The "dots" circled in pink are likely neuronal varicosities which can be induced by stress (even just plating conditions). The "feathery" portions circled in blue may be a sign poor neuron health, but I wouldn't conclude too much from them without further counterstains on your cultures. DAPI can be used to assess nuclei size and health of particular neurons, though some of these structures appear distal to any somas. Primary cultures aren't perfect and the stress of plating and growing these cells often cause artifacts. Measuring RNA expression of pro- or anti-apoptotic genes or even basic synaptic proteins may give you a good readout of the population health.

From the image you presented, the primary neuron seems to have partial aggregation, indicating some issues happened during primary culture preparation. Like Elliot said, the swelling structures along the dendritic shaft of a neuron are typically referred to as dendritic varicosities or dendritic swellings. These structures can have different functional and pathological implications, depending on the context. Small, bulbous protrusions along the dendrite, involved in synaptic transmission and primary site of excitatory synapses. These enlargements along the dendritic shaft can be transient or stable, sometimes forming en passant synapses (synapses along the shaft rather than at spines) during synaptic remodeling, or in response to activity. Moreover, neurodegenerative conditions (e.g., Alzheimer’s disease, Parkinson’s disease) can lead to dystrophic dendrites, characterized by abnormal swellings. Hypoxic/Ischemic damage can cause dendritic beading, an indicator of neuronal stress. Excitotoxicity due to excessive glutamate can also lead to dendritic swelling. The feather-like structure is difficult to say anything under this staining. At least the MAP2 neural marker and DAPI counter stain should be performed for the further investigation.

Hi Naomi,

• Feather-like projections usually reflect stressed or degenerating neurons rather than healthy processes.
• The small dots along axons are not nodes of Ranvier in culture — more likely varicosities or debris.
• Double-check coating quality and media freshness; stressed cultures exaggerate these features.
• For more stable adhesion and healthier morphology, DendroTEK dPGA | Protease-Resistant Culture Matrix provides a stronger substrate than standard coatings.

Source: I work at DendroTEK Biosciences.

www.dendrotek.ca