Lecture 02. The Anomalies of Thyroid Gland & Gross Features of Suprarenal Gland. By:

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1 Lecture 02 The Anomalies of Thyroid Gland & Gross Features of Suprarenal Gland By: A. Prof. Dr Farooq A. Khan PMC Date: 16 th March. 2018

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3 Thyroid Gland Enlargement Conditions which is characterized by an enlargement of the thyroid. Physiological Enlargement: It could be caused by normal changes in the body like Pregnancy. Menstruation and Puberty. Pathological Enlargement: By diseases like Thyroiditis, Tuberculosis, Hashimoto`s disease, and Iodine deficiency or Cancer. With thyroid enlargement thyroid hormone could be: Normally produced (euthyroid), or Increased (hyperthyroidism), or Decreased (hypothyroidism). Left thyroid lobe enlargement due to hyperthyroidism shown in blue color, normal thyroid tissue shown in pink color.

4 Thyroid Goiter The generalized enlargement of the thyroid gland is called goiter. With most large thyroid enlargements seen in developing countries due to iodine deficiency. These goiters are asymmetrical, soft, and can reach enormous sizes. Anaplastic carcinomas (thyroid cancer) may also cause large thyroid swelling. Bleeding in the thyroid cyst can cause thyroid enlargement as well.

5 Thyroid goiter con t. Thyroid enlargement (goiter) due to iodine deficiency is less common now because iodine is added to the diet. Symptoms usually include compression of the nearby structures, and result in hoarseness of the voice when the recurrent laryngeal nerve is involved. Stridor is an abnormal high-pitched musical breathing sound, and results if the trachea (windpipe) is displaced or compressed.

6 Congenital Hypothyroidism It is due to the derangement in the development of the thyroid. Rather then central cause related to the hypothalamic pituitary axis. AGENESIS of THYROID GLAND: Complete absence or one of its lobes is rare. In unilateral agenesis, the left lobe is more commonly absent.

7 Thyroglossal Duct and sinus: A thyroglossal cyst may lie at any point along the migratory pathway of the thyroid gland but is always near or in the midline of the neck. 50% of these cysts are close to or just inferior to the hyoid bone. May also be found at the base of the tongue or close to the thyroid cartilage. Cyst when infected, may rupture leading to sinus formation.

8 ECTOPIC THYROID GLAND: Rarely, a fragment of thyroid becomes detached, and may be found anywhere along the migratory path of the thyroid gland. May be: LINGUAL: Just behind the foramen caecum. SUBLINGUAL: In the neck. Is subject to the same diseases as the thyroid gland. CLINICAL SIGNIFICANCE: It may be the only thyroid tissue, so important to differentiate it from a cyst.

9 Tc-99m is the most widely used radionuclide.

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11 Thyroidectomy? A thyroidectomy is the removal of all or part of the thyroid gland as: Total thyroidectomy. Subtotal thyroidectomy, Hemi thyroidectomy or lobectomy). The most common indications for removal of the thyroid, or part of it are as follows: Large mass in the thyroid gland, causing difficulties with breathing or swallowing related to a thyroid nodule. Cancer of the thyroid gland. Goiter (swelling of the thyroid gland), and For treatment of an overactive (hyperthyroidism) thyroid refractory to drugs.

12 Suprarenal Gland

13 Development of suprarenal Gland The cortex and medulla of suprarenal glands are derived from different sources. The cortex is mesodermal in origin, Whereas medulla is ectodermal and is derived from the neural crest cells. The cortex begins to develop during the 5th week from the coelomic mesothelium covering the posterior abdominal wall between the root of the mesentery and developing gonad.

14 Development of suprarenal gland..con t The mesothelial cells proliferate and differentiate into large acidophilic cells that constitute the fetal cortex. Later a second wave of mesothelial proliferation occurs and smaller cells are formed that surround the fetal cortex. These cells give rise to the definitive cortex. The cells of the definitive cortex begin to differentiate into characteristic cortical zones during the late fetal period and zona glomerulosa and zona fasciculata are present at birth.

15 development of suprarenal gland..con t After birth the fetal cortex regresses quickly resuiting in rapid decrease in the size of the suprarenal gland. The fetal cortex disappears during the first postnatal year expect for its outermost part that differentiates into the zona reticularis. The function of Foetal cortex is not clearly known,. But it has been revealed that Foetal cortex produce large amount of estrogen and thus helps the placenta to maintain high levels of this hormone during gestational period. Note: Late Fetal Period - differentiates to form cortical zones Birth - zona glomerulosa, zona fasiculata present Year 3 - zona reticularis present

16 development of suprarenal gland..con t The medulla of the suprarenal gland is derived from the neural crest cells. Some of the neural crest cells that form the celiac ganglion migrate from this sympathetic ganglion and form a mass on the medial aspect of the fetal cortex. In the 7th week these cells begin to invade the cortical primordium to form the primitive medulla.

17 development of suprarenal gland..con t 2 cell types - secrete epinepherine (adrenaline). secrete norepinepherine (noradrenaline

18 Pneumonic for the Gland. Go For Rest and Make Good Sweets. G= Glumerulosa Mineralocorticoides. F= Fasciculate Glucocorticoides. R= Reticularis. Steroids (Androgens)

19 Anatomy of Suprarenal Gland The suprarenal gland or adrenal glands are endocrine glands. They are pair glands. Situated in the posterior abdominal wall over the upper pole of the kidneys. It is retroperitoneal. Has two parts: Cortex: Outer mesodermal origin, secretes number of hormones. Medulla: Inner neural crest origin, which is made up of Chromaffin cells.

20 Anatomy of Suprarenal Gland Location: Each gland lies in the epigastrium, slightly anterior the upper pole of the kidneys. Golden yellow in color, consists of functionally and structurally distinct cortex and medulla. Lies opposite to the vertebral end of the 11 th intercostal space and the 12 th rib. Right is lower then the left. Retroperitoneal.

21 Anatomy of Suprarenal gland.con t Size, Shape and Weight: Each gland measures 50mm in height (Vertically). 30mm in breadth (transversely), and 10 mm in thickness (anteroposteriorly). It is approximately 1/3 rd of the kidney at birth and gradually reduces to 1/30 th in adult life. Its weighs about 05 g. The medulla forms 1/10 th of the gland. Right suprarenal gland is Pyramidal in shape while left is Semilunar in shape.

22 Right Suprarenal Gland The right suprarenal gland is triangular to pyramidal in shape. It has: An apex. A base Two surfaces.anterior and posterior. Three borders anterior, Medial and lateral. Relations: Anterior: Right lobe of liver. IVC. Posterior: Diaphragm.

23 LEFT Suprarenal Gland The left suprarenal gland is Semilunar. It has: Two ends: Upper end is narrow Lower end is rounded. Two surfaces.anterior and posterior. Two borders: Medial convex and lateral Concave. Relations: Anterior: Pancreas Lesser sac and Stomach. Posterior: Diaphragm.

24 anatomy of suprarenal gland.con t SHEATHS: The gland is surrounded by the areolar tissue containing considerable amount of fat. Outside the fatty sheath, there is a perirenal fascia. Between the two layers lies the suprarenal gland. The gland is seperated from kidney by a septum.

25 Histology of Cortex The adrenal cortex is the outermost layer of the adrenal gland. Within the cortex are three layers, called "zones". When viewed under a microscope each layer has a distinct appearance, and each has a different function. Zona Glomerulosa: The outermost zone of the adrenal cortex is the zona glomerulosa. It lies immediately under the fibrous capsule of the gland. Cells in this layer form oval groups, separated by thin strands of connective tissue from the fibrous capsule of the gland and carry wide capillaries. This layer is the main site for production of aldosterone, a mineralocorticoid.

26 Zona Fasciculata: The zona fasciculata is situated between the zona glomerulosa and zona reticularis. Cells in this layer are responsible for producing glucocorticoids such as cortisol. It is the largest of the three layers, accounting for nearly 80% of the volume of the cortex. In the zona fasciculata, cells are arranged in columns radially oriented towards the medulla. Cells contain numerous lipid droplets, abundant mitochondria and a complex smooth endoplasmic reticulum.

27 Zona Reticularis: The innermost cortical layer, the zona reticularis, lies directly adjacent to the medulla. It produces androgens,. Its small cells form irregular cords and clusters, separated by capillaries and connective tissue. The cells contain relatively small quantities of cytoplasm and lipid droplets, and sometimes display brown lipofuscin pigment.

28 Histology of Medulla The chromaffin cells of the medulla are the body's main source of the catecholamines, i.e: adrenaline and noradrenaline, released by the medulla. Approximately 20% noradrenaline (norepinephrine) and 80% adrenaline (epinephrine) are secreted here. The most abundant cell in the adrenal medulla is the chromaffin cell. Chomaffin cells are also referred to by some as pheochromocytes. Chromaffin cells are columnar in shape and rather basophilic.

29 Blood supply Of Gland The adrenal glands have one of the greatest blood supply rates per gram of tissue of any organ: Up to 60 small arteries may enter each gland. Three arteries usually supply each adrenal gland: The superior suprarenal artery, a branch of the inferior phrenic artery. The middle suprarenal artery, a direct branch of the abdominal aorta. The inferior suprarenal artery, a branch of the renal artery. These blood vessels supply a network of small arteries within the capsule of the adrenal glands.

30 Venous Drainage The left suprarenal vein drains into the left renal vein or the left inferior phrenic vein. The right suprarenal vein drains into the inferior vena cava.

31 Variability The adrenal glands may not develop at all, or may be fused in the midline behind the aorta. These are associated with other congenital abnormalities, such as failure of the kidneys to develop, or fused kidneys. The gland may develop with a partial or complete absence of the cortex, or may develop in an unusual location.

32 Hormones related to the specific Area:

33 Congenital Anomalies. Pheochromocytomas (PCC) Catecholamine-producing (neuro)endocrine tumor located in the adrenal medulla. Similar catecholamine-producing tumors outside the adrenal gland are called paragangliomas (PGL). Cushing's Syndrome Also called as hypercortisolism. A relatively rare metabolic hormonal disorder caused by prolonged exposure of the body s tissues to high levels of the adrenal hormone cortisol. Most commonly affects adults aged between 20 to 50 and also the obese with type 2 diabetes.

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