Zona Reticularis Flashcards

Examine the zona reticularis, its cellular organization, androgen synthesis, hormonal regulation, vascular supply, and clinical relevance.

Card 1 of 26Question

What is the zona reticularis?

The innermost layer of the adrenal cortex, specialized primarily for adrenal androgen production.

In This Section

1. What is the zona reticularis?

The innermost layer of the adrenal cortex, specialized primarily for adrenal androgen production.

2. Where is the zona reticularis located within the adrenal gland?

Between the zona fasciculata and the adrenal medulla.

3. How are endocrine cells arranged in the zona reticularis?

In irregular, branching, interconnected cords forming a network.

4. How do zona reticularis cells typically appear in routine histological sections?

Relatively small cells with compact, often eosinophilic cytoplasm and round nuclei.

5. How does the lipid content of zona reticularis cells compare with that of zona fasciculata cells?

Zona reticularis cells generally contain fewer lipid droplets.

6. Which intracellular pigment commonly accumulates in zona reticularis cells with age?

Lipofuscin, a yellow-brown residual pigment.

7. Which organelles are especially prominent in zona reticularis cells?

Smooth endoplasmic reticulum and mitochondria with tubular cristae.

8. Which class of steroid hormones is primarily produced by the zona reticularis?

Adrenal androgens.

9. What is a principal androgen synthesized by the zona reticularis?

Dehydroepiandrosterone (DHEA).

10. What is the sulfated form of dehydroepiandrosterone called?

Dehydroepiandrosterone sulfate (DHEAS).

11. How does the androgenic potency of DHEA compare with testosterone?

DHEA is a weak androgen that can be converted into more potent androgens in peripheral tissues.

12. Which anterior pituitary hormone primarily regulates zona reticularis steroidogenesis?

Adrenocorticotropic hormone (ACTH).

13. Which intracellular signaling pathway mediates the effects of ACTH on zona reticularis cells?

The cyclic adenosine monophosphate (cAMP) and protein kinase A pathway.

14. What is the initial precursor for adrenal androgen synthesis?

Cholesterol.

15. Which enzyme enables the zona reticularis to produce androgen precursors?

CYP17A1, which has 17-alpha-hydroxylase and 17,20-lyase activities.

16. Which enzyme cofactor enhances the 17,20-lyase activity required for DHEA synthesis?

Cytochrome b5.

17. Which enzyme converts DHEA into DHEAS?

Dehydroepiandrosterone sulfotransferase (SULT2A1).

18. What is adrenarche?

The developmental increase in adrenal androgen secretion associated with maturation of the zona reticularis.

19. At approximately what age does adrenarche typically begin?

Around 6 to 8 years of age, although timing varies.

20. Which secondary sexual characteristics are partly influenced by adrenal androgens during adrenarche?

Pubic and axillary hair development.

21. What is the embryological origin of zona reticularis cells?

Mesoderm-derived adrenal cortical cells originating from the coelomic epithelium.

22. When does the definitive zona reticularis become clearly developed?

During childhood, with progressive maturation before and during adrenarche.

23. What type of blood vessels pass through the zona reticularis?

Fenestrated sinusoidal capillaries that drain toward the adrenal medulla.

24. What happens to zona reticularis activity during prolonged ACTH deficiency?

Adrenal androgen production decreases, and the zone may undergo atrophy.

25. How can congenital adrenal hyperplasia affect androgen production in the zona reticularis?

Certain enzyme deficiencies, especially 21-hydroxylase deficiency, increase ACTH stimulation and adrenal androgen production.

26. What clinical findings may result from excessive adrenal androgen secretion?

Hirsutism, acne, and virilization, depending on androgen levels and patient characteristics.