The Endocrine System

Dr. Samar AskerDr. Samar AskerAsst.Professor of HistologyAsst.Professor of Histology

Faculty of MedicineFaculty of Medicine

Glands: pituitary, suprarenal, thyroid, parathyroid, pineal body.

Masses of cells: islets of Langerhans, testis ovary, thymus………

Cells scatered all over the body ;APUD cells (Amine Precursor Uptake Decarboxylase)

THE PITUITARY GLAND (HYPOPHYSIS CEREBRI)

Base of the skull in (sella turcica).

Connected to hypothalamus by infundibular stalkFormed of :Adenohypophysis :develops from oral ectoderm as upward growth from the roof of oral cavity forming Rathke's pouch.

Neurohypophysis: develops as neuroectoderm as downward growth from the floor of diencephalon

ADENOHYPOPHYSIS

Pars DistalisCells arranged in groups or branching cords separated by fenestrated capillaries.

They are classified into:

Chromophobes

Chromophils.

Chromophobes(52%):Small with pale cytoplasm & mild affinity to stains

Some are granular & may secrete hormones.

Some are non granular & considered as stem cells or exhausted Chromophils.

Chromophils(48%)

Have affinity to stain.

Classified into:

Acidophils (37%)

Basophils(11%).

Acidophils :

Medium sized cells () Chromophobes & basophils

2 types

Somatotrophs

Mammotrophs

Somatotrophs • secrete the growth H.

• Secretion gigantism

acromegally Secretion dwarfism• Spherical cells with central

rounded nucleus & acidophilic granules

• +ve reaction with

orange G.

Mammotrophs • Secrete prolactin milk sec.

• Oval cells with Oval nucleus & acidophilic granules

• +ve reaction with carmine

http://en.wikipedia.org/wiki/File:Lavinia_Warren_-_Brady-Handy.jpg

Basophils:

Largest cells Basophilic granulesThree types:

ThyrotrophsCorticotrophsGonadotrophs

Cell typeThyrotrophs Corticotrophs

FSHLHHormone & its action

TSHT3 T4

ACTHMSHEndorphinLipotrophic factor

FSHLH

Shape Rounded with central rounded

nucleus

oval with eccentric nucleus

Rounded with rounded nucleus

Gonadotrophs

Pars Nervosa

Secrete no hormones.

Contain :

1‑Pituicytes.

2‑ Nerve fibres no nerve cells.

3‑ Herring bodies

4‑ Fenestrated capillaries.

2 glands, lying over the upper border of the kidney.

THE SUPRARENAL GLANDS

The Stroma:Capsule :

thick dense fibrous CT covered with adipose CT.

Trabeculae: arise from the capsule and extend in the cortex dividing it into compartments

Reticular fibres.

The parenchyma: is divided into cortex and

medulla.

The Cortex:

Zona glomerulosa:Narrow zone under the capsule. The cells are columnar arranged in arched groups surrounded by fenestrated capillaries basal oval nuclei and pale cytoplasm .Function: secretemineralo corticoid (aldosterone) ‑ which

regulate electrolyte & water balance) controlled by angiotensinogen II.

Zona Fasciculata:Widest zone, cells in a radial in directionpolyhedral cells arranged in narrow straight cords one or two cells wide separated by straight fenestrated capillaries.Central rounded pale vesicular nuclei, some cells have 2 nucleiTheir cytoplasm is vacuolated so called spongiocytes.

Function: Secrete gluco corticoids (Cortisol) ‑ which

controles protein & carbohydrate metabolism under control of ACTH

Anti inflammatory & immunosuppressive effects.

Zona reticularis:Deepest zone.polyhedral cells arranged

in branching and anastomosing cords

separated by fenestrated blood sinusoids.

Central rounded nuclei acidophilic cytoplasm

Function: secrete androgen and small amounts of gluco corticoids‑ under control of ACTH.