Sociedade Brasileira de Dermatolodia Surgical & Cosmetic Dermatology


ISSN-e 1984-8773

Questoes e Gabaritos

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Stem cells in the skin


1. It is correct to state that
a. somatic stem cells are found exclusively in the skin, bone marrow, and adipose tissue
b. the renewal capacity of stem cells is linked to the process of differentiation into other types of cells
c. the interaction between different types of cells that are present in the niches is responsible for the differentiation of stem cells
d. iPSCs are obtained from embryonic stem cells
e. the epidermis is renovated with cells originally from the sweat glands
2. Which of the following is false?
a. Transcription factors (TF) are proteins involved in gene transcription
b. The binding of transcription factors to DNA sequences may block the activation of genes
c. Genes that are transcribed based on the interaction of TFs may regulate cell division
d. TFs have been introduced into adult cells, transforming them into embryonic cells
e. The use of iPSCs allows the in vitro study of drugs and diseases
3. About stem cells derived from adipose tissue, it is
false to state that
a. they are similar to bone marrow mesenchymal cells
b. they can generate osseous and cartilage tissues
c. they increase the recurrence of breast cancers due to the effect of cytokines
d. they are used to enrich fat grafts
e. enriched fat grafts can be used in reconstructions after radiation therapy
4. The bulge region has stem cells
a. that are responsible for reconstructing the lower portion of the hair follicle in the anagen phase
b. that are precursors of melanocytes
c. that are responsible for regenerating the sebaceous gland
d. none of the above
e. a, b, and c
5. In the epidermis, there are stem cells in the basal layer
a. migrate to the more superficial layers of the skin without differentiating
b. form units of epidermal proliferation
c. divide into identical daughter cells, which repopulate the affected epidermis
d. exclusively repopulate the epidermis
e. divide asymmetrically in the hair follicle bulge
6. The onset of the anagen phase is characterized by
a. the bulge region’s cells signalling for that phase’s characteristic migration and differentiation
b. the asymmetric division of basal layer cells
c. the migration of the bulge’s melanocytes to the basal layer of the epidermis
d. the differentiation of melanocyte precursors in the base of hair follicles due to the stimulation of adipocytes
e. the regeneration of sebaceous and sweat glands
7. Regarding alopecia,
a. the androgenic action is responsible for inhibiting the signalling that leads to differentiation in the bulge cells
b. factors that stimulate the differentiation of bulge cells can be used to treat lichen planopilaris alopecia, given its pathogenesis
c. inflammatory infiltrate in the bulge explains the regrowth in alopecia areata
d. CD8 lymphocytes must be targeted in the treatment of non-cicatricial alopecia
e. the niche cells in the bulge area are not affected
8. Reprogramming somatic cells can be useful, except for
a. obtaining cell types for studying drugs
b. treating spinal cord lesions with embryonic cells
c. in areas of medicine in which it is difficult to obtain biopsies, as in psychiatry
d. in understanding the pathogenesis of various diseases
e. in regenerating injured tissues due to various pathological processes
9. In the anagen phase,
a. there is apoptosis in the lower portion of the follicle
b. there is a migration of melanocytes from the basal layer to the hair pigmentation
c. the bulge mesenchymal cells release cytokines that act on the precursors of keratinocytes in this region
d. the keratinocytes receive signals from mesenchymal cells and enter into a resting state until the next anagen phase
e. the hair pigmentation precedes the bulge keratinocytes’ signalling about the precursors of melanocytes
10. Skin stem cells are
a. embryonic
b. responsible for differentiating into various tissues
c. reprogrammed by transcription factors
d. easily characterized
e. arranged in niches

Gabarito do número anterior

1. D 2. A 3. A 4. B 5. E 6. A 7. C 8. B 9. E 10. B

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