Segment: a ring or division bounded by incisions or sutures: a segment of an insect or of any articulate is a transverse portion reaching entirely across the body, originally separated on the exterior by incisions or sutures from the preceding and the succeeding segments, having attached to it not more than one pair of ventral appendages, containing internally not more than one pair of nerve ganglia which supply nerves to the pair of appendages; = somite, arthromere: fusion of segments frequently obscures, as in the head: externally the walls of one segment may be composed of a number of sclerites separated from each other by secondary sutures.
Segmentate: made up of rings or segments.
Segmentation of egg: the division of the originally single celled egg into a number of coherent cells or blastomeres; = cleavage.
Segregated: detached or scattered into groups.
Segregation: a separation or placing apart.
Sejunctus: separated.
Sellate: saddle-shaped.
Sematophore: a seminal packet, composed of the seminal fluid mixed with the excretions of the accessory glands.
Sembling: = assembling; q.v.
Semen: the fluid secreted in the testes, containing the spermatozoa.