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Endocrine Glands pineal pituitary release product into blood stream thyroid major organs thymus small groups of cells in GIT & kidney adrenal hormones pancreas gonad gonad Hormones Chemical messengers = circulate = receptors Cell surface = protein & peptide Intracellular = steroid & thyroid Hormone actions: Endocrine Paracrine Autocrine 4 structural groups: Protein/peptide = size variation secretion Steroids = cholesterol AA derivatives = tyr, tryp, glut FA derivatives = polyunsaturated The Pituitary: Development = master gland Amalgamation of 2 tissue developments Ectodermal finger grown upwards = Rathke’s pouch = anterior pituitary/ adenihypophysis Ectodermal finger evaginates from diencephalon = posterior pituitary or neurohypophysis 1 The Pituitary: Gross Anatomy and Histology Adenohypophysis: Pars distalis - largest Pars tuberalis - collar Pars intermedia - narrow band cleft Neurohypophysis: Pars nervosa - largest infundibulum - stalk Median emminence Cells of the Adenohypophysis Pars distalis = 75% Irregular cell clumps and lamina, hardly any CT Proteins & glycoproteins Acidophil round, small, about 65%= polypeptides Somatotrophs = growth hormone Lactotrophs = prolactin Basophil Glycoproteins = PAS = carbohydrates Thyrotrophs = TSH Gonadotrophs = FSH & LH Corticotrophs = adrenocorticotrophic lipotropin Chromophobes = depleted or stem cells Cells of the Neurohypophysis Unmyelinated axons Nerves terminate close to capillaries Herring bodies = oxytocin, ADH/vasopressin Pituicytes = rounded nuclei 2 The Pineal Gland 7 mm long, 0.2 g poorly defined lobes pinealocytes: forming clusters pleomorphic nucleus/ nuclei melatonin Corpora aranacea = brain sand mineralized concretions puberty Thyroid and Parathyroid Frontal neck, 2 lobes, capsule Follicles = simple cuboidal colloid 50-500 µm C cells = single or groups interfollicular Thyroxine & triiodothyronine 4 bodies, posterior surface of thyroid, 130 mgs each, capsule Abundant capillaries Fat cells Chief cells = round, light nucleus PTH Oxyphil = lacking in children eosionphilic single/ clumps Adrenal Glands Roughly triangular, flattened Cortex = needed to live 1. Zona glomerulosa (15%) = mineralocorticoids Rounded groups/ curved columns Dark nuclei, basophilic cytoplasm 2. Zona fasciculata (75%) = cortisol Radially arranged cells cords Spongiocytes 3. Zona reticularis (10%) = androgens Anastomosing cell cords, sinusoids Small cells, eosinophilic cytoplasm Medulla Not delineated Cell strands, capillaries, basophilic cytoplasm Chromaffin cells = adrenalin/ noradrenalin 3
