RETECIOUS 



1258 



RETINA 



R. mirabile (of Galen) , a network of vessels formed 

 by the intracranial portion of the internal carotid 

 artery in some animals. R. mirabile geminum or 

 conjugatum, a plexus in which arteries and veins 

 are combined. R. mirabile simplex, a network 

 involving only veins or arteries. R. mucosum, the 

 three lower layers of living cells of the epidermis. 

 R. olecrani, the network of vessels around the olec- 

 ranon and at the back of the elbow, formed by the 

 divisions of the profunda and other arteries. R. patel- 

 iare, the plexus of vessels surrounding the patella. 

 R. tarseum dorsale, an arterial network upon the 

 dorsal surface of the tarsus. R. testis, the network 

 of seminal tubules in the corpus highmori of the tes- 

 ticle. R., Unipolar, the capillary divisions of blood- 

 vessels which do not reunite. R., Vascular (of B. 

 Ridge) , a membranous sac, very vascular, which with 

 the meconic membrane forms an envelop for the 

 meconium of the fetus. R. vasculosum, a net- 

 work of blood-vessels. R. vasculosum testis. 

 See R. halleri. R. venosum dorsale manus, a 

 venous network on the back of the hand. R. venos- 

 um dorsale pedis, a venous network on the dorsum 

 of the foot. 



R^tecious (re-te'-se-us). Same as Retiform. 



Retene (re* -ten), C 18 H 18 . A hydrocarbon occurring in 

 the highest fractions of coal-tar and also a derivative of 

 phenanthrene. It occurs in the tar of highly resinous 

 pines and in some mineral resins. It is very soluble 

 in alcohol and benzene, and crystallizes in leaflets 

 with a mother-of-pearl luster; it melts at 98 C, and 

 boils at about 390 C. 



Retention (re-ten' 'shim) [retentio ; re, back; tenere, to 

 hold] . The holding back or stoppage of any of the 

 natural discharges of the body, as the feces, lochia, 

 urine, menstrual flow, etc. R.-cyst, a cyst formed 

 by a secretion, the natural outlet being closed. 

 R., Hystero-cystic, retention of urine caused by 

 pressure from a gravid uterus. R. of Milk. Same 

 as Galactoschesis, q. v. R. of Menses : 1. Reten- 

 tion of menstrual blood due to mechanical interference 

 with its outward flow. 2. Postponement of menstrua 

 tion after the proper age for its establishment. R. of 

 Placenta, failure of expulsion of a placenta as a result 

 of improper or deficient uterine contractions. R. of 

 Urine, inability to empty the bladder voluntarily. 



Retentive (re-ten' '-tiv ) [retinere, to retain]. That 

 which holds anything in place. 



Retia (r-'-te-ah) [L. , plural of Rete~\. See Rett. 



Retial (re'-te-al) [rete, a net]. Relating to, or of the 

 nature of, a rete. 



Retiary (re' -te-a-re) \_rete, a net]. Net-like. 



Reticular (ret-ik'-u-lar) [reticulum, a little net]. 

 Formed by reticulation ; areolar ; abounding in inter- 

 stices. R. Cartilage. Same as yellow elastic car- 

 tilage, q. v. R. Formation, a formation occupying 

 the anterior and lateral area of the oblongata dorsad of 

 the pyramids and lower olives and extending up into 

 the pons. R. Lamina of Kolliker. See Meni/irane, 

 Reticular. R. Layer of the Skin, the deep layer of 

 the derma, consisting of strong interlacing bands of 

 white and yellow fibrous tissue. 



Reticulare (ret-ik-ula'-re) [reticularis, like a net]. The 

 rete mucosum. See Rete. 



Reticulate (re-tik' '-u-lat) {reticulum, a little net]. In 

 biology, in the form of network ; said of the veins of 

 leaves and the surface-markings of different organs. 



Reticulated (ret-ik'-u-la-ted). Having net like meshes. 

 Reticulation (ret -ik -u- la'- shun) [reticul.itiis, like a 



net]. The character of being reticulated 

 Reticulose (ret-ik'-u-loz) [reticulum,* net]. Minutely 

 Ox finely reticulate. 



Reticulum (re-tik' -u-lutn) [reticulum, a little net : p!., 

 Reticula~\. 1. A network. 2. In biology, applied to 

 various reticulated structures, e. g. , (a) the second divi- 

 sion (hood or honey-comb bag) of the complicated 

 stomach of a ruminant ; (/') the intracellular or intra- 

 nuclear network; (c) the neuroglia; (d) the fibrous 

 substance growing at the base of the petioles of certain 

 palms, also called mattulla. R. cutaneum, R. mu- 

 cosum. See Rete mucosum. R.-Germ (of Von 

 Ebner), a network of fibers occasionally seen between 

 layers of seminal cells. 



Retiferous (re-tif -er-us) [rete, a net; ferre, to bear]. 

 That which has a rete. 



Retiform (re' -tif-orm) [retiformis\ Net-shaped ; re- 

 ticulated. R. Tissue. See Animal Tissue. 



Retina (rel'-in-a/i) [rete, a net]. The chief and essen- 

 tial peripheral organ of vision, the third or internal 

 coat or membrane of the eye, made up of the end- 

 organs or expansion of the optic nerve within the 

 globe. It is composed of ten layers from without in- 

 ward, as follows: 1. Pigment-cells. 2. Rods and 



1, 1. Layer of 

 rods and cones. 

 2 Rods. 3. 

 Cones. 4. Upper 

 portion of rods. 

 S. Lower por- 

 tion. 6. Point of 

 union of these 

 two parts. 7, 7. 

 Two cells of the 

 granular layer. 

 S, 8. Two other 

 cells of the same 

 layer. 9, 9. Still 

 two other cells 

 of the same 

 layer. 10. Cell 

 of the la 

 gr iv 'natter with 

 which thesecom* 

 tnnnicate 11. 12. 

 Other cells of the 

 granu'ar layer. 

 13 Tripolar cell 

 with which these 

 are continuous. 

 it A rod contin- 

 uous with the 

 elements of the 

 other lay 

 Process 1' v 

 which it cotnnui- 

 tiicatesw 

 of t h e external 

 graintlai 

 16. Proci 

 which !l 

 co tn m u n icates 

 with a cell of the 

 internal granu- 

 lar layer. 17- 

 1'rni't'ss by 

 which : ! 

 co in in 11 11 icates 

 with the laverot 



Process from the last entering into the fibrous layer. II 

 A radiating fiber of Miiller. 20. Conoid swelling by which 

 this fiber is attached to the internal limiting I 

 cone continuous with the other elements oi the 1 

 Cell of external granular layer. 23 Intermedia! 

 between two cells of the granular layer. 24 Pn 

 meting a cell of the granular layer with a cell ol the la 

 of gray matter. 25. Process of cell of layer of gray m 

 2fi. A radiating fiber. 



cones. 3. External limiting. .'. External granular. 

 5, Outer molecular. 6. Internal granular. 7. Inter- 

 nal molecular. 8. Ganglionic. 9. Nerve-fib 

 Internal limiting. R., Central Artery of, a bi 

 of the ophthalmic artery that pierces the optic 

 in the orbit, branching 'within the globe, and supply- 

 ing the retina. R., Coarctate, a term used to desi 



Elements of thk Retina. 



