Depart. Of Histology & Embryology Endocrine system Depart. Of Histology & Embryology Luo Bin 罗 彬

Why can you grow up?

General description Components Endocrine glands Endocrine tissues （ Pancreas islet ） Endocrine cells Function Endocrine system produce Hormones target organs Act on target cells What is hormone？ Hormones are molecules that function in the body as chemical signals.

Endocrine glands Thyroid gland Adrenal glands Pituitary gland

General description Components Endocrine glands Endocrine tissues （ Pancreas islet ） Endocrine cells Function Endocrine system produce Hormones target organs Act on target cells What is hormone？ Hormones are molecules that function in the body as chemical signals.

Hormones secretion Special secreting forms Autocrine （自分泌） Paracrine （旁分泌）

common features ⑴ Ductless ⑵ Endocrine cells arrange into nests, cords, clusters or follicles ⑶ Rich in capillaries

Two types of endocrine cells Steroid-hormone secreting cell 类固醇激素分泌细胞 Nitrogenous-hormone secreting cell 含氮激素分泌细胞

Thyroid gland General structure --- capsule : L.C.T forming septa --- parenchyma: lobules follicles interstitium: CT

Thyroid gland follicles Constitution: Follicle: Colloid is surrounded by a single layer epithelium. 1. Epithelium: Simple squamous (hypoactive), cuboidal or columnar (hyperactive), depending upon the functional status. 2. Colloid: Homogeneous secretion of epithelium. Acidophilic and PAS (+). Contains iodinated thyroglobulin.

Thyroid gland follicles Follicular epithelial cells EM: microvilli RER, Golgi apparatus secretory granules lysosome, mitochondria endocytotic vesicles Function: synthesize and release thyroid hormones thyroxine (T4) triiodothyronine (T3) According to the structures of follicular epithelial cells, can you illustrate their functions? 四碘甲状腺原氨酸 三碘甲状腺原氨酸

What is the secretory process? i.   Synthesis of thyroglobulin ii.  Iodination of thyroglobulin iii. Release of thyroid hormones

Formation of T3 & T4: a. AA→ RER→ thyroglobulin → (Gogi, glycosylated→ (G, secreting granules) → colloid. b. Iodide → (iodide pump) → iodide oxidation in cytoplasm → colloid → bound to tyrosine residues of thyroglobulin → iodated thyroglobulin.

c. iodated thyroglobulin → (TSH, microvilli) → endocytic vesicles →LYS → T3 & T4. Function of T3, T4: a. elevate the basal metabolic rate. b. influence the body growth and nervous system development during fetal life. Modulation of T3, T4 secretion: hypothalamus-pituitary-thyroid axis

Pathological state hypothyroidism exophthalmic goiter myxoedema In adults, thyroid hormone overproduction underproduction myxoedema hyperthyroidism Thyroid hormone deficiency slows body processes: Clinical features: ★ dry, puffy skin ★ inability to keep warm ★ weight gain ★ a slow heart rate ★ loss of energy and appetite ★ constipation A consequence of an increase in body’s metabolism: Clinical features: ★ feeling hot ★ increased sweating ★ weight loss, with poximal muscle weakness ★ rapaid heart rate ★ anxiety and restless hyperactivity ★ diarrhoea

Pathological state Hypothyroidism present at birth: Mental retardation Short stature Coarse facial features Protruding tongue Umbilical hernia

Parafollicular cell ---single between follicular cells ---in small groups in interstitial tissue Also called calcitonin cell / C cell LM: ovoid, polygonal larger pale-stained: eosinophilic argyrophilic granules Function: synthesize and release calcitonin, make blood calcium

Parathyroid gland Structure capsule parenchyma chief cells Function synthesize parathyroid hormone (PTH) make blood calcium glandular cells chief cells oxyphil cells stroma

Adrenal gland ---capsule: CT ---cortex: yellow, derived from mesoderm ---medulla: reddish-brown, derived from neural ectoderm 内胚层 神经外胚层

Adrenal gland cortex 球状带 束状带 网状带 Zona glomerulosa Zona fasciculata Zona reticularis 网状带 Zona reticularis

Zona glomerulosa 15% of cortex volume ---Structure: LM cells: small, low columnar or polygonal be arranged into nests or clusters nuclei: deep stained, round cytoplasm: light basophilic ---Function: secrete mineralocorticoid ( eg. aldosterone) 盐皮质激素 醛固酮 regulate electrolyte and water balance

appear vacuolated(formy)-empty Zona fasciculata About 78% of cortex volume ---Structure: LM cells : large，clear margin be arranged in straight cords cytoplasm: light staining appear vacuolated(formy)-empty ---Function: secrete glucocorticosteroid 盐皮质激素 (e.g cortisol、corticosterone) and androgen 雄激素(less) regulate carbohydrate, protein and lipid metabolism influence immune response

Zona reticularis 7% of cortex volume ---Structure: LM cells: polyhedral and small; be arranged in irregular anastomosing cords cytoplasm: acidophilic ---Function: secret androgen(testosterone) and small amount of oestrogen 雌激素

Adrenal medulla ---Structure: medullary cell ( chromaffin cell ) : LM: cells: polyhedral, be arranged in nests or short cords cytoplasm: weakly basophilic, brownish granules- when fixed by bichromate-containing fixative. central vein ganglial cells: multipolar neurons large, 2~3 in groups

Adrenal medulla ---Function: secrete adrenaline and noradrenaline EM electron-dense granules adrenaline cell: 80% 肾上腺素细胞 noradrenaline cell: 20% 去甲肾上腺细胞 Adr. cell Noradr. cell i.  heart rate ii. dilate blood vessel i.  blood pressure ii. the flow speed of blood ---Function: secrete adrenaline and noradrenaline secrete some polypeptides(galanin, neuropeptide Y, enkephalin)

Excessive adrenal secretion of glucocorticoid hormones Pathological state Excessive adrenal secretion of glucocorticoid hormones Cushing’s syndrome

Pituitary gland capsule: CT adenohypophysis pars intermedia pars distalis pars tuberalis pars intermedia anterior lobe adenohypophysis neurohypophysis 远侧部 前叶 结节部 腺垂体 posterior lobe 中间部 后叶 pars nervosa infundibular stalk median eminence 神经部 神经垂体 漏斗柄 正中隆起

Pituitary gland

Pituitary gland Infundibular Pars intermedia Pars distalis Pars nervosa

Pas distalis Classification: Chromophobes Chromophils Acidophils Glandular cells are arranged in nests Rich in capillaries around the cells Classification: Chromophobes Chromophils Acidophils Basophils A --- Acidophil round or oval , eosinophilic stainning B --- Basophil less, large cell, ovoid or polygonal basophilic granules C --- Chromophobe more, small, pale, no clear boundary

thyroid stimulating hormone(TSH) follicle stimulating hormone(FSH) Tropic hormones of pas distalis cell type secreting hormone acidophil somatotropic hormone(STH) or growth hormone(GH) somatotrope 生长激素细胞 mammotrope lactogenic hormone(LTH) or prolactin(PRL) 催乳激素细胞 basophil thyrotrope thyroid stimulating hormone(TSH) 促甲状腺激素细胞 corticotrope adrenocorticotropic hormone(ACTH) 促肾上腺皮质激素细胞 follicle stimulating hormone(FSH) luteinizing hormone(LH) interstitial cell-stimulating hormone(ICSH)---male gonadotrope 促性腺激素细胞

Pathological state Titan Jack Sprat

Pathological state growth hormone in kids Dwarfism Gigantism deficient too much Dwarfism Gigantism

Too much growth hormone occurs in adults Pathological state Too much growth hormone occurs in adults Acromegaly 肢端肥大症 Protruding jaw Broaden lower face Enlarged hands

Pas intermedia Pas tuberalis Secrete gonadotropin. Structure: chromophobe cells basophils be arranged into cords/follicles. Function: Secrete melanocyte-stimulating hormone (MSH) 黑素细胞刺激素 Pas tuberalis Secrete gonadotropin.

Neurohypophysis Pars nervosa Components Pituicytes ( glial cells) Capillaries (fenestrated) Unmyelinated nerve fibers Function: Store and release oxytocin and antidiuretic hormone (ADH) 催产素 抗利尿激素

Neurohypophysis Herring bodies: Neurosecretory granules accumulate in the dilated portions of the axons near their terminals. LM: acidophilic, irregular structure

Blood supply (Hypophyseal portal system) Superior hypophyseal artery (Primary plexus)capillaries Hypophyseal portal vein （Secondary plexus） capillaries Hypophyseal vein

Relationship between hypothalamus and adenohypophysis Arcuate nucleus of hypothalamus (neuroendocrine cell): secrete releasing hormones (RH) -GRH, PRH, TRH, GnRH, CRH, MSRH secrete release inhibiting hormones (RIH) -SOM, PIH, MSIH their axons end in infundibular stalk and release hormones into primary capillaries network of hypophyseal portal circulation positive and negative feedback

肾上腺皮质三带的比较 球状带 束状带 网状带 位 置 被膜下 中层 深层，近髓质 厚 度 最薄 最厚 较薄 体积比 15％ 78％ 7％ 细胞排列 球状 纵行的单或双行细胞索 细胞短索吻合成网 毛细血管 球间血窦 索间纵行血窦 网间血窦 细胞大小 较小 大 小 形 状 矮柱状或椎形 多边形 多边形 核 核小色深 核大圆色浅 核小色较深 胞 质 少量脂滴 大量脂滴 少量脂滴，脂褐素 分泌激素 盐皮质激素 糖皮质激素 雄激素及少量糖皮质激素 作用 调节水盐代谢（排钾保钠） 糖异生、应激、抗炎、抑制免疫等 蛋白质代谢 ACTH 受调节 肾素－血管紧张素系统 ACTH 较典型 电镜结构 较典型 典型的类固醇激素细胞的超微结构

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