Histology of Endocrine System

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)

(Neurosecretion)
Synapse

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, 5th ed, 2006, fig 21.4, pg 690

Pituitary nomenclature

Pituitary nomenclature
Please also see Ross and Pawlina. Histology: Text and Atlas, 5th ed, 2006, fig 21.3b, pg 689
Gray’s Anatomy, wikimedia commons

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. Poorly developed and of doubtful function in humans.
Intermedia
Anterior
Posterior
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 intoi. Acidophils (40%)ii. Basophils (10%)

Anterior pituitary, LM, H&E stain

Basophil
Stan Erlandsen Medical Histology slide collection, slide MH-9B3


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-melanocyte-stimulating 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 (human)
Adrenocorticotropin (ACTH) = corticotropin
A.K. Christensen

THANK YOU