raphe
noun
ra·phe ˈrā-(ˌ)fē 
1
: the seamlike union of the two lateral halves of a part or organ (such as the tongue) having externally a ridge or furrow
2
a
: the part of the stalk of an anatropous ovary that is united in growth to the outside covering and forms a ridge along the body of the ovule
b
: the median line or slit of the valve of certain diatoms
Example Sentences
Recent Examples on the Web To better understand the role the dorsal raphe neurons play in loneliness, the researchers genetically engineered the dopamine cells to respond to certain wavelengths of light, a technique known as optogenetics. 
Quanta Magazine, 10 May 2016 The researchers focused on dopamine neurons in a brain region called the dorsal raphe nucleus, best known for its link to depression. Quanta Magazine, 10 May 2016 The region, known as the dorsal raphe nucleus, or D.R.N., is best known for its link to depression. Katie Hafner, New York Times, 5 Sep. 2016
Quanta Magazine, 10 May 2016 The researchers focused on dopamine neurons in a brain region called the dorsal raphe nucleus, best known for its link to depression. Quanta Magazine, 10 May 2016 The region, known as the dorsal raphe nucleus, or D.R.N., is best known for its link to depression. Katie Hafner, New York Times, 5 Sep. 2016 Word History
Etymology
New Latin, from Greek rhaphē seam, from rhaptein to sew
First Known Use
circa 1753, in the meaning defined at sense 1
Medical Definition
raphe
noun
ra·phe
variants also rhaphe
ˈrā-fē
: the seamlike union of the two lateral halves of a part or organ (as of the tongue, perineum, or scrotum) having externally a ridge or furrow and internally usually a fibrous connective tissue septum