Asynaptic cleft, and synaptic gap, can be found between a neuron and

answer is: another neuron, a gland cell, a muscle cell.

A synaptic cleft, also called synaptic gap, is a space between the cell membrane of an axon terminal and  the target cell.  That target cell which will receive the chemical messengers (neurotransmitters) can be another neuron, a gland cell or a muscle cell.

The answer is observations and interpreting.