280 GLOSSARY OF EMBRYOLOGICAL TERMS 



Germinal Epithelium — peritoneal epithelium out of which reproductive 

 cells of both male and female presumably develop. (Syn., germinal 

 ridges, gonadal ridges.) 



Germinal Localization — every area of blastoderm or of unfertilized egg, 

 corresponds to some future organ. Unequal growth produces differ- 

 entiation of parts (His, 1874). This concept led to Mosaic Theory of 

 Roux (see Fate Map, p. 101). 



Germinal Spot — nucleolus of ovum. 



Germinal Vesicle — pre-maturation nucleus of egg. 



Gestalten — system of configuration consisting of a ladder of levels; elec- 

 trons, atom, molecule, cell tissue, organ, and organism, each one of 

 which exhibits specifically new modes of action that cannot be under- 

 stood as mere additive phenomena of the previous levels. With each 

 higher level new concepts become necessary. The parts of the cell 

 cannot exist independently, hence the cell is more than a mere aggre- 

 gation of its parts — it is a patterned whole. A coherent unit reaching 

 a final configuration in space (W. Kohler). Gestaltung means forma- 

 tion. 



Gill — See Branchial Arch, Branchial Chamber, Branchial Cleft. 



Gill Plate — elevated and thickened areas of ectoderm posterior to sense 

 plate of embryo where visceral grooves will subsequently form. 



Gill Rakers — ectodermal, finger-like obstructions which sift water as it 

 passes from oral cavity to gill chambers of frog tadpole. 



Glia Cells — small rounded supporting cells of spinal cord, derived from 

 germinal cells of neural ectoderm. 



Glomerulus — aggregation of capillaries associated with branches of dorsal 

 aorta but lying within substance of functional kidney; function is 

 excretory. 



Glomus — vascular aggregations within head kidney or pronephros, never 

 to become a glomerulus. 



Glottis — opening between pharynx and larynx. 



Gonad — organ within which germ cells are produced and generally matured 

 (e.g., ovary or testis). (Syn., sex or germ gland.) 



Gonadromorph — condition in which part of an animal may be male and 

 another part female; not to be confused with hermaphroditism. 



Gonium — suffix referring to a stage in maturation of a germ cell prior to 

 any maturation division (e.g., spermatogonium, or oogonium). 



