Resting stage see growth stage

restitution n. [L. re, back; statuare, to put] Rejoining broken chromosomes, thereby restoring prebreakage structure.

restitution nucleus In either meiosis or mitosis, a nucleus with double the normal number of chromosomes due to non-disjunction.

resupinate a. [L. resupinare, to bend back] Having the appearance of being inverted, reversed, or upside down.

rete n. [L. rete, net] 1. A net or network; a plexus. 2. (ACAN-THO) A thin-walled tubular network between the longitudinal and circular muscle layers, or inside the longitudinal muscles. 3. Any structureless membrane or layer.

retecious a. [L. rete, net] In the form of a network.

reticular membrane (PORIF: Hexactinellida) A membrane formed by the fused bases of the choanocytes.

reticulate a. [L. rete, net] Forming a network of obliquely intersecting linear ridges or lines; a network; cancellated. see retiform.

reticulate evolution Evolution dependent on repeated intercrossing between a number of lines.

reticulosome n. [L. dim. rete, net; Gr. soma, body] Cytoplasmic inclusion thought to be involved in membrane formation.

reticulum n.; pl. reticula [L. dim. rete, net] A network of anastomosing fibers or tubules.

retiform a. [L. rete, net; forma, form] Having the form of a network; composed of crossing lines.

retina n. [L. rete, net] The receptive apparatus of an eye. retinal a.

retinaculum n.; pl. -la [L. retinaculum, holdfast] 1. A con necting or retaining band. 2. (ACANTHO) Muscular sheath of a nerve. 3. (ARTHRO: Crustacea) In Malacostraca, small hook at the tip of the appendix interna, interlocking the right and left pleopods; cincinnulus. 4. (ARTHRO: Insecta) a. In Lepidoptera, the frenulum; wing coupling device. b. In Collembola, hamula that holds the furcula in place in springtails. c. In Hymenoptera, the ring that prevents the sting from being darted out too far. d. In Coleoptera larvae, a fixed sclerotized, tooth-like structure on the mandible.

retinal cell The photosensitive neurosensory cells.

retinal pigment cells (ARTHRO: Insecta) Pigment cells in the retinal region of the eye. see accessory pigment cells, corneal pigment cells, retinular pigment cells.

retinula n.; pl. -lae [L. dim. rete, net] 1. Sensory neuron in the eye. 2. (ARTHRO) A group of cells and their associated rhabdoms that are surrounded by a sheath of pigment cells containing dense granules of red, yellow or brown pigments making up each ommatidium of the arthropod compound eye. retinular a.

retinular pigment cell/basal pigment cell (ARTHRO: Insecta) When present, a second sleeve of pigment cells that surrounds the proximal end of the retinulae. see corneal pigment cells, accessory pigment cells.

retort-shaped organs (ARTHRO: Insecta) In Hemiptera, oval areas of glandular tissue at the enlarged proximal ends of both pairs of the mouth stylets, that secrete a new stylet at each nymphal molt.

retractile a. [L. retractus, withdrawn] Capable of being drawn inwards; having the tendency to retract.

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