Histology of the Endocrine System Dr Ahmed Abdulhussein

Histology of the Endocrine System Dr. Ahmed Abdulhussein AL-Huchami

Endocrine system is the system that regulates the tissue activities by a secretory product (hormone) Hormones are chemicals that are released ( from an endocrine cell ) in a small amount , directly to the blood or tissue fluids. They usually act on special cells that are called Target cells.

(receptors) Hormon e delivery Synapse (Neurosecretion )

Endocrine system Pituitary (hypophysis) – Anterior pituitary – Posterior pituitary Adrenal gland (suprarenal) – Adrenal cortex – Adrenal medulla Thyroid gland – Follicles – Parafollicular cells Parathyroid gland

PITUITARY

Regulation of the anterior pituitary Hedges, 1987

Pituitary development Ross and Pawlina. Histology: Text and Atlas, 5 th ed, 2006, fig 21. 4, pg 690

Pituitary nomenclature Gray’s Anatomy, wikimedia commons Please also see Ross and Pawlina. Histology: Text and Atlas, 5 th ed, 2006, fig 21. 3 b, pg 689

Pituitary, low power LM Humio Mizoguti, Kobe Univ Sch Med, slide 515

Posterior pituitary, LM Axon cross sections? A. K. Christensen

Pars intermedia, between anterior and posterior pituitary, human, LM. Anterior Posterior Poorly developed and of doubtful function in humans. Intermedia Humio Mizoguti, Kobe Univ Sch Med, slide 516

A. Adenohypophysis – subdivided into: � Pars distalis (Anterior lobe) � Pars tuberalis ( Cranial part) � Pars intermedia (Intermediate lobe) B. Neurohypophysis – subdivided into: � Pars nervosa (Posterior lobe) � Stalk (Infundibulum) – composed of median eminence and stem.

Pars distalis (Ant. Lobe): composed of two types of cells: a) Chromophobes (50%) Their function is unknown, b) Chromophils – subdivided into i. Acidophils (40%) ii. Basophils (10%)

Anterior pituitary, LM, H&E stain Basophil Stan Erlandsen Medical Histology slide collection, slide MH-9 B 3

Acidophils – 1. Somatotrophs – (hormone (GH) secretion. (childhood and adolescent leads to gigantism, in adults, leads to acromegaly. The reduction in GH in childhood leads to dwarfism. 2. Mammotrophs for prolactin secretion.

Basophils – are subdivided into: 1) Gonadotrophs –� Follicular – stimulating hormone (FSH) –� Leuteinizing hormone (LH) – 2) Thyrotrophs (TSH) 3) Corticotrophs – (ACTH.

Pars Intermedia: In human, it is a rudimentary region secretion of α-melanocytestimulating hormone (α-MSH) Pars Tuberalis: It is a sleeve like that surround the infundibulum. . Most of them secret gonadotropins (FSH & LH).

Pars nervosa (posterior lobe) Oxytocin and vasopressin are believed to be synthesized in the cell bodies and then transported through the axons to the nerve terminals where they are released in response to hypothalamic nerve impulses

Cells and hormones of the anterior pituitary LM staining Cell type Hormone Acidophil Growth hormone (GH) = somatotropin Acidophil Prolactin (PRL) Basophil Thyroid stimulating hormone (TSH) = thyrotropin Basophil Luteinizing hormone (LH), follicle stimulating hormone (FSH); both = gonadotropin Basophil A. K. Christensen (human) Adrenocorticotropin (ACTH) = corticotropin

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