Twelve bulls of three age groups namely prepubertal (below 1 year of age, n=4), pubertal (1.5 to 2.5 years, n=4) and castrated adult (above 4 years, n=4) were selected in this study. Thyroid glands of slaughtered bulls were collected for histological studies. The thyroid gland was found to cover by a thick connective tissue capsule consisted of dense collagen fibers having two layers, outer and inner layer. The follicles consisted of follicular epithelium and intra follicular colloid substances. Shapes of the follicles were seen round, oval, pentagonal or hexagonal and irregular in appearance. In prepubertal group, most of the follicles were smaller. In pubertal group, most of the follicles were larger in sizes including somes maller follicles. Significant differences were found in the follicular diameters of the prepubertal from the pubertal bulls. Castrated bulls showed larger inactive follicles with few smaller follicles. Colloid was more homogenous, predominantly eosinophilic by H&E staining in most active follicles. Follicular epithelium become simple squamous to low cuboidal in prepubertal bulls, low cuboidal to columnar in pubertal bulls and squamous epithelium in castrated adult bulls. Para follicular cells were frequently found beneath the basal lamina in prepubertal bulls, but in pubertal and castrated bulls a fewer or no parafollicular cells were found. Finally, thyroid glands were found to undergo age related changes and histological features indicated the functional status of the thyroid gland.

Keywords: Histology, Pubertal stage, Thyroid gland, Indigenous bull

Location: Department of Anatomy and Histology, Sylhet Agricultural University, Bangladesh

Start Date: 00-07-2013

End Date: 00-06-2014

Program Area: Animal Health and Management

Commodity: Bull

Objectives:

The objective of this study was to detect the variation of histoarchitectural features of thyroid gland of indigenous bulls of Bangladesh.

Methodology:

The experiment was conducted in the laboratory of the Department of Anatomy and Histology, Sylhet Agricultural University, Bangladesh from July 2013 to June 2014. Twelve bulls of three age groups were selected from the local market before Muslim sacrifice on year round: pre-pubertal group (below 1 year of age, n=4), pubertal group (1.5 to 2.5 years, n=4) and castrated adult group (above 4 years, n=4) which were castrated earlier in the pubertal stage, respectively. The age of bulls was determined based on tooth eruption patterns (Getty, 1975). The animals were reared by the local farmer neighboring the Sylhet Agricultural University. The bulls were kept individually in the stall and fed with adlibitum balanced ration for 4 weeks. Ante mortem examination of bulls was done before slaughter. The glands were then cut into few pieces and few pieces were collected for microscopic study. A part of each cut tissue samples were fixed in more than 20 times the volume of each in Bouin’s fixatives for 24 hours, dehydrated in series of submerging progressively more concentrated ethyl alcohol (70%, 80%, 90%, 95%, 100%). The tissues were kept for 3 hours in each grade of ethyl alcohol. Tissues were then transferred in a hydrophobic clearing agent, xylene in two changes to remove the ethyl alcohol. In both cases, the tissues were kept for 40 minutes. Infiltrated the tissues through 2 changes of liquid paraffin in the micro oven taking two hours in each step to remove thexylene from tissues. Then they were placed in liquid paraffin for embedding, which was achieved by cooling them in room temperature.The hardened tissue blocks containing the tissue samples were then sectioned at 6μm thickness using microtome (Microm GmbH, type HM 325, Germany) and the sections were floated in a water bath at 45ºC for flattening out on water. Then floated sections were picked up carefully on clean slides, which had been smeared with egg albumin and dried on the slide warmer. The serial sections were chosen position on at every 21 section to ensure the different position of tissue.The sectioned tissues were deparaffinized by transferring them through xylene for two changes; 15 minutes in each case. Then they were transferred through descending grades of alcohol (100%, 95%, 90%, 80%, 70%). Afterward, they were passed through the normal water and distilled water. Tissues were stained with Hematoxyline and Eosin (Gridly, 1960). The tissue sections were then dehydrated by transferring and immerging in progressively more concentrated ethyl alcohol (70%, 80%, 90%, 95%, and 100%) and then were passed through xylene. Tissue sections were clean blotted and mounted in Canada balsam with a cover slip. Four slides were prepared for each bull in which each slide contained four tissue sections from each sample. The microscopic evaluation of thyroid glands includes diameters of the follicles and epithelial height of the follicles through oculo-micrometer observation. The data generated from this experiment were processed for further analysis. Mean value, standard error (SE) and correlations were estimated using the software Statistical Analysis System (SAS, 1998).

Source of Information: J. SylhetAgril. Univ. 1(2):147-153,2014 ISSN: 2308-1597

Article Link (Online Journal):

Funding Source:

Budget:

Total Budget (Tk.) :

Achievement/Findings:

Histological features of the thyroid gland of prepubertal, pubertal and castrated adult bulls showed that prepubertal bulls showed lower histometric parameters of the thyroid follicles than the pubertal and castrated adult stage. Follicular epithelium become simple squamous to low cuboidal in prepubertal bulls, simple low cuboidal to columnar in pubertal bulls and simple squamous epithelium in the castrated bulls. So, the study may conclude that the activity of the thyroid gland increases from prepubertal to pubertal stage and decrease at castrated adult bulls. Finally, thyroid gland undergoes changes with age; in course of aging and physiological status, histological features and function also changes.

Knowledge Management: Journal