A light- and electron-microscopic study of primordial germ cells in the early mouse embryo.

摘要: The primordial germ cells (PGC9s) of the early mouse embryo have been identified in semi-thin and ultra-thin plastic sections on combined bases location a distinctive set morphological features. These originate extra-gonadally their path migration during stages investigated agrees with results previous histological experimental studies. At 8–9 days development, PGC9s are observed among endoderm mid- hindgut yolk stalk; at 10–11 days, seen dorsal mesentery, coelomic lining, rudimentary genital ridge; by 13 gonad is abundantly populated cells. During migratory period appear as small (10–12 μm diameter), oval, basophilic which large nucleo-cytoplasmic ratio. possess numerous free ribosomes polysomes, filamentous ground cytoplasm, few profiles endoplasmic reticulum. Mitochondria display oval thread-like profiles. A Golgi complex not prominent PGC9s. densely granular fibrillar nucleus often outline but sometimes shows irregular contours. nucleolus present. Although located groups that exhibit extensive cell junctions, found to share such junctions neighboring Furthermore, cytoplasmic processes contain microfilaments. observations interpreted correlates activity these In gut, regions reticulum where membranes closely apposed, perhaps fused, present appearance annulate cisternae. addition, compact aggregates granulofibrillar material cytoplasm same Neither structures detected mesenteric PGC9s, gonadal cells, or any other studied. It suggested two elements may be related further differentiation developing large, very round contour. Both retain appearance. expanded contains still Free polysomes abundant. gap one another adjacent stromal