1) Ingress 1) Means of entering 
[biology] Ingression is one of the many changes in the location or relative position of cells that takes place during the gastrulation stage of animal development. It produces an animal`s mesenchyme cells at the onset of gastrulation. During the epithelial-mesenchymal transition (EMT), the primary mesenchyme cells (PMCs) detach from the epi...
pronounced with inhalation rather than exhalation
• (n.) Act of entering; entrance.
In·gres'sion noun [ Latin ingressio : confer French ingression .] Act of entering; entrance. Sir K. Digby. 
According to A. N. Whitehead, participation of potentialities in the creation of complex actualities; 'a concretion -- that is, a growing together -- of diverse elements.' -- R.B.W.