HISTOLOGY Endocrine Block – 432 Histology Team Lecture 1:

Done by: Shroog Al-Harbi Reviewed by: Ibrahim Al-Furaih

Color Guide:

 Black: Slides.  Red: Important.  Green: Doctor’s notes (Female).  Blue: Doctor’s notes (Male).  Orange: Explanation.

Objectives

At the end of this lecture, you should describe the microscopic structure and the function of: 1. The microscopic structure of the different parts of the pituitary gland in correlation with their functions. 2. The hypophyseal portal circulation; components and significance.

Mind Map

PITUITARY GLAND (A) ADENOHYPOPHYSIS (B) NEUROHYPOPHYSIS CEREBRI (anterior lobe): CEREBRI (posterior lobe): 1- Pars Distalis 1- . (pars anterior). 2- Infundibulum: Neural 2- . (Infundibular) Stalk. 3- . 3- Pars Nervosa.

Pituitary Gland

PARS DISTALIS Types of parenchymal cells: 1- Chromophils 2- Chromophobes (pale) A-Acidophils (red): B- Basophils(blue): May represent: 1- Somatotrophs (GH secreting 1- Thyrotrophs (TSH secreting 1- Stem cells. cells). cells). 2- Degranulated 2- Mammotrophs (Prolactin 2- Gonadotrophs chromophils. secreting cells); Increase during (Gonadotropic cells) (FSH, LH). 3- Degenerated cells. and late pregnancy. 3- Corticotrophs (ACTH cells).

Blue arrow: Acidophils. Red arrow: Basophils.

Yellow arrow: Chromophobes.

Y PARS NERVOSA e l CONTENTS: l 4- Fenestrated 1- Unmyelinated axons 2- Herring bodies 3- Pitucytes o blood capillaries w  Unmyelinated axons of  Are distensions of the  Are glial-like cells in secretory neurons situated in axons in pars nervosa. pars nervosa. a supraoptic & paraventricular  Structure: r r nuclei (i.e. Axons of  Representing Have numerous o hypothalamo-hypophyseal accumulation of cytoplasmic processes. w tract). neurosecretory  Function: :  Function: granules at axon termini Support the axons of Storage & release of: and along the length of the pars nervosa. c 1) (ADH; the axons in pars h r antidiuretic ) nervosa. N.B. No secretory or o By Supraoptic nuclei. neuronal cells in pars m 2) : By Paraventricular nervosa. o nuclei. p h o b e s

e l l o w

BLOOD SUPPLY 1- Superior Hypophyseal Arteries (Right & Left) 2- Inferior Hypophyseal Arteries (Right & Left)  To median eminence & neural stalk.  Mainly to pars nervosa  Not participating in hypophyseal portal circulation.  [ Hypophyseal Portal System ]:- a) 1ry capillary plexus of fenestrated capillaries.

b) Hypophyseal portal Veins (or venules).

c) 2ry capillary plexus of capillaries in adenohypophysis (mainly in pars distalis).

 It carries neurohormones from median eminence to adenohypophysis.

Summary:

By: Shaimaa Alrefaie PITUITARY GLAND

Components Blood Supply Adenohypophysis Cerebri Neurohypophysis Cerebri

Pars Pars Median Pars distalis Infundibul 1. Superior Hypoph. tuber interme eminen Pars Nervosa Arteries (Rt&Lt): (pars anterior) um alis dia ce To median eminence & Types of parenchymal cells: Neural 1. Unmyelinated axons of neural stalk. 2- stalk. secretory neurons situated in 1- Chromophils Chromophobes supraoptic & paraventricular - 1ry capillary plexus of nuclei fenestrated capillaries. a) Acidophils: 1. Stem cells. - Function: - Hypophyseal portal - Somatotrophs 2. Degranulated storage & release of: veins (venules). (GH). chromophils. * Vasopressin (ADH). - 2ry capillary plexus of - 3. Degenerated * Oxytocin. capillaries in Mammotrophs cells. 2. Fenestrated blood adenohypophysis. (Prolactin) capillaries. Increasing 3. Herring Bodies: { Hypophyseal portal during - Are distensions of the axons system } lactation. in pars nervosa. It carries neurohormones ------Representing accumulation from median eminence to b) Basophilic: of neurosecretory granules at adenohypophysis. - Thyrotrophs axon termini. (TSH). 4. Pitucytes: - Gonadotrophs Are glial like cells in Pars 2. Inferior Hypoph. Nervosa. (FSH, LH) Arteries (Rt & Lt): - Structure: - Corticotrophs Mainly to pars nervosa, Neumerous cytoplasmic (ACTH). they are NOT process. participating in - Functions: hypophyseal portal Support the axons of pars circulation. nervosa.

N.B. NO secretory or neural cells in pars nervosa.

Questions

A Q1: Identify structure A in the pic:

A. Pars Distalis. B. Pars Intermedia.

C. Pars Tuberalis. D. Pars Nervosa.

Q2: Which one of the following increase during lactation: A. Mammotrophs. B. Somatotrophs. C. Thyrotrophs. D. Gonadotrophs.

Q3: Which one of the following supports the axons of the pars nervosa: A. Herring bodies. B. Pitucytes. C. Thyrotrophs. D. Corticotrophs.

Q4: the PARS NERVOSA Store & release: A. GH. B. TSH. C. ADH. D. ACTH.

Q5: the Hypophyseal Portal System is formed by: A. Superior hypophyseal arteries. B. Inferior hypophyseal arteries.

Answers

1 2 3 4 5 D A B C A

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Histology Team Leaders: Nada Alouda Faisal Alshuwair

Best of luck!