# DBT JRF 2020 — Question 139

Exam: DBT JRF 2020 · Section: B · Topic: Cell Biology · Difficulty: Easy

## Question

Embryonic stem cells are

## Options

- **A.** unipotent
- **B.** totipotent
- **C.** pluripotent
- **D.** differentiated

## Answer

Option C

## Explanation

Embryonic Stem Cells (ESCs) are derived from the inner cell mass (ICM) of the blastocyst (embryonic day 5–6 in humans). Potency classification: Totipotent — ability to form ALL cell types including trophectoderm and placenta (only the zygote and cells of the 2–8 cell stage are totipotent). PLURIPOTENT — ESCs can differentiate into all three germ layers (endoderm, mesoderm, ectoderm) and their derivatives — all 200+ somatic cell types — but NOT trophectoderm/placenta. Pluripotency is maintained by OCT4, SOX2, NANOG transcription factor network. iPSCs (induced pluripotent stem cells) are also pluripotent (Yamanaka factors: OCT4, SOX2, KLF4, c-MYC). Multipotent cells (adult stem cells) can form multiple but limited cell types within a lineage. Unipotent cells form only one cell type.

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