# Migration as a Selection Paradigm for Primordial Germ Cells

> **NIH NIH F31** · UNIVERSITY OF CALIFORNIA, SAN FRANCISCO · 2020 · $41,239

## Abstract

PROJECT SUMMARY
 Cellular heterogeneity, the discrete differences between cells within the same population, is recognized
as a contributor to malignant conditions. However, the contribution of cellular heterogeneity to normal
development is only beginning to be appreciated. The idea that minute differences among cells of the same
type are capable of determining cell state is especially pertinent when considering the development of the
germline. Functional heterogeneity among primordial germ cells (PGCs, the embryonic precursors to sperm
and egg cells) is evident from their inception; as PGCs migrate individually from their site of specification to the
gonadal ridges (Ginsburg et al., 1990; Kunwar et al., 2006), they spread into early migratory "Leaders" and
later migratory "Laggards" (Gomperts et al., 1994). Additionally, not every PGC will make it to the gonadal
ridge; many PGCs die along the migratory route. Successful colonizers of the gonadal ridge maintain the
potential to contribute gametes to the next generation. Ex vivo cell culture experiments suggest that
independent of tissue niche, PGCs exhibit signaling responses to migratory cues that vary at the single cell
level (Cantú et al., 2016). These differences in migratory potential suggest that there may be subtypes within
the population of PGCs that are intrinsically determined, but how these discrete cell-to-cell differences impact
development is unknown. Distinctions between Leaders and Laggards may be heritable through mitosis,
transcriptionally distinct, and reflect differences in metabolic function. These preliminary data fuel my overall
hypothesis that PGC migration acts selectively to favor more fit PGCs while excluding those that are less fit. I
expect that loss of stable, heritable epigenetic states, inability undergo metabolic processes, or cell damage
may render PGCs less fit, manifesting in altered RNA expression at the transcriptional level. This proposal
aims to characterize how heterogeneities among germline cells impact development and reproductive capacity,
and how migration is a mechanism to ensure only the highest quality cells are present for the next generation.
 How PGCs are selected to generate the next generation is not known. Understanding the basis of PGC
heterogeneity and selection could reveal how development limits the transmission of gametes and shapes
inheritance. Therefore, I suggest that PGCs that successfully colonize the nascent gonad do not do so by
random chance, but rather through a migration-based selection to ensure the most fit cells contribute to future
species lineage.

## Key facts

- **NIH application ID:** 10004141
- **Project number:** 5F31HD096840-03
- **Recipient organization:** UNIVERSITY OF CALIFORNIA, SAN FRANCISCO
- **Principal Investigator:** Rebecca Garrett Jaszczak
- **Activity code:** F31 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2020
- **Award amount:** $41,239
- **Award type:** 5
- **Project period:** 2018-09-01 → 2021-08-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10004141

## Citation

> US National Institutes of Health, RePORTER application 10004141, Migration as a Selection Paradigm for Primordial Germ Cells (5F31HD096840-03). Retrieved via AI Analytics 2026-05-24 from https://api.ai-analytics.org/grant/nih/10004141. Licensed CC0.

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